Barnes maze

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The Barnes maze is a tool used in psychological laboratory experiments to measure spatial learning and memory. The test subjects are usually rodents such as mice or lab rats, which either serve as a control or may have some genetic variable or deficiency present in them which will cause them to react differently to the maze.

[edit] Set-Up

The Barnes maze consists of a circular table with 20 circular holes around the circumference of the table. Under each hole is a slot for a box, called the drop box. The goal of the maze is to reach the drop box, which is a box that has an open top, and can be reached through one of the holes in the top of the table. Exposure on the surface of the table serves as negative reinforcement, motivating the test subject to seek shelter. The only shelter available is the drop box, to which the test subject must flee. In order to accustom the test subject to the maze, it is guided into the drop box by a sheltering hand. After four to five runs, a normal test subject can quickly make a beeline for the drop hole. Fixed visual cues set up around the platform serve to orient the rodent during the trials.

[edit] Performance

Performance is typically measured by number of errors the rodent makes, i.e. the number of times it pokes its nose into, or hovers its head over a circular hole that does not contain the drop box. The rate of decline in the number of errors/trial is measured across subjects. Other performance values can also be measured, for example the strategy used by each rodent can be scored as random (randomly checking each hole), systematic (checking each hole in a pattern) or spatial (direct movement to the hole with the drop box).

[edit] Problems

One problem with the Barnes maze is the constant need to clean up after each trial. When nervous, most rodents will urinate and defecate on the table, necessitating the experimenter to clean up the entire table with disinfectant. Also, other animals who have not yet been tested cannot be allowed to witness the experiment in action, or they will have prior knowledge to the nature of the experiment, which will allow them to find the drop box more easily^{[citation needed]}. Another consequence of untested animals witnessing the experiment is pre-experiment nervousness, which will make the animals experience more stress, and will make it harder for the experimenter to take hold of the animal.

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