Stimulus- and frequency-specific oscillatory mass responses to visual stimulation in man

Oscillatory mass responses centered at about 20-35 Hz or 100-120 Hz occur ( after contrast or luminance visual stimulation, respectively) in the retina and cortex of animals and man and are recorded by electrical or magnetic m ethods. These oscillatory events reflect stimulus-related uni/multicellular oscillations of the firing rate/membrane potential and result from synchro nization of neuronal assemblies selectively responding to the stimulus char acteristics. Methodological problems in the study of these events derive fr om the contiguity in frequency between the ERG or VEP and the oscillatory r esponses and from the need to reliably define oscillatory events in time an d frequency. Two methods (time-frequency analysis by matching pursuit and l ocking index) have been implemented to approach this issue. Theory and appl ication are reviewed.