Modulation of induced gamma band activity in the human EEG by attention and visual information processing

Here we present a series of four studies aimed to investigate the link betw een induced gamma band activity in the human EEG and visual information pro cessing. We demonstrated and validated the modulation of spectral gamma ban d power by spatial selective visual attention. When subjects attended to a certain stimulus, spectral power was increased as compared to when the same stimulus was ignored. In addition, we showed a shift in spectral gamma ban d power increase to the contralateral hemisphere when subjects shifted thei r attention to one visual hemifield. The following study investigated induc ed gamma band activity and the perception of a Gestalt. Ambiguous rotating figures were used to operationalize the law of good figure (gute Gestalt). We found increased gamma band power at posterior electrode sites when subje cts perceived an object. In the last experiment we demonstrated a different ial hemispheric gamma band activation when subjects were confronted with em otional pictures. Results of the present experiments in combination with ot her studies presented in this volume are supportive for the notion that ind uced gamma band activity in the human EEG is closely related to visual info rmation processing and attentional perceptual mechanisms. (C) 2000 Publishe d by Elsevier Science B.V. All rights reserved.