Self-stimulation in 7- and 10-day-old rats.
Recently, it has been shown that the infant rat exhibits learned behaviors characteristic of the adult. With a modified self-stimulation paradigm, this study explored whether 7- and 10-day-old rat pups could learn a discriminated operant to obtain direct electrical stimulation in neural sites that support self-stimulation in adults. By nudging one of two response manipulanda, at two ages (7 and 10 days) and temperatures (22 and 35 degrees C), pups self-stimulated with electrodes implanted in a variety of forebrain sites, including the prefrontal cortex, bed nucleus of the stria terminalis, medial nucleus of the amygdala, and the medial forebrain bundle. The only temperature-sensitive site might be the nucleus accumbens which was positive only at the higher temperature in 10-day-olds. These results indicate that several forebrain sites demonstrate rewarding properties of stimulation in the preweanling rat pup.