Recovery of Postural Control After an Acute Unilateral Vestibular Lesion in Humans

1991 ◽  
Vol 1 (4) ◽  
pp. 373-383
Author(s):  
Michael Fetter ◽  
Hans-Christoph Diener ◽  
Johannes Dichgans
Keyword(s):  
Postural Control ◽  
Acute Phase ◽  
Time Course ◽  
Sensory Input ◽  
Characteristic Pattern ◽  
Support Surface ◽  
Upright Stance ◽  
Spinal Balance ◽  
Vestibular Lesion ◽  
Postural Responses

Postural control during stance was investigated using the EQUITEST® system in 10 patients during recovery after an acute unilateral vestibular lesion and was compared to the time course of recovery of the static and dynamic vestibulo-ocular imbalance. During the acute phase the patients showed a characteristic pattern with normal upright stance as long as at least one accurate sensory input (visual or somatosensory) was provided and severe postural disturbances when they had to rely primarily on vestibular afferences. Both static vestibulo-ocular and vestibulo-spinal balance recovered very fast, showing basically normal results on postural testing within about 2 weeks after the lesion. Thereafter, no pathological pattern was detectable during postural testing even in patients with persistent complete unilateral vestibular lesions. Reflexive postural responses to unexpected rapid displacements of the support surface seemed not to be influenced by vestibular imbalance even in the acute phase of the lesion.

A Feedback Model Reproduces Muscle Activity During Human Postural Responses to Support-Surface Translations

2008 ◽  
Vol 99 (2) ◽  
pp. 1032-1038 ◽  
Author(s):  
Torrence D. J. Welch ◽  
Lena H. Ting
Keyword(s):  
Postural Control ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Control Process ◽  
Temporal Patterns ◽  
Human Dimensions ◽  
Support Surface ◽  
Level Control ◽  
Muscle Activation Patterns ◽  
Postural Responses

Although feedback models have been used to simulate body motions in human postural control, it is not known whether muscle activation patterns generated by the nervous system during postural responses can also be explained by a feedback control process. We investigated whether a simple feedback law could explain temporal patterns of muscle activation in response to support-surface translations in human subjects. Previously, we used a single-link inverted-pendulum model with a delayed feedback controller to reproduce temporal patterns of muscle activity during postural responses in cats. We scaled this model to human dimensions and determined whether it could reproduce human muscle activity during forward and backward support-surface perturbations. Through optimization, we found three feedback gains (on pendulum acceleration, velocity, and displacement) and a common time delay that allowed the model to best match measured electromyographic (EMG) signals. For each muscle and each subject, the entire time courses of EMG signals during postural responses were well reconstructed in muscles throughout the lower body and resembled the solution derived from an optimal control model. In ankle muscles, >75% of the EMG variability was accounted for by model reconstructions. Surprisingly, >67% of the EMG variability was also accounted for in knee, hip, and pelvis muscles, even though motion at these joints was minimal. Although not explicitly required by our optimization, pendulum kinematics were well matched to subject center-of-mass (CoM) kinematics. Together, these results suggest that a common set of feedback signals related to task-level control of CoM motion is used in the temporal formation of muscle activity during postural control.

scholarly journals A Feedback Model Explains the Differential Scaling of Human Postural Responses to Perturbation Acceleration and Velocity

2009 ◽  
Vol 101 (6) ◽  
pp. 3294-3309 ◽  
Author(s):  
Torrence D. J. Welch ◽  
Lena H. Ting
Keyword(s):  
Muscle Activity ◽  
Time Course ◽  
Delayed Feedback Control ◽  
Support Surface ◽  
Peak Acceleration ◽  
Neural Basis ◽  
Initial Burst ◽  
Entire Time ◽  
Postural Responses ◽  
Emg Patterns

