MASTICATION-RELATED NEURONS IN THE OROFACIAL FIRST SOMATOSENSORY CORTEX OF AWAKE CATS

In the orofacial area of the first somatosensory cortex (SI), we recor ded single unit activity from 699 neurons in 11 awake cats. Fifty-two percent (362/699) were mastication-related neurons (MRNs) showing acti vity related to some aspects of masticatory movements. MRNs were divid ed into three types by their activity patterns: (1) the rhythmical typ e, showing rhythmical bursts in pace with the masticatory rhythm; (2) the sustained type, showing a sustained firing during the period of ta king food and (3) the transient (biting) type, showing intense dischar ges in coincidence with biting hard food. MRNs had mechanoreceptive fi elds in the perioral, tongue, periodontal and mandibular regions. The activities of perioral rhythmical-MRNs, mandibular transient-MRNs, ton gue rhythmical-MRNs and periodontal transient-MRNs were correlated wit h food texture, while perioral rhythmical-MRNs, perioral sustained-MRN s and tongue sustained-MRMs were not. Both facial and intraoral MRNs w ere scattered throughout the facial and intraoral projection areas in SI. These findings provide evidence that the orofacial SI monitors mas ticatory movements for food ingestion.