Question

Compare and contrast the effects of right hemisphere vs. left hemisphere damage on Intelligence as measured by the Weschler Adult Intelligence Scale (WAIS).

Answer 1

Effects:

The Wechsler Adult Intelligence Scale (WAIS) assesses a wide range of cognitive abilities and impairments. Factor analyses have documented four underlying indices that jointly comprise intelligence as assessed with the WAIS: verbal comprehension (VCI), perceptual organization (POI), working memory (WMI), and processing speed (PSI). We used non-parametric voxel-based lesion-symptom mapping with focal brain damage to neural underpinnings. Statistically significant lesion-deficit relationships were found in left inferior frontal cortex for VCI, in left frontal and parietal cortex for WMI, and in right parietal cortex for POI. There was no reliable single localization for PSI. Statistical power maps and cross-validation analyses quantified specificity and sensitivity of the index scores in predicting lesion locations. Findings provide the most comprehensive lesion maps of intelligence factors.

Comparison:

In adults acute left hemisphere lesions generally depress Verbal IQ and right hemisphere lesions depress Performance IQ. Here, early right lesions depress both Verbal IQ and Performance IQ skills, lowering IQ functioning in general. Left lesions spare Verbal IQ skills, but depress the Performance IQ.