Neuron Article Transient Induced Gamma-Band Response in EEG as a Manifestation of Miniature Saccades

The induced gamma-band EEG response (iGBR) re-corded on the scalp is widely assumed to reflect syn-chronous neural oscillation associated with object representation, attention, memory, and conscious-ness. The most commonly reported EEG iGBR is a broadband transient increase in power at the gamma range!200–300ms following stimulus onset. A conspicuous feature of this iGBR is the trial-to-trial poststimulus latency variability, which has been in-sufficiently addressed. Here, we show, using single-trial analysis of concomitant EEG and eye tracking, that this iGBR is tightly time locked to the onset of involuntary miniature eye movements and reflects a saccadic ‘‘spike potential.’ ’ The time course of the iGBR is related to an increase in the rate of saccades following a period of poststimulus saccadic inhibi-tion. Thus, whereas neuronal gamma-band oscilla-tions were shown conclusively with other methods, the broadband transient iGBR recorded by scalp EEG reflects properties of miniature saccade dynam-ics rather than neuronal oscillations