Vestibular System May Provide Equivalent Motor Actions Regardless of the Number of Body Segments Involved in the Task

2007 ◽  
Vol 97 (6) ◽  
pp. 4069-4078 ◽  
Author(s):  
H. A. Raptis ◽  
E. Dannenbaum ◽  
N. Paquet ◽  
A. G. Feldman
Keyword(s):  
Vestibular System ◽  
Healthy Subjects ◽  
Hand Position ◽  
Trunk Flexion ◽  
Motor Equivalence ◽  
Trunk Motion ◽  
Body Segments ◽  
Equivalent Motor ◽  
Motor Actions ◽  
Reach Movements

The vestibulospinal system likely plays an essential role in motor equivalence—the ability to reach the desired motor goal despite intentional or imposed changes in the number of body segments involved in the task. To test this hypothesis, we compared the ability of healthy subjects and patients with unilateral vestibular lesions (surgical acoustic neuroma resection 0.6 to 6.7 yr before the study) to maintain either the same hand position or the same trajectory of within arm reach movements while flexing the trunk, in the absence of vision. In randomly selected trials, the trunk motion was prevented by an electromagnetic device. Healthy subjects were able to preserve the hand position or trajectory by modifying the elbow and shoulder joint rotations in a condition-dependent way, at a minimal latency of about 60 ms after the trunk movement onset. In contrast, six of seven patients showed deficits in the compensatory angular modifications at least in one of two tasks so that 30–100% of the trunk displacement was not compensated and thus influenced the hand position or trajectory. Results suggest that vestibular influences evoked by the head motion during trunk flexion play a major role in maintaining the consistency of arm motor actions in external space despite changes in the number of body segments involved. Our findings also suggest that despite long-term plasticity in the vestibular system and related neural structures, unilateral vestibular lesion may reduce the capacity of the nervous system to achieve motor equivalence.

scholarly journals Referent control and motor equivalence of reaching from standing

2017 ◽  
Vol 117 (1) ◽  
pp. 303-315 ◽  
Author(s):  
Yosuke Tomita ◽  
Anatol G. Feldman ◽  
Mindy F. Levin
Keyword(s):  
Actual Body ◽  
Control Process ◽  
The Body ◽  
Motor Equivalence ◽  
Body Segments ◽  
Eyes Closed ◽  
Pointing Movement ◽  
Referent Configuration ◽  
The Difference ◽  
Motor Actions

Motor actions may result from central changes in the referent body configuration, defined as the body posture at which muscles begin to be activated or deactivated. The actual body configuration deviates from the referent configuration, particularly because of body inertia and environmental forces. Within these constraints, the system tends to minimize the difference between these configurations. For pointing movement, this strategy can be expressed as the tendency to minimize the difference between the referent trajectory (RT) and actual trajectory (QT) of the effector (hand). This process may underlie motor equivalent behavior that maintains the pointing trajectory regardless of the number of body segments involved. We tested the hypothesis that the minimization process is used to produce pointing in standing subjects. With eyes closed, 10 subjects reached from a standing position to a remembered target located beyond arm length. In randomly chosen trials, hip flexion was unexpectedly prevented, forcing subjects to take a step during pointing to prevent falling. The task was repeated when subjects were instructed to intentionally take a step during pointing. In most cases, reaching accuracy and trajectory curvature were preserved due to adaptive condition-specific changes in interjoint coordination. Results suggest that referent control and the minimization process associated with it may underlie motor equivalence in pointing.NEW & NOTEWORTHY Motor actions may result from minimization of the deflection of the actual body configuration from the centrally specified referent body configuration, in the limits of neuromuscular and environmental constraints. The minimization process may maintain reaching trajectory and accuracy regardless of the number of body segments involved (motor equivalence), as confirmed in this study of reaching from standing in young healthy individuals. Results suggest that the referent control process may underlie motor equivalence in reaching.

scholarly journals Eye Gaze Correlates of Motor Impairment in VR Observation of Motor Actions

2016 ◽  
Vol 55 (01) ◽  
pp. 79-83 ◽  
Author(s):  
A. Vourvopoulos ◽  
A. Bernardino ◽  
i Bermúdez Badia ◽  
J. Alves
Keyword(s):  
Virtual Reality ◽  
Smooth Pursuit ◽  
Healthy Subjects ◽  
Eye Gaze ◽  
Action Observation ◽  
Motor Impairment ◽  
Motor Deficits ◽  
Stroke Patients ◽  
Motor Actions ◽  
Healthy Participants

