Diagnostic magnetic stimulation system

Abstract

Apparatus and methods are described including a stimulation subunit (72) that includes stimulation circuitry, configured to connect to a coil (23) positioned over a body of a patient, and pass electrical current through the coil (23), thereby magnetically stimulating the body of the patient. A signal-receiving subunit (74) includes signal-receiving circuitry that is configured to connect to multiple electrodes (22) positioned over the body of the patient, and receive, from the electrodes (22), response signals generated by the body of the patient in response to the magnetic stimulation. A chassis (70) that houses the stimulation circuitry and signal-receiving circuitry includes an internal wall (70w) that physically isolates the stimulation circuitry from the signal-receiving circuitry. Other applications are also described.

Description

[0001] DIAGNOSTIC MAGNETIC STIMULATION SYSTEM

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] The present application claims priority to US Provisional Application 63 / 614,691 to Fogel et al., filed December 26, 2023, entitled “Diagnostic magnetic stimulation system,” which is incorporated herein by reference.

[0004] FIELD OF THE INVENTION

[0005] The present invention is related generally to the field of medical diagnostics, and particularly to diagnostic systems using magnetic stimulation.

[0006] BACKGROUND OF THE INVENTION

[0007] Electrophysiological measurements have been used extensively to characterize and monitor brain network activity. Electrophysiological measurements can be generally divided into two groups of parameters: network integrity, i.e., the connectivity and coherence of the network, and network plasticity, also referred to as “neuroplasticity” or “brain plasticity.” Network connectivity depends on the synchronous activation of neurons. Network coherence refers to the level of synchrony between two or more brain regions and is used to determine the strength of connectivity between specific brain regions. Neuroplasticity is an ability of the brain to continuously adapt its functional and structural organization to changing requirements. Neuronal plasticity allows the brain to reorganize neuronal networks in response to environmental stimulation, to remember information, and to recover from brain and spinal cord injuries. Neuronal plasticity is essential to the establishment and maintenance of brain circuitry.

[0008] Magnetic simulation is a non-invasive brain stimulation method that allows the study of human cortical function in vivo. Using magnetic stimulation for examining human cortical functionality is enhanced by combining such stimulation with registration of an electrical evoked response, such as an electroencephalograph (EEG). EEG provides an opportunity to directly measure the cerebral response to magnetic stimulation, measuring the cortical evoked potential. An important feature of the evoked potential topography is that even though only one cortical hemisphere is stimulated, bi-hemispheric EEG responses are evoked with different features. Magnetic-stimulation- evoked activity propagates from the stimulation site ipsilaterally via association fibers, contralaterally via transcallosal fibers, and to subcortical structures via projection fibers. A single stimulating pulse (delivered over the primary motor cortex (Ml), for example) results in a sequence of positive and negative EEG peaks at specific latencies (typically, negative peaks at 45 ms (N45) and 100 ms (N 100) after stimulation, and positive peaks at 60 ms (P60) and 180 ms (Pl 80) after stimulation). This pattern of response indicates synaptic activity. These evoked cortical potentials last for up to 300 ms both in the vicinity of the stimulation and in remote interconnected brain areas.

[0009] SUMMARY OF THE INVENTION

[0010] Some diagnostic procedures analyze the electrophysiological response of the patient’s brain to magnetic stimulation. Such procedures require a significant amount of specialized hardware, including circuitry for generating the high voltages required for the stimulation and additional circuitry for receiving the brain’s response signals. Moreover, the former circuitry typically generates electromagnetic interference (EMI) and / or capacitive interference that can interfere with both the former circuitry and the latter circuitry.

