What are the characteristics of the mu rhythms on EEG?

Updated: Oct 09, 2019
  • Author: Selim R Benbadis, MD; Chief Editor: Helmi L Lutsep, MD  more...
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Characteristics of the mu rhythms are as follows:

  • Frequency of 7-11 Hz - Generally in alpha frequency band (8-12 Hz)

  • Location - Centroparietal area

  • Morphology - Archlike shape or like an "m"; most often asymmetric and asynchronous between the 2 sides and may be unilateral

  • Amplitude - Generally low to medium and comparable to that of the alpha rhythm

  • Reactivity - Most characteristic feature defining the mu rhythm; mu rhythm attenuates with contralateral extremity movement, the thought of a movement, or tactile stimulation; contrary to the alpha rhythm, does not react to eye opening and closing

    Mu rhythm over the left (greater than right) centr Mu rhythm over the left (greater than right) central region. To be absolutely certain that this is a mu rhythm, reactivity should be tested. However, morphology (not absolutely typical but fairly so), frequency, and distribution strongly suggest that this is a mu rhythm.

The mu rhythm has been documented on subdural recording of both sensory and motor cortex and shows the same characteristics as that seen on surface EEG, including distribution, morphology, and reactivity. [4] Furthermore, some correspondence exists between functional mapping of sensorimotor function and somatotopic distribution of mu reactivity. [3, 5, 6]

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