Summary Introduction: This article is part of the Focus Theme of Methods of Information in Medicine on “Methodologies, Models and Algorithms for Patients Rehabilitation”. Objective: Identify eye gaze correlates of motor impairment in a virtual reality motor observation task in a study with healthy participants and stroke patients. Methods: Participants consisted of a group of healthy subjects (N = 20) and a group of stroke survivors (N = 10). Both groups were required to observe a simple reach-and-grab and place-and-release task in a virtual environment. Additionally, healthy subjects were required to observe the task in a normal condition and a constrained movement condition. Eye movements were recorded during the observation task for later analysis. Results: For healthy participants, results showed differences in gaze metrics when comparing the normal and arm-constrained conditions. Differences in gaze metrics were also found when comparing dominant and non-dominant arm for saccades and smooth pursuit events. For stroke patients, results showed longer smooth pursuit segments in action observation when observing the paretic arm, thus providing evidence that the affected circuitry may be activated for eye gaze control during observation of the simulated motor action. Conclusions: This study suggests that neural motor circuits are involved, at multiple levels, in observation of motor actions displayed in a virtual reality environment. Thus, eye tracking combined with action observation tasks in a virtual reality display can be used to monitor motor deficits derived from stroke, and consequently can also be used for re -habilitation of stroke patients.

Biodynamic Characteristics of Upper Limb Reaching Movements of the Seated Human Under Whole-Body Vibration

2013 ◽  
Vol 29 (1) ◽  
pp. 12-22 ◽  
Author(s):  
Heon-Jeong Kim ◽  
Bernard J. Martin
Keyword(s):  
Right Hemisphere ◽  
Whole Body Vibration ◽  
The Body ◽  
Upper Body ◽  
Whole Body ◽  
Vibration Transmission ◽  
Body Vibration ◽  
Body Segments ◽  
Human Movements ◽  
Reach Movements

Simulation of human movements is an essential component for proactive ergonomic analysis and biomechanical model development (Chaffin, 2001). Most studies on reach kinematics have described human movements in a static environment, however the models derived from these studies cannot be applied to the analysis of human reach movements in vibratory environments such as in-vehicle operations. This study analyzes three-dimensional joint kinematics of the upper extremity in reach movements performed in static and specific vibratory conditions and investigates vibration transmission to shoulder, elbow, and hand along the body path during pointing tasks. Thirteen seated subjects performed reach movements to five target directions distributed in their right hemisphere. The results show similarities in the characteristics of movement patterns and reach trajectories of upper body segments for static and dynamic environments. In addition, vibration transmission through upper body segments is affected by vibration frequency, direction, and location of the target to be reached. Similarities in the pattern of movement trajectories revealed by filtering vibration-induced oscillations indicate that coordination strategy may not be drastically different in static and vibratory environments. This finding may facilitate the development of active biodynamic models to predict human performance and behavior under whole body vibration exposure.

Head-Trunk Coordination During Linear Anterior-Posterior Translations

2003 ◽  
Vol 89 (4) ◽  
pp. 1891-1901 ◽  
Author(s):  
Emily A. Keshner
Keyword(s):  
Vestibular System ◽  
Healthy Subjects ◽  
Low Frequency ◽  
Head Acceleration ◽  
Response Latencies ◽  
Distraction Task ◽  
Analysis System ◽  
Post Hoc ◽  
Linear Accelerometer ◽  
Anterior Posterior

The purpose of this study was to evaluate the relative contributions of inputs from the vestibular system and the trunk to head-trunk coordination. Twelve healthy adults and 6 adults with diminished bilateral labyrinthine input (LD) were seated with their trunk either fixed to the seat or free to move. Subjects received 10-cm, 445-cm/s2 anterior-posterior ramps and 0.35- to 4.05-Hz sum-of-sines translations while performing a mental distraction task in the dark. Kinematics of the head and trunk were derived from an Optotrak motion analysis system and a linear accelerometer placed on the head. EMG signals were collected from neck and paraspinal muscles. Data were tested for significance with multivariate ANOVA (MANOVA) and Bonferroni post hoc analyses. Initial linear and angular head acceleration directions differed in healthy subjects when the trunk was fixed or free, but did not differ in LD subjects. Peak head angular accelerations were significantly greater with the trunk fixed than when free, and were greater in LD than in control subjects. EMG response latencies did not differ when the trunk was fixed or free. Low-frequency phase responses in the healthy subjects were close to 90° and had a delayed descent as frequency increased, suggesting some neural compensation that was absent in the LD subjects. Results of this study revealed a strong initial reliance on system mechanics and on signals from segmental receptors. The vestibular system may act to damp later response components and to monitor the position of the head in space secondary to feedback from segmental proprioceptors rather than to generate the postural reactions.

