Mu rhythm

Mu rhythm (μ rhythm) is kind of EEG rhythm of maximal amplitude of somatosensory cortices at rest. It is also called arciform rhythm because of the shape of the waveforms.

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Description

Usually encompassed in the alpha range (8-12Hz), it is strongly suppressed during the performance of contralateral motor acts. Modulation of the μ rhythm is believed to reflect the electrical output of the synchronization of large portions of pyramidal neurons of the motor cortex which control the hand and arm movement when inactive. In a 2005 article, it has been proposed that mu rhythm could reflect visuomotor integrative processes, and would "translate seeing and hearing into doing." Indeed, fluctuation on mu rhythm during the observation of a motor action is highly similar to the one seen during the direct performance of the action by the individual. This motor resonance mechanism witnessed by mu rhythm modulation could be due to a special category of cells called mirror neurons. However, the exact nature of the mu rhythm is still uncertain, as some have situated the source of this thalamocortical rhythm in the somatosensory region (Caetano, 2007). Moreover, Hari and collaborators (2007, 1994) stipulate that the mu rhythm, as quantified in the alpha band, could be an epiphenomenon of an higher (20Hz) frequency band activity.

References

• Pineda JA. The functional significance of mu rhythms: translating "seeing" and "hearing" into "doing". Brain Res Brain Res Rev. 2005 Dec 1;50(1):57-68. PMID 15925412
• Ernst Niedermeyer, Fernando Lopes da Silva Electroencephalography. Basic principles, Clinical Applications and Related Fields. 3rd edition, Williams & Wilkins Baltimore 1993