Space memory task device and paradigm method based on egocentric and allocentric navigation strategy

Abstract

The application provides a spatial memory task device and a paradigm method based on a self-center and heterocentric navigation strategy. The device comprises an open field, a reward plate and a rest box. The open field is formed by a bottom plate and four side plates and has an open top end. The rest box opening is formed in the middle of the four side plates. The rest box door is installed at the rest box opening. The rest box is installed outside the side plate and is arranged correspondingly to the rest box opening. The reward wells are uniformly distributed on the reward plate. The reward wells are used for containing water. The reward plate is placed on the bottom plate. The experimental process comprises water limiting of the rats before the experiment and the experimental stage, i.e. a free exploration stage and a spatial memory task stage. The beneficial effects of the application are as follows: the paradigm method is used to measure the navigation strategy priority of the rats when the rats navigate, and to evaluate the strategy damage of the rats with Alzheimer's disease and how the rats with Alzheimer's disease navigate after the damage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of navigation strategy use of rats in spatial navigation, and more particularly to a spatial memory task device and paradigm method based on egocentric and allocentric navigation strategies. BACKGROUND

[0002] With the aggravation of population aging in China, Alzheimer's disease (AD) has become the most typical cognitive impairment disease and the incidence rate is increasing year by year, and it is the main cause of disability and death of the elderly in today's aging society. The World Health Organization reported in 2021 that the global AD patients have exceeded 30 million, among which, the AD patients over 60 years old in China have reached 9.83 million, and the mild cognitive impairment (MCI) patients have also reached 38.77 million, ranking first in the world.

[0003] AD, as the most common dementia, its main clinical manifestations are memory impairment, among which, spatial memory impairment is one of the most typical symptoms in the early stage of AD, which occurs in more than 60% of patient population. Spatial memory is a kind of memory for representing the geographical position and direction of the external environment, which is closely related to the self and the environment. When performing spatial navigation, both humans and rats will rely on the spatial memory formed under a certain navigation strategy to complete the goal-oriented positioning. Existing researches show that the navigation strategy is divided into egocentric navigation strategy which relies on the self direction sense and allocentric navigation strategy which relies on the world coordinates, and the use of navigation strategy is a necessary condition for efficient completion of spatial navigation. In addition, the research on clinical AD found that, compared with healthy elderly people, the allocentric navigation strategy of AD patients is impaired.

[0004] However, at present, there is still no experimental paradigm in the research on rodents that can measure the priority of different navigation strategies in spatial memory tasks, and evaluate the strategy damage of AD rats and how to perform precise goal-oriented navigation after the damage. Based on this status, the technical personnel in the field propose a spatial memory task paradigm method based on egocentric and allocentric navigation strategies for evaluating the strategy damage of AD rats and how to perform precise goal-oriented navigation after the damage. SUMMARY

[0005] The present application overcomes the deficiencies in the prior art and provides a spatial memory task device and paradigm method based on egocentric and allocentric navigation strategies, which measures the priority of navigation strategies in spatial navigation of rats and evaluates the strategy damage of AD rats and how to perform precise goal-oriented navigation after the damage based on the above-mentioned paradigm method.

[0006] The object of the present application is achieved by the following technical solutions.

[0007] The device for spatial memory task based on egocentric and allocentric navigation strategy comprises an open field, a reward plate and a rest box, wherein the open field is formed by a bottom plate and four side plates, the open field is open at the top end, a rest box opening is formed in the middle of each of the four side plates, a rest box door is installed at the rest box opening, the rest box is installed outside the side plate and is arranged corresponding to the rest box opening, and the reward plate is placed on the bottom plate and is uniformly provided with reward wells for containing water.

[0008] The bottom plate adopts a plate structure with a size of 120cm*120cm*40cm, the side plate is spliced by two plate structures with a size of 50cm*40cm and one plate structure with a size of 20cm*40cm, and the plate structure with a size of 20cm*40cm is used as the rest box door.

[0009] The reward plate adopts a wooden plate structure with a size of 120cm*120cm*1.5cm.

[0010] The reward well adopts a conical structure with a diameter of 1.5cm and a height of 5mm, the number of the reward wells is 36, and the reward wells are uniformly distributed on the reward plate in the form of 6 rows and 6 columns.

[0011] The rest box adopts an open-top box structure with a size of 28cm*21cm*31cm, an exit is formed on one side wall of the rest box, and a rat can enter the open field through the rest box door from the exit.

[0012] Visual cues for fixing landmarks and distinguishing directions are arranged on the inner wall of the side plate, the visual cues are selected in different shapes to distinguish different landmarks and directions, and the shapes of the visual cues can be, for example, oval, arrow, trapezoid, triangle, diamond, rectangle and square.

