## Abstract Somesthetic temporal discrimination (STD) is impaired in focal hand dystonia (FHD). We explored the electrophysiological correlate of the STD deficit to assess whether this is due to dysfunction of temporal inhibition in the somatosensory inhibitory pathway or due to dysfunction in stru
Task-dependent intracortical inhibition is impaired in focal hand dystonia
✍ Scribed by Cathrin M. Bütefisch; Babak Boroojerdi; Robert Chen; Fortunato Battaglia; Mark Hallett
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 125 KB
- Volume
- 20
- Category
- Article
- ISSN
- 0885-3185
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✦ Synopsis
Abstract
We tested whether task‐dependent modulation of inhibition within the motor cortex is impaired in patients with dystonia. Paired‐pulse transcranial magnetic stimulation (TMS) at an interstimulus interval of 2 msec was used to measure the effect of two different tasks on short ISI intracortical inhibition (SICI) in dystonic and normal subjects. In two experiments, SICI of the fourth dorsal interosseus (4DIO) and abductor pollicis brevis (APB) muscles were measured before and at the end of the training task. In the first experiment, subjects performed a nonselective task consisting of abducting the thumb, where the APB acted as agonist and the 4DIO as synergist. In the second experiment, the function of the 4DIO was changed as the subjects were asked to consciously inhibit this muscle while abducting the thumb (selective task). Therefore, while the APB was activated in both tasks, the 4DIO was activated in the nonselective task but was in the inhibitory surround in the selective task. We found that performance of the selective but not the nonselective task resulted in increased SICI in the 4DIO of normal but not in dystonic subjects. We conclude that task‐dependent SICI is disturbed in patients with dystonia. © 2005 Movement Disorder Society
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