Right hemispheric participation in semantic decision improves performance.

Functional neuroimaging studies in healthy adults demonstrate involvement of a left-lateralized network of frontal, temporal, and parietal regions during a variety of semantic processing tasks. While these areas are believed to be fundamental to semantic processing, it is unclear if task performance is correlated with differential recruitment of these or other brain regions. The objective of this study was to identify the structures underlying improved accuracy on a semantic decision task. We also investigated whether extra-scanner performance on the Boston Naming Test (BNT) and Semantic Fluency Test (SFT), neuropsychological measures of semantic retrieval, is correlated with specific areas of activation during the semantic decision/tone decision (SDTD) fMRI task. Fifty-two healthy, right-handed individuals performed a block-design SDTD task. Regression analyses revealed that increased performance on this task was associated with activation in the right inferior parietal lobule. Higher SFT performance resulted in greater recruitment of right frontal regions; improved performance on BNT was associated with more widespread activation in prefrontal, temporal, and parietal cortex bilaterally, although this activation appeared to be stronger in the right hemisphere. Overall, our results suggest that improved performance on both intra- and extra-scanner measures of semantic processing are associated with increased recruitment of right hemispheric regions.

Moderating effect of optimism on emotional distress and seizure control in adults with temporal lobe epilepsy.

Stress is a commonly reported seizure precipitant among individuals with epilepsy. Yet, the relationship between stress and seizure susceptibility remains unclear. This study examined the relationship between emotional distress and lifetime seizure load in individuals with temporal lobe epilepsy (TLE), as well as the potential moderating effect of explanatory style on this relationship. Data were collected from 148 individuals with TLE. Scales 2 and 7 of the Minnesota Multiphasic Personality Inventory were used as a measure of emotional distress, and explanatory style was measured using the Revised Optimism-Pessimism Scale. Elevated Scale 2 scores were associated with an increase in seizure load only in subjects with Full Scale IQ scores> or =92. An interaction between emotional distress and explanatory style was not observed. Thus, for individuals with higher levels of intelligence, depression may be an important pathway in linking emotional distress to poor seizure control.

Temporal lobe epilepsy does not impair visual perception.

Temporal lobe epilepsy (TLE) can impair interictal cognitive function. In the perceptual domain, previous psychophysical studies demonstrated specific deficits in auditory and tactile perception in patients with TLE. This study compared performance of 25 TLE subjects and 27 controls on two low-level, visual tasks: luminance discrimination and frequency discrimination. Both tasks were performed under a relatively easy and a relatively difficult condition, by adjusting the stimulus duration. TLE subjects performed as well as controls on both tasks at both stimulus durations. These results imply that interictal occipital lobe function, as reflected in performance on low-level visual tasks, is not impaired in TLE, consistent with functional imaging data. Furthermore, since TLE subjects performed normally while taking therapeutic doses of multiple AEDs, the data suggest that these AEDs do not impair visual perception.