Use of active pharmaceutical compounds for the treatment of central nervous system disorders

Abstract

To provide selective GABA Aα5 negative allosteric modulators for the treatment, prevention and / or delay of progression of central nervous system (CNS) diseases related to excessive GABAergic inhibition in the cortex and hippocampus.SOLUTION: The present invention provides a compound represented by formula (II) or a pharmaceutically acceptable salt thereof (R4 is aryl or heteroaryl. R5 is H, alkyl or the like. R6 is CONR7R8. R7 and R8 form heterocycloalkyl or heteroaryl together with the nitrogen to which they bind.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to the pharmaceutical use of selective GABA A α5 negative allosteric modulators for the treatment, prevention and / or delay of progression of central nervous system (CNS) diseases associated with excessive GABAergic inhibition in the cortex and hippocampus. More specifically, the present invention relates to the pharmaceutical use of selective GABA A α5 negative allosteric modulators for the treatment, prevention and / or delay of progression of CNS diseases caused by neurodevelopmental abnormalities resulting in excessive GABAergic inhibition in the cortex and hippocampus, wherein the CNS diseases are selected from cognitive disorders in Down's syndrome, in autism, in neurofibromatosis type I, or during post-stroke recovery.

[0002] In particular, the present invention relates to the use of a selective GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a CNS disease, wherein the selective GABA A α5 negative allosteric modulator is a compound of formula (I) and / or a compound of formula (II): [ka] [In the formula, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 is as defined herein] or a pharma- ceutically acceptable salt thereof.

[0003] Down's syndrome (DS), caused by triploidy of chromosome 21, is the most frequent genetic cause of intellectual disability, with an incidence of approximately 1 in 650-1000 live births worldwide [Bittles AH et al., Eur J Public Health (2007) 17(2):221-225]. Although the etiology of cognitive impairment in DS remains uncertain, cellular and anatomical abnormalities in the forebrain and cerebellum before and at birth suggest that early brain development is altered in individuals with DS. Similar central nervous system (CNS) abnormalities have been described in mouse models of DS. In particular, the Ts65Dn mouse, the most widely used model of DS, has abnormal forebrain and cerebellar development, deficits in synaptogenesis and neurophysiology, and behavioral defects.

[0004] Recent studies suggest that the primary functional defect in the postnatal Ts65Dn brain may be an imbalance between excitation and inhibition, e.g., a reduction in the number of excitatory synapses and a relative increase in inhibitory synaptic markers in the cortex and hippocampus. Further studies suggest that an increase in inhibitory synaptic impulse may be a general physiological phenotype in the Ts65Dn forebrain.

[0005] Currently, there are no therapeutic options available for the treatment of cognitive impairment in people with DS. It has now been discovered that inhibition of GABA A receptor function represents an attractive mechanism for treating cognitive impairment in DS.

[0006] GABA A receptors, which regulate chloride channels, are the main inhibitory neurotransmitter receptors in the mammalian central nervous system and are widely used as targets for neuromodulators. Many compounds in clinical use, e.g., anxiolytics, sedatives, hypnotics, or antiepileptics, increase GABA A receptor activation via the allosteric benzodiazepine (BZD) binding site. Such compounds are called "BZD site receptor agonists." BZD binding site ligands that produce the opposite effect, i.e., reduce receptor activation, are called "BZD site receptor inverse agonists." "BZD site receptor antagonists" are ligands that bind to the receptor without modulating its function, but block the activity of both agonists and inverse agonists [Haefely WE, Eur Arch Psychiatry Neurol Sci (1989) 238:294-301]. BZD receptor inverse agonists have so far only been tested in animal behavioral experiments and a few preliminary human studies. Results have shown beneficial activity, however, further development of compounds into the clinic has been hindered by anxiogenic effects, possibly resulting from the lack of selectivity exhibited by these agents for specific BZD receptor subtypes.

[0007] Non-selective antagonists of GABA A receptors, also called channel blockers (e.g. picrotoxin or PTZ), most likely due to their action on the GABA A α1, α2 and α3 subunit containing receptors, increase the risk of seizures and therefore cannot be used safely in people with DS. It is therefore a prerequisite that suitable GABA A receptor inhibitors are selective for the receptor subtypes primarily involved in memory formation.

[0008] GABA A receptors are usually pentamers consisting of two α, two β and one γ subunit. Several gene products are available for each of the subunits giving rise to many receptor variants. The importance of the different α subunit subtypes has been elucidated by the generation of transgenic mice lacking the normal diazepam sensitivity of α1, α2, α3 or α5 subunits (α4 and α6 are diazepam insensitive). The results suggest that α1 is responsible for the sedative effects and α2 and possibly α3 for the anxiolytic effects of BZD receptor ligand agonists [Low K et al., Science (2000) 290(5489):131-134; Mohler H, Cell Tissue Res (2006) 326(2):505-516]. The consequences of modified pharmacology of the α5 subunit are less clear, but reduced or non-expression of the subunit can be associated with cognitive enhancement in hippocampal-dependent tasks and, importantly, has no effect on anxiety or seizure induction paradigms, consistent with the selective localization of the α5 subunit in the hippocampus.

[0009] It is therefore hypothesized that BZD site ligands with selective inverse agonism for GABA A α5 subunit-containing receptors should enhance cognitive function without anxiogenic and proconvulsant side effects.

[0010] The selectivity of the BZD site ligands can be achieved by different affinities for GABA A receptor subtypes ("binding selectivity"). Alternatively, in the case of similar subtype affinities, different degrees of receptor modulation ("functional selectivity") can be attempted; i.e., inverse agonism at the GABA A α5 receptor subtype and no activity at other subtypes. Compounds can also have a combination of both binding and functional selectivity, but this has been rare so far. Recently, many compounds have been synthesized that are described as active as inverse agonists at GABA A α5 subunit-containing receptors [WO 2006 / 045429, WO 2006 / 045430, WO 2007 / 042421, WO 2009 / 071476]. It has now been found that some of these compounds have beneficial pharmacological profiles, including excellent binding and functional selectivity for GABA A α5 subunit-containing receptors. The results confirm the hypothesis that compounds with such a pharmacological profile can improve cognitive function without CNS-mediated adverse effects, including anxiety and / or convulsions [Ballard TM et al., Psychopharmacology, (2009) 202:207-223].

[0011] The pharma- ceutically active compounds used in the present invention are molecules that combine both binding and functional selectivity at GABA A α5 subunit-containing receptors and improve cognition. Importantly, the pharma- ceutically active compounds used in the present invention lack anxiogenic or proconvulsant effects at the exposures tested in toxicity studies.

[0012] In the present invention, it was found that selective GABA A α5 negative allosteric modulators have cognitive enhancing effects on several animal models, but are not anxiogenic or proconvulsant. The active pharmaceutical compounds used in the present invention were chronically administered to Ts65Dn and control (euploid) mice, and a series of behavioral tests including assessment of sensorimotor ability, anxiety, and cognition were performed. The active pharmaceutical compounds used in the present invention improved the performance of Ts65Dn mice in the Morris water maze, but not that of control mice, and did not affect the sensorimotor ability, general activity, motor coordination, or anxiety of Ts65Dn or control mice. The plasma concentrations of the active pharmaceutical compounds from blood samples taken from treated Ts65Dn and control mice were related to 25-75% GABA A α5 receptor occupancy levels from in vivo binding mimicry studies. Importantly, these experiments confirm selective occupancy of brain GABA A α5 receptors and reinforce the idea that dual binding and functional selectivity provides an ideal profile for cognitive enhancing effects without the unwanted side effects associated with activity at other GABA A receptor subtypes.

[0013] Interestingly, chronic administration of the active pharmaceutical compounds used in the present invention: 1. Did not modify any of the sensorimotor abilities tested in Ts65Dn or control mice; 2. It did not affect motor coordination in the rotarod test; 3. Did not modify locomotor activity in the home cage during the light or dark phase of the cycle; 4. Did not modify anxiety or locomotor activity of Ts65Dn and control mice in the open field test; 5. Reduced the hyperactivity seen in vehicle-treated Ts65Dn mice in the Hole Board test; 6. Improved Ts65Dn mouse performance during acquisition and cued sessions in the Morris water maze. It became clear that...

[0014] Additionally, the active pharmaceutical compound used in the present invention is: a) reverse spatial learning deficits in Nf1+ / - mutant mice under conditions in which such compounds do not enhance learning in control mice; b) under conditions that prevent the behavioral deficits of Nf1+ / − mice, their behavior is not affected; c) no effect on motor learning in the rotarod test in Nf1+ / - and control mice; d) useful as a potential treatment for NF1-associated cognitive impairment; It was found that:

[0015] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below.

[0016] The nomenclature used in this application is based on IUPAC systematic nomenclature unless otherwise specified.

[0017] Any open valency appearing on a carbon, oxygen, sulfur or nitrogen atom in the structures herein indicates the presence of a hydrogen, unless otherwise stated.

[0018] The definitions set forth herein apply regardless of whether the terms in question appear alone or in combination. It is contemplated that the definitions set forth herein may be added to form chemically relevant combinations, such as "heterocycloalkyl-aryl", "haloalkyl-heteroaryl", "aryl-alkyl-heterocycloalkyl" or "alkoxy-alkyl". The last member of the combination is the group that is substituted in reverse order with the other members of the combination.

[0019] When indicating the number of substituents, the term "one or more" refers to a range from one substituent to the maximum possible number of substitutions, i.e., replacement of one hydrogen to replacement of all hydrogens with a substituent.

[0020] The terms "optionally" or "optionally" indicate that the subsequently described event or circumstance may occur, but need not occur, and that the description encompasses both instances when the event or circumstance occurs and instances when it does not occur.

[0021] The term "substituent" refers to an atom or group of atoms that replaces a hydrogen atom on a parent molecule.

[0022] The term "substituted" indicates that the specified group has one or more substituents. Any group may bear multiple substituents, and when various possible substituents are provided, the substituents are independently selected and need not be the same. The term "unsubstituted" means that the specified group has no substituents. The term "optionally substituted" means that the specified group is unsubstituted or substituted with one or more substituents independently selected from a group of possible substituents. When indicating the number of substituents, the term "one or more" means from one substituent to the maximum possible number of substitutions, i.e., from replacement of one hydrogen to replacement of all hydrogens with a substituent.

[0023] The terms "compounds for use in the present invention" and "compounds for use in the present invention" refer to compounds of Formula (I) or (II), as well as stereoisomers, tautomers, solvates and salts (e.g., pharma-ceutically acceptable salts) thereof.

[0024] The term "pharmaceutically acceptable salt" refers to salts that are not biologically or otherwise undesirable. Pharmaceutically acceptable salts include both acid and base addition salts.

[0025] The term "pharmaceutically acceptable acid addition salts" refers to pharmaceutically acceptable salts formed with inorganic acids (e.g., hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, carbonic acid, phosphoric acid) and organic acids selected from the aliphatic, alicyclic, aromatic, araliphatic, heterocyclic, carboxyl and sulfonic classes of organic acids (e.g., formic acid, acetic acid, propionic acid, glycolic acid, gluconic acid, lactic acid, pyruvic acid, oxalic acid, malic acid, maleic acid, maloneic acid, succinic acid, fumaric acid, tartaric acid, citric acid, aspartic acid, ascorbic acid, glutamic acid, anthranilic acid, benzoic acid, cinnamic acid, mandelic acid, embonic acid, phenylacetic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid and salicylic acid).

[0026] The term "pharmacologically acceptable base addition salts" refers to pharma-ceutically acceptable salts formed with organic or inorganic bases. Examples of acceptable inorganic bases include sodium, potassium, ammonium, calcium, magnesium, iron, zinc, copper, manganese, and aluminum salts. Salts derived from pharma-ceutically acceptable organic non-toxic bases include salts of primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines, and basic ion exchange resins, such as isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, ethanolamine, 2-diethylaminoethanol, trimethamine, dicyclohexylamine, lysine, arginine, histidine, caffeine, procaine, hydrabamine, choline, betaine, ethylenediamine, glucosamine, methylglucamine, theobromine, purines, piperidine, piperidine, N-ethylpiperidine, and polyamine resins.

[0027] The terms "halo", "halogen" and "halide" are used interchangeably herein and refer to fluoro, chloro, bromo or iodo. In particular, halo refers to F, Cl or Br, most particularly F.

