In one study neural activity underlying MSs was investigated by simultaneously measuring eye video, response behavior, EEG, and fMRI in normally-rested individuals engaged in a sensory-motor task. Twenty participants tracked a visual stimulus with a joystick for 50 minutes in 2 dimensions (up/down/right/left) on a computer screen. Participants performed this task in an fMRI scanner such that joystick response, right eye-video, EEG (60 EEG electrodes), and fMRI data were recorded simultaneously. Most participants had frequent microsleeps (>35) in a continuous visuomotor task (tracking visual stimulus on a screen), corresponding with decreased activity in arousal-related brain regions over time (thalamus, midbrain, and the posterior cingulate cortex).