[0011] Embodiments of the present invention therefore provide the required hardware while also addressing the interference challenge. The hardware includes stimulation circuitry, configured to connect to a coil positioned over the head of a patient and to pass electrical current through the coil, thereby magnetically stimulating the brain of the patient. The hardware further includes signalreceiving circuitry, configured to connect to multiple electrodes positioned over the patient’s head and to receive, from the electrodes, response signals generated by the patient’s brain in response to the magnetic stimulation. (More generally, the stimulation may be applied to, and the response signals may be received from, any suitable portion of the patient’s body.) Advantageously, the stimulation circuitry and signal-receiving circuitry are housed in a single chassis, which includes an internal wall that physically isolates the stimulation circuitry from the signal-receiving circuitry and is typically configured to block electromagnetic interference and / or capacitive interference. Typically, the stimulation circuitry includes one or more electromagnetic interference filters. Alternatively or additionally, to inhibit electrical interference, the stimulation circuitry and signal-receiving circuitry are electrically isolated (i.e., galvanically isolated) from one another.

[0012] Typically, the stimulation circuitry includes a capacitor, which is configured to connect to the coil, and a capacitor charger configured to charge the capacitor. The capacitor is configured to discharge, after being charged by the capacitor charger, such that electrical current passes through the coil, thereby magnetically stimulating the patient’s brain. Due to the large voltage on the capacitor, the capacitor charger is at risk from reverse voltage as the capacitor discharges. To address this challenge, embodiments of the present invention provide a switch, which is positioned between the capacitor charger and the capacitor and is configured to open (typically, under the control of a controller) as the capacitor discharges, such that the capacitor charger is protected from reverse voltage.

[0013] There is therefore provided, in accordance with some embodiments of the present invention, an apparatus including a stimulation subunit that includes stimulation circuitry, configured to connect to a coil positioned over a body of a patient, and to pass electrical current through the coil, thereby magnetically stimulating the body of the patient. The apparatus further includes a signal-receiving subunit that includes signal-receiving circuitry, configured to connect to multiple electrodes positioned over the body of the patient, and to receive, from the electrodes, response signals generated by the body of the patient in response to the magnetic stimulation. The apparatus further includes a chassis that houses the stimulation circuitry and signal-receiving circuitry, and includes an internal wall that physically isolates the stimulation circuitry from the signal-receiving circuitry.

[0014] In some embodiments, the internal wall is configured to protect the signal-receiving circuitry from electromagnetic interference generated by the stimulation circuitry.

[0015] In some embodiments, the internal wall is configured to protect the signal-receiving circuitry from capacitive interference generated by the stimulation circuitry.

[0016] In some embodiments, the stimulation circuitry includes one or more electromagnetic interference filters.

[0017] In some embodiments, the stimulation circuitry and signal -receiving circuitry are electrically isolated from one another.

[0018] In some embodiments, the stimulation circuitry includes: a capacitor; and a capacitor charger, configured to charge the capacitor, and the stimulation circuitry is configured to pass the electrical current through the coil by discharging the capacitor.

[0019] In some embodiments, the stimulation circuitry further includes a switch positioned between the capacitor charger and the capacitor and configured to open so as to protect the capacitor charger from reverse voltage as the capacitor discharges.

[0020] In some embodiments, the stimulation circuitry further includes a controller and an optical fiber that connects the controller to the capacitor charger, the controller being configured to control the capacitor charger via the optical fiber.

[0021] In some embodiments, the stimulation circuitry further includes a switching unit configured to cut off a supply of electricity to the capacitor charger in response to the coil being disconnected from the stimulation circuitry.

[0022] In some embodiments, the stimulation circuitry further includes: a first line, configured to connect to a power supply; and a second line connected to the switching unit, and the apparatus further includes: a first connecting interface, which is connected to the stimulation circuitry; the coil; a cable configured to connect to the coil at a first end of the cable; and a second connecting interface at a second end of the cable and configured to connect the stimulation circuitry to the coil by connecting to the first connecting interface, the second connecting interface including: a first electrically-conductive element configured to connect to the first line when the second connecting interface is connected to the first connecting interface; and a second electrically-conductive element shorted to the first electrically- conductive element and configured to connect to the second line when the second connecting interface is connected to the first connecting interface such that, when the second connecting interface is connected to the first connecting interface, the switching unit is connected to the power supply.