Directional Sensitivity of Velocity Sense in the Lumbar Spine

2008 ◽  
Vol 24 (3) ◽  
pp. 244-251 ◽  
Author(s):  
Joseph S. Soltys ◽  
Sara E. Wilson
Keyword(s):  
Paraspinal Muscle ◽  
Movement Speed ◽  
Directional Sensitivity ◽  
Muscle Vibration ◽  
Trunk Flexion ◽  
Paraspinal Muscles ◽  
Spinal Motion ◽  
Trunk Motion ◽  
Dynamic Motion ◽  
The Difference

Regulating spinal motion requires proprioceptive feedback. While studies have investigated the sensing of static lumbar postures, few have investigated sensing lumbar movement speed. In this study, proprioceptive contributions to lateral trunk motion were examined during paraspinal muscle vibration. Seventeen healthy subjects performed lateral trunk flexion movements while lying prone with pelvis fixed. A 44.5-Hz vibratory stimulus was applied to the paraspinal muscles at the L3 level. Subjects attempted to match target paces of 9.5, 13.5, and 17.5 deg/s with and without paraspinal muscle vibration. Vibration of the paraspinal musculature was found to result in slower overall lateral flexion. This effect was found to have a greater influence in the difference of directional velocities with vibration applied to the left musculature. These changes reflect the sensitivity of lumbar velocity sense to applied vibration leading to the perception of faster muscle lengthening and ultimately resulting in slower movement velocities. This suggests that muscle spindle organs modulate the ability to sense velocity of motion and are important in the control of dynamic motion of the spine.

TRUNK FLEXION STRATEGY AND THE LOADS IN THE LOWER LIMBS WHEN WALKING UP SURFACES OF DIFFERENT SLOPES

2012 ◽  
Vol 24 (04) ◽  
pp. 295-305 ◽  
Author(s):  
Tsai-Hsueh Leu ◽  
Jia-Da Li ◽  
Shih-Wun Hong ◽  
Ting-Ming Wang ◽  
Shier-Chieg Huang ◽  
...  
Keyword(s):  
Stance Phase ◽  
Current Data ◽  
Lower Limbs ◽  
Trunk Flexion ◽  
Locomotor System ◽  
Trunk Motion ◽  
Inclination Angles ◽  
Angular Impulse ◽  
Weight Acceptance ◽  
Uphill Walking

Walking inclined ground surfaces presents a number of challenges to the human locomotor system, especially for those with neuromusculoskeletal injuries or diseases. The purpose of the current study was to perform a complete 3D kinetics analysis of the locomotor system during uphill walking on surfaces of different inclinations in order to reveal interactions of the joints and the trunk motion, and the related mechanical demands for future clinical applications. Fifteen young adults were asked to walk on inclined sloped walkways with 0, 5, 10, 15 degrees of slopes while kinematic and kinetic data were collected and analyzed. The results showed that the subjects increased the anterior tilt of the pelvis and the flexion of the trunk with increased inclination angles, maintaining more or less constant moments at the ankle, but modulating the moments at the hip and knee during the first half of the stance phase, and the moments at the hip only during the second half of the stance phase. In response to weight acceptance and propulsion of the body's COM, differences in the peak inter-segmental joint resultant force magnitudes at different inclination angles occurred primarily in the anterioposterior direction for all the joints of the lower extremities. The angular extensor impulses at all the joints increased linearly with increased slope, suggesting an overall linear joint angular impulse control during uphill walking. The current data and findings may serve as baseline data for future clinical purposes and may be helpful for other ergonomic applications.

Trunk Motion of Male Professional Golfers Using Two Different Golf Clubs

2002 ◽  
Vol 18 (4) ◽  
pp. 366-373 ◽  
Author(s):  
David M. Lindsay ◽  
John F. Horton ◽  
Robert D. Paley
Keyword(s):  
Golf Swing ◽  
Trunk Flexion ◽  
Shaft Length ◽  
Spinal Motion ◽  
Trunk Motion ◽  
Golf Clubs ◽  
Motion Characteristics ◽  
Professional Golfers ◽  
Back Problems ◽  
Side Bending

