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Summary
We developed a novel behavioral task in which rats learn to recognize the configuration of objects in an animated scene displayed on a computer screen. The scene consisted of a moving bar and a stationary rectangle. Rats deprived of food were trained to press a lever for reward in a small chamber located in front of the screen. Lever presses were rewarded only when the bar was at the rectangle. Rats anticipated the reward by gradually increasing frequency of lever pressing as the bar approached the rectangle. Control experiments showed that neither the timing nor the discrimination of rewarded and non-rewarded periods as two discrete conditions explain behavior of the rat. Because the changes in the scene were generated by movement of the object, the presented task could be used for studying neural structures involved in spatial behavior of rats using virtual reality technology.
Key words
Configuration recognition * Position recognition * Pattern discrimination * Operant behavior * Virtual reality
Introduction
Animals assess position and speed of nearby or distant objects, for example, when they are escaping a predator, hunting a prey or when they use celestial bodies for orientation. The representation of position of a moving object is clearly spatial.
Rodent neural structures involved in spatial behavior are mostly studied in tasks in which animals actively move through space (Olton et al. 1978, Barnes 1979, Morris 1981, Rossier et al. 2000, Cimadevilla et al. 2001). Deficit in spatial behavior could then be attributed to a deficit in recognizing subject's position or to a deficit in planning or executing movement towards the target. Few tasks (Klement and Bures 2000, Past'álková et al. 2003) were designed to test specifically the recognition component of spatial behavior. In experiments of Klement and Bures (2000), rats were passively transported through an environment. They were trained to recognize certain place by reinforcing lever presses in that location. Past'álková et al. (2003) observed rats watching a rotating scene. They were trained to recognixe when the angular displacement of the scene was within a specific sector by reinforcing lever presses in this sector. The presented task follows the task described by Past'álková et al. (2003), but the real scene was replaced by a virtual one. The virtual scene has...