Reduction of visual P300 during transient global amnesia.

Transient global amnesia (TGA) is a syndrome of selective loss of recent memory without other neurological deficits. Auditory and visual P300s were recorded during and after TGA to investigate the contribution of the short-term memory system to P300 generation. The auditory P300 during TGA was comparable to that recorded 1 week and 9 months after TGA. In contrast to the auditory modality, the visual target P300 was reduced in amplitude during TGA and at 1 week after the attack. The P300 to novel visual stimuli was also reduced during TGA. Both target and novelty visual P300 recovered by 9 months after TGA. The results support the notion that the neuronal networks responsible for P300 generation are modality dependent and that brain structures perfused by the posterior circulation are involved in visual P300 generation.