Material-specific memory in the intracarotid amobarbital procedure.

Abstract

We examined material-specific memory in 45 left hemisphere language dominant patients with temporal complex partial seizures (24 right, 21 left) during the intracarotid amobarbital procedure (IAP) by showing eight cards displaying two line drawings of common objects, two printed words, one colored shape, one math expression, one face, and one abstract shape following amobarbital injection (mean = 109.9 mg). We assessed delayed recall and recognition following clearing. Patients with right foci recognized significantly fewer verbally mediated stimuli (words, object drawings, colored shape) with left than with right injection. Patients with left foci recognized a nonverbal stimulus (abstract shape) more poorly following right versus left injection. Discriminant function analysis lateralized 85% of the sample from memory predictors, upheld to 81% on crossvalidation. Material-specific memory remains intact in the hemisphere contralateral to a seizure focus, but wider representation may occur for stimuli normally dominant for the hemisphere with the seizure focus. The IAP significantly lateralizes a seizure focus with use of both types of stimuli.