A5004197966- Muscle activation and electromyography studies
- Motor Control and Adaptation
- Spinal Cord Injury Research
- Neuroscience and Neural Engineering
- EEG and Brain-Computer Interfaces
- Neural dynamics and brain function
- Balance, Gait, and Falls Prevention
- Zebrafish Biomedical Research Applications
- Robotic Locomotion and Control
- Action Observation and Synchronization
- Transcranial Magnetic Stimulation Studies
- Musculoskeletal pain and rehabilitation
- Advanced Sensor and Energy Harvesting Materials
- Robot Manipulation and Learning
- Pain Management and Treatment
- Nerve injury and regeneration
- Conducting polymers and applications
- Nerve Injury and Rehabilitation
- Neurogenetic and Muscular Disorders Research
- Advanced Memory and Neural Computing
- Neuroscience of respiration and sleep
- Cerebral Palsy and Movement Disorders
- Analytical Chemistry and Sensors
- Neural Networks and Applications
- Cardiovascular Syncope and Autonomic Disorders
Drexel University
2013-2024
Massachusetts Institute of Technology
1989-2002
Hahnemann University Hospital
2000-2002
Allegheny College
1997-2000
Institute of Cognitive and Brain Sciences
1993
University of Oregon
1984
The hypothesis that the central nervous system (CNS) generates movement as a shift of limb's equilibrium posture has been corroborated experimentally in studies involving single- and multijoint motions. Posture may be controlled through choice muscle length-tension curve set agonist-antagonist torque-angle curves determining an position for limb stiffness about joints. Arm trajectories seem to generated control signal defining series postures. equilibrium-point drastically simplifies...
Motor primitives and modularity may be important in biological movement control. However, their neural basis is not understood. To investigate this, we recorded 302 neurons, making multielectrode recordings the spinal cord gray of spinalized frogs, at 400, 800, 1200 mum depth, L2/L3 segment border. Simultaneous muscle activity were used with independent components analysis to infer premotor drive patterns. Neurons divided into groups based on motor pattern modulation sensory responses, depth...
Spinal cord modularity impacts on our understanding of reflexes, development, descending systems in normal motor control, and recovery from injury. We used independent component analysis best-basis or matching pursuit wavepacket to extract the composition temporal structure bursts hindlimb muscles frogs. These techniques make minimal a priori assumptions about drive pattern structure. compared premotor burst structures spinal frogs with less reduced fuller repertoire locomotory, kicking,...
Spinal circuits form building blocks for movement construction. In the frog, such have been described as isometric force fields. Microstimulation studies showed that individual fields can be combined by vector summation. Summation and scaling of a few force-field types can, in theory, produce large range dynamic structures associated with limb behaviors. We tested first time whether summation underlies construction real behavior frog. examined organization correction responses circumvent...
1. Spinal frogs are known to make coordinated and successful wiping movements almost all places on the body legs. Such involve a sensorimotor transformation. Information from both spatial locations of stimuli skin configuration frog is transformed into set motor commands that generate adequate successfully remove irritant. The spinal cord itself therefore has limited capacity for transformations. 2. We examined kinematics motions in intact leopard bullfrogs. This data was used assess...
Complex actions may arise by combining simple motor primitives. Our studies support individual premotor drive pulses or bursts as execution primitives in spinal cord. Alternatively, the fundamental at segmental level could be time-varying synergies. To distinguish these hypotheses, we examined sensory feedback effects during targeted wiping organized This behavior comprises three bursts. We tested (1) whether altered structure of primitives, and (2) differentially modulated different burst...
Neurons coordinate their activity to produce an astonishing variety of motor behaviors. Our present understanding control has grown rapidly thanks new methods for recording and analyzing populations many individual neurons over time. In contrast, current the nervous system's actual output - activation muscle fibers by typically cannot detect electrical events produced during natural behaviors scale poorly across species groups. Here we a novel class electrode devices ('Myomatrix arrays')...
Spinal circuits may organize trajectories using pattern generators and synergies. In frogs, prior work supports fixed-duration pulses of fixed composition synergies, forming primitives. wiping behaviors, spinal frogs adjust their motor activity according to the starting limb position generate fairly straight accurate isochronous across workspace. To test whether a compact description primitives modulated by proprioceptive feedback could reproduce such trajectory formation, we built...
Motor patterns in legged vertebrates show modularity both young and adult animals, comprising motor synergies or primitives. Are such spinal modules observed mammals conserved into adulthood altered? Conceivably, early circuit alter radically through experience descending pathways' activity. We analyze lumbar of intact rats the same after transection compare these with transected 5 days postnatally, before most experience, using only that never developed hind limb weight bearing. use...
Pieces of fetal spinal tissue were transplanted into the site complete midthoracic transections in neonatal rat pups (transplant rats). The development locomotion these animals was compared with that unoperated control rats and received alone (spinal Reflex, treadmill overground locomotion, staircase descent, horizontal ladder crossing for a water reward tested control, spinal, transplant from 3 weeks to adulthood. All tests readily performed by animals. Most unable make many linked...
We analyzed whether acute treatment with serotonergic agonists would improve motor function in rats transected spinal cords (spinal rats) and that received transplants of fetal cord into the transection site (transplant rats). Neonates midthoracic transections within 48 hr birth; transplant (embryonic day 14) grafts at time transection. At 3 weeks, began 1-2 months training treadmill locomotion. Rats group developed better weight-supported stepping than rats. Systemic administration two...
AbstractSpinalized frogs were microstimulated in the intermediate grey layers of lumbar spinal cord; forces evoked hindlimb measured at several limb positions. The data expressed as force fields. After collection many fields, dorsal roots cut with stimulating electrode place, and position-dependent stimulation-evoked again repeatedly. We found that pattern forces—the fields—did not change after cut. In other words, postcut pointed same direction precut forces. This result was predicted...
Brain–machine interfaces (BMIs) should ideally show robust adaptation of the BMI across different tasks and daily activities. Most BMIs have used overpracticed tasks. Little is known about in dynamic environments. How are mechanically body-coupled integrated into ongoing rhythmic dynamics, for example, locomotion? To examine this, we designed a novel using neural discharge hindlimb/trunk motor cortex rats during locomotion to control robot attached at pelvis. We tested when experienced (1)...
Objective-To test a novel braided multi-electrode probe design with compliance exceeding that of 50-micron microwire, thus reducing micromotion and macromotion induced tissue stress.Approach-We use up to 24 ultra-fine wires interwoven into tubular braid obtain highly flexible probe.The tether-portion are simply non-braided extensions the structure, allowing microprobe follow gross neural movements.Mechanical calculation direct measurements evaluated bending stiffness axial compression forces...
The hindlimb wiping reflex of the frog is an example a targeted trajectory that organized at spinal level. In this paper, we examine in 45 frogs to test importance proprioceptive afferents formation We tested wiping, which or effector limb and target move together. Loss afferent feedback from was produced by cutting dorsal roots 7–9. This caused altered initial direction, increased ankle path curvature, knee-joint velocity reversals, overshooting misses limb. established these kinematic...
Brain-machine interface (BMI) systems hold the potential to return lost functions patients with motor disorders. To date, most efforts in BMI have concentrated on decoding neural activity from forearm areas of cortex operate a robotic arm or perform other manipulation tasks. Efforts neglected locomotion hindlimb/trunk cortex. However, role hindlimb intact rats, which are often model for testing, is usually considered be small. Thus, quality representations available this area was uncertain....