[0028] The term "alkyl" refers to a monovalent straight or branched chain saturated hydrocarbon radical of 1 to 12 carbon atoms, particularly 1 to 7 carbon atoms, more particularly 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, iso-butyl, sec-butyl or tert-butyl. In particular, alkyl refers to methyl or isopropyl, most particularly methyl.

[0029] The term "alkoxy" refers to a radical of the formula -O-R', where R' is an alkyl radical. Examples of alkoxy moieties include methoxy, ethoxy, isopropoxy, and tert-butoxy.

[0030] The term "haloalkyl" refers to an alkyl group in which at least one of the hydrogen atoms of the alkyl group is replaced with the same or different halogen atom, in particular with a fluoro atom. Examples of haloalkyl include monofluoro-, difluoro- or trifluoro-methyl, -ethyl or -propyl, such as 3,3,3-trifluoropropyl, 2-fluoroethyl, 2,2,2-trifluoroethyl, fluoromethyl or trifluoromethyl. The term "perhaloalkyl" refers to an alkyl group in which all of the hydrogen atoms of the alkyl group are replaced with the same or different halogen atom. In particular, haloalkyl refers to monofluoromethyl and difluoromethyl.

[0031] The term "hydroxyalkyl" refers to an alkyl group in which at least one of the hydrogen atoms of the alkyl group has been replaced with a hydroxy group. Examples of hydroxyalkyl include hydroxymethyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 1-(hydroxymethyl)-2-methylpropyl, 2-hydroxybutyl, 3-hydroxybutyl, 4-hydroxybutyl, 2,3-dihydroxypropyl, 2-hydroxy-1-hydroxymethylethyl, 2,3-dihydroxybutyl, 3,4-dihydroxybutyl, or 2-(hydroxymethyl)-3-hydroxypropyl.

[0032] The term "heterocycloalkyl" refers to a monovalent, saturated or partially unsaturated, mono- or bicyclic ring system of 4 to 9 ring atoms containing 1, 2 or 3 ring heteroatoms selected from N, O and S, the remaining ring atoms being carbon. Bicyclic means consisting of two rings sharing two ring atoms, i.e. the bridge separating the two rings is either a single bond or a chain of 1 or 2 ring atoms. Examples of monocyclic saturated heterocycloalkyl are azetidinyl, pyrrolidinyl, tetrahydrofuranyl, tetrahydro-thienyl, pyrazolidinyl, imidazolidinyl, oxazolidinyl, isoxazolidinyl, thiazolidinyl, piperidinyl, tetrahydropyranyl, tetrahydrothiopyranyl, piperazinyl, morpholinyl, thiomorpholinyl, 1,1-dioxo-thiomorpholin-4-yl, azepanyl, diazepanyl, homopiperazinyl or oxazepanyl. Examples of bicyclic saturated heterocycloalkyl are 8-aza-bicyclo[3.2.1]octyl, quinuclidinyl, 8-oxa-3-aza-bicyclo[3.2.1]octyl, 9-aza-bicyclo[3.3.1]nonyl, 3-oxa-9-aza-bicyclo[3.3.1]nonyl or 3-thia-9-aza-bicyclo[3.3.1]nonyl. Examples of partially unsaturated heterocycloalkyl are dihydrofuryl, imidazolinyl, dihydro-oxazolyl, tetrahydro-pyridinyl or dihydropyranyl. Heterocycloalkyl can be optionally substituted as described herein. In particular, heterocycloalkyl refers to morpholinyl, thiomorpholinyl, dioxothiomorpholinyl, 2-oxa-6-aza-spiro[3.3]hept-6-yl, pyrrolidinyl and oxopyrrolidinyl. Most particularly heterocycloalkyl refers to morpholinyl, thiomorpholinyl or dioxothiomorpholinyl.

[0033] The term "heterocycloalkylalkyl" refers to an alkyl group in which at least one of the alkyl group's hydrogen atoms has been replaced with a heterocycloalkyl group. Examples of heterocycloalkylalkyl include pyrrolidinyl-methyl and pyrrolidinyl-methyl.

[0034] The term "aryl" denotes a monovalent aromatic carbocyclic mono- or bicyclic ring system containing 6 to 10 carbon ring atoms. Examples of aryl moieties include phenyl and naphthyl. Aryl can be optionally substituted as described herein. Particular aryls are phenyl and monofluoro-phenyl.

[0035] The term "heteroaryl" denotes a monovalent aromatic heterocyclic mono- or bicyclic ring system of 5 to 12 ring atoms containing 1, 2, 3 or 4 heteroatoms selected from N, O and S, and the remaining ring atoms are carbon. Examples of heteroaryl moieties include pyrrolyl, furanyl, thienyl, imidazolyl, oxazolyl, thiazolyl, triazolyl, oxadiazolyl, thiadiazolyl, tetrazolyl, pyridinyl, pyrazinyl, pyrazolyl, pyridazinyl, pyrimidinyl, triazinyl, azepinyl, diazepinyl, isoxazolyl, benzofuranyl, isothiazolyl, benzothienyl, indolyl, isoindolyl, isobenzofuranyl, benzimidazolyl, benzoxazolyl, benzisoxazolyl, benzothiazolyl, benzisothiazolyl, benzoxadiazolyl, benzothiadiazolyl, benzotriazolyl, purinyl, quinolinyl, isoquinolinyl, quinazolinyl, quinoxalinyl, carbazolyl, or acridinyl. Heteroaryl can be optionally substituted as described herein. In particular, heteroaryl refers to pyridinyl, monofluoropyridinyl and 5,6-dihydro-8H-[1,2,4]triazolo[4,3-a]pyrazin-7-yl, most particularly pyridinyl and monofluoropyridinyl.

[0036] The term "oxo" refers to a divalent oxygen atom, ═O.

[0037] The term "active pharmaceutical ingredient" (or "API") refers to a compound in a pharmaceutical composition that has a specific biological activity.

[0038] The term "pharmaceutical acceptable" refers to the characteristics of a material that is generally safe, non-toxic, and not biologically or otherwise undesirable, and that is useful in preparing pharmaceutical compositions that are veterinarily acceptable as well as for human pharmaceutical use.

[0039] The term "pharmaceutically acceptable excipient" refers to any ingredient that has no therapeutic activity and is non-toxic, such as a disintegrant, binder, filler, solvent, buffer, isotonicity agent, stabilizer, antioxidant, surfactant, or lubricant, used in formulating a pharmaceutical product.

[0040] The term "pharmaceutical composition" (or "composition") refers to a mixture or solution containing a therapeutically effective amount of an active pharmaceutical ingredient together with a pharma- ceutically acceptable excipient to be administered to a mammal, such as a human in need thereof.

[0041] The term "modulator" refers to a molecule that interacts with a target receptor. Interactions include, for example, agonist activity, antagonist activity, or inverse agonist activity.

[0042] The term "inhibitor" refers to a compound that competes with, reduces or prevents the binding of a particular ligand to a particular receptor, or reduces or prevents the inhibition of the function of a particular protein.

[0043] The term "agonist" refers to a compound that has affinity for a receptor binding site and enhances the activity of a receptor-mediated response as defined, for example, in Goodman and Gilman's "The Pharmacological Basis of Therapeutics, 7th ed." in page 35, Macmillan Publ. Company, Canada, 1985. A "full agonist" produces a full response, whereas a "partial agonist" does not produce full activation even when it occupies the entire receptor population. An "inverse agonist" produces an effect opposite to that of an agonist by binding to the same agonist binding site, or reduces the effect of an agonist by binding at a different allosteric binding site.

[0044] The term "antagonist" refers to a compound that reduces or prevents the action of another compound or receptor site, as defined, for example, in Goodman and Gilman's "The Pharmacological Basis of Therapeutics, 7th ed." in page 35, Macmillan Publ. Company, Canada, 1985. In particular, antagonist refers to a compound that weakens the effect of an agonist. A "competitive antagonist" binds to the same site as an agonist but does not activate it, thus blocking the action of the agonist. A "non-competitive antagonist" binds to an allosteric (non-agonist) site on the receptor and prevents activation of the receptor. A "reversible antagonist" binds non-covalently to the receptor and can therefore be "washed out". An "irreversible antagonist" binds covalently to the receptor and cannot be displaced by either a competing ligand or by washing out.

[0045] The term "allosteric modulator" refers to a compound that binds to a receptor at a site ("allosteric site") that is different from the agonist binding site. It induces a conformational change in the receptor, which changes the affinity of the receptor for endogenous ligands or agonists. "Positive allosteric modulators" increase the affinity, whereas "negative allosteric modulators" (NAMs) decrease the affinity and therefore indirectly decrease the activity of the receptor. In the present invention, negative allosteric modulators specifically bind to the benzodiazepine binding site with inverse agonism selective for GABA A α5 subunit-containing receptors.

[0046] The term "inhibitory constant" (Ki) refers to the absolute binding affinity of a particular inhibitor to a receptor. It is measured using a competitive binding assay and is equal to the concentration at which a particular inhibitor occupies 50% of the receptors in the absence of a competing ligand (e.g., a radioligand). Ki values ​​can be logarithmically converted to pKi values ​​(-log Ki), with higher values ​​indicating exponentially higher potency.

[0047] The term "submaximal effective concentration" (EC10) refers to the concentration of a particular compound required to obtain 10% of the maximum specific effect.

[0048] The term "binding selectivity" refers to the ratio between the binding affinities of a particular compound for two or more different receptor subtypes. A particular compound is characterized as "binding selective" if its binding selectivity is 10 or more, more particularly if its binding selectivity is 20 or more, and most particularly if its binding selectivity is 50 or more.

[0049] The term "functional selectivity" refers to the different degree of modulation by a particular compound at different receptor subtypes, for example by acting as an inverse agonist at one particular receptor subtype, while acting as an antagonist at another receptor subtype.In the present invention, a compound is particularly functionally selective when it acts as an inverse agonist at GABA A α5β3γ2 receptor subtype, by reducing the effect of GABA by more than 30%, while affecting other GABA A receptor subtypes by less than 15%, particularly less than 10%.

[0050] The terms "condition," "abnormality," "disability," "disorder," "disease" or "pathology" are used interchangeably to refer to any disease, condition, symptom, disorder or indication.

[0051] The term "neurodevelopmental disorder" refers to a disorder of neurodevelopment in which the growth and development of the brain or central nervous system is impaired (Reynolds CR et al., Handbook of neurodevelopmental and genetic disorders in children (1999) Guilford Press, NY).

[0052] The term "GABAergic inhibition" refers to GABA-mediated neurotransmission that is inhibitory to mature neurons in vertebrates (Bernard C et al., Epilepsia (2000) 41(S6):S90-S95).

[0053] The term "excessive GABAergic inhibition" refers to increased GABA-mediated neurotransmission that leads to a disruption of excitatory / inhibitory (E / I) circuit balance due to inhibition (Kleschevnikov AM et al., J. Neurosci. (2004) 24:8153-8160).

[0054] The term "cognitive disorder" or "cognitive impairment" describes any feature that acts as a barrier to cognitive performance. The term refers to a defect in general intellectual performance, such as mental retardation, or to a specific defect in cognitive ability (learning disability, dyslexia), or to a drug-induced memory disorder. Cognitive impairment may be congenital or caused by environmental factors such as brain damage, neurological disorders, or psychiatric diseases. The term "cognitive impairment in Down's syndrome" or "cognitive impairment in Down's syndrome" refers to cognitive impairment in subjects who show triploidy of chromosome 21, in particular abnormalities in learning, memory, and language that lead to mild to severe impairment of intellectual function in such subjects.

[0055] The term "intellectual disability" (ID) or "mental retardation" refers to an early-onset cognitive impairment beginning before adulthood, with lasting effects on development, manifested by a significantly reduced ability to comprehend new or complex information, to learn new skills, and accompanied by a reduced ability to cope independently.

[0056] The term "procognitive" describes any characteristic that reduces or reverses symptoms such as confusion, disorientation, delirium, or cognitive impairment, or improves cognition.

[0057] The term "neurofibromatosis type 1" (NF1) refers to a disorder caused by mutations in a gene on chromosome 17 that encodes a protein known as neurofibromin, which is involved in intracellular signaling (Cui Y et al., Cell (2008) 135:549-60).

