Morris water maze experimental method (2)

Morris water maze experimental method (2)

【Purpose】

1. Learn about the principles of the Morris Water Maze experiment.

2. Master the Morris water maze experimental method.

3. Master the evaluation and analysis of the results of the Morris water maze experiment.

[Experimental principle]

Analyze and infer the ability of animals to learn, memory, and spatial cognition by observing and documenting the time it takes for animals to swim in water tanks and find the time, strategies, and swimming trajectories hidden in the underwater escape platform. It can objectively measure changes in animal spatial memory, working memory, and spatial discriminability.

[Laboratory Animals]

Rat, mouse.

【experiment equipment】

The Morris Water Maze Experiment System consists of a circular pool, automatic image acquisition and processing system. The automatic image acquisition and processing system is mainly composed of a camera, a computer and an image monitor. After the animal enters the water, the monitoring device is started to record the movement track of the animal, and the relevant parameters are automatically analyzed and reported after the experiment is completed.

1. Morris water maze circular pool is a round ABS engineering bucket (good insulation coefficient), diameter 160cm, height 50~60cm, pool water depth 30~40cm, a circular platform diameter 9cm, hidden in 2cm water surface under. There should be no marks on the inside of the pool. Add appropriate amount of fresh milk or milk powder to the water to make the pool opaque milky white. At the upper edge of the drum, four points of east, south, west and north are arranged equidistantly as the water inlet point of the animal inlet pool, and the water surface and the bucket portion are projected at the projection points of the four water inlet points on the water surface and the bottom of the water bucket. Equally divided into 4 quadrants. According to the experimental requirements, the platform can be arbitrarily set in the middle of a certain quadrant. A suitable thermostat keeps the water temperature at 23 to 25 °C. The water labyrinth pool should be equipped with good water injection and drainage equipment. Once the position of the pool is determined, it should not be easily changed, especially in the same round of water maze test.

2. The water maze image automatic acquisition and processing system can automatically collect parameters such as the water position of the animal, the speed of swimming, the time required to search for the target, the running trajectory and the search strategy, and can collect and analyze various data collected. Laboratories with limited equipment can still use the manual recording methods used by many laboratories in Western countries today.

[Experimental methods and steps]

The experimental training phase was continuously performed for 3 days and trained 4 times a day. During training, the rats are placed in the pool from the four water inlet points to the pool wall, and the time required for the rats to enter the water to find the underwater concealed platform and stand on it is recorded as the incubation period, expressed in seconds (s). After the mouse finds the platform, let it stand on the platform for 10s. If the 60s rat failed to find the platform after entering the water, gently pull it from the water onto the platform and stay for 10s, then proceed to the next training. Each rat was placed in the pool from four water inlet points for one training session, and the interval between the two training sessions was 30 s.

【experimental project】

1. Place navigation is used to measure the ability of rats to acquire water and maze learning and memory. The experiment observed and recorded the road map and the time required for the rat to find and climb the platform, that is, record its latency.

2. The spatial probe test is used to measure the ability of the rat to maintain the memory of the platform space after learning to find the platform. After the positioning navigation experiment is completed, the platform is removed, and the water is placed in the water from the same water inlet point, and the time of the first arrival at the original platform position and the number of crossing the original platform are measured.

3. Spatial discriminability, a dual-platform experiment, is used to measure the "space discrimination ability" of rats. Set up two visible platforms in the water maze that look exactly the same (excluding "visual discrimination") but with different positions (space differences). One of the platforms will not sink (safety platform), and the other platform will sink at the touch (pseudo-security platform). The "correct number of responses" of the rats, ie the number of times the rats reached the safety platform without touching the pseudo-safety platform during a certain number of experiments. Obviously, the higher the "correct number of correct responses", the better the "space discrimination" ability.

【Precautions】

1. Both the environment in the laboratory and the position of the experimenter can be used as a reference for the search target of the rat. Therefore, the position of the equipment and the experimenter in the laboratory should be relatively fixed.

2. The water maze laboratory should be quiet and the light is soft and even.

【Evaluation】

The Morris Water Maze Experiment is an experimental method for allowing experimental animals to learn to find hidden platforms in the water and to judge their memory function by analyzing the time and path taken to find the platform. It is a standard experiment to study spatial learning and memory. The Morris water maze is not only used to study the functional evaluation of brain regions related to spatial learning and memory, but also to evaluate the effects of drug effects, environment, genes, electromagnetic radiation, etc. on learning and memory. Easy to operate and reliable.