Although the neural basis of balance control remains unknown, recent studies suggest that a feedback law on center-of-mass (CoM) kinematics determines the temporal patterning of muscle activity during human postural responses. We hypothesized that the same feedback law would also explain variations in muscle activity to support-surface translation as perturbation characteristics vary. Subject CoM motion was experimentally modulated using 34 different anterior–posterior support-surface translations of varying peak acceleration and velocity but the same total displacement. Electromyographic (EMG) recordings from several muscles of the lower limbs and trunk were compared to predicted EMG patterns from an inverted pendulum model under delayed feedback control. In both recorded and predicted EMG patterns, the initial burst of muscle activity scaled linearly with peak acceleration, whereas the tonic “plateau” region scaled with peak velocity. The relatively invariant duration of the initial burst was modeled by incorporating a transient, time-limited encoding of CoM acceleration inspired by muscle spindle primary afferent dynamic responses. The entire time course of recorded and predicted muscle activity compared favorably across all conditions, suggesting that the initial burst of muscle activity is not generated by feedforward neural mechanisms. Perturbation conditions were presented randomly and subjects maintained relatively constant feedback gains across all conditions. In contrast, an optimal feedback solution based on a trade-off between CoM stabilization and energy expenditure predicted that feedback gains should change with perturbation characteristics. These results suggest that an invariant feedback law was used to generate the entire time course of muscle activity across a variety of postural disturbances.

Effects of Maintaining Touch Contact on Predictive and Reactive Balance

2007 ◽  
Vol 97 (4) ◽  
pp. 2686-2695 ◽  
Author(s):  
Leif Johannsen ◽  
Alan M. Wing ◽  
Vassilia Hatzitaki
Keyword(s):  
Time Course ◽  
Center Of Pressure ◽  
The Body ◽  
Contact Forces ◽  
Quiet Standing ◽  
Support Surface ◽  
Light Touch ◽  
Postural Control System ◽  
Postural Responses ◽  
Body Self

Light touch contact between the body and an environmental referent reduces fluctuations of center of pressure (CoP) in quiet standing although the contact forces are insufficient to provide significant forces to stabilize standing balance. Maintenance of upright standing posture (with light touch contact) may include both predictive and reactive components. Recently Dickstein et al. (2003) demonstrated that reaction to temporally unpredictable displacement of the support surface was affected by light touch raising the question whether light touch effects also occur with predictable disturbance to balance. We examined the effects of shoulder light touch on SD of CoP rate (dCoP) during balance perturbations associated with forward sway induced by pulling on (voluntary), or being pulled by (reactive), a hand-held horizontal load. Prior to perturbation, SD dCoP was lower with light touch, corresponding to previous findings. Immediately after perturbation, SD dCoPAP was greater with light touch in the case of voluntary pull, whereas no difference was found for reflex pull. However, in the following time course, light touch contact again resulted in a significantly lower SD dCoP and faster stabilization of SD dCoP. We conclude that shoulder light touch contact affects immediate postural responses to voluntary pull but also stabilization after voluntary and reflex perturbation. We suggest that in voluntary perturbation CoP fluctuations are differentially modulated in anterioposterior and mediolateral directions to maintain light touch, which not only provides augmented sensory feedback about body self-motion, but may act as a “constraint” to the postural control system when preparing postural adjustments.

Muscle Synergies Characterizing Human Postural Responses

2007 ◽  
Vol 98 (4) ◽  
pp. 2144-2156 ◽  
Author(s):  
Gelsy Torres-Oviedo ◽  
Lena H. Ting
Keyword(s):  
Postural Control ◽  
Muscle Activation ◽  
Muscle Synergies ◽  
Support Surface ◽  
Muscle Coordination ◽  
Natural Behavior ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Postural Responses ◽  
Automatic Postural Responses

Postural control is a natural behavior that requires the spatial and temporal coordination of multiple muscles. Complex muscle activation patterns characterizing postural responses suggest the need for independent muscle control. However, our previous work shows that postural responses in cats can be robustly reproduced by the activation of a few muscle synergies. We now investigate whether a similar neural strategy is used for human postural control. We hypothesized that a few muscle synergies could account for the intertrial variability in automatic postural responses from different perturbation directions, as well as different postural strategies. Postural responses to multidirectional support-surface translations in 16 muscles of the lower back and leg were analyzed in nine healthy subjects. Six or fewer muscle synergies were required to reproduce the postural responses of each subject. The composition and temporal activation of several muscle synergies identified across all subjects were consistent with the previously identified “ankle” and “hip” strategies in human postural responses. Moreover, intertrial variability in muscle activation patterns was successfully reproduced by modulating the activity of the various muscle synergies. This suggests that trial-to-trial variations in the activation of individual muscles are correlated and, moreover, represent variations in the amplitude of descending neural commands that activate individual muscle synergies. Finally, composition and temporal activation of most of the muscle synergies were similar across subjects. These results suggest that muscle synergies represent a general neural strategy underlying muscle coordination in postural tasks.

