Abstract

Electrical stimulation of certain brain areas produces a robust effect that directs the animal towards obtaining more stimulation. This phenomenon is believed to result from the activation of neural circuits that direct the animal towards naturally-occurring reinforcers such as food. The lateral hypothalamus (LH) is considered a particularly good site for obtaining vigorous self-stimulation in rats. There is evidence that chronic food restriction enhances the reward value of LH electrical stimulation when the electrode is positioned in the perifornical region. The objective of the present work was to characterize the forward circuitry activated by perifornical stimulation by examining the effects of long- and short-term energy balance manipulations within the same subjects. In this regards, Experiment 1 was carried out to replicate the findings that chronic food restriction facilitates perifornical self-stimulation. Experiment 2 was carried out to investigate the effect of a 48 hour period of food derivation on self-stimulation. To examine whether leptin signaling is involved in the process whereby food restriction enhances the rewarding effect of the perifornical stimulation the effect of an intraventricular infusion of leptin on self-stimulation was tested in Experiment 3.