Feeding and behavioral activation in infant rats.

Three-day-old rats that were separated from their mothers and deprived of food were found to be capable of feeding either from small puddles of milk or when milk was infused into the front of their mouths. Such feeding was accompanied by a dramatic increase in behavioral activity and only occurred in a warm environment. These data demonstrate that neural systems for ingestive behavior are present at birth and suggest the existence of feeding-related arousal or motivational systems.