Comparison of motor effects following subcortical electrical stimulation through electrodes in the globus pallidus internus and cortical transcranial magnetic stimulation
| Autor: | Andreas Kupsch, Andrea A. Kühn, Stephan A. Brandt, Kerstin Irlbacher, Jan Brocke, Bernd-Ulrich Meyer, Thomas Trottenberg, Gerd Schneider |
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| Rok vydání: | 2003 |
| Předmět: |
Adult
Male Internal capsule Adolescent medicine.medical_treatment Globus Pallidus Electromagnetic Fields medicine Reaction Time Humans Cerebral Cortex Analysis of Variance business.industry General Neuroscience Motor control Motor neuron Middle Aged Evoked Potentials Motor Electric Stimulation Electrodes Implanted Motor unit Transcranial magnetic stimulation medicine.anatomical_structure nervous system Corticospinal tract Female Primary motor cortex business Neuroscience Motor cortex |
| Zdroj: | Experimental brain research. 155(1) |
| ISSN: | 0014-4819 |
| Popis: | Current concepts of transcranial magnetic stimulation (TMS) over the primary motor cortex are still under debate as to whether inhibitory motor effects are exclusively of cortical origin. To further elucidate a potential subcortical influence on motor effects, we combined TMS and unilateral subcortical electrical stimulation (SES) of the corticospinal tract. SES was performed through implanted depth electrodes in eight patients treated with deep brain stimulation (DBS) for severe dystonia. Chronaxie, conduction velocity (CV) of the stimulated fibres and poststimulus time histograms of single motor unit recordings were calculated to provide evidence of an activation of large diameter myelinated fibres by SES. Excitatory and inhibitory motor effects recorded bilaterally from the first dorsal interosseus muscle were measured after SES and focal TMS of the motor cortex. This allowed us to compare motor effects of subcortical (direct) and cortical (mainly indirect) activation of corticospinal neurons. SES activated a fast conducting monosynaptic pathway to the alpha motoneuron. Motor responses elicited by SES had significantly shorter onset latency and shorter duration of the contralateral silent period compared to TMS induced motor effects. Spinal excitability as assessed by H-reflex was significantly reduced during the silent period after SES. No ipsilateral motor effects could be elicited by SES while TMS was followed by an ipsilateral inhibition. The results suggest that SES activated the corticospinal neurons at the level of the internal capsule. Comparison of SES and TMS induced motor effects reveals that the first part of the TMS induced contralateral silent period should be of spinal origin while its later part is due to cortical inhibitory mechanisms. Furthermore, the present results suggest that the ipsilateral inhibition is predominantly mediated via transcallosal pathways. |
| Databáze: | OpenAIRE |
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