BEHAVIORAL-EFFECTS OF ABLATIONS OF THE PRESUMED PREFRONTAL CORTEX OR THE CORTICOID IN PIGEONS

This study further explored functional similarities of mammalian prefr ontal cortex and its presumed equivalent in pigeons. Our results show that the performance of delayed alternation of pigeons in an Y-maze is impaired following ablations of the prefrontal equivalent together wi th the corticoid but not of the corticoid alone. In the same maze, dis crimination between vertical and horizontal stripes was unimpaired reg ardless of the lesion. Our results added the following new information . (1) Corticoid is not essentially involved in mediation of delayed re sponding. (2) Like monkeys, pigeons take much fewer trials to learn de layed alternation in a maze than in an operant chamber. (3) Lesions of the pigeon equivalent of the prefrontal cortex impair delayed respond ing also in the new apparatus. (4) These lesions do not impair visual pattern discrimination. Our results do not contradict the hypothesis t hat the postero-dorso-lateral neostriatum in pigeons is comparable to the prefrontal cortex in mammals.