T Labyrinth
Nearly half a century ago, Kivy and Dember et al. Demonstrated that rats can discern the color changes in the arms of a T-maze. They found that male rats were placed on the main arm of the T-shaped maze for 15 to 30 minutes so that they could see, but not enter the black and white arms. Then, change the color of one of the arms so that both arms are black or white. Let the rat choose the T-arm freely. The results show that the rat always chooses the arm that has changed its color (new arm). This process depends on the animal's memory to complete. The T-shaped maze experiment developed from this has become one of the most commonly used animal models for evaluating spatial memory. Of course, the current T-shaped maze uses food rather than the color of the arm as the motivation for animal exploration. This model is usually used to study the spatial working memory of an animal, that is, to determine the information that the animal is only useful during the current operation. The improved T-shaped maze can also be used to evaluate the reference memory (reference memory), that is, the information recorded in this experiment is useful for any day and any test.
(1) Experimental equipmentHere introduces the T labyrinth produced by Shanghai Xinsoft Information Technology Game Company. The labyrinth consists of two goal arms 46cm long, 10cm wide and 10cm high, and a vertical stem 71cm long with the same width and height as the stem or approach alley. The main arm is built with a 16cm * 16cm starting box, and a gate is connected to the other part of the main arm. Male adult rats were used for the experiment. Drinking water is not limited, but eating is controlled at 16-20g per day to keep the body weight at 85% of the weight of non-eating rats. During the entire training and testing period, the weight of rats increased by no more than 5g per week.
(2) Experimental methodHere we introduce the traditional T-shaped labyrinth experiment and the T-shaped labyrinth autonomous experiment.
1. Traditional T-shaped labyrinth experiment
(1) Adaptation Distribute 6 pills (45g) into the T-shaped labyrinth arm to allow the rat to adapt to the maze for 5min, once a day for 5 consecutive days.
(2) Forced selection training Put the rat into the starting box of the trunk arm, open the gate, and let the rat enter the trunk arm of the maze. Randomly and alternately choose one of the left and right arms to put 4 pills, and close the other arm at the same time, forcing the animal to choose the food fortified arm and complete feeding; 6 times a day for 4 consecutive days.
(3) Delayed matching-to-position (DMP) training
1) Put the animal into the starting box where the gate is closed, open the gate, and let the animal enter the trunk arm.
2) Close the target arm on one side and force the animal into the open arm on the other side to get 2 pills pills reward.
3) Immediately (the shortest delay, less than 5s) put the animal back into the main arm and start the second training in the training; at this time both target arms are open. The animal completes "one-time selection" when placing two forelimbs and at least a part of both hindlimbs on a target arm. When the animal returns to the arm entered during the forced selection training, it will receive a food reward (4 pills), and record the correct choice once. One wrong choice.
4) After one match training is finished, put the animal back into the cage for 5 ~ 10min (while training other animals), and repeat the next match training. 8 times a day.
If the number of correct selections of the animal reaches 15/16 for two consecutive days, it is considered that the standard has been reached and the experiment can be started. If the animal still fails to meet the standard after 30 days of training, it will be eliminated.
5) One day after the animal training reaches the standard, a matching training will be given. The difference is that after the forced selection training, the T-shaped maze is rotated 180 degrees, and then the open arm training is performed. The purpose of this is to evaluate whether the animal is a localized operation (relying on extramaze signals) or a reactive operation (not dependent on extramaze signals).
6) On the next two days, 10 matching trainings are given every day, each training interval is 60s, to evaluate the working memory operation of the animal. Record the number of times you enter the fortified arm and the number of times you enter the non-enhanced arm again. The latter is considered a working memory error. Normal healthy young rats can operate accurately almost every time. When the operation is stable and the selection accuracy is high (the working memory error is less than 10%), the drug experiment or the operation experiment after the brain area is damaged can be performed.
2. Spontaneous altemation on a T-maze In 1925, Tolman first reported an interesting finding: In the labyrinth experiment, rats rarely enter the same arm of the labyrinth repeatedly. Rats explore their surroundings in this repeated and alternating manner. Thus, even without food rewards, rats still retain a certain sense of novelty in the area explored. Normal alternate operation is consistent with complete working memory. Pharmacological or anatomical damage methods can change this alternating operation behavior. The experimental method is as follows:
(1) Fully stroke the rat for 1 ~ 2min every day for 5 ~ 7 days continuously. Since the rats were not deprived of eating, the only driving effect for the rats was their desire to explore the maze. Therefore, the animal must be fully adapted to the experimenter and the experimental environment, without fear. It is particularly important to fully touch the rat.
(2) Put the rat into the trunk arm of the T-shaped maze; open the gate and let the rat leave the trunk and enter a target arm (the limbs enter the arm).
(3) Put the rat back into the main arm, and limit it to the arm for a period of time (countdown to zero, but it is more appropriate to set 5s at the beginning).
(4) Repeat steps 2 and 3 9 times, and record the number of times each arm is entered. Control rats should alternately select two target arms during each experimental period (a total of 10 training sessions). The results of the experiment are expressed as the number of alternations divided by the total number of choices during the same experiment period. When using drugs or related brain damage to reduce memory, this ratio drops.
(3) Matters needing attention1. Rats and mice have a good spatial discrimination function, can quickly learn and accurately operate the maze. Therefore, both T-shaped maze and radial arm maze are widely used to test the spatial memory ability of animals. T-shaped maze is used to study the effect of different brain regions on spatial memory. It is sensitive to the damaging effects of certain brain structures, especially the hippocampus. In addition, many drugs or toxins can enhance or weaken the animal's spatial memory in the T-shaped maze. Animals used in the experiment include pigs, sheep, turtles and pigeons in addition to rats and mice.
2. The accuracy of animal selection is related to the interval between two selections and the number of selection trainings during each training interval. The selection accuracy of normal animals is very high after a short time interval (for example, 5s). After a very long time interval (for example, more than 1h), its selection is close to random operation. After forced to choose training. If the target arm is selected only once, the accuracy is usually high. However, if multiple choices are given, the more choices, the worse the accuracy.
3. Rodents have a one-way preference. This one-way preference is related to animal species and strains. For example, C57BL / 6J mice, ICR mice, and Purdue-Wistar rats prefer the left side, while Spague-Dawley rats and Wistar rats prefer the right side. Studies have shown that more than 2/3 of male Spague-Dawley rats prefer the right side and less than 1/5 of the left side. This one-way preference can affect the evaluation of animal learning and memory.
4. The main arm gate is an important feature of the T-shaped maze. It can be used to limit the animal to the starting box for a certain period of time between the two choices, and can also prevent the animal from exploring the maze between the two choice trainings. Therefore, between the two selection exercises, the animal should be quickly returned to the starting box in the trunk arm. This is important because it ensures that the animal does not explore the contralateral target arm.
5. When the animal's fear of the maze or the experimenter's stress exceeds its desire for exploration and foraging, the animal's exploration of the maze decreases, and even stays somewhere in the maze without exploring the maze. This fear manifests as the animal defecating and urinating in the maze; when it is caught, the animal also screams. Therefore, adequate stress adaptation is necessary. Otherwise, if the animal does not choose the arm in the maze, it is impossible to know whether its memory is normal or weakened.
Wash Sink,Sink Cabinet,Thin Edge Basin,Ceramic Wash Sink
GUANGDONG ZHIJIE SANITARY WARE CO., LTD. , https://www.zhijiesanitary.com