[0013] The paradigm method for spatial memory task based on egocentric and allocentric navigation strategy is performed according to the following steps:

[0014] (1) Before the experiment starts, the rats are limited to water every day, and the water limit standard is that, in the formal test period of two weeks, i.e. 14 days, the rats are allowed to drink water freely for only 1h per day;

[0015] (2) Each day experiment includes two stages, i.e. a free exploration stage and a spatial memory task stage:

[0016] Firstly, the free exploration stage is performed: 4 reward wells are randomly selected as reward positions in the reward wells, and 200 microliters of water is respectively contained in the above reward wells as rewards;

[0017] After the rat enters the open field from the rest box, the rest box door is closed, at this time, a medium frequency sound is accompanied to prompt the start of the free exploration stage, after the rat explores in the open field for 5 minutes, the rest box door is opened, and the rat returns to the rest box, at this time, a low frequency sound is accompanied to prompt the end of the free exploration stage, and after a delay of 2 minutes, the spatial memory task stage starts, and a wet towel is used to wipe the surface of the reward plate during the delay period to remove the odor marks left by the rat;

[0018] Then, the spatial memory task stage is performed, and the spatial memory task stage includes: a self-center spatial memory task stage and an eccentric spatial memory task stage:

[0019] The self-center spatial memory task stage: one of the four reward wells in the free exploration stage is selected as the only reward position in the self-center spatial memory task, and 200 microliters of water is filled as the reward;

[0020] After the rat enters the rest box, the rest box door is closed, at this time, a medium frequency sound is accompanied to prompt the start of an experiment, after the rat finds the reward well containing water in the open field, a high frequency sound is accompanied to indicate that the correct reward position is found;

[0021] After the rat finds the reward and returns to the rest box, the rest box door is closed, at this time, a low frequency sound is accompanied to prompt the end of the above experiment, and the above experiment process is repeated, a total of 10 experiments, each experiment interval is 30 seconds, after completing 10 experiments, a stage experiment is completed, after a delay of 1 minute after completing the above stage experiment, the rest box position is replaced for the next stage experiment, the rest box position is replaced during the above delay period, and the reward well position containing water corresponding to the replaced rest box position is set to ensure that the position of the rest box and the reward well containing water in the next stage experiment is relatively unchanged compared with the last stage experiment, at the same time, a wet towel is used to wipe the surface of the reward plate to remove the odor marks left by the rat, and the above experiment is repeated 10 times;

[0022] In the self-center spatial memory task stage each day, the rest box position needs to be replaced 4 times, that is, 4 stage experiments are performed, and each stage experiment includes 10 experiments, that is, 40 experiments need to be completed each day;

[0023] The eccentric spatial memory task stage: one of the four reward wells in the free exploration stage is selected as the only reward position in the eccentric spatial memory task, and 200 microliters of water is filled as the reward;

[0024] After the rat enters the rest box, the rest box door is closed, at this time, a medium frequency sound is accompanied to prompt the start of an experiment, after the rat finds the reward well containing water in the open field, a high frequency sound is accompanied to indicate that the correct reward position is found;

[0025] After the rat finds the reward and returns to the resting box, the door of the resting box is closed, at this time, a low-frequency sound is accompanied to prompt the end of the above experiment, and the above experiment process is repeated, a total of 10 experiments, each experiment interval is 30s, after completing 10 experiments, a stage experiment is completed, after delaying 1min after completing the above stage experiment, the resting box position is replaced for the next stage experiment, the resting box position is replaced during the above delay period, and the position of the reward well containing water is fixed unchanged, at the same time, a wet towel is used to wipe the surface of the reward plate to remove the odor marks left by the rat, and the above experiment is repeated 10 times;

[0026] In the trans-chamber spatial memory task stage every day, the resting box position needs to be replaced 4 times, that is, 4 stage experiments are performed, and each stage experiment includes 10 experiments, that is, 40 experiments need to be completed every day.

[0027] In the experiment, we found that the use of the above navigation strategy dependent spatial memory task paradigm can not only study the discharge characteristics of grid cells in two-dimensional open field and the damage pattern of grid cells in AD rats, but also analyze the use and damage of rat navigation strategy according to the path trajectory and discharge characteristics of rat in spatial memory task on the same day, that is, whether the rat uses egocentric or allocentric strategy, or first uses egocentric and then gradually changes to allocentric strategy, which can create conditions for scientific research of spatial navigation.

