Older Age Increases the Amplitude of Muscle Stretch-Induced Cortical Beta-Band Suppression But Does not Affect Rebound Strength

Abstract

Healthy aging is associated with deterioration of the sensorimotor system, which impairs balance and somatosensation. However, the exact age-related changes in the cortical processing of sensorimotor integration are unclear. This study investigated primary sensorimotor cortex (SM1) oscillations in the 15-30 Hz beta band at rest and following (involuntary) rapid stretches to the triceps surae muscles (i.e., proprioceptive stimulation) of young and older adults. A custom-built, magnetoencephalography (MEG)-compatible device was used to deliver rapid (190 • •s −1) ankle rotations as subjects sat passively in a magnetically-shielded room while MEG recorded their cortical signals. Eleven young (age 25 ± 3 years) and 12 older (age 70 ± 3 years) adults matched for physical activity level demonstrated clear 15-30 Hz beta band suppression and rebound in response to the stretches. A sub-sample (10 young and nine older) were tested for dynamic balance control on a sliding platform. Older adults had greater cortical beta power pre-stretch (e.g., right leg: 4.0 ± 1.6 fT vs. 5.6 ± 1.7 fT, P = 0.044) and, subsequently, greater normalized movement-related cortical beta suppression post-proprioceptive stimulation (e.g., right leg: −5.8 ± 1.3 vs. −7.6 ± 1.7, P = 0.01) than young adults. Furthermore, poorer balance was associated with stronger cortical beta suppression following proprioceptive stimulation (r = −0.478, P = 0.038, n = 19). These results provide further support that cortical processing of proprioception is hindered in older adults, potentially (adversely) influencing sensorimotor integration. This was demonstrated by the impairment of prompt motor action control, i.e., regaining perturbed balance. Finally, SM1 cortex beta suppression to a proprioceptive stimulus seems to indicate poorer sensorimotor functioning in older adults.

A Perturbed Postural Balance Test Using an Instrumented Treadmill – Precision and Accuracy of Belt Movement and Test-Retest Reliability of Balance Measures

“…COP peak displacements, times to peak displacement, and recovery displacement showed comparable results with the group of young adults in that study. Moreover, the peak displacements observed in the current study were in line with the study by Walker et al (2020) which utilized a protocol closely resembling the one used here in the fast condition. The finding suggests treadmill-based perturbed postural balance assessment has good concurrent validity compared with the test performed using a purpose-built device consisting of a commercial force plate driven by electromechanical cylinders.…”

Long-Lasting Event-Related Beta Synchronizations of Electroencephalographic Activity in Response to Support-Surface Perturbations During Upright Stance: A Pilot Study Associating Beta Rebound and Active Monitoring in the Intermittent Postural Control

“…Smith et al (2012) demonstrated that PD patients exhibit greater beta ERD after a cue, but prior to a predictable small-magnitude perturbation, compared to healthy control participants in the Cz electrode. Similarly, in the lower extremities study during sitting, Walker et al (2020) reported that beta ERD and ERS appear after the stimulation to rotate the ankle, where the beta ERD was enhanced in the elderly, compared to young people. In addition, some studies showed that brief mechanical perturbations applied by pulling the body during standing posture induced beta ERD after the theta and alpha ERSs with short latencies (Peterson and Ferris, 2018).…”

Reproducibility of Rolandic beta rhythm modulation in MEG and EEG

“…This is especially important, since the beta rhythm rebound has been proposed to be a biomarker reflecting functional recovery of the SMI cortex after acute stroke, whereas no clear association between suppression and motor recovery has been found ( 11 , 32 , 33 ). The beta power and the strength of beta modulation have been shown to increase in relation to aging ( 6 , 47 ). However, such changes seem not to occur within a 1-year follow-up period, at least in relatively young adult participants.…”

“…In children, the beta power has shown to be reduced than in adults ( 61 ). Concomitantly, several studies have shown that in elderly subjects the beta power at rest is increased than in younger subjects, leading to an increase of beta suppression ( 6 , 47 , 57 , 62 , 63 ), with the exception of Alzheimer’s disease, where the resting-state beta power has been shown to decrease ( 64 ). The frequency of the beta rhythm has also been shown to be lower with increasing age ( 63 ).…”

“…Oscillatory activity in the sensorimotor cortex at rest is dominated by the ~20-Hz beta rhythm, which attenuates as a result of the person's voluntary movement (1), evoked passive movement or imagined movement (2)(3)(4)(5)(6). In addition, the ~20-Hz beta rhythm is modulated by somatosensory afferent stimuli, such as tactile or electrical stimulation (7)(8)(9)(10)(11).…”