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.

Kinematic and Kinetic Constraints on Arm, Trunk, and Leg Segments in Target-Reaching Movements

2005 ◽  
Vol 93 (1) ◽  
pp. 352-364 ◽  
Author(s):  
James S. Thomas ◽  
Daniel M. Corcos ◽  
Ziaul Hasan
Keyword(s):  
Degrees Of Freedom ◽  
Neural Control ◽  
Time Course ◽  
Sagittal Plane ◽  
Principal Component ◽  
Joint Torque ◽  
Trunk Flexion ◽  
Joint Torques ◽  
Joint Task ◽  
Task Conditions

We studied target reaching tasks involving not only the arms but also the trunk and legs, which necessitated some trunk flexion. Such tasks can be successfully completed using an infinite number of combinations of segment motions due to the inherent kinematic redundancy with the excessive degrees of freedom (DOFs). Sagittal plane motions of six segments (shank, thigh, pelvis, trunk, humerus, and forearm) and dynamic torques of six joints (ankle, knee, hip, lumbar, shoulder, and elbow) were analyzed separately by principal component (PC) analyses to determine if there was a commonality among the shapes of the respective waveforms. Additionally, PC analyses were used to probe for constraining relationships among the 1) relative magnitudes of segment excursions and 2) the peak-to-peak dynamic joint torques. In summary, at the kinematic level, the tasks are simplified by the use of a single common waveform for all segment excursions with 89.9% variance accounted for (VAF), but with less fixed relationships among the relative scaling of the magnitude of segment excursions (62.2% VAF). However, at the kinetic level, the time course of the dynamic joint torques are not well captured by a single waveform (72.7% VAF), but the tasks are simplified by relatively fixed relationships among the scaling of dynamic joint torque magnitudes across task conditions (94.7% VAF). Taken together, these results indicate that, while the effective DOFs in a multi-joint task are reduced differently at the kinematic and kinetic levels, they both contribute to simplifying the neural control of these tasks.

Changes in postural control strategy during quiet standing in individuals with knee osteoarthritis

2021 ◽  
pp. 1-8
Author(s):  
Kento Sabashi ◽  
Satoshi Kasahara ◽  
Harukazu Tohyama ◽  
Takeshi Chiba ◽  
Yuta Koshino ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Angular Velocity ◽  
Postural Control ◽  
Knee Osteoarthritis ◽  
Lower Limb ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Quiet Standing ◽  
Control Group ◽  
Knee Oa

BACKGROUND: Knee osteoarthritis (OA) impairs postural control and may be affected by how the lower limb joints are used. OBJECTIVE: To investigate how individuals with knee OA use lower limb joints for static postural control. METHODS: Ten patients with knee OA and thirteen healthy controls performed quiet standing for 30 s. The standard deviation of the center of mass (COM) and lower limb joint motions in the anterior-posterior (AP) and medial-lateral (ML) planes were calculated from three-dimensional marker trajectories. Pearson’s correlation analysis and independent t-tests were conducted to investigate the relationship between COM and lower limb joint motion and to compare group difference, respectively. RESULTS: The AP hip angular velocity alone in the knee OA group and the AP hip and knee angular velocity in the control group were significantly correlated with the AP COM velocity. The ML hip angular velocity was significantly correlated with the ML COM velocity in both groups. The knee OA group exhibited a significantly larger standard deviation of AP COM velocity than the control group. CONCLUSIONS: Individuals with knee OA depended solely on the contribution of the hip to the AP COM velocity, which could not be successfully controlled by the knee.

