Basic mechanisms of central rhythms reactivity to preparation and execution of a voluntary movement: a stereoelectroencephalographic study.
OBJECTIVE
To localize the sources of mu, beta and gamma rhythms and to explore the functional significance of their reactivity.


METHODS
We used the method of quantification of event-related desynchronization (ERD) and synchronization (ERS) to analyze the reactivity of intracerebral rhythms recorded in stereoelectroencephalography within the sensorimotor areas during the preparation and the execution of a simple self-paced hand movement. We recorded 3 epileptic subjects who were explored before a surgical treatment.


RESULTS
An ERD of mu and beta rhythms has been recorded before the movement onset in the precentral gyrus, spreading then to the postcentral gyrus and to the frontal medial cortex. The frontal lateral cortex was inconstantly involved during the movement. The movement offset was followed by an important and focused beta ERS which was found within the pre- and post-central gyrus and the frontal medial cortex. Within the beta band, we observed several narrower bands with different reactivities and locations. Focused gamma reactivity was also found in the precentral and postcentral gyri.


CONCLUSIONS
The reactivities of mu and beta rhythms are different but their locations overlap. Mu ERD is a diffuse phenomenon that reflects the activation of all the sensorimotor areas during a simple movement. Beta band is likely to be composed of different rhythms with different functional significance. The primary motor area seems to contain two distinct areas with different reactivity to the movement preparation and execution.
Szurhaj
William
W
EA HU6, Department of Clinical Neurophysiology, Hôpital Salengro, CHRU, 59037, Lille Cedex, France.
Derambure
Philippe
P
Labyt
Etienne
E
Cassim
François
F
Bourriez
Jean-Louis
JL
Isnard
Jean
J
Guieu
Jean-Daniel
JD
Mauguière
François
F
D001931:Brain Mapping / Q000379:methods*; D003344:Cortical Synchronization; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods*; D017034:Epilepsy, Frontal Lobe / Q000503:physiopathology*; D005071:Evoked Potentials; D006801:Humans; D009044:Motor Cortex / Q000503:physiopathology*; D009068:Movement; D011930:Reaction Time; D013238:Stereotaxic Techniques; D014836:Volition