[Behavioral reactions in simians after ablation of the pole of the frontal cortex]

In 4 baboons and 3 macaques ablation of the frontal pole (area 10) as compared to other areas of the frontal cortex did not impair previously elaborated instrumental reflexes of different complexity and did not interfere with the elaboration of new ones. An increase in stability, speed, accuracy and intensity of conditioned reflexes was noted. The ablation did not result in motor or vegetative disturbances. In the general behaviour inhibitory elements disappeared along with an enhancement in motor goal-directed activity. It is suggested that frontal poles do not participate in closing-function but control conditioned reflexes and complex behaviour by means of inhibitory influences.