Parallel distributed network characteristics of the DSCT

1992 ◽  
Vol 68 (4) ◽  
pp. 1100-1112 ◽  
Author(s):  
C. E. Osborn ◽  
R. E. Poppele
Keyword(s):  
Time Course ◽  
Functional Organization ◽  
Activity Patterns ◽  
Three Dimensional ◽  
Principal Component ◽  
Specific Information ◽  
Distributed Network ◽  
Network Characteristics ◽  
Large Populations ◽  
Excitatory Responses

1. We examined the functional organization of the dorsal spinocerebellar tract (DSCT) and found that it is similar to that of a parallel distributed network having widespread connectivity among parallel elements. The prevailing view is that the DSCT provides receptor-specific information to the cerebellum regarding muscle and cutaneous inputs from the hindlimbs, but that view does not consider the convergent inputs to DSCT neurons from multimodal polysynaptic pathways. 2. Spontaneously active DSCT neurons respond to peripheral stimulation with changes in their firing probability. We characterized the temporal patterns of poststimulus excitability changes for a large number of neurons using principal component analysis. The response of each neuron was represented by a response vector in three-dimensional principal component space, in which similar vectors represent responses having a similar waveform for their poststimulus activity patterns. 3. We compared the responses of large populations of DSCT units to two types of stimuli: small (3-8 deg) passive rotations of the foot at the ankle of an intact limb (234 cells) and stretch or contraction of an isolated muscle group (gastrocnemius-soleus, 168 cells). Most of the cells tested had significant responses (P < 0.05) to both types of stimuli (40-78% responded to muscle stimulation and 88% to foot rotation), and they exhibited similar patterns of poststimulus activity. Long-lasting inhibitory responses and excitatory responses with a range of peak times (< 10- > 60 ms) were prevalent in all cases. The population response to each stimulus was characterized by the relative incidence of response types among the units in a representative sample of the population. 4. The time course of excitability changes induced in DSCT cells by the stimuli could have been determined primarily by the presynaptic circuitry or by postsynaptic factors intrinsic to the DSCT cells. The evidence presented suggests that the selection of response waveforms and their distribution among the DSCT cells was determined presynaptically. We found that individual cells were capable of diverse responses to different stimuli. 5. Sample groups of 7-30 cells were selected at random and also on the basis of the similarity of their responses to one type of stimulus. The distributions of response types among the cells of the sample groups were compared to the distributions for the entire population recorded for each stimulus.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Effect of Three Technical Arms Swings on The Elevation of the Center of Mass During a Standing Back Somersault

2014 ◽  
Vol 40 (1) ◽  
pp. 37-48 ◽  
Author(s):  
Bessem Mkaouer ◽  
Monèm Jemni ◽  
Samiha Amara ◽  
Helmi Chaabène ◽  
Johnny Padulo ◽  
...  
Keyword(s):  
Center Of Mass ◽  
Body Height ◽  
Force Plate ◽  
Three Dimensional ◽  
Movement Analysis ◽  
Vertical Displacement ◽  
Technical Performance ◽  
Risk Of Falls ◽  
Analysis System ◽  
High Level

Abstract Arms swing during standing back somersaults relates to three different “gymnastics schools”, each is considered “optimal” by its adepts. In the three cases, technical performance, elevation and safety differ. Therefore, the aim of this study was to compare the mechanical variables of three different arms swing techniques in the performance of a standing back tucked somersault. Five high-level male gymnasts (age: 23.17±1.61 yrs; body height: 1.65±0.05 m; body mass: 56.80±7.66 kg) randomly performed standing somersaults under three conditions, each following a different arms’ swing technical angle (270°, 180° and 90°). A force plate synchronized with a three dimensional movement analysis system was used to collect kinetic and kinematic data. Significant differences were observed between somersaults’ performance. The back somersault performed with 270° arms swing showed the best vertical displacement (up to 13.73%), while the back somersaults performed with 180° arms swing showed a decrease in power (up to 22.20%). The back somersault with 90° arms swing showed the highest force (up to 19.46%). Considering that the higher elevation of the centre of mass during the flight phase would allow best performance and lower the risk of falls, this study demonstrated that optimal arms’ swing technique prior to back tucked somersault was 270°.

scholarly journals Treatment of cystic craniopharyngiomas with yttrium-90 colloid solution.

