Do the correct posture of the water maze experiment
Richard G. Morris's two consecutive publications in 1981 and 1984 made the water maze experiment famous. For more than 30 years, it has become an indispensable evaluation experiment in learning and memory research. In the previous article, the white and white mice BB-8 went through the four stages of the experiment in turn. In this paper, we will carefully introduce the strategy of the water maze experiment. Since it is a strategy, the purpose of the experiment is not to mention the experimental principle. In a word, in order to evaluate the spatial orientation learning and memory ability of the experimental mouse. First gossip, this experiment was originally designed for rats. Later, because of the maturity of transgenic technology, mice became the protagonist of the experiment, but compared with rats, the mice are really stupid!
1. Equipment articles
The experimental equipment is simple to say, a basin, an image analysis system, That's it!
1.1 washbasin
Although the name is called the water maze, it is actually a large basin of water, and there is no wool relationship with the familiar labyrinth. The basin used by Morris in 1981 was 1.3 meters in diameter and 60 centimeters deep. In 1984, the old man changed his mind and used a large basin of 2.1 meters, but the depth was only 40 centimeters. This head is not well-opened, so until now there is no rule for the size of the basin. At present, the practice is to use different diameter water basins for mice and rats. The mouse is the smallest to be used with a diameter of 0.8 meters, and the diameter is usually 1.2 meters. The maximum of the rats is generally less than 2 meters. The common one is 1.6. Meter diameter. As for the depth, it is generally 60 cm. For the experimental rats, the smaller the basin, the simpler the task, the bigger the harder.
Said to be the basin, still a little required. The first is the color. Because the experimental rats are usually divided into black and white, the early basins will be divided into white pots and black pots (don't think wrong, of course, the white pots are black rats, the black pots are white rats, otherwise the ghosts know where the mice go. )), but it is too cumbersome, so the basins of neutral colors (such as blue, gray) are generally available to adapt to various colors of experimental rats.
Followed by water supply and drainage. Do not underestimate this basin of water, it is easy to be a ton, water supply and drainage is definitely to be considered. The water supply is still convenient, and the faucet is connected to the tube to the basin. Drainage is generally connected to the drain at the bottom of the basin to the drain. Therefore, the location of the water maze is required to have a water inlet and outlet, otherwise the pipeline for water supply and drainage will be very long... The requirement for water temperature control is not rigid, because the water temperature (20-27 ° C) required for the experiment is very close to the room temperature. It is enough to put a basin of water overnight. However, given the vast climate of our country, we usually require water temperature control equipment. Fortunately, the requirements for temperature control are not high, otherwise it will be paralyzed. In general, the low water temperature on the one hand will cause the aversion of the experimental rats and accelerate the swimming to find the platform. On the other hand, the experimental rats will slow down the swimming speed due to temperature loss. For temperature, mice are more sensitive than rats, so as previously experienced in BB-8, placing the effluent mice on a warm pad is an effective strategy for restoring body temperature.
The third is an important accessory, the platform. This thing is equivalent to the exit of the labyrinth. The whole experiment is to examine whether the mouse remembers the position of the platform. The experience of BB-8 has already told us that this thing is sometimes higher than the water surface, sometimes lower than the water surface (usually 0.5-2cm), and it can change position. But don't worry, all commercially available products can easily meet this requirement. The diameter of the platform is relatively uniform, 10-12cm, and the experimental rats can stand up. Of course, in principle, the ratio of the platform diameter to the diameter of the basin affects the difficulty of the experimental task, but usually everyone cares more about the diameter of the basin.
Since it is a strategy, it is necessary to talk about how to pick, although there is nothing to say. Just like picking a mobile phone, just pick a pleasing eye. Only one point, be careful with the metal basin, be sure to be stainless steel, otherwise it will rust after two days of experimentation, and the whole person will feel bad...
1.2 Image Analysis System
Tell the truth, this is the point. Although an experiment is only 6 minutes in general, but a lot of mice are added together, and the time is quite long. If we all need one by one to look at the stopwatch with our eyes, people will soon be paralyzed and cannot draw. The trajectory of the mouse, and thus the process of finding it, cannot be finely evaluated. So a good image tracking and analysis system is essential. What is easy to use? Applying a famous saying by Grandpa Deng: Regardless of the white cat and the black cat, it is a good cat to catch the mouse. It’s true that as long as you can “catch†the mouse, it’s a good system. The more careful you “catchâ€, the better! The judgment in this regard is actually very easy. To read the articles of the international top neuroscience related journals, the system mentioned above will not be bad.
Then why is it possible to "catch" badly? The first is because the actual situation may be very complicated. The most typical interference comes from the image changes caused by water wave sloshing. Many low-end products will misjudge the swaying light spot as the experimental mouse and “disregard†the real experimental mouse. Secondly, there are differences in the underlying technology of image recognition. High-end products will identify many (up to 4) parts of the experimental mouse, so that the trajectory of the experimental mouse can not be depicted, and the head orientation of the experimental mouse can be determined in real time. Looking for such fine indicators in the in-situ circle, and the low-end products will only treat the experimental mouse as a single particle to simply depict its trajectory, which will lead to too rough experimental results and drown the objective differences. Of course, like all good things, the most sensible decision is always based on your actual needs.
2 steps
A complete water maze experiment includes three stages: Cue Trials, Response acquisition trials, and Probe and extinction trials. The “Enhanced†version of the water maze experiment will be new after the regression. ) Tips and acquisition experiments.
2.1 Tips (Cue Trials)
As experienced by BB-8, it is common for mice to swim along the pelvic wall after launching. At this time, the platform is raised above the water surface for the experimental animals to find the platform. This step is to tell the experimental mouse: Don't be tossed, it is the last word. It is the most common way to make the platform above the water surface, and some experimenters put a prominent logo on the basin wall to achieve this "notification" function. This is not much different for the experimental rats, and they belong to the close-up logo. For the experimental mouse, the skill required for this step is the most basic directional swimming ability. If this ability is missing, it will be eliminated from the experiment.
2.2 Acquisition (Response acquisition trials)
This step is the key. It is necessary for the experimental mouse to learn and memorize the position of the platform according to the distance marker. This is equivalent to letting the mouse fill the map with the brain. The position of the platform can be quickly confirmed no matter where the water is placed. Many times there have been differences in this step, and the speed and quality of acquisition is already a good indicator. This step may take a long time, and changing the position of the experimental mouse into the water may need to be repeated for several days.
2.3 Probe and extinction trials
This step is considered "advanced". When the experimental mouse learns the orientation of the platform, the platform is removed and the experimental mouse is still remembering the position of the platform. At this time, the "correct" attitude of the experimental mouse is to stop at the original platform position even if there is no platform, that is, the so-called "space preference." If you don't do a new experiment, the test section will do a batch. If this step is repeated, the original memory of the experimental mouse will subside and prepare for the next experiment.
2.4 New positioning experiment
This step is almost a repeated prompt and acquisition experiment. The most important difference is that the position of the platform is changed. This requires the experimental mouse to generate a new platform orientation map based on the original remote marker, which is a good test of cognitive plasticity. In this case, the difference in large mice can be seen here. Rats usually find the platform in a new location through a new search strategy, and the performance of the mice is much worse, which is significantly affected by proactive memory.
Conclusion: The part of the experiment is completed here. In fact, there are still a lot of details to be aware of, and there are still hundreds of times more work, analysis and statistics than the experiment. The road here, you know, absolutely need another A long article can make it clear, or listen to it and break it down!
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