[0023] In some embodiments, the stimulation circuitry further includes a controller configured to control the capacitor charger, and the first line is connected to the controller.

[0024] In some embodiments, the apparatus further includes an optical fiber that connects the stimulation circuitry to the signal-receiving circuitry.

[0025] In some embodiments, the signal-receiving circuitry includes: a universal serial bus (USB) interface; and a converter connected to the optical fiber and to the USB interface and configured to convert signals between the USB interface and the optical fiber.

[0026] There is further provided, in accordance with some embodiments of the present invention, an apparatus including a capacitor, configured to connect to a coil positioned over a body of a patient, and a capacitor charger, configured to charge the capacitor. The capacitor is configured to discharge, after being charged by the capacitor charger, such that electrical current passes through the coil, thereby magnetically stimulating the body of the patient. The apparatus further includes a switch positioned between the capacitor charger and the capacitor and configured to open so as protect the capacitor charger from reverse voltage as the capacitor discharges.

[0027] The present invention will be more fully understood from the following detailed description of embodiments thereof, taken together with the drawings, in which:

[0028] BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Fig. 1 is a schematic illustration of a chnician performing a diagnostic procedure on a patient using a diagnostic system, in accordance with some embodiments of the present invention; and

[0030] Fig. 2 is a schematic diagram of components of a control unit, in accordance with some embodiments of the present invention.

[0031] DETAILED DESCRIPTION

[0032] Reference is initially made to Fig. 1, which is a schematic illustration of a clinician 10 performing a diagnostic procedure on a patient 12 using a diagnostic system 28, in accordance with some embodiments of the present invention.

[0033] System 28 comprises a magnetic stimulation device 20 configured for placement near the head of patient 12, e.g., by virtue of being placed over a cap 30 worn on the head. Device 20 comprises at least one coil 23 (Fig. 2) configured to generate a magnetic field, which stimulates activity within the brain of patient 12. In general, device 20 may be placed over any suitable portion of the patient’s brain, such any suitable portion of the frontal cortex (e.g., the primary motor cortex or dorsolateral prefrontal cortex), occipital cortex, parietal cortex, or temporal cortex of the patient’s brain, so as to stimulate that portion of the brain.

[0034] System 28 further comprises multiple electrodes 22 configured to record respective signals produced by the brain in response to the stimulation. Electrodes 22 may be coupled to the patient’s head via a low-impedance adhesive material. Alternatively, electrodes 22 may be coupled to cap 30 such that, when cap 30 is fittingly placed over the patient’s head, the electrodes contact the head (optionally via an impedance-reducing gel). Typically, electrodes 22 belong to an electroencephalograph (EEG) detector.

[0035] Alternatively, magnetic stimulation device 20 stimulates another portion of the patient’s body, such as another portion of the patient’s nervous system or the patient’s muscular system, and electrodes 22 are positioned to detect the response signals generated by the body of the patient in response to the magnetic stimulation. System 28 further comprises a control unit 24, which comprises stimulation circuitry configured to drive and monitor the operation of magnetic stimulation device 20, and additional circuitry configured to receive the EEG signals recorded by the electrodes. Typically, control unit 24 is connected to stimulation device 20 via a cable 36. Also typically, control unit 24 is connected to an external computing system 34, such as a non-medical workstation (e.g., a laptop), via a wired or wireless communication interface 35, such as a universal serial bus (USB) cable. System 34 comprises a computer processor 32. (Alternatively, the functionality of processor 32, as described herein, is performed by main processor 98 (Fig. 2) or another component belonging to control unit 24, and external computing system 34 is omitted.)

