In a parent project on the cerebral representation of the separation call, it was found that ablation of the midline frontal cortex caudal to the polar area in squirrel monkeys did not (as was also known in the case of rhesus monkeys) result in discernible retrograde degeneration in the thalamus. The present project is employing cytochemical tracing techniques for obtaining clarification of the matter. Last year's reprot included a description of diverse thalamic nuclei, as well as extrathalamic structures, shown to be connected with different midline frontal areas. The present report focuses on additional findings suggesting an orderly projection of respective parts of the ventral anterior nucleus to different midline frontal areas. In the light of assorted experimental and clinical evidence that the thalamocingulate division of the limbic system and the striopallidonigral thalamic connections are implicated in crying and laughter, the anatomical findings suggest a link-up of mechanisms implicated in both the affect and expression of these manifestations.