[0058] The term "autism" refers to a neurodevelopmental disorder characterized by impairments in social interaction and communication and by restricted and repetitive behaviors (American Psychiatric Association Inc., Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) (2000) 4th ed.).

[0059] The term "stroke" refers to a rapidly progressive loss of brain function due to a disturbance in the blood supply to the brain. This can result from ischemia (lack of blood flow) caused by an obstruction (thrombosis, arterial embolism) or from hemorrhage (Sims NR et al, Biochimica et Biophysica Acta (2009) 1802(1):80-91).

[0060] The term "post-stroke recovery" refers to the ability to reverse impaired brain function after a stroke (Dimyan MA et al., Nat Rev Neurol. (2011) 7(2):76-85).

[0061] The term "treating" a pathological condition or "treatment" of a pathological condition includes (1) preventing the pathological condition, i.e., preventing the development of clinical symptoms of the pathological condition in a subject who may have been exposed to or is susceptible to the pathological condition, but who has not yet experienced or is not displaying symptoms of the pathological condition; (2) inhibiting the pathological condition, i.e., arresting the development of the pathological condition or its clinical symptoms; or (3) ameliorating the pathological condition, i.e., causing the temporary or permanent regression of the pathological condition or its clinical symptoms.

[0062] The term "therapeutically effective amount" refers to an amount of a compound of the invention that, when administered to a subject, will (i) treat or prevent a particular disease, condition or disorder, (ii) attenuate, ameliorate or eliminate one or more symptoms of a particular disease, condition or disorder, or (iii) prevent or delay the onset of one or more symptoms of a particular disease, condition or disorder described herein. The therapeutically effective amount will vary depending on the compound, the condition being treated, the severity of the disease being treated, the age and relative health of the subject, the route and form of administration, the judgment of the attending physician or veterinarian, as well as other factors.

[0063] The term "subject" or "patient" refers to an animal, more specifically a vertebrate. In certain embodiments, the vertebrate is a mammal. Mammals include humans, non-human primates (e.g., chimpanzees and other ape and monkey species), livestock (e.g., cows, horses, sheep, goats and pigs), domestic animals (e.g., rabbits, dogs and cats), and laboratory animals (including rodents such as rats, mice and guinea pigs). In certain embodiments, the mammal is a human. The term subject does not denote a particular age or sex.

[0064] Detailed Description of the Invention In particular, the present invention relates to the use of GABA A α5 negative allosteric modulators for the treatment, prevention and / or delay of progression of central nervous system (CNS) diseases caused by neurodevelopmental abnormalities resulting in excessive GABAergic inhibition in the cortex and hippocampus.

[0065] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease caused by a neurodevelopmental abnormality resulting in excessive GABAergic inhibition in the cortex and hippocampus, wherein said CNS disease is selected from cognitive impairment in Down's syndrome, in autism, in neurofibromatosis type I or after stroke.

[0066] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease caused by a neurodevelopmental abnormality resulting in excessive GABAergic inhibition in the cortex and hippocampus, wherein said CNS disease is selected from cognitive impairment in Down's syndrome.

[0067] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease caused by a neurodevelopmental abnormality resulting in excessive GABAergic inhibition in the cortex and hippocampus, wherein said CNS disease is selected from cognitive impairment in autism.

[0068] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease caused by a neurodevelopmental abnormality resulting in excessive GABAergic inhibition in the cortex and hippocampus, wherein said CNS disease is selected from cognitive impairment in neurofibromatosis type I.

[0069] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease caused by a neurodevelopmental abnormality resulting in excessive GABAergic inhibition in the cortex and hippocampus, wherein said CNS disease is selected from cognitive impairment after stroke.

[0070] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease caused by a neurodevelopmental abnormality resulting in excessive GABAergic inhibition in the cortex and hippocampus, wherein said CNS disease is selected from intellectual disability.

[0071] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, which is a ligand for the BZD binding site and acts as an inverse agonist at the GABA A α5 subunit containing receptor.

[0072] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, which is a ligand for the BZD binding site of the GABA A receptor and acts as an inverse agonist at the GABA A α5β3γ2 receptor subtype.

[0073] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator has binding selectivity at a GABA A α5 subunit-containing receptor.

[0074] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator has functional selectivity at a GABA A α5 subunit containing receptor.

[0075] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator binds to the human GABA A α5β3γ2 receptor subtype with 10-fold or greater binding selectivity compared to the binding affinity to the human GABA A α1β2 / 3γ2, α2β3γ2 and α3β3γ2 receptor subtypes.

[0076] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator has binding selectivity at a GABA A α5 subunit-containing receptor.

[0077] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, which exhibits functional selectivity by acting as an inverse agonist at the human GABA A α5β3γ2 receptor subtype by reducing the effect of GABA by more than 30% and further affecting the effect of GABA at the human GABA A α1β2 / 3γ2, α2β3γ2 and α3β3γ2 receptor subtypes by less than 15%.

[0078] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator is a compound of formula (I) or a compound of formula (II): [ka] [In the formula, R 1 is hydrogen, halo, alkyl, haloalkyl, or cyano; R 2 is hydrogen, halo, alkyl, haloalkyl, or cyano; R 3 is hydrogen, alkyl, or heterocycloalkylalkyl, where heterocycloalkylalkyl is optionally substituted with one or more hydroxy, oxo, alkyl, alkoxy, haloalkyl, hydroxyalkyl, halo, or cyano; R 4 is aryl or heteroaryl, each optionally substituted with 1, 2 or 3 halo; R 5is hydrogen, alkyl, haloalkyl, or hydroxyalkyl; R 6 is -C(O)-NR 7 R 8 and R 7 is hydrogen; R 8 is alkyl; or R 7 and R 8 together with the nitrogen to which they are attached form a heterocycloalkyl or heteroaryl, each optionally substituted with one or more hydroxy, oxo, alkyl, alkoxy, haloalkyl, hydroxyalkyl, halo, or cyano, or a pharma- ceutically acceptable salt thereof.

[0079] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator has the formula (I): R 1 is hydrogen, halo, alkyl, haloalkyl, or cyano; R 2 is hydrogen, halo, alkyl, haloalkyl, or cyano; R 3 is hydrogen, alkyl, or heterocycloalkylalkyl, where heterocycloalkylalkyl is optionally substituted with one or more hydroxy, oxo, alkyl, alkoxy, haloalkyl, hydroxyalkyl, halo, or cyano, or a pharma- ceutically acceptable salt thereof.

[0080] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator has the formula (I): R 1 is hydrogen, halo, haloalkyl or cyano; R 2 is halo or haloalkyl; R 3 is hydrogen, alkyl, or heterocycloalkylalkyl substituted with one oxo, or a pharma- ceutically acceptable salt thereof.

[0081] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator is: 3-Fluoro-10-fluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-Bromo-10-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-Cyano-10-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-Chloro-10-fluoromethyl-6-methyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Chloro-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3,10-Dichloro-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Chloro-3-cyano-6-methyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Chloro-3-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-Bromo-10-chloro-6-methyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Bromo-3-fluoro-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-bromo-10-methyl-6-(2-oxo-pyrrolidin-1-ylmethyl)-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; or a pharma-ceutically acceptable salt thereof.

[0082] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator is 3-bromo-10-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; or a pharma- ceutically acceptable salt thereof.

[0083] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator is not 3-bromo-10-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; or a pharma- ceutically acceptable salt thereof.

[0084] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator has the formula (II): [In the formula, R 4 is aryl or heteroaryl, each optionally substituted with 1, 2 or 3 halo; R 5 is hydrogen, alkyl, haloalkyl, or hydroxyalkyl; R 6 is -C(O)-NR 7 R 8 and; R 7 is hydrogen; R8 is alkyl; or R 7 and R 8 taken together with the nitrogen to which they are attached form a heterocycloalkyl or heteroaryl, each optionally substituted with one or more hydroxy, oxo, alkyl, alkoxy, haloalkyl, hydroxyalkyl, halo, or cyano, or a pharma- ceutically acceptable salt thereof.

[0085] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator has the formula (II): R 4 is aryl or heteroaryl, each optionally substituted with 1 halo; R 5 is alkyl; R 6 is C(O)-NR 7 R 8 and; R 7 is hydrogen, and R 8 is alkyl; or R 7 and R 8 together with the nitrogen to which they are attached form a heterocycloalkyl optionally substituted with 1 or 2 oxo, or form a heteroaryl, or a pharma- ceutically acceptable salt thereof.

[0086] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator is: N-isopropyl-6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-nicotinamide; (5,6-dihydro-8H-[1,2,4]triazolo[4,3-a]pyrazin-7-yl)-[6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-methanone; [6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-(2-oxa-6-aza-spiro[3.3]hept-6-yl)-methanone; (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(4-fluoro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; {6-[3-(4-chloro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-morpholin-4-yl-methanone; [6-(5-methyl-3-pyridin-2-yl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-morpholin-4-yl-methanone; 6-[3-(5-fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-isopropyl-nicotinamide; (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(5-fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; {6-[3-(5-chloro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-thiomorpholin-4-yl-methanone; or a pharma- ceutically acceptable salt thereof.

[0087] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator is N-isopropyl-6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-nicotinamide; or a pharma- ceutically acceptable salt thereof.

[0088] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator is (5,6-dihydro-8H-[1,2,4]triazolo[4,3-a]pyrazin-7-yl)-[6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-methanone; or a pharma- ceutically acceptable salt thereof.

[0089] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator is [6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-(2-oxa-6-aza-spiro[3.3]hept-6-yl)-methanone; or a pharma- ceutically acceptable salt thereof.

[0090] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator is (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(4-fluoro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; or a pharma- ceutically acceptable salt thereof.

[0091] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator is {6-[3-(4-chloro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-morpholin-4-yl-methanone; or a pharma- ceutically acceptable salt thereof.

[0092] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator is [6-(5-methyl-3-pyridin-2-yl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-morpholin-4-yl-methanone; or a pharma- ceutically acceptable salt thereof.

[0093] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator is 6-[3-(5-fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-isopropyl-nicotinamide; or a pharma- ceutically acceptable salt thereof.

[0094] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator is (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(5-fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; or a pharma- ceutically acceptable salt thereof.

[0095] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein the GABA A α5 negative allosteric modulator is {6-[3-(5-chloro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-thiomorpholin-4-yl-methanone; or a pharma- ceutically acceptable salt thereof.

[0096] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator, wherein said GABA A α5 negative allosteric modulator is used in combination with a second active pharmaceutical compound, either separately, sequentially or simultaneously.

[0097] In certain embodiments, the present invention relates to a method for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease caused by a neurodevelopmental abnormality resulting in excessive GABAergic inhibition in the cortex and hippocampus in a subject in need of such treatment, comprising administering to said subject a therapeutically effective amount of a GABA A α5 negative allosteric modulator as described herein in a pharma- ceutically acceptable form.

[0098] In certain embodiments, the present invention relates to a method for treating, preventing and / or delaying the progression of a central nervous system (CNS) disease in a subject in need of such treatment, wherein said CNS disease is selected from cognitive impairment in Down's syndrome, comprising administering to said subject a therapeutically effective amount of a GABA A α5 negative allosteric modulator as described herein in a pharma- ceutically acceptable form.

[0099] In certain embodiments, the present invention relates to a method for treating, preventing and / or delaying the progression of a central nervous system (CNS) disorder in a subject in need of such treatment, wherein said CNS disorder is selected from cognitive impairment in autism, comprising administering to said subject a therapeutically effective amount of a GABA A α5 negative allosteric modulator as described herein in a pharma- ceutically acceptable form.

[0100] In certain embodiments, the present invention relates to a method for treating, preventing and / or delaying the progression of a central nervous system (CNS) disease in a subject in need of such treatment, wherein said CNS disease is selected from cognitive impairment in neurofibromatosis type I, comprising administering to said subject a therapeutically effective amount of a GABA A α5 negative allosteric modulator as described herein in a pharma- ceutically acceptable form.

[0101] In certain embodiments, the present invention relates to a method for treating, preventing and / or delaying the progression of a central nervous system (CNS) disease in a subject in need of such treatment, wherein said CNS disease is selected from post-stroke cognitive impairment, comprising administering to said subject a therapeutically effective amount of a GABA A α5 negative allosteric modulator as described herein in a pharmacologic acceptable form.

