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Functional neuroimaging studies have implicated the fusiform gyri (FG) in structural encoding of faces, while event-related potential (ERP) and magnetoencephalography studies have shown that such encoding occurs approximately 170 ms poststimulus. Behavioral and functional neuroimaging studies suggest that processes involved in face recognition may be strongly modulated by socially relevant information conveyed by faces. To test the hypothesis that affective information indeed modulates early stages of face processing, ERPs were recorded to individually assessed liked, neutral, and disliked faces and checkerboard-reversal stimuli. At the N170 latency, the cortical three-dimensional distribution of current density was computed in stereotactic space using a tomographic source localization technique. Mean activity was extracted from the FG, defined by structure-probability maps, and a meta-cluster delineated by the coordinates of the voxel with the strongest face-sensitive response from five published functional magnetic resonance imaging studies. In the FG, approximately 160 ms poststimulus, liked faces elicited stronger activation than disliked and neutral faces and checkerboard-reversal stimuli. Further, confirming recent results, affect-modulated brain electrical activity started very early in the human brain (approximately 112 ms). These findings suggest that affective features conveyed by faces modulate structural face encoding. Behavioral results from an independent study revealed that the stimuli were not biased toward particular facial expressions and confirmed that liked faces were rated as more attractive. Increased FG activation for liked faces may thus be interpreted as reflecting enhanced attention due to their saliency.
This study investigated the effects of imagery on flexibility and the relations among verbal and non-verbal and spontaneous and adaptive flexibility measures. Finally, the effects of brain damage on flexibility and imagery were investigated. Historical and more recent concepts of the cognitive rigidity flexibility dimension were discussed with special emphasis on the effects of brain damage. Forty female and fourteen male volunteer students were tested with verbal and non-verbal flexibility tests. Measures of spontaneous flexibility were the Word Fluency Test and the Five Point Test and measures of adaptive flexibility were the Stroop Test and a newly introduced concept identification test, assessing imagery and interference concepts. Furthermore, a questionnaire to assess individual imagery styles was employed as well as the vocabulary and block design subtests of the WAIS. The results of brain damaged subjects were compared to a matched control group. Furthermore, z-score profiles were prepared to compare the test patterns between the different patient groups. Four dimensions of cognitive flexibility-rigidity were found in healthy subjects. Furthermore it was found that individual imagery styles had little influence on the performance in flexibility tests. A trend was showing that "habitual verbalizers" had no advantage in solving the tests and had in fact more difficulty with the identification of non-verbal concepts. No significant gender effects were found. Brain damaged patients performed significantly more poorly than normal subjects in all flexibility tests. Several test- and subject variables that effect the performance on flexibility tests were discussed. It was concluded that rigidity-flexibility measures represent different dimensions depending on stimulus mode and type of task. It was further concluded that behavioral rigidity-flexibility is not only the function of test variables, but also of various subject variables namely imagery style, intelligence, age, gender and brain damage. In healthy people, the performance on one test was not found to be predictive for the performance on another flexibility test. On the other hand, in brain damaged subjects rigid behavior seems to extend to a wider range of test performance. Finally, different performance patterns were described for different lesion sites in brain damaged.