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Motor Function 

Motor Function
Chapter:
Motor Function
Author(s):

Riitta Hari

, and Aina Puce

DOI:
10.1093/med/9780190497774.003.0016
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date: 03 March 2021

Voluntary movements are preceded by slow brain activity, visible in EEG as the Bereitschaftspotential (the readiness potential), and in MEG as the readiness field. These slow shifts can begin a few seconds before movement onset in the primary motor cortex and in the premotor areas. Cortex–muscle coherence refers to coupling between MEG/EEG signals and the surface EMG of a steadily contracted muscle; it typically occurs at around 20 Hz and implies an efferent drive from the cortex to the muscle. Corticokinematic coherence can be measured as the coupling between MEG/EEG signals and the acceleration or velocity of a rhythmically moving limb; it typically occurs are the movement frequency and its first harmonic. Coherence of MEG/EEG signals can be computed also with respect to other peripheral signals, such as the fundamental frequency of the voice measured with an accerometer above the subject’s throat.

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