[0102] In certain embodiments, the present invention relates to a method for treating, preventing and / or delaying the progression of a central nervous system (CNS) disease in a subject in need of such treatment, wherein said CNS disease is selected from intellectual disability, comprising administering to said subject a therapeutically effective amount of a GABA A α5 negative allosteric modulator as described herein in a pharma- ceutically acceptable form.

[0103] In a particular embodiment, the present invention relates to a pharmaceutical composition comprising a GABA A α5 negative allosteric modulator as described herein, in a pharma- ceutically acceptable form, for the treatment, prevention and / or delay of progression of central nervous system (CNS) diseases caused by neurodevelopmental abnormalities resulting in excessive GABAergic inhibition in the cortex and hippocampus.

[0104] In a particular embodiment, the present invention relates to a pharmaceutical composition comprising a GABA A α5 negative allosteric modulator as described herein in a pharma- ceutically acceptable form for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from cognitive impairment in Down's syndrome.

[0105] In a particular embodiment, the present invention relates to a pharmaceutical composition comprising a GABA A α5 negative allosteric modulator as described herein in a pharma- ceutically acceptable form for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from cognitive impairment in autism.

[0106] In a particular embodiment, the present invention relates to a pharmaceutical composition comprising a GABA A α5 negative allosteric modulator as described herein in a pharma- ceutically acceptable form for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from cognitive impairment in neurofibromatosis type I.

[0107] In a particular embodiment, the present invention relates to a pharmaceutical composition comprising a GABA A α5 negative allosteric modulator as described herein in a pharma- ceutically acceptable form for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from post-stroke cognitive impairment.

[0108] In a particular embodiment, the present invention relates to a pharmaceutical composition comprising a GABA A α5 negative allosteric modulator as described herein in a pharma- ceutically acceptable form for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from intellectual disability.

[0109] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator as described herein for the preparation of a medicament for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease caused by a neurodevelopmental abnormality resulting in excessive GABAergic inhibition in the cortex and hippocampus.

[0110] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator as described herein for the preparation of a medicament for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from cognitive impairment in Down's syndrome.

[0111] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator as described herein for the preparation of a medicament for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from cognitive impairment in autism.

[0112] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator as described herein for the preparation of a medicament for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from cognitive impairment in neurofibromatosis type I.

[0113] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator as described herein for the preparation of a medicament for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from post-stroke cognitive impairment.

[0114] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator as described herein for the preparation of a medicament for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from intellectual disability.

[0115] In a particular embodiment, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease caused by a neurodevelopmental abnormality resulting in excessive GABAergic inhibition in the cortex and hippocampus.

[0116] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from cognitive impairment in Down's syndrome.

[0117] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from cognitive impairment in autism.

[0118] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from cognitive impairment in neurofibromatosis type I.

[0119] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from post-stroke cognitive impairment.

[0120] In a particular embodiment, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, wherein said CNS disease is selected from intellectual disability. In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease caused by a neurodevelopmental abnormality resulting in excessive GABAergic inhibition in the cortex and hippocampus, wherein said CNS disease is selected from cognitive impairment in Down's syndrome, and the GABA A α5 negative allosteric modulator is 3-bromo-10-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine or a pharma- ceutically acceptable salt thereof.

[0121] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease caused by a neurodevelopmental abnormality resulting in excessive GABAergic inhibition in the cortex and hippocampus, wherein said CNS disease is selected from cognitive impairment in Down's syndrome, and the GABA A α5 negative allosteric modulator is (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(4-fluoro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; or a pharma- ceutically acceptable salt thereof.

[0122] In a particular embodiment, the present invention relates to a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease caused by a neurodevelopmental abnormality resulting in excessive GABAergic inhibition in the cortex and hippocampus, wherein said CNS disease is selected from cognitive impairment in Down's syndrome, and the GABA A α5 negative allosteric modulator is 3-bromo-10-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine or a pharma- ceutically acceptable salt thereof.

[0123] In a particular embodiment, the present invention relates to a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease caused by a neurodevelopmental abnormality resulting in excessive GABAergic inhibition in the cortex and hippocampus, wherein said CNS disease is selected from cognitive impairment in Down's syndrome, and the GABA A α5 negative allosteric modulator is (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(4-fluoro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; or a pharma- ceutically acceptable salt thereof.

[0124] In another embodiment, the present invention relates to a compound of formula (I) or a compound of formula (II): [ka] [In the formula, R 1 is hydrogen, halo, alkyl, haloalkyl, or cyano; R 2 is hydrogen, halo, alkyl, haloalkyl, or cyano; R 3is hydrogen, alkyl, or heterocycloalkylalkyl, where heterocycloalkylalkyl is optionally substituted with one or more hydroxy, oxo, alkyl, alkoxy, haloalkyl, hydroxyalkyl, halo, or cyano; R 4 is aryl or heteroaryl, each optionally substituted with 1, 2 or 3 halo; R 5 is hydrogen, alkyl, haloalkyl, or hydroxyalkyl; R 6 is -C(O)-NR 7 R 8 and R 7 is hydrogen; R 8 is alkyl; or R 7 and R 8 (combined with the nitrogen to which they are attached to form a heterocycloalkyl or heteroaryl, each optionally substituted with one or more hydroxy, oxo, alkyl, alkoxy, haloalkyl, hydroxyalkyl, halo, or cyano) or a pharma- ceutically acceptable salt thereof.

[0125] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator as described above for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease related to excessive GABAergic inhibition in the cortex and hippocampus, wherein said excessive GABAergic inhibition in the cortex and hippocampus is caused by a neurodevelopmental abnormality.

[0126] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator as described above for the treatment, prevention and / or delay of progression of central nervous system (CNS) diseases caused by neurodevelopmental abnormalities resulting in excessive GABAergic inhibition in the cortex and hippocampus.

[0127] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator as described above for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, in particular caused by neurodevelopmental abnormalities, related to excessive GABAergic inhibition in the cortex and hippocampus, wherein said CNS disease is selected from cognitive disorders in Down's syndrome, in autism or in neurofibromatosis type I.

[0128] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator as described above for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease related to excessive GABAergic inhibition in the cortex and hippocampus, in particular caused by neurodevelopmental abnormalities, wherein said CNS disease is cognitive impairment in Down's syndrome.

[0129] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator as described above for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease related to excessive GABAergic inhibition in the cortex and hippocampus, in particular caused by neurodevelopmental abnormalities, wherein said CNS disease is cognitive impairment in autism.

[0130] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator as described above for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease related to excessive GABAergic inhibition in the cortex and hippocampus, in particular caused by neurodevelopmental abnormalities, wherein said CNS disease is cognitive impairment in neurofibromatosis type I.

[0131] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator as described above for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease related to excessive GABAergic inhibition in the cortex and hippocampus, wherein said CNS disease is characterized by disability after stroke.

[0132] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator binds to the human GABA A α5β3γ2 receptor subtype with 10-fold or greater binding selectivity compared to its binding affinity to the human GABA A α1β2 / 3γ2, α2β3γ2 and α3β3γ2 receptor subtypes.

[0133] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator exhibits functional selectivity by acting as an inverse agonist at the human GABA A α5β3γ2 receptor subtype by reducing the effect of GABA by more than 30% and further affecting the effect of GABA at the human GABA A α1β2 / 3γ2, α2β3γ2 and α3β3γ2 receptor subtypes by less than 15%.

[0134] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is represented by formula (I): 1 , R 2 and R3 is as defined herein] or a pharma- ceutically acceptable salt thereof.

[0135] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is represented by formula (I): 1 is hydrogen, halo, haloalkyl or cyano; R 2 is halo or haloalkyl; R 3 is hydrogen, alkyl, or heterocycloalkylalkyl substituted with one oxo, or a pharma- ceutically acceptable salt thereof.

[0136] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is 3-Fluoro-10-fluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-Bromo-10-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-Cyano-10-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-Chloro-10-fluoromethyl-6-methyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Chloro-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3,10-Dichloro-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Chloro-3-cyano-6-methyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Chloro-3-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-Bromo-10-chloro-6-methyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Bromo-3-fluoro-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-bromo-10-methyl-6-(2-oxo-pyrrolidin-1-ylmethyl)-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; or a pharma-ceutically acceptable salt thereof.

[0137] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is represented by formula (II): 4 , R 5 and R 6 is as defined herein] or a pharma- ceutically acceptable salt thereof.

[0138] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is represented by formula (II): 4 is aryl or heteroaryl, each optionally substituted with 1 halo; R 5 is alkyl; R 6 is C(O)-NR 7 R 8 ;R 7 is hydrogen, and R 8 is alkyl; or R 7 and R 8 together with the nitrogen to which they are attached form a heterocycloalkyl optionally substituted with 1 or 2 oxo, or form a heteroaryl, or a pharma- ceutically acceptable salt thereof.

[0139] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is: N-isopropyl-6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-nicotinamide; (5,6-dihydro-8H-[1,2,4]triazolo[4,3-a]pyrazin-7-yl)-[6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-methanone; [6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-(2-oxa-6-aza-spiro[3.3]hept-6-yl)-methanone; (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(4-fluoro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; {6-[3-(4-chloro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-morpholin-4-yl-methanone; [6-(5-methyl-3-pyridin-2-yl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-morpholin-4-yl-methanone; 6-[3-(5-fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-isopropyl-nicotinamide; (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(5-fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; {6-[3-(5-chloro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-thiomorpholin-4-yl-methanone; or a pharma- ceutically acceptable salt thereof.

[0140] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is N-isopropyl-6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-nicotinamide; or a pharma- ceutically acceptable salt thereof.

[0141] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is (5,6-dihydro-8H-[1,2,4]triazolo[4,3-a]pyrazin-7-yl)-[6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-methanone; or a pharma- ceutically acceptable salt thereof.

[0142] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is [6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-(2-oxa-6-aza-spiro[3.3]hept-6-yl)-methanone; or a pharma- ceutically acceptable salt thereof.

[0143] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(4-fluoro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; or a pharma- ceutically acceptable salt thereof.

[0144] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is {6-[3-(4-chloro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-morpholin-4-yl-methanone; or a pharma- ceutically acceptable salt thereof.

[0145] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is [6-(5-methyl-3-pyridin-2-yl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-morpholin-4-yl-methanone; or a pharma- ceutically acceptable salt thereof.

[0146] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is 6-[3-(5-fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-isopropyl-nicotinamide; or a pharma- ceutically acceptable salt thereof.

[0147] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(5-fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; or a pharma- ceutically acceptable salt thereof.

[0148] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is {6-[3-(5-chloro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-thiomorpholin-4-yl-methanone; or a pharma- ceutically acceptable salt thereof.

[0149] In certain embodiments, the present invention relates to the use of a GABA A α5 negative allosteric modulator for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is used in combination with a second active pharmaceutical compound, either separately, sequentially or simultaneously.

[0150] In certain embodiments, the present invention relates to a method for the treatment, prevention and / or delay of progression of cognitive impairment in Down's syndrome, in autism, in neurofibromatosis type I or during post-stroke recovery in a subject in need of such treatment, comprising administering to said subject a therapeutically effective amount of a GABA A α5 negative allosteric modulator as described herein in a pharma- ceutically acceptable form.

[0151] In a particular embodiment, the present invention relates to a pharmaceutical composition comprising a GABA A α5 negative allosteric modulator as described herein in a pharma- ceutically acceptable form for the treatment, prevention and / or delay of progression of cognitive impairment in Down's syndrome, in autism, in neurofibromatosis type I or during post-stroke recovery.

[0152] In a particular embodiment, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of cognitive impairment in Down's syndrome, in autism, in neurofibromatosis type I or during post-stroke recovery.

[0153] In a particular embodiment, the invention relates to a GABA A α5 negative allosteric modulator as described herein for the preparation of a medicament for the treatment, prevention and / or delay of progression of cognitive impairment in Down's syndrome, in autism, in neurofibromatosis type I or during post-stroke recovery.

[0154] In a particular embodiment, the present invention relates to the use of a GABA A α5 negative allosteric modulator as described herein for the preparation of a medicament for the treatment, prevention and / or delay of progression of cognitive impairment in Down's syndrome, in autism, in neurofibromatosis type I or during post-stroke recovery.