scholarly journals 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

2021 ◽  
Vol 15 ◽  
Author(s):  
Akihiro Nakamura ◽  
Yasuyuki Suzuki ◽  
Matija Milosevic ◽  
Taishin Nomura
Keyword(s):  
Postural Control ◽  
Upper Extremity ◽  
Half Period ◽  
Support Surface ◽  
Intermittent Control ◽  
Upright Stance ◽  
Beta Band ◽  
Active Monitoring ◽  
Related Potentials ◽  
Postural Recovery

Movement related beta band cortical oscillations, including beta rebound after execution and/or suppression of movement, have drawn attention in upper extremity motor control literature. However, fewer studies focused on beta band oscillations during postural control in upright stance. In this preliminary study, we examined beta rebound and other components of electroencephalogram (EEG) activity during perturbed upright stance to investigate supraspinal contributions to postural stabilization. Particularly, we aimed to clarify the timing and duration of beta rebound within a non-sustained, but long-lasting postural recovery process that occurs more slowly compared to upper extremities. To this end, EEG signals were acquired from nine healthy young adults in response to a brief support-surface perturbation, together with the center of pressure, the center of mass and electromyogram (EMG) activities of ankle muscles. Event-related potentials (ERPs) and event-related spectral perturbations were computed from EEG data using the perturbation-onset as a triggering event. After short-latency (<0.3 s) ERPs, our results showed a decrease in high-beta band oscillations (event-related desynchronization), which was followed by a significant increase (event-related synchronization) in the same band, as well as a decrease in theta band oscillations. Unlike during upper extremity motor tasks, the beta rebound in this case was initiated before the postural recovery was completed, and sustained for as long as 3 s with small EMG responses for the first half period, followed by no excessive EMG activities for the second half period. We speculate that those novel characteristics of beta rebound might be caused by slow postural dynamics along a stable manifold of the unstable saddle-type upright equilibrium of the postural control system without active feedback control, but with active monitoring of the postural state, in the framework of the intermittent control.

First trial and StartReact effects induced by balance perturbations to upright stance

2013 ◽  
Vol 110 (9) ◽  
pp. 2236-2245 ◽  
Author(s):  
A. D. Campbell ◽  
J. W. Squair ◽  
R. Chua ◽  
J. T. Inglis ◽  
M. G. Carpenter
Keyword(s):  
Startle Response ◽  
Support Surface ◽  
Wrist Movement ◽  
Repeated Presentation ◽  
Trial Effect ◽  
Acoustic Stimuli ◽  
Postural Responses ◽  
Startreact Effect ◽  
Startling Stimulus ◽  
Repeated Test

Postural responses (PR) to a balance perturbation differ between the first and subsequent perturbations. One explanation for this first trial effect is that perturbations act as startling stimuli that initiate a generalized startle response (GSR) as well as the PR. Startling stimuli, such as startling acoustic stimuli (SAS), are known to elicit GSRs, as well as a StartReact effect, in which prepared movements are initiated earlier by a startling stimulus. In this study, a StartReact effect paradigm was used to determine if balance perturbations can also act as startle stimuli. Subjects completed two blocks of simple reaction time trials involving wrist extension to a visual imperative stimulus (IS). Each block included 15 CONTROL trials that involved a warning cue and subsequent IS, followed by 10 repeated TEST trials, where either a SAS (TESTSAS) or a toes-up support-surface rotation (TESTPERT) was presented coincident with the IS. StartReact effects were observed during the first trial in both TESTSAS and TESTPERT conditions as evidenced by significantly earlier wrist movement and muscle onsets compared with CONTROL. Likewise, StartReact effects were observed in all repeated TESTSAS and TESTPERT trials. In contrast, GSRs in sternocleidomastoid and PRs were large in the first trial, but significantly attenuated over repeated presentation of the TESTPERT trials. Results suggest that balance perturbations can act as startling stimuli. Thus first trial effects are likely PRs which are superimposed with a GSR that is initially large, but habituates over time with repeated exposure to the startling influence of the balance perturbation.

