Neural correlates of eye blinking; improved by simultaneous fMRI and EOG measurement.

Neural correlates of eye blink in healthy human subjects can be investigated using functional magnetic resonance imaging. However, the focus of most previous studies has been on intentional eye blinking. The goal of the present study was to examine the neural correlates of spontaneous eye blinking with the help of EOG measurements during data acquisition of fMRI. After the removal of the pulse artifact in the EOG signal, EOG waveform clearly indicates eye blinking, which was equivalent to those measured outside of the MRI scanner. On the basis of this detection, each blinking event can be used as a temporal cue for the event-related fMRI. In a comparison, we also investigated the neural correlates of blink inhibition. Based on the brain activation pattern, the activation of the bilateral parahippocampal, the visual cortex was commonly observed for both conditions. The additional activation of the precentral gyrus, corresponding to blink inhibition, and the right medial frontal gyrus, corresponding to spontaneous blinking were observed. Based on these results, we conclude that the medial frontal gyrus is responsible for spontaneous eye blinking, whereas precentral activation appears to be related to blink inhibition.