[0155] In another embodiment, the present invention relates to a compound of formula (I) or a compound of formula (II): [ka] [In the formula, R1 is hydrogen, halo, alkyl, haloalkyl, or cyano; R 2 is hydrogen, halo, alkyl, haloalkyl, or cyano; R 3 is hydrogen, alkyl, or heterocycloalkylalkyl, where heterocycloalkylalkyl is optionally substituted with one or more hydroxy, oxo, alkyl, alkoxy, haloalkyl, hydroxyalkyl, halo, or cyano; R 4 is aryl or heteroaryl, each optionally substituted with 1, 2 or 3 halo; R 5 is hydrogen, alkyl, haloalkyl, or hydroxyalkyl; R 6 is -C(O)-NR 7 R 8 and R 7 is hydrogen; R 8 is alkyl; or R 7 and R 8 together with the nitrogen to which they are attached form a heterocycloalkyl or heteroaryl, each optionally substituted with one or more hydroxy, oxo, alkyl, alkoxy, haloalkyl, hydroxyalkyl, halo, or cyano, or a pharma- ceutically acceptable salt thereof.

[0156] In a particular embodiment, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of central nervous system (CNS) diseases related to excessive GABAergic inhibition in the cortex and hippocampus, caused by neurodevelopmental abnormalities.

[0157] In a particular embodiment, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease caused by a neurodevelopmental abnormality resulting in excessive GABAergic inhibition in the cortex and hippocampus.

[0158] In a particular embodiment, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease, in particular caused by neurodevelopmental abnormalities, related to excessive GABAergic inhibition in the cortex and hippocampus, wherein said CNS disease is selected from cognitive disorders in Down's syndrome, in autism or in neurofibromatosis type I.

[0159] In a particular embodiment, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease related to excessive GABAergic inhibition in the cortex and hippocampus, in particular caused by neurodevelopmental abnormalities, wherein said CNS disease is cognitive impairment in Down's syndrome.

[0160] In a particular embodiment, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease related to excessive GABAergic inhibition in the cortex and hippocampus, in particular caused by neurodevelopmental abnormalities, wherein said CNS disease is cognitive impairment in autism.

[0161] In a particular embodiment, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease related to excessive GABAergic inhibition in the cortex and hippocampus, in particular caused by neurodevelopmental abnormalities, wherein said CNS disease is cognitive impairment in neurofibromatosis type I.

[0162] In a particular embodiment, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease related to excessive GABAergic inhibition in the cortex and hippocampus, wherein said CNS disease is characterized by disability after stroke.

[0163] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator binds to the human GABA A α5β3γ2 receptor subtype with 10-fold or greater binding selectivity compared to its binding affinity to the human GABA A α1β2 / 3γ2, α2β3γ2 and α3β3γ2 receptor subtypes.

[0164] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator exhibits functional selectivity by acting as an inverse agonist at the human GABA A α5β3γ2 receptor subtype by reducing the effect of GABA by more than 30% and further affecting the effect of GABA at the human GABA A α1β2 / 3γ2, α2β3γ2 and α3β3γ2 receptor subtypes by less than 15%.

[0165] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is represented by formula (I) [wherein R 1 , R 2 and R 3 is as defined herein] or a pharma- ceutically acceptable salt thereof.

[0166] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is represented by formula (I) [wherein R 1 is hydrogen, halo, haloalkyl or cyano; R 2 is halo or haloalkyl; R 3 is hydrogen, alkyl, or heterocycloalkylalkyl substituted with one oxo; or a pharma- ceutically acceptable salt thereof.

[0167] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is 3-Fluoro-10-fluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-Bromo-10-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-Cyano-10-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-Chloro-10-fluoromethyl-6-methyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Chloro-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3,10-Dichloro-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Chloro-3-cyano-6-methyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Chloro-3-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-Bromo-10-chloro-6-methyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 10-Bromo-3-fluoro-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; 3-bromo-10-methyl-6-(2-oxo-pyrrolidin-1-ylmethyl)-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine; or a pharma-ceutically acceptable salt thereof.

[0168] In a particular embodiment, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is 3-bromo-10-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine or a pharma- ceutically acceptable salt thereof.

[0169] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is not 3-bromo-10-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine or a pharma- ceutically acceptable salt thereof.

[0170] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is represented by formula (II) [wherein R 4 , R 5 and R 6is as defined herein] or a pharma- ceutically acceptable salt thereof.

[0171] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is represented by formula (II) [wherein R 4 is aryl or heteroaryl, each optionally substituted with 1 halo; R 5 is alkyl; R 6 is C(O)-NR 7 R 8 ;R 7 is hydrogen, and R 8 is alkyl; or R 7 and R 8 together with the nitrogen to which they are attached form a heterocycloalkyl optionally substituted with 1 or 2 oxo, or form a heteroaryl; or a pharma- ceutically acceptable salt thereof.

[0172] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is: N-isopropyl-6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-nicotinamide; (5,6-dihydro-8H-[1,2,4]triazolo[4,3-a]pyrazin-7-yl)-[6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-methanone; [6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-(2-oxa-6-aza-spiro[3.3]hept-6-yl)-methanone; (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(4-fluoro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; {6-[3-(4-chloro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-morpholin-4-yl-methanone; [6-(5-methyl-3-pyridin-2-yl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-morpholin-4-yl-methanone; 6-[3-(5-fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-isopropyl-nicotinamide; (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(5-fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; {6-[3-(5-chloro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-thiomorpholin-4-yl-methanone; or a pharma- ceutically acceptable salt thereof.

[0173] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is N-isopropyl-6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-nicotinamide; or a pharma- ceutically acceptable salt thereof.

[0174] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is (5,6-dihydro-8H-[1,2,4]triazolo[4,3-a]pyrazin-7-yl)-[6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-methanone; or a pharma- ceutically acceptable salt thereof.

[0175] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is [6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-(2-oxa-6-aza-spiro[3.3]hept-6-yl)-methanone; or a pharma- ceutically acceptable salt thereof.

[0176] In a particular embodiment, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(4-fluoro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone or a pharma- ceutically acceptable salt thereof.

[0177] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is {6-[3-(4-chloro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-morpholin-4-yl-methanone; or a pharma- ceutically acceptable salt thereof.

[0178] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is [6-(5-methyl-3-pyridin-2-yl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-morpholin-4-yl-methanone; or a pharma- ceutically acceptable salt thereof.

[0179] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is 6-[3-(5-fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-isopropyl-nicotinamide; or a pharma- ceutically acceptable salt thereof.

[0180] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(5-fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; or a pharma- ceutically acceptable salt thereof.

[0181] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein said GABA A α5 negative allosteric modulator is {6-[3-(5-chloro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-thiomorpholin-4-yl-methanone; or a pharma- ceutically acceptable salt thereof.

[0182] In certain embodiments, the present invention relates to a GABA A α5 negative allosteric modulator as described herein for the treatment, prevention and / or delay of progression of a central nervous system (CNS) disease as described herein, wherein the GABA A α5 negative allosteric modulator is used in combination with a second active pharmaceutical compound, either separately, sequentially or simultaneously.

[0183] Working Example Materials and Methods A. Animals Table 1 shows the number of male animals used in this study. Ten control mice and ten Ts65Dn mice aged 6 months at the beginning of treatment received 8581; 16 control mice and 15 Ts65Dn mice aged 5-6 months at the beginning of treatment received R1, and two other groups of control mice (n=13) and Ts65Dn mice (n=13) received vehicle.

[0184] b. Active pharmaceutical compound The active pharmaceutical compounds used in the present invention were prepared as previously described in WO2006 / 045429, WO2006 / 045430, WO2007 / 042421 and WO2009 / 071476:

[0185] Compound 8580 3-Fluoro-10-fluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine was prepared as described in WO2006 / 045430, page 17, example 3.

[0186] Compound 8581 3-Bromo-10-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine was prepared as described in WO2006 / 045430, page 21, example 7.

[0187] Compound 8582 3-Cyano-10-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine was prepared as described in WO2006 / 045430, page 23, example 13.

[0188] Compound 8583 10-Difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine was prepared as described in WO2006 / 045430, page 26, example 16.

[0189] Compound 8584 3-Chloro-10-fluoromethyl-6-methyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine was prepared as described in WO2006 / 045430, page 28, example 20.

[0190] Compound 8585 10-Chloro-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine was prepared as described in WO2006 / 045429, page 15, example 1.

[0191] Compound 8586 3,10-Dichloro-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine was prepared as described in WO2006 / 045429, page 23, example 20.

[0192] Compound 8587 10-Chloro-3-cyano-6-methyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine was prepared as described in WO2006 / 045429, page 37, example 47.

[0193] Compound 8588 10-Chloro-3-difluoromethyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine was prepared as described in WO2006 / 045429, page 29, example 32.

[0194] Compound 8589 3-Bromo-10-chloro-6-methyl-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine was prepared as described in WO2006 / 045429, page 33, example 38.

[0195] Compound 8590 10-Bromo-3-fluoro-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine was prepared as described in WO2006 / 045429, page 37, example 47.

[0196] Compound 8591 3-Bromo-10-methyl-6-(2-oxo-pyrrolidin-1-ylmethyl)-9H-imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine was prepared as described in WO2007 / 042421, page 67, example 101.

[0197] Compound O1 N-isopropyl-6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-nicotinamide was prepared as described in WO2009 / 071476, page 50, example 26.

[0198] Compound P1 (5,6-Dihydro-8H-[1,2,4]triazolo[4,3-a]pyrazin-7-yl)-[6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-methanone was prepared as described in WO2009 / 071476, page 62, example 75.

[0199] Compound Q1 [6-(5-Methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-(2-oxa-6-aza-spiro[3.3]hept-6-yl)-methanone was prepared as described in WO2009 / 071476, page 64, example 81.

[0200] Compound R1 (1,1-Dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(4-fluoro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone was prepared as described in WO2009 / 071476, page 75, example 112.

[0201] Compound S1 {6-[3-(4-Chloro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-morpholin-4-yl-methanone was prepared as described in WO2009 / 071476, page 78, example 123.

[0202] Compound T1 [6-(5-Methyl-3-pyridin-2-yl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-morpholin-4-yl-methanone was prepared as described in WO2009 / 071476, page 123, example 274.

[0203] Compound U1 6-[3-(5-Fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-isopropyl-nicotinamide was prepared as described in WO2009 / 071476, page 127, example 289.

[0204] Compound V1 (1,1-Dioxo-1λ6-thiomorpholin-4-yl)-{6-[3-(5-fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone was prepared as described in WO2009 / 071476, page 127, example 293.

[0205] Compound W1 {6-[3-(5-Chloro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-thiomorpholin-4-yl-methanone was prepared as described in WO2009 / 071476, page 132, example 310.

[0206] The binding affinity of the above active pharmaceutical compounds at GABA A receptor subtypes was determined by binding to HEK293 cells expressing the constitutive α1β2 / 3γ2, α2β3γ2, α3β3γ2 and α5β3γ2 rat (stably transfected) or human (transiently transfected) receptors. 3 H] flumazenil (85 Ci / mmol; Roche) as measured by competition. As can be seen from Table 2a, the active pharmaceutical compounds used in the present invention show high affinity at the α5β3γ2 receptor subtype and better selectivity than the α1β2 / 3γ2, α2β3γ2 and α3β3γ2 receptor subtypes.

[0207] As can be seen from Table 2b, the active pharmaceutical compounds used in the present invention also show substantial functional selectivity. Subtype-selective action was determined on cloned receptors expressed in Xenopus oocytes. Human recombinant GABA A receptors were expressed in Xenopus oocytes. Current responses were evoked in two-microelectrode voltage clamp conditions by applying EC10 GABA before and during co-application of test compounds. Response amplitudes in the presence of test compounds are expressed as a percentage of the amplitude before drug addition.

[0208] C. Pharmaceutical Composition For mouse studies, the active pharmaceutical compounds of the present invention were formulated in chocolate milk (Puleva, Barcelona, ​​Spain). The active pharmaceutical compounds of the present invention or vehicle were orally administered at a dose of 20 mg / kg for 6 weeks. Their administration was extended for 30 days of behavioral evaluation.

