Oscillatory cortical activity related to voluntary muscle relaxation: influence of normal aging.
OBJECTIVE
In this study we aimed to investigate if there are age-related differences in cortical oscillatory activity induced by self-paced muscular pure relaxation in comparison with muscle contraction as reference movement.


METHODS
Event-related (de)synchronization (ERD/ERS) have been recorded related to voluntary muscle contraction and relaxation in 10 young and 10 elderly right-handed healthy subjects. The muscle relaxation task consisted in a voluntary relaxation of maintained wrist extension without any overt, associated muscle contraction. The muscle contraction task corresponded to a self-initiated brief wrist extension.


RESULTS
In elderly subjects compared to young ones, mu and beta ERD preceding muscular relaxation was more widespread, beginning significantly earlier over contralateral frontocentral and parietocentral regions (p<0.05) as well as over ipsilateral regions (p<0.05). The beta synchronization was significantly attenuated (p<0.05).


CONCLUSIONS
These results suggest an alteration of inhibitory motor systems and an altered post-movement somesthetic inputs processing with normal aging. These alterations were accompanied by compensatory mechanisms.


CONCLUSIONS
These age-related alterations during different phases of muscle relaxation could participate to explain global sensorimotor slowing observed with normal aging.
Labyt
E
E
Department of Clinical Neurophysiology, R. Salengro Hospital, Lille University Medical Center, EA 2683, Lille Cedex F-59037, France.
Cassim
F
F
Szurhaj
W
W
Bourriez
J L
JL
Derambure
P
P
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D003344:Cortical Synchronization; D004576:Electromyography / Q000379:methods; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D009126:Muscle Relaxation / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology