Lack of bilateral coherence of mu rhythm.

An investigation has been carried out in 25 normal subjects on quantitative differences of mu rhythm and alpha rhythm parameters. The parameters were frequency, average power over 102 sec and bilateral coherence. It was found that: (1) in the majority of cases the frequencies of the mu rhythms were higher than those of the alpha rhythms; (2) in the majority of subjects the average power was smaller for the mu rhythms for the alpha rhythms; (3) in none of the subjects was bilateral coherence of mu rhythms observed while in the majority the alpha rhythms were obviously bilaterally coherent. It is proposed that the latter difference represents a fundamental difference in the origin of alpha and mu rhythms.