[0209] For human use, pharmaceutical compositions or medicaments comprising an active pharmaceutical compound as described above and a therapeutically inert carrier, diluent or excipient may be prepared, as well as methods of using the compounds of the invention to prepare such compositions and medicaments.

[0210] The compositions are formulated, dosed and administered in a manner consistent with good medical practice. Factors to be considered in this context include the particular disorder being treated, the particular mammal being treated, the clinical condition of the individual patient, the cause of the disorder, the site of delivery of the agent, the method of administration, the scheduling of administration, and other factors known to medical practitioners.

[0211] The active pharmaceutical compounds used in the present invention may be administered by any suitable means, including oral, topical (including buccal and sublingual), rectal, intravaginal, transdermal, parenteral, subcutaneous, intraperitoneal, intrapulmonary, intradermal, intrathecal and epidural, and intranasal, and, where localized treatment is desired, by intralesional administration. Parenteral administration includes intramuscular, intravenous, intraarterial, intraperitoneal or subcutaneous administration.

[0212] The active pharmaceutical compounds used in the present invention may be administered in any convenient dosage form, such as tablets, powders, capsules, liquids, dispersions, suspensions, syrups, sprays, suppositories, gels, emulsions, patches, etc. Such compositions may contain conventional ingredients in pharmaceutical preparations, such as diluents, carriers, pH adjusters, preservatives, solubilizers, stabilizers, wetting agents, emulsifiers, sweeteners, colorants, flavors, salts for changing osmotic pressure, buffers, masking agents, antioxidants, and additional active agents. They may also further contain other therapeutically valuable substances.

[0213] A typical pharmaceutical composition is prepared by mixing the active pharmaceutical compound used in the present invention with a carrier or excipient. Suitable carriers and excipients are well known to those skilled in the art and are described in detail, for example, in Ansel HC et al., Ansel's Pharmaceutical Dosage Forms and Drug Delivery Systems (2004) Lippincott, Williams & Wilkins, Philadelphia; Gennaro AR et al., Remington: The Science and Practice of Pharmacy (2000) Lippincott, Williams & Wilkins, Philadelphia; and Rowe RC, Handbook of Pharmaceutical Excipients (2005) Pharmaceutical Press, Chicago. The pharmaceutical compositions may contain one or more buffers, stabilizers, surfactants, wetting agents, lubricants, emulsifiers, suspending agents, preservatives, opaquing agents, glidants, processing aids, colorants, sweeteners, fragrances, flavorings, diluents, and other known additives to provide an elegant presentation of the medicament (i.e., a compound of the present invention or a pharmaceutical composition thereof) or to aid in the manufacture of a pharmaceutical product (i.e., a medicament).

[0214] The dosage that the active pharmaceutical compounds used in the present invention can be administered in can vary within wide limits and will of course be adapted to the individual requirements in each individual case.In general, for oral administration, a daily dosage of about 0.1-1500 mg, more particularly 1-1000 mg, most particularly 5-500 mg per person of the active pharmaceutical compounds used in the present invention should be appropriate, although the above upper limits can also be exceeded if necessary.

[0215] An example of a suitable oral dosage form is a tablet containing about 100 mg to 500 mg of the active pharmaceutical compound used in the present invention mixed with about 90 to 30 mg of anhydrous lactose, about 5 to 40 mg of croscarmellose sodium, about 5 to 30 mg of polyvinylpyrrolidone (PVP) K30, and about 1 to 10 mg of magnesium stearate. The powdered ingredients are first mixed together and then mixed with a solution of PVP. The resulting composition can be dried, granulated, mixed with magnesium stearate, and compressed into tablet form using conventional equipment.

[0216] An example of an aerosol composition can be prepared by dissolving, for example, 10-100 mg of an active pharmaceutical compound used in the present invention in a suitable buffer solution, for example, phosphate buffer, and adding, if desired, a tonicifier, for example, a salt such as sodium chloride. The solution may be filtered, for example, using a 0.2 μm filter, to remove impurities and contaminants.

[0217] d.Statistical analysis Data were analyzed using two-way ('genotype' x 'treatment') ANOVA. Morris water maze data were analyzed using two-way ANOVA with repeated measures ('session' x 'genotype' x 'treatment'). Means of each experimental group were compared post-hoc by Student's t-test when comparing two groups or by Bonferroni's test when comparing more than two groups. All analyses were performed using SPSS for Windows version 17.0 (SPSS AG, Zurich, Switzerland).

[0218] Brief explanation of the table: Table 1. Experimental groups of animals used in the present invention for Examples 1-6. Table 2a. Binding affinities and binding selectivities of active pharmaceutical compounds used in the present invention. Table 2b. Modulation of GABA A receptor subtypes expressed in Xenopus oocytes by active pharmaceutical compounds. Effect at human GABA A α5 receptors: % change in submaximal (EC10) response to GABA determined at 30×Ki value from flumazenil binding assay. Effect at human GABA A α1, α2 and α3 receptors: % change in submaximal (EC10) response to GABA determined at 3 μM or 30×Ki value from flumazenil binding assay if Ki is less than 0.1 μM. Table 3. Sensorimotor test battery for 8581, R1 and vehicle treated Ts65Dn and control mice (mean scores ± SEM). Table 4. Hole board test results for R1, 8581 and vehicle treated Ts65Dn and control mice (mean scores ± SEM). ** p<0.01 Ts65Dn vs. control Table 5. 8581 concentrations (ng / mL) in serum of Nf1+ / - and control mice at 0.5, 3, 7, and 24 hours after intraperitoneal injection. [Brief description of the drawings]

[0219] [Figure 1] Mean±SEM of latency to fall from different constant speed rotarods for 8581, R1 and vehicle treated Ts65Dn and control mice. [Diagram 2] Mean±SEM of latency to fall from the rotarod during the accelerating cycle for 8581, R1 and vehicle treated Ts65Dn and control mice. [Diagram 3] Mean±SEM of spontaneous activity in their home cages performed by Ts65Dn and control mice under vehicle, R1 or 8581 treatment over a complete 24-h light-dark cycle. [Figure 4] Mean±SEM of the average activity performed by Ts65Dn and control mice under vehicle, R1 or 8581 treatment during the light or dark phase of the cycle. [Diagram 5]Mean±SEM of the number of crossings performed by R1, 8581 and vehicle treated Ts65Dn and control mice in the center and periphery of the open field. *: p<0.05; **: p<0.01 significant ANOVA followed by Bonferroni's test. [Figure 6] Mean±SEM of the number of rearing behaviors performed by R1, 8581 and vehicle treated Ts65Dn and control mice in the open field. [Figure 7] Mean ± SEM of latency to reach the platform during eight acquisition sessions in the MWM. [Figure 8A] Mean ± SEM of latency to reach the platform during eight acquisition sessions by Ts65Dn and control vehicle (A), 8581 (B) and R1 treated mice, and by vehicle and 8581 treated Ts65Dn (C) and control (D) mice. *: p<0.05; **: p<0.01; ***: p<0.001 significant ANOVA post T-test. [Figure 8B] Mean ± SEM of latency to reach the platform during eight acquisition sessions by Ts65Dn and control vehicle (A), 8581 (B) and R1 treated mice, and by vehicle and 8581 treated Ts65Dn (C) and control (D) mice. *: p<0.05; **: p<0.01; ***: p<0.001 significant ANOVA post T-test. [Figure 8C] Mean ± SEM of latency to reach the platform during eight acquisition sessions by Ts65Dn and control vehicle (A), 8581 (B) and R1 treated mice, and by vehicle and 8581 treated Ts65Dn (C) and control (D) mice. *: p<0.05; **: p<0.01; ***: p<0.001 significant ANOVA post T-test. [Figure 9A]Mean ± SEM of latency to reach the platform during eight acquisition sessions by vehicle- and 8581-treated Ts65Dn (A) and control (B) mice, and by vehicle- and R1-treated Ts65Dn (C) and control (D) mice. *: p<0.05; **: p<0.01; ***: p<0.001 significant ANOVA post t-test. [Figure 9B] Mean ± SEM of latency to reach the platform during eight acquisition sessions by vehicle- and 8581-treated Ts65Dn (A) and control (B) mice, and by vehicle- and R1-treated Ts65Dn (C) and control (D) mice. *: p<0.05; **: p<0.01; ***: p<0.001 significant ANOVA post t-test. [Figure 9C] Mean ± SEM of latency to reach the platform during eight acquisition sessions by vehicle- and 8581-treated Ts65Dn (A) and control (B) mice, and by vehicle- and R1-treated Ts65Dn (C) and control (D) mice. *: p<0.05; **: p<0.01; ***: p<0.001 significant ANOVA post t-test. [Figure 9D] Mean ± SEM of latency to reach the platform during eight acquisition sessions by vehicle- and 8581-treated Ts65Dn (A) and control (B) mice, and by vehicle- and R1-treated Ts65Dn (C) and control (D) mice. *: p<0.05; **: p<0.01; ***: p<0.001 significant ANOVA post t-test. [Figure 10] Mean ± SEM of latency to reach the platform during the cued session. *: p<0.05 Ts65Dn vs. control; #: p<0.05; ##: p<0.01 8581 and R1 vs. vehicle. [Figure 11]8581 reverses defects in long-term potentiation in hippocampal slices from Ts65Dn mice after chronic treatment. Data are presented as mean ± SEM of evoked EPSPs recorded from hippocampal slices of vehicle, 8581-treated Ts65Dn (TS) and control (CO) mice. After a stable baseline period of 20 min, high-frequency repetitive stimulation was applied to the hippocampal slices to induce LTP. Field ESPS slopes were normalized and presented as mean ± SEM (n=5-7 / group). *p<0.05 vs. vehicle (V). [Figure 12] R1 reverses defects in long-term potentiation in hippocampal slices from Ts65Dn mice after chronic treatment. Data are presented as mean ± SEM of evoked EPSPs recorded from hippocampal slices of vehicle, R1-treated TS and CO mice. After a stable baseline period of 20 min, high-frequency repetitive stimulation was applied to the hippocampal slices to induce LTP. Excitatory postsynaptic field potential gradients were normalized and presented as mean ± SEM (n = 5-7 / group). * p < 0.05 vs. vehicle (V). [Figure 13] 8581 restores neuronal proliferation in the hippocampus of TS and CO mice. Data are presented as mean ± SEM of density of Ki67+ cells in vehicle and 8581-treated TS and CO mice. ANOVA 'genotype': F(1,20) = 7.39, p = 0.024; 'treatment': F(1,20) = 6.30, p = 0.033; 'genotype x treatment': F(1,20) = 1.81, p = 0.21. **: p < 0.01 TS vs. CO; #: p < 0.05, ##: p < 0.01 vehicle vs. 8581-treated mice; significant ANOVA post Bonferroni's test. [Figure 14A]8581 restored granule cell density in the hippocampus of TS mice. Data are presented as mean ± SEM of the density of DAPI+ cells in the granule cell layer of vehicle- and 8581-treated TS and CO mice (A). ANOVA 'genotype': F(1,20) = 0.51, p = 0.49; 'treatment': F(1,20) = 7.09, p = 0.026; 'genotype x treatment': F(1,20) = 4.00, p = 0.076. *: p < 0.05 TS vs. CO; ##: p < 0.01 vehicle vs. 8581-treated mice; significant ANOVA after Bonferroni's test. (B) Representative images of DAPI immunostaining of vehicle- and 8581-treated TS and CO mice. [Figure 14B] 8581 restored granule cell density in the hippocampus of TS mice. Data are presented as mean ± SEM of the density of DAPI+ cells in the granule cell layer of vehicle- and 8581-treated TS and CO mice (A). ANOVA 'genotype': F(1,20) = 0.51, p = 0.49; 'treatment': F(1,20) = 7.09, p = 0.026; 'genotype x treatment': F(1,20) = 4.00, p = 0.076. *: p < 0.05 TS vs. CO; ##: p < 0.01 vehicle vs. 8581-treated mice; significant ANOVA after Bonferroni's test. (B) Representative images of DAPI immunostaining of vehicle- and 8581-treated TS and CO mice. [Figure 15A] 8581 normalized the percentage of area occupied by GAD+ boutons in the hippocampus of TS mice. Data are presented as mean ± SEM of the percentage of area occupied by GAD+ boutons in the hippocampus of vehicle- and 8581-treated TS and CO mice (A). ANOVA 'genotype': F(1,20) = 0.085, p = 0.77; 'treatment': F(1,20) = 1.14, p = 0.30; 'genotype x treatment': F(1,20) = 7.15, p = 0.017. *: p < 0.05 TS vs. CO; #: p < 0.05 vehicle vs. 8581-treated mice; significant ANOVA after Bonferroni's test. (B) Representative images of GAD immunostaining in vehicle- and RO4938581-treated TS and CO mice. [Figure 15B]8581 normalized the percentage of area occupied by GAD+ boutons in the hippocampus of TS mice. Data are presented as mean ± SEM of the percentage of area occupied by GAD+ boutons in the hippocampus of vehicle- and 8581-treated TS and CO mice (A). ANOVA 'genotype': F(1,20) = 0.085, p = 0.77; 'treatment': F(1,20) = 1.14, p = 0.30; 'genotype x treatment': F(1,20) = 7.15, p = 0.017. *: p < 0.05 TS vs. CO; #: p < 0.05 vehicle vs. 8581-treated mice; significant ANOVA after Bonferroni's test. (B) Representative images of GAD immunostaining in vehicle- and RO4938581-treated TS and CO mice. [Figure 16] 8581 (1 mg / kg) rescues spatial learning deficits in Nf1+ / - mice. Mean percentage of time spent in each quadrant during exploration trials (QL: left of target quadrant; QT: target quadrant; QR: right of target quadrant; QO: opposite target quadrant). [Figure 17] 8581 (1 mg / kg) rescues spatial learning deficits in Nf1+ / - mice. Mean approach to the target platform during exploration trials. [Figure 18] 8581 (1 mg / kg) does not affect the behavior of Nf1+ / - mice under conditions that mask their behavioral deficits. Mean percentage of time spent in each quadrant during exploration trials (QL: left of target quadrant; QT: target quadrant; QR: right of target quadrant; QO: opposite target quadrant). [Figure 19] 8581 (1 mg / kg) does not affect the behavior of Nf1+ / - mice under conditions that mask their behavioral deficits. Mean approach to the target platform during exploration trials. [Figure 20] Contextual conditioning: Dose-response curves in control mice treated with 8581 (0.3, 1.0 and 3.0 mg / kg) (P<0.05). [Figure 21] Contextual conditioning in control mice given 8581 (1 mg / kg) on ​​two consecutive days. [Figure 22] Performance of vehicle or 8581 (1 mg / kg) treated control mice on the rotarod. [Figure 23] Performance of Nf1+ / − mice treated with vehicle or 8581 (1 mg / kg) on ​​the rotarod.