[0028] The two-dimensional space in actual life is simulated, different visual cues are arranged in the inner side of the four side plates of the open field to simulate fixed landmarks in the actual environment, which can prevent the rat from getting lost in the open field, and the rat can distinguish the direction according to the different visual cues with fixed position, the rat only needs to judge the position of the reward well, so as to simulate the multi-strategy spatial navigation.

[0029] The rat is not limited to linear track, and the direction selectivity and strategy flexibility of the rat are increased.

[0030] During the experiment, if the rat always cannot find the reward well position, or some experiments in the experiment are wrong due to the rat, the experiment personnel can quickly change the experiment program and re-record.

[0031] The beneficial effects of this invention are as follows: Compared with the prior art, the innovation of this invention lies in the fact that the behavioral device used in rats is a multi-strategy spatial memory task based on a two-dimensional open field and including multiple reward wells. This experimental device simulates the complexity of the actual environment as much as possible. This experimental paradigm also measures the priority of strategy use in distinguishing normal and AD rats, as well as the impairment pattern of navigation strategies in AD, from egocentric and heterocentric spatial memory tasks. This experimental paradigm is currently the only method that can not only analyze the representation of egocentric / heterocentric spatial information by entorhinal cortex grid cells, but also specifically analyze the priority of strategy use in spatial navigation, the impairment of certain strategies in AD rats, and how to perform correct goal-oriented navigation. Therefore, this experimental paradigm provides a feasible method for current research on navigation strategies and for the neural basis research on spatial cognitive dysfunction in AD rats. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the experimental apparatus of the present invention;

[0033] Figure 2 This is a flowchart of the paradigm method of this invention;

[0034] Figure 3 This is a graph showing the behavioral performance of 12-month-old AD rats and WT rats on a spatial memory task.

[0035] Figure 4 This is a graph showing the behavioral performance of 5-month-old AD rats and WT rats on a spatial memory task;

[0036] In the image: 1 is the rest box, 2 is the side panel, 3 is the reward board, 4 is the reward well, 5 is the rest box door, and 6 is a visual cue. Detailed Implementation

[0037] The technical solution of the present invention will be further described below through specific embodiments.

[0038] like Figure 1 As shown, a spatial memory task device based on self-centered and heterocentric navigation strategies includes an open field, a reward plate 3, and a rest box 1. The open field is formed by a base plate and four side plates 2, with an open top. Rest box openings are formed in the middle of the four side plates 2, and rest box doors 5 are installed at these openings. The rest box 1 is installed on the outside of the side plates 2, corresponding to the rest box openings. Reward wells 4 are evenly distributed on the reward plate 3, used to hold water. The reward plate 3 is placed on the base plate. Figure 1 As shown;

[0039] The bottom plate adopts a plate structure with a specification of 120 cm x 120 cm x 40 cm, the side plate 2 is spliced by two plate structures with a specification of 50 cm x 40 cm and one plate structure with a specification of 20 cm x 40 cm, and the plate structure with a specification of 20 cm x 40 cm serves as the rest box door 5.

[0040] The reward plate 3 adopts a wooden plate structure with a specification of 120 cm x 120 cm x 1.5 cm.

[0041] The reward well 4 adopts a conical structure with a diameter of 1.5 cm and a height of 5 mm, and the number of the reward well 4 is 36, which are evenly distributed on the reward plate 3 in the form of 6 rows and 6 columns.

[0042] The rest box 1 adopts a top-open box structure with a specification of 28 cm x 21 cm x 31 cm, and an exit is formed on one side wall of the rest box 1, so that the rat can leave the rest box 1 through the exit and enter the open field through the rest box door 5.

[0043] Visual cues 6 for fixing landmarks and distinguishing directions are arranged on the inner wall of the side plate 2, and the visual cues 6 are selected in different shapes to distinguish different landmarks and directions, and in this embodiment, the shapes of the visual cues 6 are respectively an ellipse, an arrow, a trapezoid and a triangle.

[0044] As shown in Figure 2 , the space memory task paradigm method based on the egocentric and allocentric navigation strategy is performed according to the following steps:

[0045] (1) Before the experiment starts, the rats are water-restricted every day, and the water-restriction standard is that during the formal test period, the formal test period is two weeks, i.e. 14 days, and the rats are only allowed to drink water freely for 1 hour every day;

[0046] (2) Each day's experiment includes two stages, i.e. a free exploration stage and a space memory task stage, as shown in Figure 2 .

