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Holth M, van der Meer ALH, van der Weel FRR (2013) Combining findings from gaze and electroencephalography recordings to study timing in a visual tracking task. NeuroReport, 24(17):968-972    
Electroencephalography (EEG) and gaze data have traditionally been separated in neurocognitive studies because of the artefacts that even small controlled eye movements produce. Study of gaze control in a visual tracking task provides information about an individual’s prospective control. By including gaze events in the EEG analysis, we studied prospective control and its neural correlates during deceleration in a visual tracking task. Adult participants followed with their gaze a small car moving horizontally on a large screen, where the final approach of the car was temporarily occluded, and pushed a button to stop the car at the reappearance point. Two gaze events, the behavioural push button response and the nonbehavioural stimulus onset, were used to time-lock the averaged event-related potential (ERP) waveform. A significant effect of deceleration on peak amplitude in parietal channel Pz (P<0.05) was found when ERP waveforms were time-locked to the prospective gaze shift over the occluder. The peak decreased in amplitude as car deceleration increased when participants successfully stopped the car, indicating successful deceleration discrimination. No such effect was found when ERP waveforms were time-locked to any of the other events. Thus, a traditional stimulus onset time-locking procedure is likely to distort the averaged signal and consequently hide important Pz-peak amplitude differences on the prospective timing of decelerating object motion during occlusion. This study shows the importance of including behavioural data when studying neural correlates of prospective control and proposes active incorporation of behavioural data into the EEG analysis