[0036] Processor 32 is configured to drive control unit 24 to generate electrical current in the form of pulses, which flow through device 20 via cable 36. The flow of the electrical current through device 20 causes the device to generate a magnetic field, which in turn evokes signals (or “potentials”) in the patient’s brain. These signals are recorded by the electrodes and passed from the electrodes, typically via leads 118 (Fig. 2), to the control unit. After optional amplifying, denoising, and digitization within control unit 24, processor 32 receives the signals.

[0037] Processor 32 is further configured to process the signals. In response to processing the signals, the processor outputs an output. For example, the processor may display the output on a display 26, which is connected to system 34 over a suitable wired or wireless communication interface.

[0038] In general, processor 32 may be embodied as a single processor, or as a cooperatively networked or clustered set of processors. The functionality of processor 32 may be implemented solely in hardware, e.g., using one or more fixed-function or general-purpose integrated circuits, Application-Specific Integrated Circuits (ASICs), and / or Field-Programmable Gate Arrays (FPGAs). Alternatively, this functionality may be implemented at least partly in software. For example, processor 32 may be embodied as a programmed processor comprising, for example, a central processing unit (CPU) and / or a Graphics Processing Unit (GPU). Program code, including software programs, and / or data may be loaded for execution and processing by the CPU and / or GPU. The program code and / or data may be downloaded to the processor in electronic form, over a network, for example. Alternatively or additionally, the program code and / or data may be provided and / or stored on non-transitory tangible media, such as magnetic, optical, or electronic memory. Such program code and / or data, when provided to the processor, produce a machine or special-purpose computer, configured to perform the tasks described herein.

[0039] Reference is now made to Fig. 2, which is a schematic diagram of components of control unit 24, in accordance with some embodiments of the present invention.

[0040] Control unit 24 comprises a stimulation subunit 72, which comprises stimulation circuitry configured to connect to device 20 and to pass electrical current through coil 23, thereby magnetically stimulating the brain of patient 12. The control unit further comprises a signal-receiving subunit 74, which comprises circuitry configured to connect to electrodes 22 and to receive, from the electrodes, response signals generated by the brain in response to the magnetic stimulation. The control unit further includes a chassis 70, which may be made of a metal (e.g., aluminum), for example. Chassis 70 houses the two subunits and comprises an internal wall 70w that physically isolates the two subunits from one another. Typically, at least by virtue of the material from which it is made, internal wall 70w is configured to protect the signal-receiving circuitry from electromagnetic interference (EMI) and / or capacitive interference generated by the stimulation circuitry, i.e., the internal wall protects signal-receiving subunit 74 from electromagnetic and / or capacitive noise radiated from stimulation subunit 72. Likewise, at least by virtue of the material from which it is made, chassis 70 typically protects both subunits from externally-generated electromagnetic interference and / or capacitive interference. Chassis 70, including internal wall 70w, may have any suitable thickness, such as 1-2 mm.

[0041] Typically, to reduce electrical noise that might interfere with the signal-receiving subunit, the two subunits are electrically isolated (i.e., galvanically isolated) from one another, i.e., there are no electrical connections between the two subunits. Nonetheless, typically, an optical fiber 126 connects the two subunits to one another for communication purposes, e.g., as further described below.

[0042] Control unit 24 further comprises an electrical connector 76, such as a socket, configured to connect the control unit to a supply of electricity, such as the mains electricity. Electrical connector 76 typically comprises a line (L) conductor, a neutral (N) conductor, and a protective earth (PE) conductor, which is typically connected to chassis 70.

[0043] Typically, stimulation subunit 72 comprises a capacitor charger 80 comprising a mains circuit 82, a high-voltage circuit 84, and a step-up transformer 83. Stimulation subunit 72 further comprises a high-voltage capacitor 94. Using electrical energy received via electrical connector 76, capacitor charger 80 charges capacitor 94, e.g., to a voltage of more than 1000 V, such as 2000 V.

