scholarly journals Body posture modulates imagined arm movements and responds to them

2013 ◽  
Vol 110 (11) ◽  
pp. 2617-2626 ◽  
Author(s):  
Hayley Boulton ◽  
Suvobrata Mitra
Keyword(s):  
Motor Imagery ◽  
Arm Movements ◽  
The Body ◽  
Body Posture ◽  
Trunk Muscles ◽  
Whole Body ◽  
Inhibition Mechanism ◽  
Upright Stance ◽  
Postural Adjustments ◽  
Postural Responses

Imagined movements are thought to simulate physical ones, with similar behavioral constraints and neurophysiological activation patterns and with an inhibition mechanism that suppresses movement execution. When upper body movements such as reaching with the arm are made from an upright stance, lower body and trunk muscles are also activated to maintain body posture. It is not clear to what extent parameters of imagined manual movements are sensitive to the postural adjustments their execution would necessitate, nor whether such postural responses are as effectively inhibited as the imagined movements themselves. We asked healthy young participants to imagine reaching movements of the arm while in upright stance, and we measured their self-reported movement times and postural sway during imagined movements. We manipulated mediolateral stance stability and the direction of arm movement (mediolateral or anteroposterior). Imagined arm movements were reportedly slower when subjects were standing in a mediolaterally less stable stance, and the body swayed more when arm movements were imagined in the direction of postural vulnerability. The results suggest that the postural state of the whole body, not just the involved limbs, informs trajectory planning during motor imagery and that measurable adjustments to body posture accompany imagined manual actions. It has been suggested that movement is suppressed during motor imagery by a premotor inhibitory mechanism operating at brain stem or spinal level. Any such inhibition must be incomplete because, for example, it does not eliminate autonomic arousal. Our results suggest that it also does not effectively suppress postural adjustments planned in support of imagined movements.

Modification of postural responses and step initiation: evidence for goal-directed postural interactions

1994 ◽  
Vol 72 (6) ◽  
pp. 2892-2902 ◽  
Author(s):  
A. L. Burleigh ◽  
F. B. Horak ◽  
F. Malouin
Keyword(s):  
External Perturbation ◽  
Anticipatory Postural Adjustments ◽  
The Body ◽  
Original Position ◽  
Foot Pressure ◽  
Postural Adjustments ◽  
Step Initiation ◽  
Postural Responses ◽  
Surface Translation ◽  
Automatic Postural Responses

1. In this study, the interaction between anticipatory postural adjustments for step initiation and automatic postural responses to an external perturbation were investigated by having subjects initiate a voluntary forward step while perturbed by a backward surface translation, which caused forward sway of the body. The postural adjustments for step initiation act to move the body center of mass (COM) forward, whereas the automatic postural responses act to move the COM backward to restore stance equilibrium. Because the postural behaviors are in opposition, we asked whether a temporal hierarchy exists in which automatic postural responses are executed to restore equilibrium and followed by stereotypic postural adjustments for step initiation, or whether the interaction between these two postural behaviors is more dynamic. 2. Lower extremity electromyographs (EMGs), ground reaction forces, and kinematics were recorded from 10 subjects during three conditions: to quantify the anticipatory postural adjustments for step initiation, subjects stepped forward as soon as they felt a proprioceptive cue; to quantify the automatic postural responses to perturbation, subjects maintained stance equilibrium in response to a backward surface translation under both feet; and to quantify the interaction between the postural adjustments for the voluntary step and the automatic responses to the perturbation, subjects were exposed to a backward surface translation and instructed to step forward as soon as they felt the platform begin to move. 3. The anticipatory adjustments for step initiation included tibialis activation [stance limb = 163 +/- 28 (SE) ms; swing limb = 173 +/- 33 ms] and soleus inhibition resulting in center of foot pressure (COP) moving backward and lateral toward the swing limb to propel the COM forward over the stance limb. Subsequently, activation of the swing limb gastrocnemius resulted in heel-off. In contrast, the automatic postural adjustments for maintenance of stance equilibrium during a backward surface translation included activation of soleus and gastrocnemius (104 +/- 23 ms and 115 +/- 14 ms, respectively) resulting in a symmetrical forward displacement of the COP that moved the COM back to its original position with respect to the feet. 4. When a forward step was initiated in response to the translation, the automatic postural responses were reduced in amplitude bilaterally in soleus and in the stance limb gastrocnemius. When present the postural response occurred at the same latency when the goal was to initiate a step as when the goal was to maintain standing.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals A Novel Viewpoint on the Anticipatory Postural Adjustments During Gait Initiation

