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Corticomuscular coherence in the 6–15 Hz band: is the cortex involved in the generation of physiologic tremor?

Corticomuscular coherence in the 6–15 Hz band: is the cortex involved in the generation of... Physiologic tremor (PT) consists of a peripheral mechanical oscillation at the limbs' resonance frequency and an independent central component in the 6–15 Hz band. This central component has mainly been attributed to spinal interneuronal systems or subcortical oscillators but more recently also to cortical rhythms. We recorded PT electromyographically and accelerometrically from different parts of the arm in parallel to epicortical recordings from grid electrodes covering the primary sensorimotor areas of the contralateral cortex in six epileptic patients. Previous bipolar electrical stimulation of the cortical electrodes resulted in a somatotopic map of the primary cortex underlying the grid. Spectral and cross-spectral analysis including coherence spectra between epicortical electrodes and EMG and the corresponding phase spectra were performed off-line. We found significant corticomuscular coherence in the 6–15 Hz range in four out of the six patients. This coherence was focal on the cortex and it was distributed somatotopically mainly within the primary motor area. The frequency band of the coherence mostly corresponding to the EMG frequency remained stable with added inertia, while the main accelerometric frequency was clearly reduced following the resonance frequency. The phase spectra between electrocorticogram (ECoG) and EMG showed a clear delay between cortex and muscle in two of the patients, which was compatible with conduction in fast pyramidal pathways. These findings indicate that the 6–15 Hz coherence between cortex and EMG reflects a corticomuscular transmission of the oscillation rather than peripheral feedback to the cortex. We conclude that cortical networks are involved in the generation of physiologic tremor. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Experimental Brain Research Springer Journals

Corticomuscular coherence in the 6–15 Hz band: is the cortex involved in the generation of physiologic tremor?

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References (53)

Publisher
Springer Journals
Copyright
Copyright © 2001 by Springer-Verlag
Subject
Biomedicine; Neurosciences; Neurology
ISSN
0014-4819
eISSN
1432-1106
DOI
10.1007/s00221-001-0914-7
pmid
11797082
Publisher site
See Article on Publisher Site

Abstract

Physiologic tremor (PT) consists of a peripheral mechanical oscillation at the limbs' resonance frequency and an independent central component in the 6–15 Hz band. This central component has mainly been attributed to spinal interneuronal systems or subcortical oscillators but more recently also to cortical rhythms. We recorded PT electromyographically and accelerometrically from different parts of the arm in parallel to epicortical recordings from grid electrodes covering the primary sensorimotor areas of the contralateral cortex in six epileptic patients. Previous bipolar electrical stimulation of the cortical electrodes resulted in a somatotopic map of the primary cortex underlying the grid. Spectral and cross-spectral analysis including coherence spectra between epicortical electrodes and EMG and the corresponding phase spectra were performed off-line. We found significant corticomuscular coherence in the 6–15 Hz range in four out of the six patients. This coherence was focal on the cortex and it was distributed somatotopically mainly within the primary motor area. The frequency band of the coherence mostly corresponding to the EMG frequency remained stable with added inertia, while the main accelerometric frequency was clearly reduced following the resonance frequency. The phase spectra between electrocorticogram (ECoG) and EMG showed a clear delay between cortex and muscle in two of the patients, which was compatible with conduction in fast pyramidal pathways. These findings indicate that the 6–15 Hz coherence between cortex and EMG reflects a corticomuscular transmission of the oscillation rather than peripheral feedback to the cortex. We conclude that cortical networks are involved in the generation of physiologic tremor.

Journal

Experimental Brain Research – Springer Journals

Published: Jan 9, 2002

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