[0044] Stimulation subunit 72 further comprises a connecting interface 37, which is connected to the stimulation circuitry. One end of cable 36 is configured to connect to coil 23, while the other end comprises a connecting interface 39 configured to connect the stimulation circuitry to the coil, by connecting to connecting interface 37.

[0045] For example, in some embodiments, one terminal of capacitor 94 is connected to a first line 96a configured to connect to a first conductor 46, which passes through cable 36, via connecting interface 37 and connecting interface 39. Likewise, the other terminal of the capacitor is connected to a second line 96b configured to connect to a second conductor 44, which also passes through cable 36, via the two connecting interfaces. Cable 36 connects to device 20 such that first conductor 46 and second conductor 44 are connected to opposite ends of coil 23.

[0046] Typically, stimulation subunit 72 further comprises a switch 88, comprising a diode for example, which is positioned on first line 96a or second line 96b. To pass each pulse of electrical current through coil 23, switch 88 is closed, such that capacitor 94 discharges. Typically, the length of each stimulating pulse is between 280 and 380 ps, e.g., approximately 300 ps. The interval between consecutive pulses, during which switch 88 is open and the capacitor is recharged, may have any suitable value, such as 300-500 ms, 500 ms - 1 s, or 1-2 s.

[0047] Typically, stimulation subunit 72 further comprises another switch 92, comprising a metal- oxide- semiconductor field-effect transistor (MOSFET), for example, positioned on a line 97a or a line 97b between capacitor charger 80 and capacitor 94. Switch 92 is configured to open so as to protect capacitor charger 80 from reverse voltage as capacitor 94 discharges. For example, switch 92 may open shortly (e.g., 10 ms) before each pulse, and close shortly (e.g., 10 ms) after the pulse so that the capacitor can recharge. (Nonetheless, in some embodiments, to avoid interfering with the recording of the EEG signals, the recharging does not begin immediately after the closing of switch 92.)

[0048] Typically, stimulation subunit 72 further comprises a main processor 98, also referred to herein as a controller, configured to perform control and monitoring functionality. In some embodiments, some of this functionality is performed via a high-voltage (HV) control unit 90, which is electrically connected to controller 98.

[0049] For example, controller 98 may control capacitor charger 80 via an optical fiber 102, which connects the controller to the capacitor charger while, for safety, maintaining the electrical isolation of controller 98 from the capacitor charger.

[0050] Alternatively or additionally, controller 98 controls the delivery of pulses to coil 23, while configuring the pulses in accordance with user instructions. For example, controller 98 may communicate control signals 108 to HV control unit 90, in response to which the HV control unit may open and close switches 88 and 92 as required.

[0051] Alternatively or additionally, the controller exchanges signals with magnetic stimulation device 20 via interface 37 and control wires 52 passing through cable 36.

[0052] Typically, main processor 98 is powered via a lower-voltage line 101, which is supplied by a step-down transformer 100 configured to step the voltage from electrical connector 76 down to the lower voltage and to convert the voltage to direct current (DC).

[0053] In some embodiments, stimulation subunit 72 further comprises a switching unit (or "safety relay") 86 configured to cut off the supply of electricity to the capacitor charger in response to coil 23 being disconnected from the stimulation circuitry. For example, switching unit 86 may comprise a switch 87 configured to connect or disconnect capacitor charger 80 from the L line, and / or a switch 87 configured to connect or disconnect the capacitor charger from the N line, and a switch control 89 configured to open and close switches 87.

