THE MEDIAL AMYGDALOID NUCLEUS MODIFIES SOCIAL-BEHAVIOR IN MALE RATS

Electrical stimulation of the medial amygdaloid nucleus (AME) produces a behavioral state in male rats that resembles the postejaculatory in terval, but electrical recording from cells in the AME shows that they become active earlier in sexual behavior, around the time that the ma le first appears to become aware of estrus in the female. In an attemp t to resolve which feature of sexual behavior was mediated by the AME, we stimulated the structure bilaterally in freely behaving males usin g voltage levels too low to produce the postejaculatory interval. We f ound that electrical activation of this kind facilitated sexual behavi or when it would not otherwise occur (i.e., in the presence of a nones trous female). However, the stimuli suppressed sexual behavior when it would normally occur (i.e., in the presence of a nonestrous female). We discuss alternative interpretations of the results in the context o f a general model for the central organization of sexual behavior in m ales. (C) 1998 Elsevier Science Inc.