The isolation call may rank as the most basic mammalian vocalization, serving originally to ensure maternal-offspring contact. Since the medial frontolimbic cortex has proved to be the main cortical area for eliciting vocalization in the squirrel monkey, the present project is concerned with testing the effects of damage to this area on the production of the isolation (separation) call. Adult squirrel monkeys of either sex are tested for their ability to produce isolation calls before and after ablations of different parts of the frontal lobe. Criterion performance is the production of 20 or more isolation calls during a 15-minute period of isolation in a sound-reducing chamber. This year's work has provided further evidence that lesions confined to a continuous band of pragenual and preseptal limbic cortex together with an as yet undefined adjacent area of medial frontal neocortex results in an enduring elimination of the spontaneous production of the call. Since lesions restricted to the different parts of the defined limbic area do not eliminate the call, the next step is to learn whether or not the medial frontal neocortex is necessary for the apparent concerted cortical action requisite for emitting the call. The relevance of this research to mental health is discussed.
