Role of the anterior cingulate cortex in volitional swallowing : an electromyographic and functional magnetic resonance imaging study

Anterior cingulate cortex (ACC) plays an important role in human volition, but its function in swallowing is not well known. We tested the hypothesis that visual inputs given before volitional swallowing modulate the ACC activity. We evaluated the relationship between visual effect on swallowing "behavior" and "brain activity" using EMG (electromyography) and fMRI (functional magnetic resonance imaging). Seven healthy volunteers participated in the EMG study, and 10 volunteers in the fMRI study. Visual images, i.e., photographs of food (DRINK) or general items (GENERAL), were used as the visual input and these were provided with (WS) or without (DS) water. Both behavioral and brain activity data were recorded during each trial in four (DRINK/WS, GENERAL/WS, DRINK/DS, GENERAL/DS) conditions. EMG study showed that the latency was significantly shorter with DRINK input than that with GENERAL input in the WS condition. Meanwhile, in the fMRI study, the maximum MR signal change was greater with GENERAL than that with DRINK in both WS and DS conditions. Thus, it appears that there was a relationship between swallowing behavior and the ACC activity in volitional swallowing