[0047] Firstly, the free exploration stage is performed: 4 reward wells are randomly selected from the 36 reward wells as reward positions, and 200 microliters of water is respectively placed in the above reward wells as rewards;

[0048] After the rat enters the open field from the rest box, the rest box door is closed, at this time, a medium frequency sound prompts the start of the free exploration stage, after the rat explores in the open field for 5 minutes, the rest box door is opened to let the rat return to the rest box, at this time, a low frequency sound prompts the end of the free exploration stage, and after a delay of 2 minutes, the space memory task stage starts, and a wet towel is used to wipe the surface of the reward plate during the delay period to remove the odor marks left by the rat;

[0049] Then, a spatial memory task phase is performed, and the spatial memory task phase includes: a egocentric spatial memory task phase and an allocentric spatial memory task phase:

[0050] The egocentric spatial memory task phase: one of the four reward wells in the free exploration phase is selected as the only reward position in the egocentric spatial memory task, and 200 microliters of water is placed in the reward well as a reward;

[0051] After the rat leaves the rest box, the rest box door is closed, at this time, a medium frequency sound prompts the start of an experiment, and after the rat finds the reward well containing water in the open field, a high frequency sound is prompted, indicating that the correct reward position is found;

[0052] After the rat finds the reward and returns to the rest box, the rest box door is closed, at this time, a low frequency sound prompts the end of the above experiment, and the above experiment process is repeated, a total of 10 experiments, each experiment interval is 30s, after completing 10 experiments, a phase experiment is completed, after a delay of 1 min after completing the above phase experiment, the rest box position is replaced for the next stage experiment, the rest box position is replaced during the above delay, and the reward well position containing water is set according to the replaced rest box position, so that the position of the rest box and the reward well containing water in the next stage experiment is relatively unchanged, at the same time, a wet towel is used to wipe the surface of the reward plate to remove the odor marks left by the rat, and the above experiment is repeated 10 times;

[0053] In the egocentric spatial memory task phase each day, the rest box position needs to be replaced 4 times, that is, 4 stage experiments are performed, and each stage experiment includes 10 experiments, that is, 40 experiments need to be completed each day;

[0054] The allocentric spatial memory task phase: one of the four reward wells in the free exploration phase is selected as the only reward position in the allocentric spatial memory task, and 200 microliters of water is placed in the reward well as a reward;

[0055] After the rat leaves the rest box, the rest box door is closed, at this time, a medium frequency sound prompts the start of an experiment, and after the rat finds the reward well containing water in the open field, a high frequency sound is prompted, indicating that the correct reward position is found;

[0056] After the rat finds the reward and returns to the rest box, the rest box door is closed, at this time, a low-frequency sound is accompanied to prompt the end of the above experiment, the above experiment is repeated, a total of 10 experiments, each experiment interval is 30s, after completing 10 experiments, it is completed one stage experiment, after completing the above one stage experiment, delay 1min, change the rest box position for the next stage experiment, change the rest box position during the above delay period, and ensure that the position of the reward well containing water is fixed, at the same time, the surface of the reward plate needs to be wiped with a wet towel to remove the odor marks left by the rat, and the above experiment is repeated 10 times;

[0057] In the allocentric spatial memory task stage every day, the rest box position needs to be changed 4 times, that is, 4 stage experiments are performed, and each stage experiment includes 10 experiments, that is, 40 experiments need to be completed every day.

[0058] The two-dimensional space in actual life is simulated, different visual clues 6 are arranged on the inner sides of the four side plates 2 of the open field to simulate fixed landmarks in the actual environment, the rat only needs to judge the position of the reward well, thereby simulating the multi-strategy space navigation condition.

[0059] In order to verify the feasibility of the paradigm method of the present application, in the early stage, we respectively use 12-month-old and 5-month-old AD rats and normal rats for testing.

[0060] The test simply includes two stage experiments, each stage experiment includes 5 experiments, and the time consumed before finding the reward position (i.e. latency) is used to measure the behavior performance. The test results show that after changing the starting direction, whether it is an allocentric task or an egocentric task, the latency of 12-month-old and 5-month-old AD rats to find the reward position is significantly longer than that of normal rats (i.e. WT rats), which shows that the allocentric and egocentric navigation strategies of AD rats are damaged from 5 months old. From the overall test, the first three experiments in each stage experiment of AD rats and normal rats have learned the experimental paradigm, and the time consumption of the last few experiments in each stage experiment is relatively stable, which shows that AD rats and normal rats can learn the experimental paradigm, as shown in Figure 3 and Figure 4 .

[0061] The above is an exemplary description of the present application, it should be noted that any simple modification, modification or other equivalent replacement which can not cost creative labor of those skilled in the art without departing from the core of the present application falls within the protection scope of the present application.

