These studies are concerned with how premature separation from the mother affects the development of the infant rat. We seek to understand the processes by which the experience becomes translated into physiological and behavioral change. We will be studying nutritional, thermoregulatory, olfactory and attachment processes underlying the mother-infant relationship. Our methods include selected electro-physiological, hormonal and neuropharmacological methods as well as behavioral observation. Building on our past work exploring the mechanisms for the response in cardiovascular, behavioral and sleep-wake cycle regulations, we plan to analyze the processes that facilitate and retard recovery in these systems, after prolonged maternal absence. Since we have demonstrated that early separation increases later susceptibility to gastric ulcer under stress in adulthood, we hope to develop models for how long-term susceptibility to hypertension and abnormal behavior under stress may be influenced by early separation.