Cortico-muscular gamma-frequency coherence is correlated with instantaneous target probability
Boston, MA : Biomag
InHalgren, E.; Ahlfors, S.; Hamalainen, M. (ed.), BIOMAG 2004: Proceedings of the 14th International Conference on Biomagnetism, pp. 143
BIOMAG 2004: The 14th International Conference on Biomagnetism (Boston, MA, August 8-12, 2004)
Article in monograph or in proceedings
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Donders Centre for Cognitive Neuroimaging
Halgren, E.; Ahlfors, S.; Hamalainen, M. (ed.), BIOMAG 2004: Proceedings of the 14th International Conference on Biomagnetism
Oscillatory neuronal synchronization plays a functional role in information processing by the nervous system. Cortico-muscular coherence (CMC) has been found to be modulated by task parameters , but its functional role is still debated. Since go-cue expectancy affects spike synchronization in primary motor cortex , we hypothesized that CMC might be involved in motor preparation, and thus be modulated in parallel with go-cue probability in a simple reaction time task. To test this, subjects were trained to hold an isometric wrist extension until a go-cue occurred. The go-cue was a speed increase of a drifting grating that could occur between 0.05 and 3.0 s after grating onset. The instantaneous probability (hazard rate) of the go-cue was manipulated. Each subject was trained separately on two different hazard functions, i.e., linearly increasing and linearly decreasing as a function of time. CMC was assessed between the muscles involved and MEG sensors overlying contralateral motor cortex. We found reaction times to be inversely correlated with the hazard rate, indicating enhanced motor preparation during periods of high target probability. Coherence around 20 Hz was generally reduced during task performance. In contrast, CMC around 40 Hz, i.e., in the gamma-frequency range, was correlated with the hazard rate. We conclude that cortico-muscular gamma-frequency coherence may play a functional role in movement preparation.  Kilner J.M. et al. 2000. Human cortical muscle coherence is directly related to specific motor parameters. J Neurosci. 8838-45.  Riehle A. et al. 1997. Spike synchronization and rate modulation differentially involved in motor cortical function. Science. 1950-3.
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