Rhinencephalon and Behavior

¹ From the Department of Neurophysiology, Army Medical Service Graduate School, Walter Reed Army Medical Center, Washington, D. C.

Lesions of the rhinencephalon, primarily restricted to the amygdaloid complex, modify aggressive behavior of lynxes (Lynx rufus), agoutis (Dasyprocta agouti), monkeys (Macacus rhesus) and domestic cats toward relative docility and precipitate a state of chronic hypersexuality. Relative docility was characterized by failure of the experimental animals to exhibit aggressive behavior, fear, or escape activity in the presence of threatening situations which precipitated such behavior in their preoperative periods. Hypersexuality was exhibited by marked increases in copulatory activity with males and females of their own and other animal species. It is concluded that the rhinencephalon and its diencephalic connections, in association with endocrine systems, are important regulators of emotional and sexual behavior of rodents, carnivores and primates.