The dynamics of EEG gamma responses to unpleasant visual stimuli: From local activity to functional connectivity

Gamma rhythm modulation was estimated by the event-related synchronization (ERS) approach, and phase synchrony between trials and between cortical regions was studied by extending the phase-locking statistics (PLS) approach.

Many electroencephalographic (EEG) studies on the cortical dynamics induced by unpleasant picture viewing demonstrated the modulation of event-related potentials (ERPs) components as a function of valence and the increase of gamma band responses to emotional stimuli; while only a few studies investigated phase synchronization phenomena such as inter-trial or between regions phase locking of gamma responses to emotional stimulation. The aim of this study was to provide a complete description of the cortical dynamics induced by unpleasant and neutral pictures viewing, from the ERP averages to gamma rhythm modulation, and its phase synchronization.