1997 ◽  
Vol 3 (6) ◽  
pp. E8 ◽  
Author(s):  
Jenö Julow ◽  
Ferenc Lányi ◽  
Márta Hajda ◽  
György T. Szeifert ◽  
Katalin Bálint ◽  
...  
Keyword(s):  
Time Course ◽  
Histopathological Examination ◽  
Three Dimensional ◽  
Long Term Results ◽  
Colloid Solution ◽  
Survival Duration ◽  
Intracavitary Irradiation ◽  
Cyst Volume ◽  
Yttrium 90

The authors analyzed long-term follow-up data to assess the value of intracavitary irradiation with stereotactically implanted beta-emitting radioisotope 90Y-silicate colloid for the treatment of craniopharyngiomas. Fifty-seven craniopharyngiomas in 42 patients were selected for retrospective analysis. The yttrium-90 was implanted intracavitally, using computerized tomography-guided and three-dimensional stereotactic treatment planning. The cumulative dose aimed at the inner surface of the cyst wall was 300 Gy. An average of 75% shrinkage of the initial cyst volume was observed. In 18 cases the reduction was more than 91%, and the cyst disappeared totally in 11 cases. A 50% decrease in cyst volume was usually apparent between the 2nd and 4th months. A 70% decrease in cyst volume was seen by the 5th and 6th months and an 80% reduction by the 7th and 8th months. Cysts that were unchanged remained so throughout the observation period. The time course of volume reduction could be expressed mathematically by the formula of 0.73 X e-0.62 X T + 0.27, where “e” is the basic number of natural logarithm and “T” is the time expressed in months. Mean survival duration after intracavitary irradiation was 9.4 years. The shrinkage of the cyst was a consequence of fibrosis of the wall, as seen on histopathological examination. The neuroophthalmological prognosis was favorable only when the optic disc was normal or nearly normal at the time of the treatment. In the presence of preexisting optic atrophy, visual deterioration proved to be irreversible. The long-term results support the view that intracavitary90Y-irradiation is a noninvasive and very effective method of treatment for craniopharyngioma cysts. Because of the 1.1 mm half-life decay of beta irradiation, it cannot influence the solid part of the tumor; therefore, the best result can be expected in solitary cysts.

scholarly journals Kinematic and Kinetic Analysis of Horticultural Activities for Postural Control and Balance Training

HortScience ◽  
2018 ◽  
Vol 53 (10) ◽  
pp. 1541-1552
Author(s):  
A-Young Lee ◽  
Sin-Ae Park ◽  
Young-Jin Moon ◽  
Ki-Cheol Son
Keyword(s):  
Postural Control ◽  
Muscle Activation ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Reaction Force ◽  
Three Dimensional ◽  
Balance Training ◽  
Lower Limbs ◽  
Kinetic Characteristics ◽  
3D Motion Analysis

The objective of this study was to analyze the kinematic and kinetic characteristics of eight horticultural activities (HAs): digging, raking, sowing seeds, transplanting plants, near-distance weeding, far-distance weeding, low-height harvesting, and high-height harvesting. Twenty-four male university students (average age, 23.4 ± 2.9 years) participated in this study. Balance and postural stability factors [e.g., center of mass (CoM), ground reaction force (GRF), and center of pressure (CoP)] and postural control strategy factors (e.g., joint angles, joint moment, and muscle activation of the trunk and lower limbs) were assessed using a three-dimensional (3D) motion analysis system, force platform, and surface electromyography. A total of eight HAs were distinguished in three motions: stepping, squatting, and stooping. In performing the eight HAs, CoM shifting occurred and balance of the subjects became unstable. These forced compensatory motor strategies to maintain balance by exertion of GRF from the two feet, movement of the CoP, and a combination of musculoskeletal system exercises of the lower limbs and trunk occurred. The kinematic and kinetic characteristics of lower limb motions were significantly different across the HAs (P = 0.05). The kinematic and kinetic characteristics of HAs were similar to those of the functional tasks during balance improvement training motions and activities of daily living. The current study provides useful reference data for developing a horticultural therapy program for balance improvement in patients who need physical rehabilitation.

