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Mouse elevated T-maze and eight-arm maze learning
Mouse elevated T- maze and eight-arm maze learning
Pick  To test the mice were observed running routes in the elevated T-maze and eight-arm maze, explore the mice foraging strategies and associated working memory. The results showed that the three mice in the experiment showed three different foraging strategies: “get-transferâ€, “get-stay†and direction preference in the T-maze experiment; and the mice involved in the eight-arm maze experiment. Showing different memory abilities. Some soon remembered where the food was placed, and designed the simplest running route; some prefer to explore the maze, and some did not actively use the previous exploration experience.
Keywords maze foraging strategies and memory in mice
Note: Shanghai Xinsoft Information Technology Co., Ltd. provides Xeye animal behavior trajectory analysis system, which can carry out almost all behavioral experiments.
1 Introduction
1.1 Principle of experiment
Maze is a very common instrument used in the experimental research of animal psychology. It plays a vital role in the formation and development of animal psychology. Psychologists often use it to test various abilities of animals.
At the end of the 19th century, Lubbock first invented the maze method in the pioneering experimental study of insects. Since then, researchers have invented a large number of labyrinth models for various studies. The different types of labyrinths used in the studies of the 1930s and 1940s included Small's Hallmark labyrinth; Yerks' T-mode labyrinth in 1900; Warden-Warner's unit labyrinth in 1929; 1946's cross-shaped or double-T-maze and many more. In 1975, Olton invented the labyrinth of elevated radiation arms; Morris designed the water maze in 1981. The T-maze and its variants, as well as the radial arm maze and water maze of more than 4 arms, are currently the most commonly used in various studies. Over the years, people have used various labyrinths to study animal learning, memory, foraging strategies, spatial cognition, etc. for birds, fish, frogs, crickets, snails, cats, dogs, etc. The most commonly used ones are rats. And mice [1] .
1.1.1 Space and memory of animals
Regardless of the type of labyrinth experiment performed with animals, the nature of the labyrinth experiment itself determines that these studies are inevitably involved in the discussion of animal memory and spatial capabilities.
Maze tasks have obvious spatial characteristics, so the results of the labyrinth provide a wealth of data and materials for understanding animal spatial information processing. Experimental evidence indicates that trained animals can efficiently find food in the maze, and different researchers have proposed various hypotheses for the excellent results of animals in the maze, especially the radiation maze. Among them, the cognitive map hypothesis and the sequence hypothesis are more famous.
The concept of cognitive maps proposed by Tolman suggests that something similar to an environmental map is established in the brain of rats such that they reorganize the spatial information obtained to establish a cognitive representation of the environment. But there is still debate among researchers about whether animals have cognitive maps, or under what conditions cognitive maps are used, and different researchers have different opinions. They also have experimental evidence of support. As with position-response learning debates, it is important to adopt cognitive maps. What is the clue information available in the environment? Animals probably do not rely on a single mechanism or strategy but rely on Multiple multiple clues to solve spatial problems or spatial orientation.
However, other researchers believe that the outstanding performance of rats in the radial maze does not use cognitive map interpretation. They believe that rats are only learning some clues of separation at the end of the maze, remembering the arms that have been and have not been. The evidence is that the rat makes a micro-selection or a perceptually directed response toward one arm before deciding to enter an arm or to explore other arms. They believe this is more likely because rats use separate clues rather than integrated cognitive maps.
In memory research, the radiation maze is more commonly used, which is composed of several arms. The arms radiate from a central platform, placing the rat in the central area of ​​the maze at the beginning of a trial, then placing a small piece of food at the end of each arm, allowing the rat to explore the maze until it collects all food. It took a lot of trials to train the rats to collect food and it was very efficient, and rarely repeated into the same arm in each trial. In this task the rat must either remember the arm that has been gone or remember the arm that has not been. The first thing a rat needs to accomplish this task is the reference memory, because the rat must learn the rules of the task—the look of the maze and the arms it should have never returned, and so on. Second, rats must also rely on working memory, and each trial must track where it has been, so that it does not repeat. Once you have successfully entered all the arms, ending a trial, it can erase this particular working memory, but keep the reference memory unchanged to prepare for the next trial [1] .
