Cerebral cortical representation of reflexive and volitional swallowing inhumans

The purpose of this study was to compare cerebral cortical representation o f experimentally induced reflexive swallow with that of volitional swallow. Eight asymptomatic adults (24-27 yr) were studied by a single-trial functi onal magnetic resonance imaging technique. Reflexive swallowing showed bila teral activity concentrated to the primary sensory/motor regions. Volitiona l swallowing was represented bilaterally in the insula, prefrontal, cingula te, and parietooccipital regions in addition to the primary sensory/motor c ortex. Intrasubject comparison showed that the total volume of activity dur ing volitional swallowing was significantly larger than that activated duri ng reflexive swallows in either hemisphere (P< 0.001). For volitional swall owing, the primary sensory/motor region contained the largest and the insul ar region the smallest volumes of activation in both hemispheres, and the t otal activated volume in the right hemisphere was significantly larger comp ared with the left (P< 0.05). Intersubject comparison showed significant va riability in the volume of activity in each of the four volitional swallowi ng cortical regions. We conclude that reflexive swallow is represented in t he primary sensory/motor cortex and that volitional swallow is represented in multiple regions, including the primary sensory/motor cortex, insular, p refrontal/cingulate gyrus, and cuneus and precuneus region. Non-sensory/mot or regions activated during volitional swallow may represent swallow-relate d intent and planning and possibly urge.