Monkey substantia nigra (pars reticulata) neuron discharges during operant feeding

Unit activity in the substantia nigra pars reticulata was recorded during monkey bar-press feeding behavior. Activity of one-third of neurons was related to motor execution such as arm extension, flexion and bar-pressing, but not to motor preparation. Motor-related neurons were distributed mainly in the rostrolateral part of the nucleus. More than one-third responded during feeding and/or drinking acts and to intra- or perioral sensory stimuli. These ingestion-related neurons were distributed mainly in the caudomedial part of the nucleus.