Low back problems account for the largest proportion of injuries among amateur and professional golfers. However, there is little data on how the trunk or spine moves during a golf swing. Also, it may be that different golf clubs produce different trunk motion characteristics. The purpose of this study was to compare trunk range of motion (ROM) and velocity in three movement planes during the execution of a full golf swing using a driver and a 7-iron. Forty-four members of the Alberta Professional Golf Association volunteered to participate in this study. Trunk ROM and velocities in the sagittal, frontal, and transverse planes were measured using a triaxial electrogoniometer. Results showed that significantly more trunk flexion was required when setting up to hit the ball with the 7-iron compared to the driver, p < 0.05. During the swing, significantly greater maximum flexion and left-side-bend ROM occurred when using the 7-iron, p < 0.05. Maximum right-side-bending velocity during the golf swing was also significantly greater with a 7-iron. These findings suggest that differences in shaft length and ball positioning associated with the different clubs affects swing mechanics and trunk/spinal motion. In particular, the shorter club (7-iron) tended to place more emphasis on lateral trunk motion than did the driver. The results from this study may help clinicians better understand how the golf swing creates stress on the back as well as how club fitting may affect trunk motion characteristics.

scholarly journals Assessment of trunk flexion in arm reaching tasks with electromyography and smartphone accelerometry in healthy human subjects

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yolanda Castillo-Escario ◽  
Hatice Kumru ◽  
Josep Valls-Solé ◽  
Loreto García-Alen ◽  
Joan Vidal ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Healthy Subjects ◽  
Human Subjects ◽  
Objective Assessment ◽  
Acoustic Stimulus ◽  
Trunk Flexion ◽  
Healthy Human ◽  
Recruitment Pattern ◽  
Trunk Stability ◽  
Arm Reaching

AbstractTrunk stability is essential to maintain upright posture and support functional movements. In this study, we aimed to characterize the muscle activity and movement patterns of trunk flexion during an arm reaching task in sitting healthy subjects and investigate whether trunk stability is affected by a startling acoustic stimulus (SAS). For these purposes, we calculated the electromyographic (EMG) onset latencies and amplitude parameters in 8 trunk, neck, and shoulder muscles, and the tilt angle and movement features from smartphone accelerometer signals recorded during trunk bending in 33 healthy volunteers. Two-way repeated measures ANOVAs were applied to examine the effects of SAS and target distance (15 cm vs 30 cm). We found that SAS markedly reduced the response time and EMG onset latencies of all muscles, without changing neither movement duration nor muscle recruitment pattern. Longer durations, higher tilt angles, and higher EMG amplitudes were observed at 30 cm compared to 15 cm. The accelerometer signals had a higher frequency content in SAS trials, suggesting reduced movement control. The proposed measures have helped to establish the trunk flexion pattern in arm reaching in healthy subjects, which could be useful for future objective assessment of trunk stability in patients with neurological affections.

scholarly journals Elaboration and assessment of clinical protocols to support the evaluation of stand-to-sit activity

2014 ◽  
Vol 27 (2) ◽  
pp. 251-259 ◽  
Author(s):  
Maíra Junkes Cunha ◽  
Carolina Mendes do Carmo ◽  
Cássio Marinho Siqueira ◽  
Kelly Takara ◽  
Clarice Tanaka
Keyword(s):  
Healthy Subjects ◽  
Physical Therapists ◽  
The Body ◽  
Neutral Position ◽  
Upper Limbs ◽  
Clinical Protocols ◽  
Body Segment ◽  
Body Segments ◽  
Sit To Stand ◽  
And Inversion

Introduction Evaluation of sit-to-stand and stand-to-sit activities is used by physical therapists in patients with neurological and musculoskeletal disorders. Sit-to-stand activity presents different descriptions of phases and movements; however the phases of stand-to-sit activity have not been established yet.Objectives To describe the movements during stand-to-sit activity and create an evaluation protocol.Materials and methods Stand-to-sit activity was described on anterior and lateral views based on the observation of 27 healthy subjects. The body segments chosen to analyze were feet, ankles, knees, hips, pelvis, trunk, spine, upper limbs, head and cervical spine. The movements of body segments were described as adduction and abduction, eversion and inversion, valgus and varus, neutral position and asymmetry. The protocol was assessed with questionnaires answered by 12 physiotherapists experts in the area.Results Stand-to-sit activity was divided in 4 phases: 1- "Neutral position", 2- "Pre-squat", 3- "Squat" and 4- "Stabilization". Two models of protocols were developed considering 5 body segments to the anterior view and 7 segments for the lateral view.Conclusion Stand-to-sit activity was described in 4 phases with sequential movements of each body segment. These protocols allow physiotherapists to identify unusual movements of body segments during the stand-to-sit activity.

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