scholarly journals Abnormal center of mass feedback responses during balance: A potential biomarker of falls in Parkinson’s disease

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0252119
Author(s):  
J. Lucas McKay ◽  
Kimberly C. Lang ◽  
Sistania M. Bong ◽  
Madeleine E. Hackney ◽  
Stewart A. Factor ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Spatial Organization ◽  
Balance Control ◽  
Center Of Mass ◽  
The Body ◽  
Antagonist Muscle ◽  
Antagonist Muscles ◽  
Potential Biomarker ◽  
Balance Deficits ◽  
Sensorimotor Feedback

Although Parkinson disease (PD) causes profound balance impairments, we know very little about how PD impacts the sensorimotor networks we rely on for automatically maintaining balance control. In young healthy people and animals, muscles are activated in a precise temporal and spatial organization when the center of body mass (CoM) is unexpectedly moved that is largely automatic and determined by feedback of CoM motion. Here, we show that PD alters the sensitivity of the sensorimotor feedback transformation. Importantly, sensorimotor feedback transformations for balance in PD remain temporally precise, but become spatially diffuse by recruiting additional muscle activity in antagonist muscles during balance responses. The abnormal antagonist muscle activity remains precisely time-locked to sensorimotor feedback signals encoding undesirable motion of the body in space. Further, among people with PD, the sensitivity of abnormal antagonist muscle activity to CoM motion varies directly with the number of recent falls. Our work shows that in people with PD, sensorimotor feedback transformations for balance are intact but disinhibited in antagonist muscles, likely contributing to balance deficits and falls.

scholarly journals Abnormal center of mass control during balance is associated with falls in Parkinson’s disease

2020 ◽  
Author(s):  
J. Lucas McKay ◽  
Kimberly C. Lang ◽  
Sistania M. Bong ◽  
Madeleine. E. Hackney ◽  
Stewart A. Factor ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Spatial Organization ◽  
Balance Control ◽  
Center Of Mass ◽  
The Body ◽  
Antagonist Muscle ◽  
Antagonist Muscles ◽  
Balance Deficits ◽  
Recent Falls ◽  
Sensorimotor Feedback

AbstractAlthough Parkinson disease (PD) causes profound balance impairments, we know very little about how PD impacts the sensorimotor networks we rely on for automatically maintaining balance control. In young healthy people and animals, muscles are activated in a precise temporal and spatial organization when the center of body mass (CoM) is unexpectedly moved. This organization is largely automatic and determined by feedback of CoM motion. Here, we show that PD alters the sensitivity of the sensorimotor feedback transformation. Importantly, sensorimotor feedback transformations for balance in PD remain temporally precise, but become spatially diffuse by recruiting additional muscle activity in antagonist muscles during balance responses. The abnormal antagonist muscle activity remains precisely time-locked to sensorimotor feedback signals encoding undesirable motion of the body in space. Further, among people with PD, the sensitivity of abnormal antagonist muscle activity to CoM motion varies directly with the number of recent falls. Our work shows that in people with PD, sensorimotor feedback transformations for balance are intact but disinhibited in antagonist muscles, likely contributing to balance deficits and falls.

scholarly journals Sensorimotor feedback based on task-relevant error robustly predicts temporal recruitment and multidirectional tuning of muscle synergies

2013 ◽  
Vol 109 (1) ◽  
pp. 31-45 ◽  
Author(s):  
Seyed A. Safavynia ◽  
Lena H. Ting
Keyword(s):  
Sagittal Plane ◽  
Balance Control ◽  
Center Of Mass ◽  
The Body ◽  
Muscle Synergy ◽  
Muscle Synergies ◽  
Muscle Coordination ◽  
Initial State ◽  
Sensorimotor Feedback ◽  
Task Level

We hypothesized that motor outputs are hierarchically organized such that descending temporal commands based on desired task-level goals flexibly recruit muscle synergies that specify the spatial patterns of muscle coordination that allow the task to be achieved. According to this hypothesis, it should be possible to predict the patterns of muscle synergy recruitment based on task-level goals. We demonstrated that the temporal recruitment of muscle synergies during standing balance control was robustly predicted across multiple perturbation directions based on delayed sensorimotor feedback of center of mass (CoM) kinematics (displacement, velocity, and acceleration). The modulation of a muscle synergy's recruitment amplitude across perturbation directions was predicted by the projection of CoM kinematic variables along the preferred tuning direction(s), generating cosine tuning functions. Moreover, these findings were robust in biphasic perturbations that initially imposed a perturbation in the sagittal plane and then, before sagittal balance was recovered, perturbed the body in multiple directions. Therefore, biphasic perturbations caused the initial state of the CoM to differ from the desired state, and muscle synergy recruitment was predicted based on the error between the actual and desired upright state of the CoM. These results demonstrate that that temporal motor commands to muscle synergies reflect task-relevant error as opposed to sensory inflow. The proposed hierarchical framework may represent a common principle of motor control across motor tasks and levels of the nervous system, allowing motor intentions to be transformed into motor actions.

