Oscillatory cortical activity related to voluntary muscle relaxation: Influence of normal aging

• Published in: Clinical neurophysiology 2006-09, Vol.117 (9), p.1922-1930
• Main Authors: Labyt, E., Cassim, F., Szurhaj, W., Bourriez, J.L., Derambure, P.
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aging - physiology; Analysis of Variance; Behavioral psychophysiology; Biological and medical sciences; Brain Mapping; Cerebral aging; Cerebral Cortex - physiology; Cortical Synchronization; Electrodiagnosis. Electric activity recording; Electromyography - methods; Electrophysiology; Event-related desynchronization; Female; Functional Laterality - physiology; Fundamental and applied biological sciences. Psychology; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Middle Aged; Muscle Contraction - physiology; Muscle Relaxation - physiology; Muscle, Skeletal - physiology; Nervous system; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Reaction Time - physiology; Voluntary muscle relaxation
• ISSN: 1388-2457; 1872-8952
• DOI: 10.1016/j.clinph.2006.05.017

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. 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. 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). 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. These age-related alterations during different phases of muscle relaxation could participate to explain global sensorimotor slowing observed with normal aging.