2021 ◽  
Vol 15 ◽  
Author(s):  
Veronica Farinelli ◽  
Francesco Bolzoni ◽  
Silvia Maria Marchese ◽  
Roberto Esposti ◽  
Paolo Cavallari
Keyword(s):  
Center Of Pressure ◽  
Force Plate ◽  
Anticipatory Postural Adjustments ◽  
The Body ◽  
Erector Spinae ◽  
Trunk Muscles ◽  
Gait Initiation ◽  
Concentrated Force ◽  
Postural Adjustments ◽  
Leg Muscles

Anticipatory postural adjustments (APAs) are the coordinated muscular activities that precede the voluntary movements to counteract the associated postural perturbations. Many studies about gait initiation call APAs those activities that precede the heel-off of the leading foot, thus taking heel-off as the onset of voluntary movement. In particular, leg muscles drive the center of pressure (CoP) both laterally, to shift the body weight over the trailing foot and backward, to create a disequilibrium torque pushing forward the center of mass (CoM). However, since subjects want to propel their body rather than lift their foot, the onset of gait should be the CoM displacement, which starts with the backward CoP shift. If so, the leg muscles driving such a shift are the prime movers. Moreover, since the disequilibrium torque is mechanically equivalent to a forward force acting at the pelvis level, APAs should be required to link the body segments to the pelvis: distributing such concentrated force throughout the body would make all segments move homogeneously. In the aim of testing this hypothesis, we analyzed gait initiation in 15 right-footed healthy subjects, searching for activities in trunk muscles that precede the onset of the backward CoP shift. Subjects stood on a force plate for about 10 s and then started walking at their natural speed. A minimum of 10 trials were collected. A force plate measured the CoP position while wireless probes recorded the electromyographic activities. Recordings ascertained that at gait onset APAs develop in trunk muscles. On the right side, Rectus Abdominis and Obliquus Abdominis were activated in 11 and 13 subjects, respectively, starting on average 33 and 54 ms before the CoP shift; Erector Spinae (ES) at L2 and T3 levels was instead inhibited (9 and 7 subjects, 104 and 120 ms). On the contralateral side, the same muscles showed excitatory APAs (abdominals in 11 and 12 subjects, 27 and 82 ms; ES in 10 and 7 subjects, 75 and 32 ms). The results of this study provide a novel framework for distinguishing postural from voluntary actions, which may be relevant for the diagnosis and rehabilitation of gait disorders.

Postural Control in the Rabbit Maintaining Balance on the Tilting Platform

2003 ◽  
Vol 90 (6) ◽  
pp. 3783-3793 ◽  
Author(s):  
I. N. Beloozerova ◽  
P. V. Zelenin ◽  
L. B. Popova ◽  
G. N. Orlovsky ◽  
S. Grillner ◽  
...  
Keyword(s):  
Frontal Plane ◽  
Threshold Value ◽  
Dorsal Side ◽  
The Body ◽  
Body Posture ◽  
Vestibular Input ◽  
Postural Responses ◽  
Extensor Muscles ◽  
Somatosensory Input ◽  
Emg Patterns

