Anomalous brain activation during face and gaze processing in Williams syndrome.

OBJECTIVE: To investigate the discrete neural systems that underlie relatively preserved face processing skills in Williams syndrome (WS). METHODS: The authors compared face and eye-gaze direction processing abilities in 11 clinically and genetically diagnosed WS subjects with 11 healthy age- and sex-matched controls, using functional MRI (fMRI). RESULTS: Compared to controls, WS subjects showed a strong trend toward being less accurate in determining the direction of gaze and had significantly longer response latencies. Significant increases in activation were observed in the right fusiform gyrus (FuG) and several frontal and temporal regions for the WS group. By comparison, controls showed activation in the bilateral FuG, occipital, and temporal lobes. Between-group analysis showed WS subjects to have more extensive activation in the right inferior, superior, and medial frontal gyri, anterior cingulate, and several subcortical regions encompassing the anterior thalamus and caudate. Conversely, controls had greater activation in the primary and secondary visual cortices. CONCLUSION: The observed patterns of activation in WS subjects suggest a preservation of neural functioning within frontal and temporal regions, presumably resulting from task difficulty or compensatory mechanisms. Persons with WS may possess impairments in visual cortical regions, possibly disrupting global-coherence and visuospatial aspects of face and gaze processing.

A comparison of four tests of malingering and the effects of coaching.

This study examined the ability of four measures of suboptimal performance to correctly classify four groups of subjects (normal controls, uncoached malingering, coached malingering, and head injured). Only the Portland Digit Recognition Test-Computerized (PDRT-C) identified simulating malingerers with greater than chance accuracy while minimizing false positives. Coached subjects were better able than their uncoached counterparts to avoid detection on all measures. In an additional analysis, a discriminant function using the response latency and total correct scores from the PDRT-C identified 70% of the coached malingerers on cross validation. The three other tests (Nonverbal Forced Choice Test, 21-Item Test, and Dot Counting Test) failed to obtain a satisfactory classification rate for the malingering groups as a whole and coached malingerers in particular.