1.1.3 Animal Foraging Strategy
Some psychologists have suggested that the most important factors in the study of animal cognition are the "win-stay" and "win-shift" strategies. Both strategies have been found in the natural environment, such as the Hawaii-based honey-sucking bird adopts the “get-transfer†strategy; the British ostrich adopts the “get-and-stay†strategy, and the animal's ecological environment and food source situation (concentration and dispersion) A strategy that directly affects predators. The researchers used the maze to conduct a series of experimental studies on rat foraging strategies, usually using the T and Y maze. The common feature of these labyrinths is that there are two options relative to a choice point or starting point. Current research indicates that for rats searching for food, the flexibility of spatial behavior is mediated by the “get-transfer;†strategy [1] .
1.2 Purpose of the experiment
Based on previous studies, this experiment used an elevated T-maze and an eight-arm maze to observe mice's foraging strategies and the ability to remember food positions during foraging.
2 Experimental materials and methods
2.1 Experimental objects
Six male mice, three were used as subjects in the T-maze experiment, and three were used as subjects in the eight-arm maze test.
2.2 Laboratory supplies
Elevated T-maze and eight-arm maze, stopwatch, four pieces of wood.
Food pellets, stains (calibrated for mice to distinguish).
2.3 Experimental design
The experiment was divided into two parts. In the first part, the foraging strategy of mice in the T-maze was observed. In the second part, the foraging strategies of the other three mice in the eight-arm maze were observed.
In the T-maze, each round of experiments is divided into mandatory trials and selective trials. The mouse is first subjected to a forced trial, that is, it is defined by a wooden block to run to the left or right arm of the T-maze, and then a selection test is performed, allowing the mouse to freely choose which side of the maze to enter. Food rewards are available no matter which side the mouse runs to. The path of each selection was recorded, and the foraging strategy of the mice was judged based on the recorded results.
In the experiment of the eight-armed maze, the food was placed at the end of the two arms of the four arms, and then the animal was placed in the middle of the maze, and the foraging route of the animals was observed and recorded, and the food in both arms was obtained by the mice. End the experiment. The detailed path of each selection was recorded, and the effect of the memory of the mice on the foraging behavior was determined based on the records.
2.4 Experimental procedure
2.4.1 T Maze
1) Limit the animal diet until the weight is reduced to 85% of the original weight before the start of the experiment.
2) Adapt to the labyrinth stage: Put food in the end of each arm in the labyrinth, in order to familiarize the mouse with the maze and learn to go to the end of the left or right arm to get food. Each mouse should stay in the maze every day. 20 -30 minutes.
3) Official test phase:
a) Three mice were first stained for differentiation, numbered 1, 2, and 3, respectively.
b) Each round of experiments consists of two trials, which are divided into mandatory and selective times according to the order of time. Forced to order the mice to run to the left and right arms of the labyrinth 5 times, the artificial random test sequence was: LRRLRLLRLR (L means to block the right channel with wooden blocks, the mice are required to enter the left arm for food; R is the opposite). Choose this without any restrictions, let the mice run freely in the maze.
c) In each round of experiments, the specific process is: first force the time, according to the direction randomly arranged in advance, if it is right, the partition is placed on the left side, preventing the mouse from entering the left arm. When the mouse enters the designated target arm, put a small piece of food at the end of the target arm. After the mouse has finished eating the food, put it back in the cage.
d) Start the experiment after 30 seconds. The septum was removed and the mouse was placed in the starting arm and the target arm selected by the mouse was observed. If the mouse's selection direction is the same as the forced secondary direction, it is the "get-stay" strategy; otherwise, it is the "get-transfer" strategy.
e) Three mice were alternately tested and each mouse was subjected to 10 rounds of experiments. The test results for each animal, the number of selections for both strategies, and the results of all animals were statistically analyzed.
2.4.2 Eight-armed maze
1) Control diet and adapt to the labyrinth phase with the T-maze experiment.
