Adaptation changes in dynamic postural control and contingent negative variation during backward disturbance by transient floor translation in the elderly

Abstract

BackgroundWe investigated adaptation changes in dynamic postural control and contingent negative variation (CNV) in 13 young and 12 elderly adults. Subjects repeatedly underwent backward postural disturbance by a forward floor translation (S2) 2 s after an auditory warning signal (S1). Initial and second sets were conducted, each set with 20 trials. Posterior peak position of the center of pressure in the anteroposterior direction (CoPy) after S2 was identified. Electroencephalograms from Cz were averaged for each set, and the CNV negative peak was identified.ResultsCompared with the first trial, the posterior peak position of CoPy changed significantly forward from the 12th trial in the young and from the 19th trial in the elderly during the initial set. The mean of the posterior peak position was more forward in second set than in the initial set for both groups and was significantly backward in the elderly compared to the young for both sets. These findings indicate that subjects in both groups adapted better to the postural disturbance in the second set than in the initial set, and the adaptation was later in the elderly. Late CNV in the young started to increase negatively from the middle of the S1-S2 period and peaked just before S2. Peak CNV amplitude was larger in the second set than in the initial set. In contrast, late CNV in the elderly exhibited no negative increase as in the young and peaked in the middle of the S1-S2 period, which was followed by gradual decreasing toward S2. No adaptive changes were found in late CNV for the elderly.ConclusionsIt is conceivable that reduced activation of the frontal lobe may be one of the factors contributing to the decrease in postural adaptability in the elderly. The elderly may use various brain regions for the adaptation of dynamic postural control compared with the young.

Precueing time but not direction of postural perturbation induces early muscular activation: Comparison between young and elderly individuals

“…These results are consistent with previous findings of changed muscular activation in the elderly [14,23,24]. This age-related effect has been interpreted to be associated with decreased efficiency of peripheral circuits, recruitment of different and/or additional brain areas [25,26], and decreased presynaptic inhibition by corticospinal postural circuits [26,27] with aging.…”

Preparatory brain activity and anticipatory postural adjustments accompanied by externally cued weighted-rapid arm rise task in non-specific chronic low back pain patients and healthy subjects

“…To detect muscle burst onset activity, 40 Hz Butterworth high-pass filter was used to eliminate motion and heart-beat artifacts (Fujiwara et al 2012 ). Next, all the filtered raw EMG signals were full-wave rectified, and then smoothed using a moving average of 50 ms time constant (Hashemirad et al 2009 ).…”

Aging increases flexibility of postural reactive responses based on constraints imposed by a manual task

“…We found that the elderly had smaller GM activation and greater intermuscular coactivation than the young. This finding could be related to decreased efficiency of lower circuits with aging, different brain recruitment patterns, recruitment of additional brain areas (Seidler et al, 2010 ; Fujiwara et al, 2012 ), greater participation of supraspinal structures and decrease in presynaptic inhibition by corticospinal circuits on postural muscles (Seidler et al, 2010 ; Papegaaij et al, 2014 ). In fact, balance maintenance in the elderly has been found to be more attentionally-demanding, i.e., less automatized, compared to young individuals (Cordo and Nashner, 1982 ; Horak et al, 1984 ; Brown et al, 1999 ; Brauer et al, 2001 ; Woollacott and Shumway-Cook, 2002 ).…”