[0054] In some embodiments, switching unit 86 (e.g., switch control 89 of the switching unit) is connected to a line 112. Interface 37 comprises an electrically-conductive element lOle, which is connected to line 101 (or to another line connected to the power supply), and another electrically- conductive element 112e, which is connected to line 112. Connecting interface 39 comprises a pair of electrically-conductive elements (e.g., pins) 114a and 114b. Elements 114a and 114b are shorted to one another and are configured to connect to electrically-conductive elements 112e and lOle, respectively, when connecting interface 39 is connected to connecting interface 37. Thus, when the connecting interfaces are connected to one another (such that coil 23 is connected to the stimulation circuitry), the switching unit is connected to the power supply. In response thereto, switching unit 86 keeps switches 87 closed. On the other hand, when cable 36 is disconnected, the switching unit keeps switches 87 open. Thus, switching unit 86 ensures that capacitor charger 80 remains inactive while control unit 24 is disconnected from the magnetic stimulation device.

[0055] In some embodiments, for safety, stimulation subunit 72 further comprises another switch 136, which is connected to line 112. Upon the disconnection of cable 36 - and hence, the disconnection of line 112 from the power supply - switch 136 closes, such that capacitor 94 discharges.

[0056] Signal-receiving subunit 74 comprises a connector 116, configured to connect to electrodes 22 via respective electrode leads 118. Typically, connector 116 comprises multiple (e.g., between 24 and 56) channels, one channel per electrode.

[0057] Typically, signal-receiving subunit 74 further comprises a recording amplifier 122, which is connected to connector 116 and is configured to amplify, denoise, and digitize the EEG signals received, from electrodes 22, via connector 116. For example, for each channel, recording amplifier 122 may comprise a respective amplifier 122a, a respective analog filter 122f, and a respective digitizer 122d. Typically, recording amplifier 122 samples the EEG signals at a relatively high frequency, such as a frequency greater than 4 kHz.

[0058] Typically, recording amplifier 122 further comprises a processor 122p, which is configured to aggregate the signals. In some embodiments, processor 122p is also configured to digitally filter the signals. Typically, recording amplifier 122 further comprises a communication interface 122c. Processor 122p communicates the aggregated EEG signals, via communication interface 122c, to a USB interface 120 (or to any other suitable communication interface), via which the signals are communicated, over communication interface 35, to external computing system 34. As described above with reference to Fig. 1, system 34 comprises processor 32, which is configured to process the EEG signals.

[0059] Typically, in addition to receiving the signals from recording amplifier 122, processor 32 is configured to exchange other communication with stimulation subunit 72 and / or signal-receiving subunit 74 via USB interface 120 (or any other suitable communication interface). For example, processor 32 may instruct controller 98 to generate each pulse with any particular specifications. Alternatively or additionally, controller 98 may communicate, to processor 32, any information obtained from the monitoring of stimulation subunit 72. Alternatively or additionally, processor 32 may configure amplifier 122.

[0060] Typically, additional communication is exchanged between the two subunits of control unit 24. For example, after triggering each pulse, the controller may instruct recording amplifier 122 to start recording the EEG signals.

[0061] Typically, to facilitate the aforementioned communication, control unit 24 further comprises an optical fiber 126, which runs between controller 98 and signal-receiving subunit 74. Typically, signal-receiving subunit 74 comprises an interface board 124, which is connected to USB interface 120 and to recording amplifier 122 via electrical lines, and optical fiber 126 connects controller 98 to interface board 124. Interface board 124 comprises a converter configured to convert signals between the optical fiber and USB interface, i.e., to provide optical-to-USB and USB-to-optical conversion, thereby facilitating communication between the controller and processor 32.

[0062] In some embodiments, capacitor charger 80 is disposed within an electromagnetic interference cage 148, whose construction is typically similar to that of chassis 70. For example, electromagnetic interference cage 148 may be made of a metal (e.g., aluminum), such that electromagnetic interference cage 148 blocks electromagnetic interference. Alternatively or additionally, one or more filters protect the components of control unit 24 from electromagnetic interference. For example, an electromagnetic interference filter 130 may be connected to the PE conductor of electrical connector 76; advantageously, this filter may qualify control unit 24 as a "class B" medical device, such that the control unit may be used within an outpatient (e.g., home) setting. Alternatively or additionally, another electromagnetic interference filter 132 may be connected between main processor 98 and ground.