2) Test phase:
a) Three mice were first stained for differentiation, numbered 1, 2, and 3, respectively.
b) In order to shorten the experiment time, four of the eight arms are blocked by the partition plate, and only the four arms numbered 1, 3, 5, and 7 are used for the experiment, and the arms are placed in the arms of 3 and 7 food.
c) Place the mouse in the middle of the maze and let it explore freely in the maze. All the mice in the 3 and 7 arms are harvested. The experiment is terminated and the mice are taken out.
d) Three mice were alternately experimented, and each mouse was subjected to 10 rounds of experiments. During the experiment, the number and order of the labyrinth arms that the mice entered were recorded in detail, and then the results were comprehensively recorded for statistical analysis.
3 Experimental results
3.1 T-maze experiment results
The specific record results are shown in Appendix 1.
The results were sorted, and the number of times each mouse entered the left and right arms of the T-maze was calculated. The number of times of forced and selected secondary selections was the same or inconsistent. The results are shown in Table 1.
Table 1 T-type labyrinth mouse selection path direction and consistency (unit: time)
Choose direction
consistency
Mouse number
left
right
Consistent
Inconsistent
1
4
6
9
1
2
1
9
4
6
3
7
3
2
8
A preliminary analysis of the results, we can see:
In the number 1 mouse, 9 out of all 10 tests were selected to obtain food in the arm of the forced test. We can roughly assume that the mouse took the “get-stay†Foraging strategy.
In the number 2 mice, the number of identical and inconsistent times was approximately equal in all 10 tests, but combined with the data of the selected direction, we can see that this mouse has 9 choices on the right side, its foraging The strategy may be based on direction.
In the number 3 mouse, 8 out of all 10 tests were selected to find inconsistent arms to find food. We can roughly assume that this mouse is taking a “get-transfer†foraging strategy.
3.2 Eight-arm maze test results
Table 2 Experimental results of 3 mice in an eight-arm radial maze
Trial
number 1
number 2
number 3
1
1-7(e)-1-3(e,to 7)
7(e)-5-3(e,to 7)
1-5-5-7(e)-3(1/2)-7-5-7(1/2)-1(1/2)-3(e)
2
1-5-3(e)-1(1/2)-7(e)
5(1/4)-7(e)-3(e,to 1)
3(e)-1-7(e)
3
7(e)-3(e)
3(e)-1-7(e)
7(e)-5-3(e)
4
3(e)-7(e)
3(e)-1-3-5-7(e)
3(e)-7(e)
5
7(e)-1-3(e)
1(1/2)-5(1/2)-7(e)-
5(1/2)-3(e,to 1)
5-7(e)-Z-1-7-Z-1-3(e)
6
3(e)-1-7(e)
7(e)-1-3(e)
3(e)-5-3-1-7(e)
7
3(e)-7(e)
5-1-7(e)-1(1/4)-
3(1/4)-7-5-3(e)
7(e)-Z-5-3(e)
8
3(e)-7(e)
7(e,unfin)-7-5-down(between 4,5)-7-
1(1/2)-7-6(x)-2(x)-
7-5(1/2)-3(e)-2(x)-
7(e, up)
1-5-3(e)-7(e)
9
7(e)-3(e)
7(e)-1-8(x)-5(1/2)-
2(x)-8(x)-7-8(x)-
6(x)-7-6(x)-1-3(e)
3(e)-1(1/2)-1-7(e)
10
3(e)-7(e)
7(e)-3(e)
7(e)-5-1(1/2)-5-3(e)
Record Description: The number represents the labyrinth arm number entered by the mouse. The brackets are supplementary instructions, where “e†stands for food, and then “to x†means that after taking the food, it is eaten in the other arm; the score in parentheses indicates that the mouse touches the food trough and represents it. The degree of the labyrinth arm; unfin means to continue to explore without eating food; down between refers to falling from the two labyrinth arms on the equipment; Z represents the long-term stagnation of the mouse; x represents the labyrinth arm that enters is closed, we part Punished (tapped his head with a pen); no up means that the mouse does not eat food for a long time and is taken out by us.
Combined with the experimental results, we can see:
The mouse with the number 1 can start from the third experiment and go directly to the 3 and 7 arms to find food, which forms a good foraging memory.
The mouse numbered 2 has been able to correctly enter the 3 and 7 arms for food in the third time, but in the subsequent trials, the arms (including the arms isolated by the wood block) were extensively explored and did not seem to form. Foraging memory.
The mouse numbered 3, starting from the second trial, can find food in a short period of time and form a certain foraging memory.
