Changes in the responses of the neurons of the sensorimotor cortex to stimulation of the hunger centre of the lateral hypothalamus.

The responses of sensorimotor cortical neurons in hungry and in fed rabbits to stimulation of the lateral hypothalamic (LH) hunger centre were studied in the presence and absence of food. It was found that in the absence of food the response of the sensorimotor cortical neurons to LH stimulation differed between hungry and fed animals. No changes in firing rate were observed in 50% of neurons in hungry rabbits, and firing was inhibited in 45% of neurons in fed animals. Feeding reinforcement changed the nature of neuronal responses to LH stimulation. Qualitative changes in the responses to LH stimulation were observed in 77% of neurons in hungry rabbits, and in 61% of neurons in fed rabbits. Most neurons increased their rate of firing both in hungry and in fed animals.