Unilateral temporal lobe lesions alter P300 scalp topography

Event related potentials were recorded from patients with unilateral temporal lobe lesions and healthy volunteers. Subjects were required to silently count on infrequent target tone interspersed among presentations of a non-target tone, with an interval between tones that was relatively long and variable (6-10s). Under these task conditions, the patients were found to have P300 amplitudes that were smaller on the lesioned side relative to the non-lesioned side. This finding is interpreted as evidence that temporal lobe lesions affect the configuration of intracranial sources generating the P300 component of event-related potentials.