A deviation from the dorsal-side-up body posture in quadrupeds activates the mechanisms for postural corrections. Operation of these mechanisms was studied in the rabbit maintaining balance on a platform periodically tilted in the frontal plane. First, we characterized the kinematics and electromyographic (EMG) patterns of postural responses to tilts. It was found that a reaction to tilt includes an extension of the limbs on the side moving down and flexion on the opposite side. These limb movements are primarily due to a modulation of the activity of extensor muscles. Second, it was found that rabbits can effectively maintain the dorsal-side-up body posture when complex postural stimuli are applied, i.e., asynchronous tilts of the platforms supporting the anterior and posterior parts of the body. These data suggest that the nervous mechanisms controlling positions of these parts of the body can operate independently of each other. Third, we found that normally the somatosensory input plays a predominant role for the generation of postural responses. However, when the postural response appears insufficient to maintain balance, the vestibular input contributes considerably to activation of postural mechanisms. We also found that an asymmetry in the tonic vestibular input, caused by galvanic stimulation of the labyrinths, can affect the stabilized body orientation while the magnitude of postural responses to tilts remains unchanged. Fourth, we found that the mechanisms for postural corrections respond only to tilts that exceed a certain (threshold) value.

scholarly journals Identification of the Plant for Upright Stance in Humans: Multiple Movement Patterns From a Single Neural Strategy

2008 ◽  
Vol 100 (6) ◽  
pp. 3394-3406 ◽  
Author(s):  
Tim Kiemel ◽  
Alexander J. Elahi ◽  
John J. Jeka
Keyword(s):  
Muscle Activation ◽  
The Body ◽  
Visual Scene ◽  
Trunk Muscles ◽  
Emg Activity ◽  
Upright Stance ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Joint Torques ◽  
Intrinsic Stiffness

We determined properties of the plant during human upright stance using a closed-loop system identification method originally applied to human postural control by another group. To identify the plant, which was operationally defined as the mapping from muscle activation (rectified EMG signals) to body segment angles, we rotated the visual scene about the axis through the subject's ankles using a sum-of-sines stimulus signal. Because EMG signals from ankle muscles and from hip and lower trunk muscles showed similar responses to the visual perturbation across frequency, we combined EMG signals from all recorded muscles into a single plant input. Body kinematics were described by the trunk and leg angles in the sagittal plane. The phase responses of both angles to visual scene angle were similar at low frequencies and approached a difference of ∼150° at higher frequencies. Therefore we considered leg and trunk angles as separate plant outputs. We modeled the plant with a two-joint (ankle and hip) model of the body, a second-order low-pass filter from EMG activity to active joint torques, and intrinsic stiffness and damping at both joints. The results indicated that the in-phase (ankle) pattern was neurally generated, whereas the out-of-phase pattern was caused by plant dynamics. Thus a single neural strategy leads to multiple kinematic patterns. Moreover, estimated intrinsic stiffness in the model was insufficient to stabilize the plant.

scholarly journals Transfer of Dynamic Learning Across Postures

2009 ◽  
Vol 102 (5) ◽  
pp. 2816-2824 ◽  
Author(s):  
Alaa A. Ahmed ◽  
Daniel M. Wolpert
Keyword(s):  
Motor Task ◽  
Standing Position ◽  
The Body ◽  
Whole Body ◽  
Robot Dynamics ◽  
The Novel ◽  
Dynamic Learning ◽  
Postural Adjustments ◽  
Body Segments ◽  
Combined Movements

When learning a difficult motor task, we often decompose the task so that the control of individual body segments is practiced in isolation. But on re-composition, the combined movements can result in novel and possibly complex internal forces between the body segments that were not experienced (or did not need to be compensated for) during isolated practice. Here we investigate whether dynamics learned in isolation by one part of the body can be used by other parts of the body to immediately predict and compensate for novel forces between body segments. Subjects reached to targets while holding the handle of a robotic, force-generating manipulandum. One group of subjects was initially exposed to the novel robot dynamics while seated and was then tested in a standing position. A second group was tested in the reverse order: standing then sitting. Both groups adapted their arm dynamics to the novel environment, and this movement learning transferred between seated and standing postures and vice versa. Both groups also generated anticipatory postural adjustments when standing and exposed to the force field for several trials. In the group that had learned the dynamics while seated, the appropriate postural adjustments were observed on the very first reach on standing. These results suggest that the CNS can immediately anticipate the effect of learned movement dynamics on a novel whole-body posture. The results support the existence of separate mappings for posture and movement, which encode similar dynamics but can be adapted independently.

scholarly journals Schoolbag weight limit: should there be a cut off?