Early prediction of falls after stroke: a 12-month follow-up of 490 patients in The Fall Study of Gothenburg (FallsGOT)

2018 ◽  
Vol 33 (4) ◽  
pp. 773-783 ◽  
Author(s):  
Carina M Samuelsson ◽  
Per-Olof Hansson ◽  
Carina U Persson
Keyword(s):  
Confidence Interval ◽  
Postural Control ◽  
Acute Phase ◽  
Odds Ratio ◽  
Stroke Unit ◽  
Inpatient Rehabilitation ◽  
Stroke Onset ◽  
Multivariable Regression ◽  
Walking Aid

Objective: To identify the incidence of falls and factors present shortly after stroke, which are associated with the occurrence of falls over the first 12 months after stroke onset, following discharge from inpatient rehabilitation. Design: Prospective follow-up study. Setting: Stroke unit and outpatient department. Subjects: A total of 490 individuals with acute stroke. Methods: Postural control was assessed using the Swedish modified version of the Postural Assessment Scale for Stroke Patients. Data on self-reported falls were collected using a standardized questionnaire at three months after discharge and six and 12 months after stroke onset. Associations between characteristics during the acute phase after a stroke and falls after six and 12 months were investigated using univariable and multivariable regression analyses. Main measures: The endpoint was a self-reported fall. Results: Within three months after discharge, 38 of 165 respondents (23%) had experienced at least one fall. Within six and 12 months after stroke onset, respectively, 108 of 376 (29%) and 140 of 348 (40%) of the respondents had experienced at least one fall. Poor postural control (odds ratio 3.92, 95% confidence interval 2.07–7.45, P < 0.0001) and using a walking aid (odds ratio 2.84, 95% confidence interval 1.71–4.72, P < 0.0001) were predictors of falls after discharge within 12 months after stroke onset. The same variables were independent predictors of falls within six months. Conclusion: Poor postural control and using a walking aid in the acute phase after a stroke are associated with falls after discharge from a stroke unit within 12 months after stroke onset.

Organization of postural responses following a rotational support surface perturbation, after TKA: Sagittal plane rotations

2007 ◽  
Vol 25 (1) ◽  
pp. 112-120 ◽  
Author(s):  
William H. Gage ◽  
James S. Frank ◽  
Stephen D. Prentice ◽  
Peter Stevenson
Keyword(s):  
Sagittal Plane ◽  
Support Surface ◽  
Surface Perturbation ◽  
Postural Responses

Static and dynamic postural control in long-term microgravity: evidence of a dual adaptation

2001 ◽  
Vol 90 (1) ◽  
pp. 205-215 ◽  
Author(s):  
Guido Baroni ◽  
Alessandra Pedrocchi ◽  
Giancarlo Ferrigno ◽  
Jean Massion ◽  
Antonio Pedotti
Keyword(s):  
Postural Control ◽  
Time Course ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Principal Component ◽  
Movement Analysis ◽  
Trunk Flexion ◽  
Dynamic Movement ◽  
Static Body

The adaptation of dynamic movement-posture coordination during forward trunk bending was investigated in long-term weightlessness. Three-dimensional movement analysis was carried out in two astronauts during a 4-mo microgravity exposure. The principal component analysis was applied to joint-angle kinematics for the assessment of angular synergies. The anteroposterior center of mass (CM) displacement accompanying trunk flexion was also quantified. The results reveal that subjects kept typically terrestrial strategies of movement-posture coordination. The temporary disruption of joint-angular synergies observed at subjects' first in-flight session was promptly recovered when repetitive sessions in flight were analyzed. The CM anteroposterior shift was consistently <3–4 cm, suggesting that subjects could dynamically control the CM position throughout the whole flight. This is in contrast to the observed profound microgravity-induced disruption of the quasi-static body orientation and initial CM positioning. Although this study was based on only two subjects, evidence is provided that static and dynamic postural control might be under two separate mechanisms, adapting with their specific time course to the constraints of microgravity.

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