Eyeblink-related potentials.

When the EEG is averaged time-locked to blinks, and the part of the potential that is proportional to the EOG is subtracted, a signal (the 'residuum') remains which resembles an event-related potential (ERP). The blink time-locked average (BTA) was investigated to determine whether the components of the residuum are due to a cerebral blink-related potential or to artifacts of the EOG which subtraction failed to remove. The BTA was obtained from 12 subjects using voluntary blinking in the light and in complete darkness. Differences between the potentials in light and dark indicate that a major component of the residuum is a visual evoked response elicited by the off-on light stimulus associated with blink eye closure. The results are discussed in relation to attempts to correct blink artifacts in ERP experiments and, by drawing parallels between the residuum and the lambda potential associated with saccades, similar inferences are made for the correction of eye movement artifacts.