[0220] Abbreviation ANOVA = analysis of variance BZD = benzodiazepine CNS = central nervous system CO = control DS = Down syndrome F = F-test value GABA = gamma aminobutyric acid ip = intraperitoneal LTP = long-term potentiation MANOVA = multivariate analysis of variance MWM = Morris Water Maze p = probability po = orally SEM = standard error of the mean TS = Ts65Dn veh = vehicle

[0221] Example 1. Sensorimotor testing A series of sensorimotor tests was performed according to the procedure described by Rueda N et al. [Neurosci Lett (2008) 433(1):22-27]. Cerebellar and vestibular functions were evaluated in the visual placing reflex test. Mice were gently lowered by their tails from a height of 15 cm onto a flat surface in three consecutive trials. The forepaw extension response was scored on a 0-4 scale [4: forepaw extension when the animal is positioned at the highest height; 3: forepaw extension before the vibrissae touch the surface; 2: forepaw extension after the vibrissae touch the surface; 1: forepaw extension after the nose touches the surface; 0: no extension].

[0222] To assess hearing sensitivity, startle responses to sudden acoustic stimuli were measured. Mice were positioned facing the wall of an unfamiliar cage, and the acoustic stimulus was delivered by clapping two stainless steel forceps (7 cm long) together. A score (0-3 points) was assigned based on the magnitude of the response: jumping >1 cm (3 points); jumping <1 cm (2 points); ear retraction (pliers reflex, 1 point); or no response (0 points).

[0223] The vibrissa placing reflex was analyzed by noting the reflexive response to touching the vibrissa with a cotton swab. Animals that touched the stimulated vibrissa with the ipsilateral paw in three consecutive trials were assigned a score of 1, and no response was assigned a score of 0.

[0224] Grip strength was assessed by quantifying the resistance to being removed from the lid of an aluminum rod (2 mm) when dragged by the tail (0: no resistance, total loss of grip strength; 1: slight; 2: moderate; 3: aggressive; 4: very aggressive resistance, normal grip strength).

[0225] To assess balance, four 20-s balance trials were performed on an elevated (40 cm high) horizontal (50 cm long) rod. Trials 1 and 2 were performed on a flat wooden rod (9 mm wide); trials 3 and 4 were performed on a cylindrical aluminum rod (1 cm diameter). In each trial, the animal was positioned within a marked central zone (10 cm) on the elevated rod. A score of 0 was given if the animal fell within 20 seconds, a score of 1 if the animal remained within the central zone for more than 20 seconds, a score of 2 if the animal left the central zone, and a score of 3 if the animal reached one of the ends of the rod.

[0226] Prehensile reflex (three 5-second trials) was measured as the ability of the animals to remain suspended by their forepaws by grasping an elevated horizontal wire (2 mm diameter). A maximum possible score of 3 was achieved if the animals remained suspended by their forepaws in all three trials (1 point per trial). Pulling ability was scored simultaneously by assessing the number of hind limbs the animals lifted to reach the wire (0: none; 1: 1 limb; 2: 2 limbs).

[0227] Table 3 shows the scores of 8581, R1 and vehicle treated Ts65Dn and control mice in different sensorimotor tests. 8581 or R1 treatment did not modify any of the sensorimotor abilities tested in Ts65Dn or control mice (vision, hearing, strength, balance, grasping reflex, traction ability or motor coordination in the coat hanging test).

[0228] Example 2. Motor coordination: rotarod Motor coordination was assessed using a rotarod apparatus (Ugo Basile; Comerio, Italy), consisting of a plastic rod 37 cm long and 3 cm in diameter rotating at different speeds. In a single session, four trials were performed, each with a maximum duration of 60 seconds. In the first three trials, the rod rotated at constant speeds of 5, 25 and 50 rpm, respectively. The final trial consisted of an acceleration cycle, in which the rod rotated progressively faster and the animal had to adapt to the increasing demands of the test. The length of time each animal remained on the rotarod was recorded.

[0229] As shown in Figures 1 and 2, motor coordination on the rotarod was not modified in mice of either genotype after 8581 or R1 treatment. Ts65Dn and control mice did not differ in the latency to fall from the rotarod at different constant speeds (ANOVA 'genotype': speed 2: F(1,76) = 0.63, p = 0.42; speed 3: F(1,76) = 1.54, p = 0.21) or during accelerating cycles (F(1,76) = 1.87, p = 0.17).

[0230] Furthermore, no differences were found in the latency to fall between 8581 or R1 and vehicle-treated Ts65Dn or control mice at different constant speeds (ANOVA 'Treatment' Speed ​​2: F(1,76) = 0.08, p = 0.92; Speed ​​3: F(1,76) = 1.42, p = 0.24) or during accelerated cycles (F(1,76) = 1.40, p = 0.25).

[0231] MANOVA revealed that there was no significant interaction of the factors 'genotype' and 'treatment' in any of the conditions tested on the rotarod (speed 2: F(1,76) = 0.31, p = 0.72; speed 3: F(1,76) = 0.48, p = 0.61; acceleration. F(1,76) = 0.43, p = 0.64).

[0232] Example 3. Spontaneous Activity: Actimetry This test evaluates the circadian variation of the animals' locomotor activity during a complete 24-h light-dark cycle. The apparatus is a device that detects the changes produced in a magnetic field by the movements of the mouse (Acti-system II, Panlab, Barcelona). It registers the movements of the animals during a continuous 24-h cycle (12 h light and 12 h dark).

[0233] Figures 3 and 4 show that Ts65Dn and control mice (ANOVA 'Genotype' Dark: F(1,76) = 2.79, p = 0.10; Light: F(1,76) = 2.24, p = 0.14) under vehicle, R1 or 8581 treatment (ANOVA 'Treatment' Dark: F(1,76) = 2.20, p = 0.12; Light: F(1,76) = 0.27, p = 0.76; ANOVA 'Genotype x Treatment': Dark: F(1,76) = 0.79, p = 0.45; Light: F(1,76) = 0.39, p = 0.67) did not differ in the amount of locomotor activity performed in their home cages during the dark or light phases of the cycle.

[0234] Example 4. Open field Exploratory behavior and anxiety were assessed using a square-shaped open field (55 cm x 55 cm, surrounded by a 25 cm high enclosure) divided into 25 equal squares. Animals were positioned in the center of the field and vertical (rearing) activity and the number of horizontal crossings (square to square, further subdivided into center vs. periphery crossings) were scored in one 5 min trial.

[0235] In the open field test, no significant differences were found in the activity performed by mice of both genotypes in the center of the maze (ANOVA 'genotype': F(1,76) = 2.77, p = 0.10; Figure 5) or in the number of rearing attempts (F(1,76) = 0.01, p = 0.90; Figure 6). However, vehicle-treated Ts65Dn mice were hyperactive when compared to control mice under the same treatment, as shown by an increase in activity in the periphery (ANOVA 'genotype': F(1,76) = 15.86, p < 0.001; Figure 5) and in overall activity (F(1,76) = 17.39, p < 0.001; Figure 6).

[0236] MANOVA revealed that R1 or 8581 treatment did not significantly affect horizontal (ANOVA 'treatment': periphery: F(1,76) = 1.08, p = 0.34; total number of crossings: F(1,76) = 1.27, p = 0.28) or vertical (rearing F(1,76) = 1.75, p = 0.18) activity in mice of either genotype. The fact that chronic administration of these two compounds did not affect activity in the center of the maze (ANOVA 'treatment': center: F(1,76) = 2.42, p = 0.096) suggests that these compounds did not produce anxiogenic effects in mice of either genotype.

[0237] No significant interaction between 'genotype' and 'treatment' was found in horizontal activity (center F(1,44) = 0.64, p = 0.71; periphery: F(1,76) = 1.06, p = 0.35; total: F(1,76) = 1.00, p = 0.37), but ANOVA revealed a significant effect of these two factors on the number of rearings (F(1,76) = 3.36, p = 0.04).

[0238] Example 5. Exploration activity: Hole board The hole board is a wooden box (32 x 32 x 30 cm) with four holes. The floor is divided into nine 10 cm squares. The number of explorations, the time spent exploring each hole, and the total activity in the apparatus were measured in one 5 min trial. Repetition indices were also calculated as a function of the number of ABA alternations (explorations of previously explored holes).

[0239] Table 4 shows the scores of R1, 8581 and vehicle treated Ts65Dn and control mice in the hole-board test. Ts65Dn mice under all treatments performed more crossings than control mice. 8581 and R1 treatments reduced this hyperactivity as shown by Ts65Dn mice. Ts65Dn mice also showed an increase in the number of explorations performed under all treatment conditions. No differences were found in vertical activity in the maze between Ts65Dn and control mice under different treatments. No significant differences were found between mice of both genotypes and treatments in the time they spent exploring the holes. Ts65Dn mice showed altered attention, since they repeated exploration of recently explored holes more times (ABA index). After 8581 (but not after R1) treatment, the Ts65Dn mice ABA index was normalized.

[0240] Example 6. Spatial learning: Morris water maze To assess spatial learning, the Morris water maze was used. The apparatus consisted of a circular tank 110 cm in diameter filled with water (22–24 °C) made opaque by adding milk powder. Inside the tank, a platform was hidden 1 cm below the water level.

[0241] Animals were tested at the end of the treatment period in 12 consecutive daily sessions: 8 acquisition sessions (platform submerged), followed by 4 cued sessions (platform visible). All trials were videotaped with a camera positioned 2 m above the water level. A SMART computer tracking system (Panlab SA, Barcelona, ​​Spain) was used to analyze mouse trajectories, treatment escape latencies, distance traveled, and swimming speed for each animal in each trial.

