Abstracts

There is a well-established relationship between verbal memory and left hippocampal integrity in patients with temporal lobe epilepsy (). A reliable association between visual memory test performance and the right hippocampus has not been found. Barrash et al. (2000) created a real-life route learning test () and administered it to a large group of patients with different types and sites of focal brain lesions. Right hippocampal injury was among the lesions associated with impaired route learning in their investigation. In this study, we assessed TLE patients and controls on a similar RLT.
The two groups did not differ significantly in gender ratio, age, education, or IQ. The participants were led by the examiner on a fixed route through unfamiliar hospital corridors at a leisurely pace for approximately four minutes. The layout of the University of Wisconsin Hospital is topographically complex. The participants were asked to pay close attention to the route so that they subsequently could follow it independently while making as few errors as possible. They were informed that they would be timed, but that accuracy was more important than speed. Following the demonstration, the participant led the way through the same route three times, or twice if performance on the first two trials was flawless. When an error occurred, the examiner immediately pointed out the correct turn. Number of errors and time to completion were recorded for each trial.
Across the three RLT trials, the patients committed significantly more errors and were slower to complete the route ([italic]p[/italic] [lt] .05). Within the TLE group, RLT errors correlated best with tests measuring visual-perception (Judgment of Line Orientation test and WAIS-III PIQ) and memory (WMS-III delayed visual memory and immediate and delayed auditory memory indexes). Speed on the RLT was associated with a wider range of cognitive measures. These results are based on data from 10 controls and 12 TLE patients. Additional data, including correlations between hippocampal volumes and RLT performance, will be reported for a larger sample of patients who will be returning for a longitudinal study.
In this study, we tested TLE patients and controls on a RLT that involved traversing a relatively complex path through hospital hallways after one demonstration of the route by the examiner. There were significant group differences in total errors and mean time to completion. Among the patients, RLT errors correlated best with tests measuring visual-perceptual ability and auditory and visual memory. These results suggest that topographical learning impairment is among the memory deficits characteristic of TLE. The incidence of RLT impairment among the patients and the relationship between RLT ability and left and right hippocampal volumes, age of onset of epilepsy, etc. will be reported.
[Supported by: NIH grants K23 NS42251, 2RO1-37738, and MO1 03186.]