PROACTIVE-INTERFERENCE IN PATIENTS WITH AMNESIA RESULTING FROM ANTERIOR COMMUNICATING ARTERY ANEURYSM

Diencephalic and temporal amnesics display an excessive sensitivity to proactive interference (PI) in memory tasks of the AB/AC kind. There exists considerable controversy about the nature of this sensitivity t o Pl. Moreover, it is an open question whether such sensitivity to PI is an obligatory feature of amnesia. or rather an incidental result of frontal damage often reported in amnesics. This question was reexamin ed by enrolling patients with an operated aneurysm of the anterior com municating artery (ACoA) and matched controls for an AB/AC learning ta sk of two lists of 12 paired-associate words. It appeared that ACoA pa tients, like diencephalic and temporal amnesics, did indeed display a marked sensitivity to PI when compared to normals (Exp. I), even when performance of both groups in the learning of the first list was equat ed (Exp. II). The distribution of errors made in learning the second l ist, as well as the correlations between performance in learning the s econd list and a Stroop test, suggest that sensitivity to PI in ACoA a mnesics could be the consequence of an inability to suppress irrelevan t information at retrieval due to defective inhibitory attentional mec hanisms. Complementary data collected in a small sample of Korsakoff's amnesic subjects are also described.