Test of the abstract attitude in chimpanzees following ablation of prefrontal cortex.

Abstract

LASHLEY 1 demonstrated that the deficit in learning and retention following cortical ablations in rats is a function of the amount of tissue removed, rather than of the locus of such removals. The search for regional specialization of function in the cortex of higher mammals, however, has continued, encouraged, no doubt, by the notion of increasing corticalization in evolutionary development. To the prefrontal areas of the cortex are usually assigned the function of mediating higher mental processes, characteristic of the primates, and especially of man. These processes are usually hazily specified, with vague references to inferential thinking, symbolism, mental synthesis, and the like. There have been various attempts, however, to define the function of the frontal lobes more exactly, usually by assigning to them some basic process which enters into a variety of intelligent performances. Thus, Jacobsen 2 suggested that they are essential for the immediate memory which underlies solution