MATERNAL AGGRESSION IN RATS - EFFECTS OF VISUAL OR AUDITORY DEPRIVATION OF THE MOTHER AND DYADIC PATTERN OF ULTRASONIC VOCALIZATIONS

Previous studies indicate that somatosensory inputs to the snout and t he ventral trunk play critical roles in the elicitation and maintenanc e of maternal aggression by postpartum lactating Long-Evans Norway rat s toward a strange male intruder. In the present studies we examined t he possible influence of visual and auditory stimuli in the display of this behavior. In Experiment I, dams temporarily deprived of visual o r auditory input by eyelid suturing or ear molds, respectively, on Day 2 postpartum, were found to have normal levels of maternal aggression 1 day later. In Experiment 2, males were found to contribute about 50 % of the short-duration 50-kHz vocalizations, which begin shortly afte r introduction of the intruder, and all of the long-duration 22-kHz vo calizations, which begin after the onset of attacks. Nonetheless, fema les tested with males surgically devocalized 7 days earlier were not s ignificantly different in aggressiveness from dams tested with vocaliz ing males on either Day 1 or Day 4 postpartum. These findings indicate that visual or auditory inputs from the pups or intruder are not crit ical to the display of maternal aggression in rats, at least within th e confines of laboratory housing. (C) 1994 Academic Press, Inc.