Publications by authors named "Noam Y Harel"

Electromagnetic stimulation probes and modulates the neural systems that control movement. Key to understanding their effects is the muscle recruitment curve, which maps evoked potential size against stimulation intensity. Current methods to estimate curve parameters require large samples; however, obtaining these is often impractical due to experimental constraints.

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Volitional movement requires descending input from the motor cortex and sensory feedback through the spinal cord. We previously developed a paired brain and spinal electrical stimulation approach in rats that relies on convergence of the descending motor and spinal sensory stimuli in the cervical cord. This approach strengthened sensorimotor circuits and improved volitional movement through associative plasticity.

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Transcutaneous spinal cord stimulation (tSCS) is an emerging therapeutic strategy to target spinal autonomic circuitry to normalize and stabilize blood pressure (BP) in hypotensive persons living with chronic spinal cord injury (SCI). Our aim is to describe our current methodological approach to identify individual tSCS parameters that result in the maintenance of seated systolic blood pressure (SBP) within a pre-defined target range. The parent study is a prospective, randomized clinical trial in which eligible participants will undergo multiple mapping sessions to optimize tSCS parameter settings to promote stable SBP within a target range of 110-120 mm Hg for males and 100-120 mm Hg for females.

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Article Synopsis
  • - Remote ischemic conditioning (RIC) is a technique involving temporary blood flow restriction to one limb, which may provide protective effects across the body and has potential benefits for conditions like heart attacks and strokes.
  • - Recent studies suggest that RIC, when paired with motor training, might improve motor learning and increase brain activity related to movement, particularly in individuals with spinal cord injuries or conditions like ALS.
  • - RIC is a cost-effective and easy-to-administer method that could enhance rehabilitation for people with chronic neurological issues, although more research is needed to fully understand how it works and its overall effectiveness.
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Volitional movement requires descending input from motor cortex and sensory feedback through the spinal cord. We previously developed a paired brain and spinal electrical stimulation approach in rats that relies on convergence of the descending motor and spinal sensory stimuli in the cervical cord. This approach strengthened sensorimotor circuits and improved volitional movement through associative plasticity.

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Article Synopsis
  • The study investigates the medications administered during the acute management of traumatic spinal cord injuries, with a focus on how they may affect neurological recovery.
  • Researchers analyzed data from large spinal cord injury datasets, revealing that 775 unique medications were given to over 2,000 patients within the first 60 days post-injury.
  • Findings indicate that polypharmacy was common, with some patients taking up to 43 medications a day, highlighting potential implications for patient outcomes and recovery.
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Background: The seemingly simple tasks of standing and walking require continuous integration of complex spinal reflex circuits between descending motor commands and ascending sensory inputs. Spinal cord injury greatly impairs standing and walking ability, but both improve with locomotor training. However, even after multiple locomotor training sessions, abnormal muscle activity and coordination persist.

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Background: The seemingly simple tasks of standing and walking require continuous integration of complex spinal reflex circuits between descending motor commands and ascending sensory inputs. Spinal cord injury greatly impairs standing and walking ability, but both improve with locomotor training. However, even after multiple locomotor training sessions, abnormal muscle activity and coordination persist.

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Although epidural stimulation of the lumbar spinal cord has emerged as a powerful modality for recovery of movement, how it should be targeted to the cervical spinal cord to activate arm and hand muscles is not well understood, particularly in humans. We sought to map muscle responses to posterior epidural cervical spinal cord stimulation in humans. We hypothesized that lateral stimulation over the dorsal root entry zone would be most effective and responses would be strongest in the muscles innervated by the stimulated segment.

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The record-breaking pace of COVID-19 vaccine development and implementation depended heavily on collaboration among academic, government, and commercial stakeholders, especially through data-sharing and robust multicenter trials. Collaborative efforts have not been as fruitful in fields such as neurorehabilitation, where non-pharmacological interventions play a much larger role. Barriers to translating scientific advancements into clinical practice in neurorehabilitation include pervasively small study sizes, exacerbated by limited funding for non-pharmacological multicenter clinical trials; difficulty standardizing-and adequately describing-non-pharmacological interventions; and a lack of incentives for individual patient-level data-sharing.

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​​​​​​ : Most spinal cord injuries (SCI) are not full transections, indicating that residual nerve circuits are retained. Rehabilitation interventions have been shown to beneficially reorganize motor pathways in the brain, corticospinal tract, and at the spinal level. However, rehabilitation training require a large number of repetitions, and intervention effects may be absent or show transient retention.

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Brain-computer interfaces (BCIs) enabling the control of a personal computer could provide myriad benefits to individuals with disabilities including paralysis. However, to realize this potential, these BCIs must gain regulatory approval and be made clinically available beyond research participation. Therefore, a transition from engineering-oriented to clinically oriented outcome measures will be required in the evaluation of BCIs.

