Cortical potentials associated with voluntary, reflex, and spontaneous blinks as bilateral simultaneous eyelid movement.

Movement-related cortical potentials (MRCPs) associated with the contraction of m. orbicularis oculi related to three types of blinks (voluntary, reflex, and spontaneous) were measured for 12 normal subjects. The purpose of the present study was to estimate the role of the cerebral cortex in close association with the blinks caused by bilateral simultaneous eyelid movements. MRCPs were recorded by surface electrodes placed over the frontal to the parietal regions. The mean amplitude and the duration of the MRCPs for the three types of blinks were evaluated by an averaging technique for each subject. MRCPs for the voluntary blinks were evoked in all subjects. For the reflex and the spontaneous blinks, however, a clear negative rising deflection from the baseline was not obtained. The maximum amplitude of the MRCPs for the voluntary blinks was localized at the vertex region, though there was no significant difference between the durations of the MRCPs for the vertex region and for the other regions. Moreover, the positive potential following the voluntary and the spontaneous blinks was recognized in the parietal region. These results suggest that only the voluntary blinks are caused by the neural activation of the supplementary motor area (SMA), and in addition, the neural activation related to visual recognition is considered to be elicited by the voluntary and the spontaneous blinks.