Properties of cortical generators of event-related potentials.

Basic properties of cortical ERP generators, as disclosed by recording within the neocortex of mammalian animals and applying the current source-density analysis, are described. It is argued that all cortical generators are most likely caused by excitatory synaptic mass activities. The spatio-temporal pattern of the generators indicates the procedure of information processing, rather than the specific information being processed. It thus represents the physiological analogue of the uniform anatomical structure of the neocortex. Discordant with conclusions from single-cell studies concerning topography, all generators are tangentially widespread. The variations in the basic cortical activation pattern draw attention to the nonspecific central systems as their presumed main causes.