Steady state visually evoked potential correlates of auditory hallucinations in schizophrenia

This study attempted to localize regions of brain electrical activity assoc iated with the onset of auditory hallucinations. Changes in Steady State Vi sually Evoked Potential(SSVEP) topography associated with the onset of spon taneous auditory hallucinations was studied in eight schizophrenic patients , The SSVEP elicited by a spatially uniform sinusoidally varying visual fli cker was recorded using a 64-channel electrode helmet. A large and signific ant decrease in SSVEP latency in the right temporo/parietal region occurred in the second prior to the report of auditory hallucinations. A control ta sk with matching motor movements produced no significant decrease in SSVEP latency in the same right temporo/parietal location. This finding suggests that activity of fine temporal resolution in the neural networks in the rig ht temporo/parietal area may be implicated in the genesis of auditory hallu cination, in conformity with certain neuropsychological theories. (C) 1998 Academic Press.