On the search for the vocal pattern generator. A single-unit recording study

In the squirrel monkey (Saimiri sciureus), single-unit activity was compare d between the midbrain periaqueductal grey and the parvocellular and centra l nuclei of the medullary reticular formation during the production of spec ies-specific vocalization. It was found that all three areas contain neuron es with vocalization-related activity. The relative number of specific reac tions types differed between areas, however. While the majority of periaque ductal cells fired just before. but not during vocalization, most cells in the reticular formation fired before and during vocalization. Modulation of discharge rate with changing fundamental frequency was only found in the r eticular formation, not the periaqueductal grey. It is concluded that the p arvocellular and central nuclei of the reticular formation, but not the per iaqueductal grey are involved in vocal pattern generation. NeuroReport 11:2 031-2034 (C) 2000 Lippincott Williams & Wilkins.