Recall deficits produced by afterdischarges in the human hippocampal formation and amygdala

The human amygdala, hippocampus and parahippocampal gyrus were stimulated in 3 epileptic patients with low-level electrical current during a paired associates learning task. Delayed recall of the response-words was severely impaired if, and only if, a unilateral afterdischarge was evoked. Stimulation at the same strength produced no deficit in immediate recall, nor in mental arithmetic, even when auras and afterdischarges were evoked. These data support the association of amnesia with medial temporal lobe paroxysms during complex partial seizures.