A5011153285- Muscle activation and electromyography studies
- Motor Control and Adaptation
- Robot Manipulation and Learning
- Cerebral Palsy and Movement Disorders
- Orthopedic Surgery and Rehabilitation
- EEG and Brain-Computer Interfaces
- Robotic Locomotion and Control
- Neuroscience and Neural Engineering
- Balance, Gait, and Falls Prevention
- Botulinum Toxin and Related Neurological Disorders
- Sports Performance and Training
- Neurological disorders and treatments
- Tactile and Sensory Interactions
- Nerve Injury and Rehabilitation
- Prosthetics and Rehabilitation Robotics
- Sports injuries and prevention
- Neural dynamics and brain function
- Peripheral Nerve Disorders
- Cellular Mechanics and Interactions
- Stroke Rehabilitation and Recovery
- Transcranial Magnetic Stimulation Studies
- Mechanics and Biomechanics Studies
- Action Observation and Synchronization
- Force Microscopy Techniques and Applications
- Foot and Ankle Surgery
University of Southern California
2016-2025
Southern California University for Professional Studies
2009-2024
Engineering Systems (United States)
2018-2021
American Physical Therapy Association
2014-2017
Universität Innsbruck
2014
Cornell University
2000-2012
Tata Institute of Fundamental Research
2011
National Centre for Biological Sciences
2011
Sibley Memorial Hospital
2005-2008
Hospital for Special Surgery
2002-2005
The static properties of tensegrity structures have been widely appreciated in civil engineering as the basis extremely lightweight yet strong mechanical structures. However, dynamic and their potential utility design robots relatively unexplored. This paper introduces based on structures, which demonstrate that dynamics such can be utilized for locomotion. Two are presented: TR3, a triangular prism with three struts, TR4, quadrilateral four struts. For each these robots, simulation models...
Muscle coordination studies repeatedly show low-dimensionality of muscle activations for a wide variety motor tasks. The basis vectors this low-dimensional subspace, termed synergies, are hypothesized to reflect neurally-established functional groupings that simplify body control. However, the synergy hypothesis has been notoriously difficult prove or falsify. We use cadaveric experiments and computational models perform crucial thought experiment develop an alternative explanation how...
Numerous observations of structured motor variability indicate that the sensorimotor system preferentially controls task-relevant parameters while allowing task-irrelevant ones to fluctuate. Optimality models show controlling a redundant musculo-skeletal in this manner meets task demands minimizing control effort. Although line inquiry has been very productive, data are mostly behavioral with no direct physiological evidence on level muscle or neural activity. Furthermore, biomechanical...
Human fingers have sufficiently more muscles than joints such that every fingertip force of submaximal magnitude can be produced by an infinite number muscle coordination patterns. Nevertheless, the nervous system seems to effortlessly select patterns when sequentially producing forces low, moderate, and maximal magnitude. The hypothesis this study is selection produce simplified appropriate modulation a pattern capable largest expected force. In each three directions, eight subjects were...
Coherence analysis has the ability to identify presence of common descending drive shared by motor unit pools and reveals its spectral properties. However, link between properties neural functional interactions among muscles remains unclear. We assessed thumb index finger while participants executed two mechanically distinct precision pinch tasks, each requiring coordination muscles. found that was systematically reduced or enhanced at specific frequencies interest (~10 ~40 Hz). While...
Current thinking attributes information processing for neuromuscular control exclusively to the nervous system. Our cadaveric experiments and computer simulations show, however, that tendon network of fingers performs logic computation preferentially change torque production capabilities. How this propagates tension enable manipulation has been debated since time Vesalius DaVinci remains an unanswered question. We systematically changed proportion tendons extensor digitorum versus two dorsal...
Computational models of the neuromuscular system hold potential to allow us reach a deeper understanding function and clinical rehabilitation by complementing experimentation. By serving as means distill explore specific hypotheses, computational emerge from prior experimental data motivate future work. Here we review tools used understand including musculoskeletal modeling, machine learning, control theory, statistical model analysis. We conclude that these tools, when in combination, have...
Traditional engineering approaches strive to avoid, or actively suppress, nonlinear dynamic coupling among components. Biological systems, in contrast, are often rife with these dynamics. Could there be, some cases, a benefit high degrees of dynamical coupling? Here we present distributed robotic control scheme inspired by the biological phenomenon tensegrity-based mechanotransduction. This emergence morphology-as-information-conduit ‘morphological communication’, enabled time-sensitive...
During force production, hand muscle activity is known to be coherent with in primary motor cortex, specifically the beta-band (15-30 Hz) frequency range. It not clear, however, if this coherence reflects control strategy selected by nervous system for a given task, or it instead an intrinsic property of cortico-spinal communication. Here, we measured corticomuscular and intermuscular between muscles index finger thumb while two-finger pinch grip identical net was applied objects which were...
A realistic biomechanical thumb model would elucidate the functional consequences of orthopedic and neurological diseases their treatments. We investigated whether a single parametric kinematic can represent all thumbs, or different structures are needed to thumbs. used Monte Carlo simulations convert anatomical variability in parameters into distributions Denavit-Hartenberg amenable for robotics-based models. Upon convergence (3550 simulations, where mean coefficient variance changed < 1%...
The neural control of tasks such as rapid acquisition precision pinch remains unknown. Therefore, we investigated the finger musculature when index fingertip abruptly transitions from motion to static force production. Nine subjects produced a downward tapping followed by vertical against rigid surface. We simultaneously recorded three-dimensional force, plus complete muscle coordination pattern using intramuscular electromyograms all seven muscles. found that clearly switched for isometric...
Much debate has arisen from research on muscle synergies with respect to both limb impedance control and energy consumption. Studies of in the context reaching movements postural tasks have produced divergent findings, this study explores whether use by central nervous system (CNS) can resolve these findings also provide insights mechanisms In study, we phrase debates at conceptual level interactions between neural degrees freedom constraints. This allows us examine ability...
Synergy analysis via dimensionality reduction is a standard approach in biomechanics to capture the dominant features of limb kinematics or muscle activation signals, which can be called "coarse synergies." Here we demonstrate that less these are often explicitly disregarded considered noise, nevertheless exhibit "fine synergies" reveal subtle, yet functionally important, adaptations. To find coarse synergies, applied non-negative matrix factorization (NMF) unilateral EMG data from eight...
Dexterous manipulation remains an aspirational goal for autonomous robotic systems, particularly when learning to lift and rotate objects against gravity with intermittent finger contacts. We use model-free reinforcement compare the effect of curriculum (i.e., combinations rotation tasks) haptic information no-tactile versus 3D-force) on a simulated three-finger hand. In addition, novel curriculum-based rate scheduler accelerates convergence. demonstrate that choice biases progression...