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Purpose: Efforts to optimize human-computer interactions are becoming increasingly prevalent, especially with virtual reality (VR) rehabilitation paradigms that utilize engaging interfaces. We hypothesized that motor and perceptional behaviors within a virtual environment are modulated uniquely through different modes of control of a hand avatar depending on limb dominance. This study investigated the effects of limb dominance on performance and concurrent changes in perceptions, such as time-based measures for intentional binding, during virtual reach-to-grasp.

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Article Synopsis
  • Transcutaneous spinal cord stimulation (TSCS) shows promise in improving motor and autonomic function in the spinal cord, specifically for hand movements.
  • A new setup for cervical TSCS was tested where electrodes are placed at different cervical and thoracic levels, and its effects were measured when paired with motor cortex or median nerve stimulation.
  • Results indicated that TSCS can enhance hand muscle responses to motor cortex stimulation, particularly when the stimulation is closely timed, suggesting a potential method for improving hand function in individuals with spinal cord injuries, though further research is needed with more participants.
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Design: Prospective cohort study.

Objectives: We aim to better understand the silent period (SP), an inhibitory counterpart to the well-known motor evoked potential (MEP) elicited by transcranial magnetic stimulation (TMS), in individuals with spinal cord injury (SCI).

Setting: Veterans Affairs Hospital in New York.

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Study Design: This is a narrative review focused on specific challenges related to adequate controls that arise in neuromodulation clinical trials involving perceptible stimulation and physiological effects of stimulation activation.

Objectives: 1) To present the strengths and limitations of available clinical trial research designs for the testing of epidural stimulation to improve recovery after spinal cord injury. 2) To describe how studies can control for the placebo effects that arise due to surgical implantation, the physical presence of the battery, generator, control interfaces, and rehabilitative activity aimed to promote use-dependent plasticity.

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Study Design: Pre-post intervention.

Objective: To explore the potential effect of exoskeletal-assisted walking (EAW) on seated balance for persons with chronic motor complete spinal cord injury (SCI).

Setting: A SCI research center.

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Sensory feedback from wearables can be effective to learn better movement through enhanced information and engagement. Facilitating greater user cognition during movement practice is critical to accelerate gains in motor function during rehabilitation following brain or spinal cord trauma. This preliminary study presents an approach using an instrumented glove to leverage sense of agency, or perception of control, to provide training feedback for functional grasp.

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Spinal cord injury (SCI) disrupts autonomic circuits and impairs synchronistic functioning of the autonomic nervous system, leading to inadequate cardiovascular regulation. Individuals with SCI, particularly at or above the sixth thoracic vertebral level (T6), often have impaired regulation of sympathetic vasoconstriction of the peripheral vasculature and the splanchnic circulation, and diminished control of heart rate and cardiac output. In addition, impaired descending sympathetic control results in changes in circulating levels of plasma catecholamines, which can have a profound effect on cardiovascular function.

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Objective: To test the hypothesis that higher-challenge gait and balance tasks are more sensitive than traditional metrics to subtle patient-reported gait dysfunction and future fall risk in early multiple sclerosis (MS).

Methods: Persons with early MS (n = 185; ≤5 years diagnosed) reported gait function (MS Walking Scale) and underwent traditional disability metrics (Expanded Disability Status Scale [EDSS], Timed 25 Foot Walk). Patients and healthy controls (n = 50) completed clinically feasible challenge tasks of gait endurance (2-Minute Walk Test), standing balance (NIH Toolbox), and dynamic balance (balance boards; tandem walk on 2 ten-foot boards of different widths, 4.

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Article Synopsis
  • The study investigates a non-invasive method called cervical transcutaneous spinal stimulation (cTSS) to activate neural circuits in patients with cervical spinal cord injury (SCI) and amyotrophic lateral sclerosis (ALS).
  • Researchers applied cTSS using electrodes placed at specific cervical and thoracic levels, measuring muscle responses and ensuring participant safety throughout more than 170 sessions.
  • Results showed that the stimulation effectively activated upper extremity muscles with optimal conditions identified, suggesting cTSS could improve motor function in affected individuals.
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  • The study is a prospective, observational research focusing on the effects of exoskeletal-assisted walking (EAW) on bowel function in individuals with spinal cord injury (SCI).
  • Conducted in a tertiary care hospital, participants aged 18-65 with thoracic paraplegia underwent EAW training and reported their bowel function and quality of life (QOL) before and after the sessions.
  • Results showed that 50-80% of participants experienced improvements in bowel management, including fewer accidents and better stool consistency, indicating EAW may help alleviate bowel issues associated with SCI, warranting further research.
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Locomotion requires the continuous integration of descending motor commands and sensory inputs from the legs by spinal central pattern generator circuits. Modulation of spinal neural circuits by transspinal stimulation is well documented, but how transspinal stimulation affects corticospinal excitability during walking in humans remains elusive. We measured the motor evoked potentials (MEPs) at multiple phases of the step cycle conditioned with transspinal stimulation delivered at sub- and suprathreshold intensities of the spinally mediated transspinal evoked potential (TEP).

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