Biomedical subjects
Publications and source records attributed to T Free.
Recent data have demonstrated the efficacy of carotid endarterectomy in patients with severe, symptomatic carotid stenosis. In this context, our study analyzes the role of carotid testing with magnetic resonance angiography and carotid duplex scanning, as compared to arterial digital subtraction angiography.
Left-handed and right-handed subjects were given two dichotic listening tasks using identical material. In one task, they were asked to determine whether or not a specific target word was present (verbal task). In the other task, subjects were asked to indicate whether or not one of the dichotically-competing words was spoken in a particular affective tone (emotion task). Overall, a right-ear advantage (REA) was found with the verbal task and a left-ear advantage (LEA) with the emotion task. Left-handers showed a slightly smaller REA than right-handers on the verbal task, but a slightly larger LEA on the emotion task. This finding suggests that left- and right-hemispheric functions are not related in a complementary fashion and that handedness effects for nonverbal tasks are different from those seen with verbal tasks. The emotional LEA was much larger for angry stimuli than for happy, sad, or neutral stimuli. Rather than providing evidence for a hemisphere by affective valence interaction, such results suggest a stimulus-specific effect.
A series of studies was carried out to investigate laterality effects in the discrimination of tactile patterns presented to the fingertips of right-handed subjects. When both hands were stimulated simultaneously, a small right-hand advantage (RHA) was observed for a sequential task and a small left-hand advantage (LHA) was found for a spatial task, but only in women and only when there was a delay or mask between presentation and response. This may indicate different attentional strategies for men and women, or better shielding against interhemispheric interference in women. When only one hand was stimulated at a time (unimanual tasks), no laterality effects were found with sequential tasks, but a substantial RHA for a spatial task was observed. Because the unimanual spatial task involves more possible alternatives than the unimanual sequential ones, this RHA may be a consequence of increased information load rather than a the spatial/sequential distinction. While laterality effects in tactile laterality studies are relatively inconsistent, there are clear differences between bimanual and unimanual presentation. Effects related to hemispheric specialization are much more evident with bilateral presentation.
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