Relationship of Firing Patterns of Units in Face Area of Monkey Precentral Cortex to Conditioned Jaw Movements

The Motor Cortex and Facial Expression:

“…[7][8][9][27][28][29][30][31][32][33][34][35] However, what remains clear as depicted in Penfield's homunculus and Woolsey's simissculi is that face/head, upper extremity, and lower extremity representations in M1 and M2 are adjacent but distinct cortical entities dedicated to subserving movement within in each general body region.…”

The role of the cerebral cortex in swallowing

“…Important insights into the functional organization of the cerebral cortex, in relation to swallowing, also can be gained through recording the activity of single cortical neurons in awake, behaving animals (for review, see [79]). Such investigations have shown that the firing patterns of single neurons in the lateral precentral cortex of the primate, including Brodmann's areas 4 and 6, and the CMA, are related to a variety of trained orofacial motor behaviors, including a trained biting task [80][81][82] or a trained tongue protrusion task [82]. Morever, the activity patterns of some neurons within this cortical region also have been shown to be related to the orofacial movements associated with naturally occurring (i.e., untrained) ingestion, licking, mastication, and/or swallowing [50,[80][81][82][83][84][85].…”

“…Such investigations have shown that the firing patterns of single neurons in the lateral precentral cortex of the primate, including Brodmann's areas 4 and 6, and the CMA, are related to a variety of trained orofacial motor behaviors, including a trained biting task [80][81][82] or a trained tongue protrusion task [82]. Morever, the activity patterns of some neurons within this cortical region also have been shown to be related to the orofacial movements associated with naturally occurring (i.e., untrained) ingestion, licking, mastication, and/or swallowing [50,[80][81][82][83][84][85]. For example, certain neurons in the lateral precentral cortex may be phasically active in relation to the opening or closing jaw movements associated with chewing [80,83] or with the orofacial motor behavior associated with licking [80,82].…”

“…For example, certain neurons in the lateral precentral cortex may be phasically active in relation to the opening or closing jaw movements associated with chewing [80,83] or with the orofacial motor behavior associated with licking [80,82]. Luschei et al [81] found that many hundreds of neurons in Brodmann's areas 4 and 6, which showed no relation to a trained biting task, fired in relation to ingestive movements, and that a typical pattern was for these neurons to be silent during the first or second ingestive movements of a series, and then to begin firing rhythmically during subsequent ingestive movements. Similarly, neurons within the primate CMA have been reported to fire in relation to movements of the jaw and tongue associated with ingestion [50].…”

Lateral Facilitation of Hoffmann-Reflexes Prior to Voluntary Movement in a Choice Reaction Time Task

“…One possibility is that the facilitation is attributable to the disinhibition of presynaptic inhibitory processes on the la-afferent terminals, a mecha nism also suggested by the apparent independence of H-reflex excitability changes and EMG discharge during the dynamic phase of plantar flexions [5]. Another possibility is that the reflex facilitation reflects the selective, temporal, post-synaptic excitation of phasic rather than tonic motoneu rons which may result from repetitive discharges along corticomotoneuronal pathways, since motoneurons require considerable integration of synaptic input before discharging [3,6,8].…”