title: Tactile stimulation of the hand causes bilateral cortical activation: a functional magnetic resonance study in humans.
abstract: The purpose of the present study was to assess the somatotopy of the cortical sensory representation of the fingers using a natural tactile stimulation of the glabrous skin. Multislice echoplanar imaging techniques were utilized to investigate blood oxygen level dependent (BOLD) signal changes as a measure of cortical activation. Repetitive sensory stimulation of the glabrous skin of digit II-III and digit IV-V resulted in a multifocal signal increase in a restricted area near the central sulcus in the contralateral hemisphere with a considerable overlap between the activated areas of digit II-III and digit IV-V. In addition, in all subjects tactile stimulation resulted in ipsilateral signal increase near the central sulcus, which was 15-22% of the contralateral effect. Stimulation of digit II-III caused significantly (P < 0.05) more activated voxels than digit IV-V in the contralateral hemisphere for both hands and for the left hand in the ipsilateral hemisphere. These findings suggest an ipsilateral activation of the primary somatosensory cortex during a natural tactile stimulation of the digits in humans.
authors.affiliation: Department of Clinical Neurophysiology, University Hospital, Linköping, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Hansson
authors.forename: T
authors.initials: T
authors.lastname: Brismar
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000294:innervation*; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D010100:Oxygen / Q000097:blood; D010812:Physical Stimulation; D012867:Skin / Q000294:innervation*; D013003:Somatosensory Cortex / Q000502:physiology*; D014110:Touch / Q000502:physiology*
chemical_list: D010100:Oxygen