RELATIONS BETWEEN VERBAL AND NONVERBAL MEMORY PERFORMANCE - EVIDENCE OF CONFOUNDING EFFECTS PARTICULARLY IN PATIENTS WITH RIGHT TEMPORAL-LOBE EPILEPSY

Confounding left hemisphere verbalization strategies can be suggested as being a major problem in the evaluation of the assumed involvement of right temporo-limbic structures in ''nonverbal'' visual/figural mem ory processing. We addressed this issue by evaluating the easily-verba lized Benton-visual-retention-test in 60 patients with either left (LT LE) or right temporal lobe epilepsy (RTLE) and 30 healthy controls. We formally estimated the informational (verbal) content of each item wh ich hypothetically would be needed to solely retain the item from verb al memory. The results indicated confounding of verbal learning and fi gural memory only in the presence of right temporal lobe dysfunctions. Selective visual/figural learning deficits in RTLE patients became ob vious when the verbal load of the figural material exceeded their verb al learning capacity. Instead of excluding verbalization by the use of abstract figural items, its inclusion provides a possibility to contr ol compensatory strategies which overshadow the presence of visual/fig ural memory deficits.