4 Analysis and discussion
4.1 T-maze
In the T-maze experiment, the three mice used in our group showed distinct feeding strategies and the specific analysis of the three mice.
For the number 1 mouse, almost all free choice trials have chosen the same arm as the forced test to find food, which we think is more in line with the "get-stay" foraging strategy. In the specific observation process, the No. 1 mouse is relatively large, and each time it is placed at the entrance of the maze, it will not hesitate to run to the side where the food was once obtained. The only time the mouse ran to the inconsistent direction was because a group member at the time made a loud noise, and the mouse was frightened. After a little hesitation, he ran to a different direction than the forced one. Therefore, it is still considered that the No. 1 mouse appears to be a “get-stay†foraging strategy.
For the number 2 mouse, there is not much difference in the number of consistent and inconsistent times, but it has the right side selected 9 times, so we think its foraging strategy may be direction preference. In the specific observation process, the No. 2 mouse only selected the left side in the fifth experiment, according to the experimental record at the time: in order to remove the traces of odor, excretion, etc. left by the mouse running in the maze, we are in the experimental process. I kept wiping the runway of the labyrinth, but since the mouse had only left the excrement in the right arm, we only wiped the right arm of the maze before the start of the free selection of this trial, and also in the water mark The second mouse was placed in the maze without being completely killed. Therefore, the reason for this inconsistent result may be caused by the difference in labyrinth conditions - the water marks and the breath left by the rag caused the mice to abandon the original foraging strategy. On the whole, it is still possible to think that the No. 2 mouse appears as a feeding preference for the direction preference (the right side), which may be caused by individual differences in mice.
For the mouse numbered 3, it mostly chose to search for food in a labyrinth arm that was inconsistent with the secondary direction. We thought that the mouse was taking a “get-transfer†foraging strategy. Combined with the specific experimental records, even in the case of the inconsistency of the two choices, the No. 3 mouse showed a tendency to run to the labyrinth arm that was inconsistent with the forced secondary direction: in the fourth trial, the mouse ran When I got to the left arm of the labyrinth (forced to ask it to run to the left), but after eating a bite of food, I quickly dropped the uneaten food and ran to the right arm of the maze, and crossed the process in the process. We saw that after it had finished selecting the direction, placed two pieces of wood on the right arm and finally brought it back to the cage by our team members before it touched the food; in addition, in the ninth test, The mouse was on the left side of the maze (forced to run to the left when it was forced). After taking the food, it did not eat immediately. Instead, it picked up the food and rushed to the right arm of the maze to prepare for food. To analyze this, we believe that the possible reason is that the mice hope to find a safe place to eat. At the time, the three members of our group were concentrated in the left arm of the maze, so it was more inclined to eat on the right arm of the maze. However, this reason does not explain the situation of all trials. The mice did not have such a preference in other trials. On the whole, we think that this mouse can be considered as a “get-transfer†foraging strategy.
Based on the above analysis, we can see that the three mice showed three different foraging strategies: “get-stayâ€, direction preference, and “get-transfer†in the experiments we conducted. Although the experimental trials were carried out less frequently, the overall trend of each mouse was consistent and the individual differences were significant. Of course, if we can carry out more and more sample experiments, we may be able to find a stable pattern of feeding patterns in mice, which needs to be carried out and discussed in further research.
4.2 Eight-armed maze
In the eight-arm maze experiment, the three mice used in our group showed different memory abilities. During the foraging process, the results of the changes were different through repeated training. The specific analysis is as follows.
For the number 1 mouse, it quickly remembered exactly where the food was placed, and in the subsequent trials, each time went straight to the arms with food to get food. Combined with the specific observation data, the performance of the mice in the first two trials is rather confusing. It does not have a clear exploration route. Even after eating the food in the 7th arm, it will still go back and explore (Try 1 ), however, from the third trial, it can enter the 3 and 7 arms more accurately to get the food - remove the two trials and enter the 1 arm in the counterclockwise and clockwise order respectively. Overall, the No. 1 mouse quickly formed a good working memory about the location of the food.