[0063] It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof that are not in the prior art, which would occur to persons skilled in the art upon reading the foregoing description.

Claims

CLAIMS1. An apparatus, comprising: a stimulation subunit that comprises stimulation circuitry, configured to: connect to a coil positioned over a body of a patient, and pass electrical current through the coil, thereby magnetically stimulating the body of the patient; a signal-receiving subunit that comprises signal-receiving circuitry, configured to: connect to multiple electrodes positioned over the body of the patient, and receive, from the electrodes, response signals generated by the body of the patient in response to the magnetic stimulation; and a chassis that houses the stimulation circuitry and signal-receiving circuitry, and comprises an internal wall that physically isolates the stimulation circuitry from the signal-receiving circuitry.

2. The apparatus according to claim 1, wherein the internal wall is configured to protect the signal-receiving circuitry from electromagnetic interference generated by the stimulation circuitry.

3. The apparatus according to claim 1, wherein the internal wall is configured to protect the signal-receiving circuitry from capacitive interference generated by the stimulation circuitry.

4. The apparatus according to claim 1, wherein the stimulation circuitry comprises one or more electromagnetic interference filters.

5. The apparatus according to claim 1, wherein the stimulation circuitry and signal-receiving circuitry are electrically isolated from one another.

6. The apparatus according to any one of claims 1-5, wherein the stimulation circuitry comprises: a capacitor; and a capacitor charger, configured to charge the capacitor, and wherein the stimulation circuitry is configured to pass the electrical current through the coil by discharging the capacitor.

7. The apparatus according to claim 6, wherein the stimulation circuitry further comprises a switch positioned between the capacitor charger and the capacitor and configured to open so as to protect the capacitor charger from reverse voltage as the capacitor discharges.

8. The apparatus according to claim 6, wherein the stimulation circuitry further comprises a controller and an optical fiber that connects the controller to the capacitor charger, the controller being configured to control the capacitor charger via the optical fiber.

9. The apparatus according to claim 6, wherein the stimulation circuitry further comprises a switching unit configured to cut off a supply of electricity to the capacitor charger in response to the coil being disconnected from the stimulation circuitry.

10. The apparatus according to claim 9, wherein the stimulation circuitry further comprises: a first line, configured to connect to a power supply; and a second line connected to the switching unit, and wherein the apparatus further comprises: a first connecting interface, which is connected to the stimulation circuitry; the coil; a cable configured to connect to the coil at a first end of the cable; and a second connecting interface at a second end of the cable and configured to connect the stimulation circuitry to the coil by connecting to the first connecting interface, the second connecting interface comprising: a first electrically-conductive element configured to connect to the first line when the second connecting interface is connected to the first connecting interface; and a second electrically-conductive element shorted to the first electrically- conductive element and configured to connect to the second line when the second connecting interface is connected to the first connecting interface such that, when the second connecting interface is connected to the first connecting interface, the switching unit is connected to the power supply.

11. The apparatus according to claim 10, wherein the stimulation circuitry further comprises a controller configured to control the capacitor charger, and wherein the first line is connected to the controller.

12. The apparatus according to any one of claims 1-5, further comprising an optical fiber that connects the stimulation circuitry to the signal-receiving circuitry.

13. The apparatus according to claim 12, wherein the signal-receiving circuitry comprises: a universal serial bus (USB) interface; and a converter connected to the optical fiber and to the USB interface and configured to convert signals between the USB interface and the optical fiber.

14. An apparatus, comprising: a capacitor, configured to connect to a coil positioned over a body of a patient;a capacitor charger, configured to charge the capacitor, the capacitor being configured to discharge, after being charged by the capacitor charger, such that electrical current passes through the coil, thereby magnetically stimulating the body of the patient; and a switch positioned between the capacitor charger and the capacitor and configured to openotect the capacitor charger from reverse voltage as the capacitor discharges.

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