title: Functional dissociation of lower and upper frequency mu rhythms in relation to voluntary limb movement.
abstract: OBJECTIVE
  The goal of this study is to investigate the reactivity of central rhythms in the alpha band during self-paced voluntary finger and foot movement and to give an answer to the question, whether different types of mu rhythms exist.
  
  
  METHODS
  The effect of self-paced, voluntary finger and foot movement was studied in a group of 12 right-handed healthy volunteers. The EEG was recorded from a grid of 34 electrodes placed over sensorimotor areas with inter-electrode distances of approximately 2.5 cm. The event-related desynchronization (ERD) was quantified in the 8-10 and 10-12 Hz bands.
  
  
  RESULTS
  Both frequency components are blocked prior to and during movement and therefore, they have to be considered as mu rhythms. The lower frequency component results in a widespread movement-type non-specific ERD pattern, whereas the upper frequency component shows a more focused and movement-type specific pattern, clearly different with finger and foot movement.
  
  
  CONCLUSIONS
  The distinct reactivity patterns provide evidence for the existence of two types of mu rhythms, a somatotopically non-specific lower frequency mu rhythm and a somatotopically specific mu rhythm characteristically found in the upper alpha frequency band.
authors.affiliation: Department of Medical Informatics, Institute of Biomedical Engineering, University of Technology Graz, Inffeldgasse 16a/II, A-8010, Graz, Austria. pfu@dpmi.tu-graz.ac.at
authors.forename: G
authors.initials: G
authors.lastname: Pfurtscheller
authors.forename: C
authors.initials: C
authors.lastname: Neuper
authors.forename: G
authors.initials: G
authors.lastname: Krausz
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003344:Cortical Synchronization; D004569:Electroencephalography; D005121:Extremities / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*