Abstracts

RATIONALE: The right and left hippocampal regions have been postulated to differentially subserve memory for visual (figural) and verbal information. Tests of verbal memory have consistently been shown to be useful for evaluating the integrity of left hippocampal functioning. No single test (or combination of tests) of figural memory, however, has consistently been reported to be useful for evaluating right hippocampal functioning. Shum (1995) introduced a test of visual learning SVLT) comprised of difficult-to-verbaize Chinese characters that discriminated between persons with right vs. left-sided CVAs. The usefulness of this test for assessing persons with temporal lobe epilepsy was therefore investigated. METHODS: 20 adult candidates for epilepsy surgery were administered the SVLT and other tests of figural (CVMT, RMF, CF) and verbal memory (AVLT, RMW, LM) as part of a comprehensive preoperative assessment. Patients varied in age (16 to 49 years) and intelligence (77 to 121 FSIQ) but were proportionate for gender and side of epileptogenic focus. Half had MRI confirmed right hippocampal lesions; the remainder had left hippocampal or extra-temporal pathology. RESULTS: SVLT total learning showed moderate to high correlation with performance on other tests of visual memory and a moderately high correlation (.73) with Performance IQ. SVLT learning correlated less highly with performance on tests of verbal memory (.52). ANOVA showed no differences in SVLT performance for groups with and without right hippocampal abnormality. CONCLUSIONS: In a small heterogeneous sample of persons with focal seizures, SVLT performance was highly correlated with performance on other tests of figural memory and with visuospatial intelligence. The latter correlation brings into question the construct validity of the SVLT. Like other tests purported to measure memory mediated by the right hemisphere, the SVLT was not preferentially useful for evaluating the integrity of right hippocampal functioning. The search continues.