EVENT-RELATED DESYNCHRONIZATION (ERD) DURING VISUAL PROCESSING

Event-related desynchronization (ERD) is the short-lasting attenuation or blocking of rhythms within the alpha (beta) band. ERD is found dur ing but also before visual stimulation. Two different types of ERD can be differentiated: one short-lasting, localized to occipital areas an d involving upper alpha components; the other longer lasting, more wid espread, most prominent over parietal areas and maximal for lower alph a components. The former most likely reflects primary visual processin g and feature extraction, the latter is more related to cognitive proc essing and mechanisms of attention.