EFFECT OF ABLATING THE FRONTAL LOBES, HIPPOCAMPI, AND OCCIPITO-PARIETO-TEMPORAL (EXCEPTING PYRIFORM AREAS) LOBES ON POSITIVE AND NEGATIVE OLFACTORY CONDITIONED REFLEXES

Abstract

The following tests were made before and after certain specific ablations with a view of ascertaining the relationships of these areas to olfaction. (a), establishment of a foreleg conditioned reflex to clove vapor; (b), transference of the clove reflex from one foreleg to the other; (c), establishment of a negative conditioned response to asafetida and conditioned differentiation, which involved a decision in 7 secs. whether to respond positively to cloves or negatively to asafetida; (d), food from no food discrimination by smell. Extensive bilateral extirpations of the parietal, occipital and temporal (exclusive of the hippocampi and pyriform areas) lobes or removal of 90 to 100% of the hippocampi (cornu ammonis) or unilateral frontal lobectomy had little, if any, effect on (a), (b) and (c) irrespective of whether the reflexes had or had not been acquired. Bilateral extirpation of the frontal lobes caused no delay in the first appearance of (a), but produced considerable delay in the establishment of (a) as a reflex. All but one dog which had acquired (a) before the operation responded to (a) sufficiently early during the first series of tests (1st to 3rd trial) after operating to indicate that the reflex had been retained. Frontal lobectomy produced some delay in the establishment of (b) in some dogs and no delay in others. Procedure (c) was absolutely abolished in all of the frontal lobectomized dogs. Attention was called to some temperamental variations of (c) in the discussion. None of the above cerebral extirpations affected (d) or interfered with taste responses to solns. of sugar, salt, quinine and acetic acid.