INTRACRANIAL ANDROGENIC ACTIVATION OF MALE-TYPICAL BEHAVIORS IN-HOUSEMICE - MOTIVATION VERSUS PERFORMANCE

Castrated male mice were bilaterally implanted with 27 ga cannulae con taining testosterone into either the septum, medial preoptic area (MPO ), or corticomedial amygdala. One additional group of castrates receiv ed no hormone and another received only systemic testosterone via subc utaneous silastic capsules. All males were subsequently tested for ult rasonic mating vocalizations, urine marking, mounting behavior, aggres sion and gender preference, all of which are androgen-dependent, male- typical behaviors. In general castrates receiving no hormone performed these behaviors at low levels and animals receiving systemic testoste rone performed the behaviors at normal male-typical levels. Ultrasonic vocalizations in response to female urine were activated by MPO impla nts. Urine marking in response to female urine appeared to be partiall y activated only with MPO implants. Very little mounting or fighting w ere seen in the brain implanted groups. Gender preference (for females over males) was restored with MPO implants and appeared to be partial ly activated with septal implants. The seminal vesicles of the castrat es receiving brain implants were not significantly different from thos e receiving no hormone indicating that little or no implanted hormone was exiting the brain into general circulation. The implications of th ese findings for the neuroanatomy of sexual motivation and performance are discussed.