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Nonlinear sensory cortex response to simultaneous tactile stimuli in writer's cramp
Author(s) -
Sanger Terence D.,
PascualLeone Alvaro,
Tarsy Daniel,
Schlaug Gottfried
Publication year - 2002
Publication title -
movement disorders
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.352
H-Index - 198
eISSN - 1531-8257
pISSN - 0885-3185
DOI - 10.1002/mds.1237
Subject(s) - sensory stimulation therapy , sensory system , neuroscience , stimulation , functional magnetic resonance imaging , dystonia , sensory processing , psychology , somatosensory system , index finger , motor cortex , receptive field , sensory cortex , electrophysiology , audiology , medicine , anatomy
Writer's cramp is a task‐specific dystonia that leads to involuntary hand postures during writing. Abnormalities of sensory processing may play a pathophysiological role in this disorder. Electrophysiology studies in a monkey model of focal dystonia have revealed de‐differentiation of sensory maps and the existence of single cells in hand regions of area 3b with enlarged receptive fields that extend to the surfaces of more than one digit. These changes may lead to abnormal processing of simultaneous sensory inputs. To study abnormal processing of simultaneous sensory information in adult humans with writer's cramp, we used functional magnetic resonance imaging to compare the response in primary sensory cortex with simultaneous tactile stimulation of the index and middle finger, with the response to stimulation of each finger alone. We tested five patients with writer's cramp and seven unaffected (normal) subjects. In the normal subjects, a linear combination of the activation patterns for individual finger stimulation predicts the pattern of activity for combined stimulation with 12% error. In writer's cramp patients, the linear combination predicted the combined stimulation pattern with 30% error. Results indicate a nonlinear interaction between the sensory cortical response to individual finger stimulation in writer's cramp. This altered interaction may contribute to the motor abnormalities. © 2001 Movement Disorder Society