Adding Light Touch While Walking in Older Adults: Biomechanical and Neuromotor Effects

2020 ◽  
Vol 28 (5) ◽  
pp. 680-685
Author(s):  
Alison R. Oates ◽  
Aaron Awdhan ◽  
Catherine Arnold ◽  
Joyce Fung ◽  
Joel L. Lanovaz
Keyword(s):  
Older Adults ◽  
Muscle Activity ◽  
Balance Control ◽  
Center Of Mass ◽  
Gait Pattern ◽  
Light Touch ◽  
Margin Of Stability ◽  
Complex Picture ◽  
Falls In Older Adults ◽  
Haptic Input

Adding haptic input may improve balance control and help prevent falls in older adults. This study examined the effects of added haptic input via light touch on a railing while walking. Participants (N = 53, 75.9 ± 7.9 years) walked normally or in tandem (heel to toe) with and without haptic input. During normal walking, adding haptic input resulted in a more cautious and variable gait pattern, reduced variability of center of mass acceleration and margin of stability, and increased muscle activity. During tandem walking, haptic input had minimal effect on step parameters, decreased lower limb muscle activity, and increased cocontraction at the ankle closest to the railing. Age was correlated with step width variability, stride length variability, stride velocity, variability of medial-lateral center of mass acceleration, and margin of stability for tandem walking. This complex picture of sensorimotor integration in older adults warrants further exploration into added haptic input during walking.

scholarly journals The motor cortex uses active suppression to sculpt movement

2020 ◽  
Vol 6 (34) ◽  
pp. eabb8395 ◽  
Author(s):  
Darcy M. Griffin ◽  
Peter L. Strick
Keyword(s):  
Motor Cortex ◽  
Muscle Activity ◽  
Primary Motor Cortex ◽  
Spatiotemporal Patterns ◽  
Complex Pattern ◽  
Antagonist Muscle ◽  
Active Suppression ◽  
Antagonist Muscles ◽  
Output Neurons ◽  
Command Signal

Even the simplest movements are generated by a remarkably complex pattern of muscle activity. Fast, accurate movements at a single joint are produced by a stereotyped pattern that includes a decrease in any preexisting activity in antagonist muscles. This premovement suppression is necessary to prevent the antagonist muscle from opposing movement generated by the agonist muscle. Here, we provide evidence that the primary motor cortex (M1) sends a command signal that generates this premovement suppression. Thus, output neurons in M1 sculpt complex spatiotemporal patterns of motor output not only by actively turning on muscles but also by actively turning them off.

Analysis of Physiological Signals of Individuals with Eyes Closed Subjected to Unexpected Direction-Specific Stimuli Causing Instability

2020 ◽  
Vol 10 (11) ◽  
pp. 2754-2763
Author(s):  
Sunhye Shin ◽  
Chul Un Hong ◽  
Kyong Kim ◽  
Tae Kyu Kwon
Keyword(s):  
Lower Extremity ◽  
Muscle Activity ◽  
Postural Balance ◽  
Balance Control ◽  
Center Of Gravity ◽  
Training System ◽  
The Body ◽  
Physiological Signals ◽  
Eyes Closed ◽  
Lower Extremity Muscle

Research regarding the cerebral cortex and muscle activity patterns of the body used for postural balance control when sudden instability stimuli occur is lacking. This study analyzed individuals' physiological signals when direction-specific instability stimuli were applied while their eyes were closed. Healthy adults in their 20s maintained their postural balance while looking at the center of gravity provided by a monitor with a three-dimensional dynamic postural balance training system. We performed electroencephalography (EEG) and measured trunk and lower extremity muscle activity of participants with their eyes closed when subjected to four direction-specific instability stimuli (anterior, posterior, left, and right). EEG results showed that gamma waves increased significantly with an unbalanced stimulus when the participant's eyes were open and closed. The increased gamma wave rate with eyes closed was low in the exercise planning area, where information is relatively integrated and exercise is planned without visual information. EMG results showed fewer gamma waves on EEG due to the low focus on postural control because participants could not observe the center of gravity, which is the basis for balance. The trunk and lower extremity muscles tended to be used more due to the larger body perturbation angle. These outcomes can be used as basic data regarding how the human brain and muscles maintain postural balance when an unexpected external instability stimulus occurs. Quantitative postural balance rehabilitation training protocols for the elderly and those with disabilities can be created based on these outcomes.