[0242] Training Sessions In the acquisition sessions (S1-S8), the platform was hidden 1 cm below the water level. From one daily session to the next, the platform was located in different locations (E, SW, center, and NW); each location was used once in every four consecutive daily sessions. Each of the eight acquisition and four cued sessions (one session per day) consisted of four paired trials separated by 30-45 min. For each pair of trials, the mouse randomly started from one of four locations (N, S, E, W), which was kept constant for both trials. The first trial of the pair ended when the mouse located the platform or when 60 s had elapsed; the second trial started after 20 s, during which the animal was allowed to remain on the platform. Several fixed cues outside the maze were always visible from the pool.

[0243] Clue Session During the cued sessions, the platform was visible: the water level was 1 cm below the platform, and its location was indicated by a flag. During each session, eight trials were conducted following the same experimental procedure as in the acquisition session.

[0244] As shown in Figure 7, mice in all groups learned the platform location throughout the acquisition session, as they decreased their latency to reach the platform (ANOVA 'Session': F(7,65) = 26.8, p < 0.001).

[0245] Ts65Dn mice showed clear learning deficits in the MWM (ANOVA 'genotype': F(1,65) = 39.26, p < 0.001; Figure 8A ), but the difference between the learning curves of Ts65Dn and controls was reduced after 8581 (ANOVA 'genotype': F(1,18) = 4.69, p < 0.05; Figure 8B ) and R1 treatment (ANOVA 'genotype': F(1,26) = 13.57, p < 0.01).

[0246] As shown in FIG. 9A, 8581 treatment significantly improved the behavior of Ts65Dn mice (ANOVA 'Treatment': F(1,24)=32.43, p<0.001). Chronic R1 treatment also improved cognition in Ts65Dn mice (F(1,24)=9.2, p<0.01; FIG. 9C). 8581 (FIG. 9B) or R1 (FIG. 9D) did not significantly affect the behavior of control mice.

[0247] During the cued session (Figure 10), vehicle-treated Ts65Dn mice showed increased latency to reach the platform relative to control mice (ANOVA 'genotype': F(1,46) = 5.35, p = 0.024). R1 ​​and 8581 treatment decreased latency to reach the platform in Ts65Dn (ANOVA 'treatment': F(1,46) = 6.52, p = 0.003), but not in control mice (ANOVA 'genotype x treatment': F(1,46) = 3.44, p = 0.038).

[0248] Example 7. Long-term potentiation (LTP) The effect of chronic administration of 8581 and R1 on LTP was evaluated in the Ts65Dn mouse model of Down's syndrome. 8581, R1 (20 mg / kg orally) or vehicle were administered for 6 weeks. Mice were decapitated 1 h after the last administration and the brains were rapidly removed. The hippocampus was dissected and 400 μm slices were cut with a tissue chopper. The slices were allowed to recover for at least 1 h at room temperature in an interface chamber with artificial cerebrospinal fluid (ACSF) containing (in mM) 120 NaCl, 3.5 KCl, 2.5 CaCl2, 1.3 MgSO4, 1.25 NaH2PO4, 26 NaHCO3 and 10 D-glucose, saturated with 95% O2 and 5% CO2. Excitatory field postsynaptic potentials (fEPSPs) were recorded from the CA1 stratum radiatum using glass micropipettes (1-4 MΩ) containing 2 M NaCl and evoked by stimulating the Schaffer collaterals with an insulated bipolar platinum / iridium electrode >500 μm away from the recording electrode. Stimulation intensity was adjusted to evoke fEPSPs equal to 50% of the relative maximum amplitude without superimposed population spikes. After stable baseline recordings (100 μsec pulse duration, 0.033 Hz), long-term potentiation (LTP) was induced by TBS (10 trains of 5 pulses at 100 Hz with 200 ms intervals). The duration of the stimulation pulses was doubled during tetanus. After 20 min of baseline recordings, LTP was induced and recorded for 80 min in each individual hippocampal slice. Signals from the recording electrodes were amplified and band-pass filtered (1 Hz-1 kHz) and stored on a computer using the Spike 2 program (Spike2, Cambridge Electronic Design, Cambridge, UK). For analysis, fEPSP slopes were expressed as a percentage of the recorded baseline value. Results from several slices were expressed as mean ± SEM. Statistical analysis was performed by repeated measures (RM) MANOVA ('time' x 'treatment' x 'genotype'). All analyses were performed using SPSS for Windows version 18.0.

[0249] As shown in Figures 11 and 12, hippocampal slices from vehicle-treated Ts65Dn mice showed deficits in LTP. In contrast, LTP induced in hippocampal slices from 8581- or R1-treated animals was not different from that induced in hippocampal slices from control mice (Figures 11 and 12, respectively). This suggests that chronic treatment of Ts65Dn mice with 8581 or R1 rescues the deficits in LTP, possibly by reducing the excessive GABA-mediated inhibition observed in these animals.

[0250] Example 8. Neurodevelopment restored Alterations in hippocampal morphology, such as a reduction in granule cell density and hippocampal neurodevelopment, were also associated with the learning deficits exhibited by Ts65Dn mice. Spatial learning is known to depend on the functional integrity of the hippocampus, a structure that plays a key role in encoding and retrieving information in the CNS. We studied the population of newborn cells in the dentate gyrus (DG) by labeling proliferating cells with anti-Ki67, a marker for cells undergoing late G1, and G2 and M phases. We confirmed that hippocampal neurodevelopment was reduced in these mice, and showed that chronic administration of 8581 completely restored the density of proliferating cells in TS mice (p=0.033; Figure 13). Neuronal survival of cells that had undergone maturation was also normalized in TS mice, as indicated by the increase in DAPI+ cells found in TS mice after chronic administration of 8581 (p=0.026; Figure 14).

[0251] Thus, the compound promotes cell proliferation and survival of mature neurons. Because both newborn and mature neurons appear to be involved in hippocampal-dependent learning and memory, restoration of proliferation and mature neuronal density is likely involved in the cognition-enhancing effects of 8581 in TS mice.

[0252] Furthermore, we found an improvement in the number of GABAergic synapses in the hippocampus of TS mice compared to control animals. Importantly, chronic treatment with 8581 reversed this change, as the number of GAD-positive boutons was dramatically reduced after chronic treatment with this selective GABAA α5 NAM (p=0.017; FIG. 15). This treatment produced a non-significant trend to increase the number of these synapses in CO mice.

[0253] Example 9. Spatial learning of Nf1+ / - mice in the Morris water maze One week after treatment, mice were trained for 8-9 days with two consecutive trials per day, 30 min after intraperitoneal injection of 8581 or vehicle. In each trial, mice were given 60 s to find the platform. After each trial, mice were placed on the platform for 15 s. On the day of the exploration trial (days 3, 5, 7, and 9), a 60 s exploration trial was performed after training. In exploration trial 1 (day 3), none of the groups tested learned to search clearly in the target quadrant; exploration trials 3 and 4 (days 7 and 9) showed that the Nf1 / vehicle group was significantly impaired compared to CO / vehicle (two-way ANOVA, quadrant x genotype interaction, F(3,51)=5.662, P<0.01). Importantly, 8581-treated Nf1+ / - mice performed comparable to control animals on all exploration trials, suggesting that 8581 rescued the spatial learning deficits of Nf1+ / - mice. Two different measures of spatial learning (% searches in quadrant (Figure 16) and mean approach to the target platform (Figure 17)) also show that the active pharmaceutical compounds used in the present invention rescue the spatial learning deficits of Nf1+ / - mice (CO / vehicle (n=10), Nf1 / vehicle (n=9), CO / 8581 (n=10), and Nf1 / 8581 (n=11).

[0254] The effect of the active pharmaceutical compounds used in the present invention on the behavior of Nf1+ / - mice was tested under conditions in which the spatial learning of mutants was indistinguishable from controls (fewer deaths due to fewer exploration trials). The average percentage of time spent in each quadrant during exploration trials is plotted in Figure 18. The average approach to the target quadrant is plotted in Figure 19. The results show that vehicle-treated Nf1+ / - mice were indistinguishable from similarly treated control mice. Comparison between the search % in the target quadrant and the approach to the target quadrant did not reveal any differences between groups. In exploration trials 1 and 2 (days 5 and 7), all groups selectively searched in the target quadrant (p<0.01), and there were no differences between groups.

[0255] Example 10. Fear conditioning Control mice (B16;129F1) were trained in the contextual fear conditioning protocol with one trial per day either on one day (Figure 20) or on two consecutive days (Figure 21). On the training day, mice were positioned in the training chamber 30 min after intraperitoneal injection of 8581 or vehicle. A foot shock (1 s, 0.4 mA) was delivered 40 s after positioning. Conditioned responses (percentage of time the mouse freezing) were recorded 24 h after training by using an automated procedure. The average freezing levels were plotted during the first 30 s of each training day and 24 h after the final training trial.

[0256] Dose-response curves (0.3, 1.0 and 3.0 mg / kg) as shown in Figure 20 revealed a dose-dependent increase in contextual fear conditioning in control mice. 3 mg / kg 8581 significantly increased freezing 24 hours after training (p<0.05). As can be seen in Figure 21, 1 mg / kg 8581 also caused a significant increase in contextual conditioning when mice were trained on two consecutive days. Drug-treated mice were significantly more freezing compared to the control / vehicle group (F(1,18)=5.254, p=0.034).

[0257] Example 11. Rotarod Control mice (Bl6;129F1) and Nf1+ / - mice were treated with vehicle or 8581 (n=10 for each of the four groups). Thirty minutes after intraperitoneal injection of 8581 (1 mg / kg) or vehicle, mice were tested using a rotarod protocol with accelerating speed (4-40 rpm, maximum duration 300 sec) for four trials with an intertrial interval of 30 minutes. Figure 22 visualizes the performance of control mice on the rotarod, and Figure 23 illustrates the performance of Nf1+ / - mice on the rotarod. 8581 did not affect the performance of either Nf1+ / - mutant or control mice.

[0258] [Table 1]

[0259] [Table 2]

[0260] [Table 3]

[0261] [Table 4]

[0262] [Table 5]

[0263] [Table 6]

Claims

1. binds to the human GABA A α5β3γ2 receptor subtype with 10-fold or greater binding selectivity compared to its binding affinity to the human GABA A α1β2 / 3γ2, α2β3γ2 and α3β3γ2 receptor subtypes for the treatment, prevention and / or delay of progression of CNS disorders associated with excessive GABAergic inhibition in the cortex and hippocampus; [6-(5-methyl-3-phenyl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-(2-oxa-6-aza-spiro[3.3]hept-6-yl)-methanone; (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(4-fluoro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; {6-[3-(4-chloro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-morpholin-4-yl-methanone; [6-(5-methyl-3-pyridin-2-yl-isoxazol-4-ylmethoxy)-pyridin-3-yl]-morpholin-4-yl-methanone; (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(5-fluoro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone; 20. A pharmaceutical composition comprising a GABA A α5 negative allosteric modulator selected from {6-[3-(5-chloro-pyridin-2-yl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-thiomorpholin-4-yl-methanone; or a pharma- ceutically acceptable salt thereof.

2. 2. The pharmaceutical composition of claim 1, wherein the CNS disorder is selected from cognitive impairment in Down's syndrome, in autism, or in Neurofibromatosis Type I, or is characterized by disability after stroke.

3. 3. The pharmaceutical composition of claim 1 or 2, wherein the GABA A α5 negative allosteric modulator exhibits functional selectivity by acting as an inverse agonist at the human GABA A α5β3γ2 receptor subtype by reducing the effect of GABA by more than 30% and further affecting the effect of GABA at the human GABA A α1β2 / 3γ2, α2β3γ2 and α3β3γ2 receptor subtypes by less than 15%.

4. The pharmaceutical composition according to any one of claims 1 to 3, wherein the GABA A α5 negative allosteric modulator is (1,1-dioxo-1,6-thiomorpholin-4-yl)-{6-[3-(4-fluoro-phenyl)-5-methyl-isoxazol-4-ylmethoxy]-pyridin-3-yl}-methanone or a pharma- ceutically acceptable salt thereof.

5. The pharmaceutical composition according to any one of claims 1 to 4, wherein the GABA A α5 negative allosteric modulator is used in combination with a second active pharmaceutical compound, either separately, sequentially or simultaneously.

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