For the number 2 mouse, its condition is more complicated, and some are unexpected. In the third time, it has been able to correctly enter the 3 and 7 arms to find food, but in the subsequent trials, it repeatedly explored the arms, even the labyrinth arm isolated by the block. There is no formation of foraging memory. Combined with the specific observation data, in the first three trials, although there was no clear foraging strategy, the No. 2 mice obtained food more effectively, but from the fourth trial, the second mouse appeared. More exploration than the previous trials - it ran in confusion in the maze, crossed the wooden blocks we set at the entrance of the 2, 4, 6, and 8 labyrinth arms, active in the labyrinth arm Walking around. At the 8th trial, the No. 2 mouse did not eat even if it touched the food placed in the 7 arms, but continued to explore other labyrinth arms, especially the labyrinth arm that was blocked by the wood block and could not be explored before. Showing great interest. In the meantime, it flipped between the 4th and 5th labyrinth arms, grabbed us and put them back into the maze. One thing that deserves attention is that in the 9th trial, since the No. 2 mouse is still actively exploring the blocked labyrinth arm, we have made a slight punishment for it - it will climb into the In the process of sealing the labyrinth arm, hit the head with a pen. As a result, in the 10th trial, it quickly found 3 and 7 labyrinth arms to get food. Therefore, combined with the above phenomenon, we believe that the No. 2 mouse may have formed a good working memory about the location of food storage after the first three explorations and attempts, but on the one hand because it has no appetite after eating, on the one hand because of individual differences. - Curious about unexplored areas, so this mouse showed the above performance.
Finally, for the mouse numbered 3, although it does not perform well in the No. 1 mouse, it can also find food in a short period of time, and we believe that it may also form a certain foraging memory. However, combined with specific experimental data, we can see that the No. 3 mouse has never formed an accurate working memory about the location of food storage: it has been in continuous exploration. In each trial, it takes almost a few attempts to get the food in the 3 and 7 arms. The previous exploration experience does not seem to have a significant impact on future behavior. From this perspective, we can even think that the working memory of No. 3 mice is not as fast and perfect as the formation of mice No.1 and No.2.
Although many factors have been controlled in the experiment, there are still some that we have not completely overcome and need to be improved in future experiments: First, because it is the first labyrinth experiment, our operation is not very skilled, there are still some leaks. In addition to the aforementioned problems, there is a point that we do not strictly control the number of people standing at each arm port of the maze, which may affect the perceived sense of security of the mouse, thereby affecting its feeding and eating strategies; Whether it is a T-maze experiment or an eight-arm maze experiment, one thing we can see from our data is that the individual differences between mice are very obvious, so if there are no further large samples, multiple trials We can't draw conclusions from this study about the mouse's foraging strategy and memory ability.
5 Conclusion
Based on the above analysis, this experiment explored the foraging strategy of mice and the working memory associated with it by observing the foraging route of mice in the T-maze and the eight-arm maze. The results showed that three mice showed different foraging strategies in the T-maze experiment, “get-transferâ€, “get-stay†and direction preference; three mice involved in the eight-arm maze experiment showed different Working memory ability. Some soon remembered where the food was placed, and designed the simplest running route; some prefer to explore the maze, and some did not actively use the previous exploration experience.
Although many unrelated factors have been controlled in the experiment, there are still some that need to be overcome in the study in Beijing. If we take a larger sample and more trials, we should be able to explore the feeding strategies and working memory problems of mice in more detail.
6 References
1. Xiao Jian, Editor-in-Chief. Modern Physiological Psychology Experimental Course [M]. Peking University Press, September 2006, First Edition: 83-84
2. Wang Yan, Su Yanjie. Maze and Animal Behavior Research [J]. Psychology Development, 2001: 264-268
7 Appendix
Table 1 Results and consistency of selection of 3 mice in the T-maze
Numbering
Experimental test
1
2
3
4
5
6
7
8
9
10
Forced selection
L
R
R
L
R
L
L
R
L
R
1
Free choice
L
R
R
L
R
L
L
R
R
R
Consistent
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
no
Yes
2
Free choice
R
R
R
R
L
R
R
R
R
R
Consistent
no
Yes
Yes
no
no
no
no
Yes
no
Yes
3
Free choice
R
L
L
L
L
R
R
L
L
L
Consistent
no
no
no
Yes
no
no
no
no
Yes
no