Quantifying Segmental Contributions to Center-of-Mass Motion During Dynamic Continuous Support Surface Perturbations Using Simplified Estimation Models

2020 ◽  
Vol 36 (4) ◽  
pp. 198-208
Author(s):  
Alison Schinkel-Ivy ◽  
Vicki Komisar ◽  
Carolyn A. Duncan
Keyword(s):  
Balance Control ◽  
Center Of Mass ◽  
Three Dimensional ◽  
The Body ◽  
Whole Body ◽  
Mass Motion ◽  
Support Surface ◽  
Body Segments ◽  
Body Model ◽  
Full Body

Investigating balance reactions following continuous, multidirectional, support surface perturbations is essential for improving our understanding of balance control in moving environments. Segmental motions are often incorporated into rapid balance reactions following external perturbations to balance, although the effects of these motions during complex, continuous perturbations have not been assessed. This study aimed to quantify the contributions of body segments (ie, trunk, head, upper extremity, and lower extremity) to the control of center-of-mass (COM) movement during continuous, multidirectional, support surface perturbations. Three-dimensional, whole-body kinematics were captured while 10 participants experienced 5 minutes of perturbations. Anteroposterior, mediolateral, and vertical COM position and velocity were calculated using a full-body model and 7 models with reduced numbers of segments, which were compared with the full-body model. With removal of body segments, errors relative to the full-body model increased, while relationship strength decreased. The inclusion of body segments appeared to affect COM measures, particularly COM velocity. Findings suggest that the body segments may provide a means of improving the control of COM motion, primarily its velocity, during continuous, multidirectional perturbations, and constitute a step toward improving our understanding of how the limbs contribute to balance control in moving environments.

scholarly journals Greater exposure to repetitive subconcussive head impacts is associated with vestibular dysfunction and balance impairments during walking

Neurology ◽  
2018 ◽  
Vol 91 (23 Supplement 1) ◽  
pp. S27.2-S27
Author(s):  
Fernando Santos ◽  
Jaclyn B Caccese ◽  
Mariana Gongora ◽  
Ian Sotnek ◽  
Elizabeth Kaye ◽  
...  
Keyword(s):  
Center Of Pressure ◽  
Balance Control ◽  
Center Of Mass ◽  
Vestibular Stimulation ◽  
Vestibular Dysfunction ◽  
Foot Placement ◽  
Head Impacts ◽  
Eyes Closed ◽  
Balance Deficits ◽  
Soccer Heading

Exposure to repetitive subconcussive head impacts (RSHI), specifically soccer heading, is associated with white matter microstructural changes and cognitive performance impairments. However, the effect of soccer heading exposure on vestibular processing and balance control during walking has not been studied. Galvanic vestibular stimulation (GVS) is a tool that can be used to probe the vestibular system during standing and walking. The purpose of this study was to investigate the association of soccer heading with subclinical balance deficits during walking. Twenty adult amateur soccer players (10 males and 10 females, 22.3 ± 4.5 years, 170.5 ± 9.8 cm, 70.0 ± 10.5 kg) walked along a foam walkway with the eyes closed under 2 conditions: with GVS (∼40 trials) and without GVS (∼40 trials). Outcome measures included mediolateral center-of-mass (COM), center-of-pressure (COP) separation, foot placement, mediolateral ankle modulation, hip adduction, and ankle push off. For each balance mechanism, a GVS response was calculated (GVS, mean [without GVS]). In addition, participants completed a questionnaire, reporting soccer heading exposure over the past year. A linear regression model was used to determine if vestibular processing and balance during walking were related to RSHI exposure. Both foot placement (R2 = 0.324, p = 0.009) and hip adduction (R2 = 0.183, p = 0.50) were predicted by RSHI; whereby, greater exposure to RSHI was associated with greater foot placement and hip adduction responses. However, COM-COP separation (R2 < 0.001, p = 0.927), ankle modulation (R2 = 0.037, p = 0.417), and push off (R2 < 0.001, p = 0.968) were not related to RSHI exposure. Individuals who were exposed to greater RSHI were more perturbed by vestibular stimulation during walking, suggesting that there may be vestibular dysfunction and balance impairments with frequent heading; specifically, individuals with greater exposure to RSHI responded with larger foot placement and hip adduction responses to GVS.

Reaching to Multiple Targets When Standing: The Spatial Organization of Feedforward Postural Adjustments

2009 ◽  
Vol 101 (4) ◽  
pp. 2120-2133 ◽  
Author(s):  
Julia A. Leonard ◽  
Ryan H. Brown ◽  
Paul J. Stapley
Keyword(s):  
Spatial Organization ◽  
Human Subjects ◽  
Body Position ◽  
Center Of Mass ◽  
The Body ◽  
Reaching Movements ◽  
Muscle Synergies ◽  
Electromyographic Activity ◽  
Postural Adjustments ◽  
Arm Reaching