Effects of Unilateral Loss of Vestibular Function on the Vestibulo-Ocular Reflex and Postural Control

1989 ◽  
Vol 98 (11) ◽  
pp. 884-889 ◽  
Author(s):  
F. Owen Black ◽  
Robert J. Peterka ◽  
Charlotte L. Shupert ◽  
Lewis M. Nashner
Keyword(s):  
Postural Control ◽  
Time Course ◽  
Normal Values ◽  
Vestibular Function ◽  
Vestibular Nerve ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Eye Velocity ◽  
Surgically Induced

Long-term recovery from surgically induced unilateral loss of vestibular function was studied in 14 patients. Seven patients underwent surgical extirpation or section of the vestibular nerve, and seven patients underwent labyrinthectomy without vestibular nerve section. The vestibulo-ocular reflex (VOR) and postural control were evaluated preoperatively and monitored for up to 4 years postoperatively with use of pseudorandom rotation (combined sinusoidal frequencies from 0.009 to 1.5 Hz) and moving platform posturography. Immediately following surgery all patients showed minimal reductions in the VOR gain constant, but marked reduction in the time constant, and marked increase in slow eye velocity bias. Bias returned to normal values within about 10 days, but time constants never returned to normal values. Results of standard Romberg tests in these patients were normal throughout the preoperative and postoperative periods. However, all patients showed marked postural control abnormalities in tests of the ability to maintain balance in unusual sensory environments in the immediate postoperative period. Seventy-five percent of the patients eventually recovered normal postural control. Postural control returned to near baseline performance with a time course similar to that of the VOR bias. However, postural control also continued to improve after the recovery of VOR bias was complete.

Practical electron tomography

1995 ◽  
Vol 53 ◽  
pp. 742-743
Author(s):  
C.L. Woodcock
Keyword(s):  
Electron Tomography ◽  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
3D Shape ◽  
Computational Resources ◽  
Shape Of Particles

Despite the potential of the technique, electron tomography has yet to be widely used by biologists. This is in part related to the rather daunting list of equipment and expertise that are required. Thanks to continuing advances in theory and instrumentation, tomography is now more feasible for the non-specialist. One barrier that has essentially disappeared is the expense of computational resources. In view of this progress, it is time to give more attention to practical issues that need to be considered when embarking on a tomographic project. The following recommendations and comments are derived from experience gained during two long-term collaborative projects.Tomographic reconstruction results in a three dimensional description of an individual EM specimen, most commonly a section, and is therefore applicable to problems in which ultrastructural details within the thickness of the specimen are obscured in single micrographs. Information that can be recovered using tomography includes the 3D shape of particles, and the arrangement and dispostion of overlapping fibrous and membranous structures.

Custom Presurgical Planning for Midfacial Reconstruction

2020 ◽  
Vol 36 (06) ◽  
pp. 696-702
Author(s):  
Nolan B. Seim ◽  
Enver Ozer ◽  
Sasha Valentin ◽  
Amit Agrawal ◽  
Mead VanPutten ◽  
...  
Keyword(s):  
Multidisciplinary Approach ◽  
Functional Performance ◽  
Three Dimensional ◽  
Free Tissue Transfer ◽  
Long Term Effects ◽  
Presurgical Planning ◽  
Dental Rehabilitation ◽  
Midface Reconstruction ◽  
Reconstructive Algorithm

AbstractResection and reconstruction of midface involve complex ablative and reconstructive tools in head and oncology and maxillofacial prosthodontics. This region is extraordinarily important for long-term aesthetic and functional performance. From a reconstructive standpoint, this region has always been known to present challenges to a reconstructive surgeon due to the complex three-dimensional anatomy, the variable defects created, combination of the medical and dental functionalities, and the distance from reliable donor vessels for free tissue transfer. Another challenge one faces is the unique features of each individual resection defect as well as individual patient factors making each preoperative planning session and reconstruction unique. Understanding the long-term effects on speech, swallowing, and vision, one should routinely utilize a multidisciplinary approach to resection and reconstruction, including head and neck reconstructive surgeons, prosthodontists, speech language pathologists, oculoplastic surgeons, dentists, and/or craniofacial teams as indicated and with each practice pattern. With this in mind, we present our planning and reconstructive algorithm in midface reconstruction, including a dedicated focus on dental rehabilitation via custom presurgical planning.

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