Claims

1. A paradigmatic method for a spatial memory task device based on self-centered and heterocentric navigation strategies, characterized in that, The spatial memory task device based on self-centered and heterocentric navigation strategies includes an open field, a reward board, and a rest box. The open field is formed by a base plate and four side plates, with an open top. A rest box opening is formed in the middle of the four side plates, and a rest box door is installed at the rest box opening. The rest box is installed on the outside of the side plates and is positioned corresponding to the rest box opening. Reward wells are evenly distributed on the reward board, and the reward wells are used to hold water. The reward board is placed on the base plate. The paradigm approach is performed according to the following steps: (1) Before the experiment, the rats were given a daily water restriction. (2) The daily experiment consists of two phases: a free exploration phase and a spatial memory task phase. First, a free exploration phase will be conducted: four reward wells will be randomly selected as reward locations, and 200 microliters of water will be placed in each of these reward wells as a reward. After the rats entered the open field from the rest box, the door of the rest box was closed. After the rats explored the open field for 5 minutes, the door of the rest box was opened and the rats were allowed to return to the rest box. After a 2-minute delay, the spatial memory task phase began. Then, the spatial memory task phase is carried out, which includes: the self-centered spatial memory task phase and the heterocentric spatial memory task phase. Self-centered spatial memory task phase: Select one of the four reward wells in the free exploration phase as the only reward location in the self-centered spatial memory task, and fill it with 200 microliters of water as a reward; After the rats leave the rest box, the door is closed. The rats find the reward well filled with water in the open field. After finding the reward, the rats return to the rest box, the door is closed, and the above experimental process is repeated. A total of 10 experiments are conducted, with a 30-second interval between each experiment. After completing 10 experiments, one stage of the experiment is completed. After completing one stage of the experiment, there is a 1-minute delay before the rest box is moved to the next stage of the experiment. During the above delay, the rest box is moved to the next stage of the experiment, and the reward well filled with water is set at the corresponding new rest box location to ensure that the positions of the rest box and the reward well filled with water remain relatively unchanged from the previous stage of the experiment. The above experiment is repeated 10 times. During the daily self-centered spatial memory task phase, the rest box location needs to be changed 4 times, which means 4 phase experiments are conducted. Each phase experiment contains 10 experiments, meaning 40 experiments need to be completed each day. The Other-Centered Space Memory Task Phase: Select one of the four reward wells from the free exploration phase as the sole reward location in the Other-Centered Space Memory Task, and fill it with 200 microliters of water as a reward; After the rats leave the rest box, the door of the rest box is closed. The rats find the reward well filled with water in the open field. After finding the reward, the rats return to the rest box, the door of the rest box is closed, and the above experimental process is repeated. A total of 10 experiments are conducted, with a 30-second interval between each experiment. After completing 10 experiments, one stage of the experiment is completed. After completing the above stage of the experiment, there is a 1-minute delay before the rest box is moved to the next stage of the experiment. During the above delay, the rest box is moved to the next stage of the experiment, while the position of the reward well filled with water remains unchanged. The above experiment is repeated 10 times. During the daily heterocentric spatial memory task phase, the rest box location needs to be changed 4 times, which means 4 phase experiments are conducted. Each phase experiment contains 10 experiments, meaning 40 experiments need to be completed each day.

2. The paradigmatic method for a spatial memory task device based on self-centered and heterocentric navigation strategies according to claim 1, characterized in that: The base plate is a plate-shaped structure with a size of 120cm×120cm×40cm. The side plate is made up of two plate-shaped structures with a size of 50cm×40cm and one plate-shaped structure with a size of 20cm×40cm. The 20cm×40cm plate-shaped structure serves as the door of the rest box.

3. The paradigmatic method for a spatial memory task device based on self-centered and heterocentric navigation strategies according to claim 1, characterized in that: The award board is made of a wooden board with dimensions of 120cm×120cm×1.5cm.

4. The paradigm method for a spatial memory task device based on self-centered and heterocentric navigation strategies according to claim 3, characterized in that: The reward wells are conical structures with a diameter of 1.5cm and a height of 5mm. There are 36 reward wells, which are evenly distributed on the reward plate in a 6-row, 6-column configuration.

5. The paradigmatic method for a spatial memory task device based on self-centered and heterocentric navigation strategies according to claim 1, characterized in that: The resting box has a top-opening box-shaped structure with dimensions of 28cm×21cm×31cm. An exit is formed on one side wall of the resting box, which allows the rats to leave the resting box through the exit and enter the open field via the resting box door.

6. The paradigmatic method for a spatial memory task device based on self-centered and heterocentric navigation strategies according to claim 1, characterized in that: Visual cues for fixing landmarks and distinguishing directions are provided on the inner wall of the side panel. The visual cues are made of different shapes to facilitate the differentiation of different landmarks and directions.

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