We examined the spatial organization of feedforward postural adjustments produced prior to and during voluntary arm reaching movements executed while standing. We sought to investigate whether the activity of postural muscles before and during reaching was directionally tuned and whether a strategy of horizontal force constraint could be observed. To this end, eight human subjects executed self-paced reach-to-point movements on the random illumination of one of 13 light targets placed within a 180° array centered along the midline of the body. Analysis was divided into two periods: a first corresponding to the 250 ms preceding the onset of the reaching movements (termed pPA period) and a second 250-ms period immediately preceding target attainment (the aPA period). For both periods, electromyographic activity of the lower limb muscles revealed a clear directional tuning, with groups of muscles being activated for similar directions of reach. Analysis of horizontal ground reaction forces supported the existence of a force constraint strategy only for the pPA period, however, with those in the aPA period being more widely dispersed. We suggest that the strategy adopted for feedforward pPAs is one where the tuned muscle synergies constrain the forces diagonally away from the center of mass (CoM) to move it within the support base. However, the need to control for final finger and body position for each target during the aPA phase resulted in a distribution of vectors across reaching directions. Overall, our results would support the idea that endpoint limb force during postural tasks depends on the use of functional muscle synergies, which are used to displace the CoM or decelerate the body at the end of the reach.

A Biomechanical Assessment of the Sliding Motion of Curling Delivery in Elite and Subelite Curlers

2012 ◽  
Vol 28 (6) ◽  
pp. 694-700 ◽  
Author(s):  
Kyoung-Seok Yoo ◽  
Hyun-Kyung Kim ◽  
Jin-Hoon Park
Keyword(s):  
Balance Control ◽  
Center Of Mass ◽  
Three Dimensional ◽  
The Body ◽  
Movement Speed ◽  
Biomechanical Assessment ◽  
Sliding Motion ◽  
Angular Velocities ◽  
Posterior Direction ◽  
The Moment

The present study examined the technical characteristics of sliding performance from push-off until stone release in curling delivery. Five elite performance level curlers (> 7 years experience) and five subelite level curlers (< 3 years experience) were analyzed during the action of delivery of a curling stone. The joint angles, angular velocities, and moments of the body center of mass (COM) were determined based on three-dimensional kinematic data. The plantar pressure data were measured using a validated in-shoe system. The results indicated that the gliding time and horizontal velocity of the mass center of the body during the sliding phase were not significantly different between the elite and subelite groups. However, there were significant differences in the gliding distance and the rate of changes in velocity profiles of body COM between the two groups. The moment of the body COM from its relative position to the ankle of the support limb in the anterior/posterior direction was positive in elite curlers and negative in subelite curlers. In addition, larger ankle dorsiflexion and greater contact area of the sliding foot were observed in elite curlers. These data suggest a superior ability of elite curlers to maintain a regulated movement speed and balance control during the performance of a curling stone delivery.

scholarly journals Improvement of Gender Balance Based on the Real-Time Visual Feedback System of the Pressure Center of Smart Wearable Devices: A Case Control Study

2020 ◽  
Author(s):  
I-Lin Wang ◽  
Li-I Wang ◽  
Shi-Jie Xue ◽  
Rui Hu ◽  
Yu Su ◽  
...  
Keyword(s):  
Real Time ◽  
Visual Feedback ◽  
Center Of Pressure ◽  
Balance Control ◽  
Center Of Mass ◽  
Physical Stability ◽  
Feedback System ◽  
Wearable Devices ◽  
The Body ◽  
Smart Wearable

Abstract Background: The body maintains stability by integrating inputs from the central nervous system of vision, hearing, proprioception, and multiple senses. With the development of smart wearable devices, smart wearable devices can provide real-time center of pressure (COP) position-assisted balance control, which is beneficial to maintain physical balance.Methods: Forty healthy college students (20 male-20 female) participated in this study, and the posture balance actions of left-leg stance non-visual feedback, left -leg stance visual feedback, right-leg stance non-visual feedback, and right-leg stance visual feedback are performed. Visual feedback provides smart insoles matching Podoon APP on a tablet computer with the COP position displayed by a dot as real-time visual feedback. A mixed-design two-way ANOVA was performed and included the study.Results: The experimental results show that the displacement, velocity, radius, and area of the COP decreased significantly in the left-leg stance visual feedback/right-leg stance visual feedback, the test compared with the parameters in the eft-leg stance non-visual feedback/right-leg stance non-visual feedback (P < 0.05). Providing visual feedback through intelligent insoles can reduce the movement of the center of mass (COM) and maintain physical stability for healthy young people of different genders. In the one leg visual/non-visual in standing, the COP maximum anteroposterior displacement, COP anteroposterior velocity, COP radius, and COP area of women are significantly decreased than men (P < 0.05). Women have better real-time balance control ability than men with smart insoles.Conclusion: The simple intelligent wearable assisted devices can immediately increase the control ability in static stance of men and women, and women have better real-time balance control ability than men.

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