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 retino-cortical dynamics for the generation of the alpha rhythm, fast synchronized oscillations (gamma rhythm), and flash visual evoked potentials (FVEP). Computer simulations are used to compare theoretical predictions 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 generates synchronized oscillations in the gamma range that coexist with low-frequency oscillations. The relative magnitude and latencies of the characteristic peaks P40, N70, P100, N130, P170 of the FVEP wave generated by the model in response to flash inputs are in good agreement with the experimental FVEP. The study predicts that intra-channel transient to sustained inhibition between parallel visual streams plays a major role in shaping these components of the FVEP and that the cortical areas beyond the visual cortex play a major role in shaping the late components of the FVEP in that if these areas were inactivated, alpha blocking would disappear and the resulting evoked potential would follow a damped sinusoidal wave.