Infant rats: sensorimotor ontogeny and effects of substantia nigra destruction

The ontogeny of sensorimotor behaviors of albino rats were evaluated from birth through adulthood (Experiment 1). Sensorimotor behaviors (e.g., visual and tactile orientation, forelimb and hindlimb hopping, righting reflexes) achieved mature (adultlike) characteristics at various ages during ontogeny and a rostral-caudal developmental pattern was revealed. In Experiment 2, the substantia nigra was bilaterally or unilaterally destroyed in rats at 10 or 25 days of age and the ontogeny of sensorimotor and regulatory (feeding, drinking, body weight regulation) behaviors were evaluated. Bilateral destruction of the substantia nigra, zona compacta, at 10 and 25 days of age resulted in transient cessation of suckling and/or feeding and drinking followed by recovery. Male brain-damaged rats had reduced body weight through 150-170 days of age. Specific feeding and drinking tests revealed the presence of residual regulatory deficits which seemed permanent. Sensorimotor testing revealed transient dysfunction for a variety of sensorimotor behaviors, with eventual recovery of normal sensorimotor capacity. The results are related to sensorimotor ontogeny and recovery from infant brain damage.