Effects of satiety on self-stimulation of the orbitofrontal cortex in the rhesus monkey.

Self-stimulation of the orbitofrontal cortex of the rhesus monkey was found to be attenuated after the monkeys were fed to satiety. Self-stimulation at some other sites (e.g. the nucleus accumbens septi, the region of the substantia nigra, and the caudate nucleus) was relatively unaffected in the same test sessions by the satiety. In recordings from single neurons in the monkey orbitofrontal cortex, neurons of the type found in the lateral hypothalamus with sustained responses associated with the sight of preferred foods were not found. However, some orbitofrontal neurons did respond to the removal of food or other desired objects. These experiments show that self-stimulation of the monkey orbitofrontal cortex in modulated by hunger, and show that some orbitofrontal neurons have complex responses which could be related to the control of feeding.