NEUROPSYCHOLOGY OF MATERNAL-BEHAVIOR IN THE RAT - C-FOS EXPRESSION DURING MOTHER-LITTER INTERACTIONS

This series of studies used the pattern of nuclear Fos-like immunoreac tivity (Fos-lir) to map the functional pathways in the brain that medi ate the onset and retention of maternal behavior. In the first two exp eriments, parturient rat dams were exposed to either pups or to other stimuli on Day 1 postpartum. Dams interacting with pups were either in tact or sustained ventral somatosensory, olfactory, or combined desens itizations. Results showed that 1) all intact pup-interacting dams sho wed elevated levels of Fos-lir in the medial preoptic area (MPOA) and the medial and cortical amygdala as compared to control groups, and 2) olfactory and ventral somatosensory desensitization, either alone, or in combination, did not decrease Fos-lir in the MPOA. However, olfact ory desensitizations did decrease Fos-lir in the medial amygdala and t he combined desensitizations significantly reduced Fos-lir in both the basolateral and central amygdala. In the third study, dams were eithe r exposed to pups or to other stimuli and were subsequently reexposed to pups or to pup cues. Regardless of prior maternal experience, femal es who were able to interact with pups upon reexposure showed increase d Fos-lir in the MPOA, the basolateral and central nuclei of the amygd ala, and the nucleus accumbens when compared to females which did not interact with pups. Taken together, these studies suggest that the neu roanatomy of maternal behavior is a complex one, involving multiple sy stems that interconnect with the MPOA and that mediate the many behavi oral processes activated when an animal responds maternally.