2018 ◽  
Vol 6 (1) ◽  
pp. 106
Author(s):  
Srikanth S. Bhat ◽  
Vinay Kumar S. ◽  
Sharanabasappa S. Dhanwadkar ◽  
Ashwini Kumari N. B.
Keyword(s):  
Body Weight ◽  
Early Intervention ◽  
Musculoskeletal System ◽  
School Children ◽  
Demographic Data ◽  
The Body ◽  
Body Posture ◽  
Whole Body ◽  
Central Tendency

Background: School children are at a development age and it is important that they do not carry excessive loads. Heavy school bags can change the body posture and the musculoskeletal system must react appropriately in order to compensate for this stress. There is still no consensus about a guideline for weight of school bags. The objective of the present study was to asses the bag weight in school going children, Compare the bag weight with the whole-body weight of children, Percentage of bag weight to whole body weight at different age groups.Methods: 727 children (413 males and 314 girls) were examined from different schools in Davangere. Descriptive analyses and measures of central tendency were performed on the demographic data to describe the sample.Results: Overall 21.7% of children carry a bag which is >25% of their body weight, 46.5% children are carrying a bag >20% of their body weight and 74.7% of children carry a bag of >15% of their body weight. 40.9% children between 8-10 years carry bag of >25% and 39.8% of them between 11 -13 years carry bag of >20% and this is statistically significant (p = 0.000).Conclusions: The weight of schoolbags of school children were higher than the internationally acceptable standards in majority of school children. The school authorities and ministry of health should further evaluate and take the necessary steps to rectify the situation. Early intervention and good regulation can prevent long term complication.

Influence of the use of dental prostheses in balance and body posture.

2014 ◽  
Vol 12 ◽  
pp. 171 ◽  
Author(s):  
Cristian Fernando Shiraishi ◽  
Afonso Shiguemi Inoue Salgado ◽  
Ivo Ilvan Kerppers ◽  
Meiriélly Furmann ◽  
Thais Barbosa De Oliveira ◽  
...  
Keyword(s):  
Postural Balance ◽  
Postural Sway ◽  
Body Position ◽  
Dental Prosthesis ◽  
The Body ◽  
Body Posture ◽  
Dental Arch ◽  
Body Balance ◽  
Dental Prostheses ◽  
Postural Responses

Introduction: The concept of body posture involves balance, neuromuscular coordination and adaptation. Automatic postural responses are adjusted to meet the needs of interaction between systems of postural organization and the environment. Postural control is to maintain body position seeking stability and orientation in space, and the maintenance of posture and balance is directly related to three main systems: visual, vestibular and proprioceptive, whose junction ensures body balance. Other factors may be related to this control, such as the use of prostheses, among them the dentures that provide the balance of the mouth and jaws, through neuromuscular balance, helping to balance the body as a whole. Stabilometry assesses postural balance through the quantification of postural sway in the orthostatic position on a force platform. Objective: To evaluate the influence of the use of dental prostheses in maintaining balance and posture through baropodometry. Method: The study included 10 women with an average age of 65 years old, all using dental prosthesis, which remained on the platform for 30 seconds, with the prosthesis, repeating the procedure without the use of the prosthesis. Results: As the postural balance is given by the sum of the balance of all body structures, where all must be wholesome, and may include dental arch, in this case replaced by dental prosthesis, there was a direct contribution of using it over body balance as a whole, since there was a decrease in the number of oscillations of the body centroid and radial displacement, among individuals who use dental prosthesis. Conclusion: The present study demonstrated that there is a direct influence of the use of dental prostheses on posture and body balance.

