Perseverative errors in normal and frontal rats in returning behavior test.

In an inverted T maze, normal rats going for food from one maze arm to the end of maze stem and required to return to the starting point, showed about 9PIo of correct responses (Eukaszewska 1961). From the start to the goal the animal is probably guided visually by the sight of cup, or he learns not to approach the opposite maze arm but t o take a turn. However, when he returns, he must choose between the left and the right path. At the moment of decision animal should remember from which place he started. In other words, at the choice p i n t he responds not to actual stimuli but to the traces of stimuli acting several seconds earlier. Thus the test belongs to category of delayed responses. It has been found (Eukaszewska 1963) that the predelay stimulus determining the correct response is elicited by a turn taken on the way to food. The time between this turn and the choice of return route constitutes the delay period. With the length of maze stem used, the delay is around 3-4 sec. When after several runs to food and back to start, the starting place was transfered to the other maze arm, animals showed a considerable amount of perseverative errors, i.e. they chose the previous return route instead of the path they had just taken to the goal (Eukaszewska 1962). Mishkin (1964) has reported that frontal operates showed qualitatively the same difficulties as normal subjects, but quantitatively enhanced. Thus, in our test a greater number of perseverative errors was expected in frontal rats than in unoperated controls. The returning behavior of frontal rats have been studied previously (Eukaszewska 1968) in a somewhat different design: the start point was changed from day to day remaining at the same place during successive trials of each session. I t