A UNIFIED ANALYSIS OF ALPHA-RHYTHM, FAST SYNCHRONIZED OSCILLATIONS, AND FLASH VISUAL-EVOKED POTENTIALS

This study explores the predictions of a neural network model of retin o-cortical dynamics for the generation of the alpha rhythm, fast synch ronized oscillations (gamma rhythm), and flash visual evoked potential s (FVEP). Computer simulations are used to compare theoretical predict ions with alpha, gamma, and FVEP activities. The spontaneous activity of the model is similar to the scalp recorded alpha in its time course and spectral content. In response to steady-state-inputs, the model g enerates synchronized oscillations in the gamma range that coexist wit h low-frequency oscillations. The relative magnitude and latencies of the characteristic peaks P40, N70, P100, N130, P170 of the FVEP wave g enerated by the model in response to flash inputs are in good agreemen t with the experimental FVEP. The study predicts that intra-channel tr ansient to sustained inhibition between parallel visual streams plays a major role in shaping these components of the FVEP and that the cort ical areas beyond the visual cortex play a major role in shaping the l ate components of the FVEP in that if these areas were inactivated, al pha blocking would disappear and the resulting evoked potential would follow a damped sinusoidal wave.