Frontal rats and some visual tests.

Our previous investigations on the returning behavior of rats (Eukaszewska 1963, 1966ab) suggested that frontal rats are more dependent on visual stimuli than normal subjects. This suggestion was derived from the following findings: (i) frontal Ss performed on a lower level than normal Ss, (ii) the performance of frontal Ss improved considerably lafter blinding, and (iii) the performance of normal Ssi lowered when additional visual cues were introduced into the experimental situation. It could be interpreted that visual stimuli hinder the correct response in our test, and that frontal rats pay more attention to visual stimuli than normal subjects. There is a relative lack of studies concerning the role of visual cues in frontal rats. In a few early studies no differences were found between frontal and normal .subjects in a white-black discrimination and two successive reversals (Bourke 1954) and in a Hebb-Williams maze which has been considered to be a primarily visual task (Landsell 1953 and Gross et al. 1965). Recently however, Jeeves (1967) reported that on an initial pattern discrimination and on each of the eight reversals, frontal Ss required fewer trials to reach criterion than a control group. Further evidence in this line was given by Dqbrowska (1968) who trained rats on a whiteblack discrimination for 300 trials and then reversed the problem for the next 300 trials. According to the author frontal Ss showed a higher number of correct responses in the whole period of original and reversal learning. Moreover, the inspection of data by Landsell, land Gross and his associates, suggests a somewhat superior performance of frontal than normal Ss, although the differences do not reach the normally accepted level of significance. Since the problem, besides its theoretical importance, indicated a striking case of superiority of operated animals it seemed reasonable to col-