A Simple and Inexpensive Clinical Whole Body Counter

1976 ◽  
Vol 15 (05) ◽  
pp. 248-253
Author(s):  
A. K. Basu ◽  
S. K. Guha ◽  
B. N. Tandon ◽  
M. M. Gupta ◽  
M. ML. Rehani
Keyword(s):  
The Body ◽  
Whole Body ◽  
Vitro Assay ◽  
Body Counter ◽  
Optimum Parameters ◽  
Whole Body Counter ◽  
Single Detector ◽  
Background Index ◽  
Iodide Crystal

SummaryThe conventional radioisotope scanner has been used as a whole body counter. The background index of the system is 10.9 counts per minute per ml of sodium iodide crystal. The sensitivity and derived sensitivity parameters have been evaluated and found to be suitable for clinical studies. The optimum parameters for a single detector at two positions above the lying subject have been obtained. It has been found that for the case of 131I measurement it is possible to assay a source located at any point in the body with coefficient of variation less than 5%. To add to the versatility, a fixed geometry for in-vitro counting of large samples has been obtained. The retention values obtained by the whole body counter have been found to correlate with those obtained by in-vitro assay of urine and stool after intravenous administration of 51Cr-albumin.

Visualization of Invasion into the Body and Internal Diffusion of Nanoparticles

2008 ◽  
Vol 396-398 ◽  
pp. 569-572
Author(s):  
Fumio Watari ◽  
Shigeaki Abe ◽  
I.D. Rosca ◽  
Atsuro Yokoyama ◽  
Motohiro Uo ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Fluorescent Microscopy ◽  
The Body ◽  
Internal Diffusion ◽  
Whole Body ◽  
X Ray ◽  
Body Level ◽  
Organ Level ◽  
Level 2 ◽  
Internal Body

Nanoparticles may invade directly into the internal body through the respiratory or digestive system and diffuse inside body. The behavior of nanoparticles in the internal body is also essential to comprehend for the realization of DDS. Thus it is necessary to reveal the internal dynamics for the proper treatments and biomedical applications of nanoparticles. In the present study the plural methods with different principles such as X-ray scanning analytical microscope (XSAM), MRI and Fluorescent microscopy were applied to enable the observation of the internal diffusion of micro/nanoparticles in the (1) whole body level, (2) inner organ level and (3) tissue and intracellular level. Chemical analysis was also done by ICP-AES for organs and compared with the results of XSAM mapping.

scholarly journals Making the choice between bioelectrical impedance measures for body hydration status assessment

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Dmitry M. Davydov ◽  
Andrey Boev ◽  
Stas Gorbunov
Keyword(s):  
Body Schema ◽  
Bioelectrical Impedance ◽  
Information Criterion ◽  
The Body ◽  
Whole Body ◽  
Hydration Status ◽  
Status Assessment ◽  
Best Fitting ◽  
Body Compartments ◽  
Fitting In

AbstractSituational or persistent body fluid deficit (i.e., de- or hypo-hydration) is considered a significant health risk factor. Bioimpedance analysis (BIA) has been suggested as an alternative to less reliable subjective and biochemical indicators of hydration status. The present study aimed to compare various BIA models in the prediction of direct measures of body compartments associated with hydration/osmolality. Fish (n = 20) was selected as a biological model for physicochemically measuring proximate body compartments associated with hydration such as water, dissolved proteins, and non-osseous minerals as the references or criterion points. Whole-body and segmental/local impedance measures were used to investigate a pool of BIA models, which were compared by Akaike Information Criterion in their ability to accurately predict the body components. Statistical models showed that ‘volumetric-based’ BIA measures obtained in parallel, such as distance2/Rp, could be the best approach in predicting percent of body moisture, proteins, and minerals in the whole-body schema. However, serially-obtained BIA measures, such as the ratio of the reactance to resistance and the resistance adjusted for distance between electrodes, were the best fitting in predicting the compartments in the segmental schema. Validity of these results should be confirmed on humans before implementation in practice.

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