Spinal Cord Reflex Neurorehabilitation Training and Device


Initial human studies of the H-Reflex Device have shown significant improvements in locomotion in spinal cord-injured (SCI) patients. Presented here is the use of a device and protocol to improve locomotor function in people with SCI by down-conditioning hyperactive reflexes or, if appropriate, up-conditioning hypoactive reflexes.  Using operant conditioning of spinal reflexes, we can target plasticity to specific reflex pathways, which results in significant improvements in walking performance.  These include less spasticity, easier stepping, increased walking speed, improved gait symmetry and decreased dependence on assistive devices.

The device consists of hardware and software that can administer the protocols in physical therapy sessions without the direct involvement of an expert.  The hardware consists of a nerve stimulation-EMG (electromyographic) recording (NS-EMG) component that can be mounted at a given place on the body (e.g., calf and knee) and a programmable controller with monitor that communicate via telemetry.  The H-Reflex Device modifies specific nervous system pathways through use of an operant conditioning protocol. Detailed studies in laboratory animals have revealed the anatomical and physiological nature of these spinal cord changes.

Current neurological rehabilitation methods consist primarily of the repeated practice of motor and cognitive skills (i.e. treadmill locomotion, reach and grasp actions, etc.).  Although this strategy is logical and often beneficial, it is seldom fully effective.  These skills depend on plasticity (i.e., changes) throughout the CNS from the cortex to the spinal cord.  By providing the ability to target change to specific reflex pathways, reflex conditioning methods can guide plasticity to achieve widespread effects on the complex nervous system networks that produce neuromuscular skills, and thereby improve these skills beyond the levels possible with conventional practice.

The spinal stretch reflex (SSR), also called the tendon jerk reflex or M1, is the initial response to sudden muscle stretch; this reflex excites the muscle that opposes the sudden stretch.  The electrical analog of the SSR, the H(i.e., Hoffman)-reflex, is elicited by weak electrical stimulation of the peripheral nerve, rather than by muscle stretch.  Both the SSR and H-reflex are produced mainly by a two-neuron, monosynaptic pathway that synapses in the spinal cord.

People with incomplete spinal cord injury (SCI) frequently suffer motor disabilities due to spasticity and poor muscle control, even after conventional therapy.  Abnormal spinal reflex activity often contributes to these problems.   In people with SCI, modulation of the soleus H-reflex across the step cycle is absent or diminished greatly and the abnormality affects locomotor EMG activity, contributing to spasticity (e.g., clonus), foot drop and other disabling problems.   Because they can target particular spinal pathways by either weakening or strengthening the activity of these pathways, reflex-conditioning protocols can be designed to focus on each individual’s particular deficits.


  • Five major groups of people directly benefit – Spinal Cord Injuries, Stroke, Cerebral Palsy, Multiple Sclerosis and Peripheral Nerve Injuries
  • Supplementation of conventional rehabilitation – Neurologists, Physiatrists, Physical Therapists and Occupational Therapists can already prescribe patient locomotion therapies; this new highly specific therapy, which can target each individual’s particular impairment, could easily be added to an already existing set of conventional therapies.
  • Rehabilitation neurophysiology research


  • Can improve locomotion resulting in faster walking, greater distance traversed, easier stepping, better foot placement, reduced spasticity/clonus, reduced foot drop, improved balance, and decreased use of assistive devices.
  • Better quality of life by enabling autonomy
  • Personalized treatment targeting individual deficits
  • Does not require extensive staff or patient training
  • In the future, it may be used by a patient at home with only periodic Internet-based oversight from a therapist.

State of Development

Middle research stage – Prototype available – USPTO #8,862,236;  #9,138,579;  #9,545,515


*** Thompson, AK, Pomerantz, FR, and Wolpaw, JR. “Operant Conditioning of a Spinal Reflex Can Improve Locomotion after Spinal Cord Injury in Humans.” J Neurosci, 2013 Feb 6,  33(6):2365-2375. Doi: 10.1523/JNEUROSCI 3968-12.2013.

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Thompson, AK and Wolpaw, JR.  “Restoring Walking after Spinal Cord Injury:  Operant Conditioning of Spinal Reflexes Can Help.”  The Neuroscientist 2014. Doi: 10.1177/1073858414527541

Chen Y, Chen L, Liu R, Wang Y, Chen XY, Wolpaw, JR. “Locomotor Impact of Beneficial or Non-Beneficial H-Reflex Conditioning After Spinal Cord Injury.” J Neurophysiol. 2013 Dec 26.

Thompson AK, Chen XY, Wolpaw JR. “Soleus H-Reflex Operant Conditioning Changes the H-Reflex Recruitment Curve.” Muscle Nerve, 2013 Apr; 47(4):539-44. Doi:10.1002/mus.23620.

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Makihara Y, Segal R, Wolpaw JR, and Thompson AK. “H-Reflex Modulation in the Human Medial and Lateral Gastrocnemii During Standing and Walking.”  Muscle Nerve 2012 Jan; 45(1): 116-25. Doi: 10.1002/mus.22265.

Chen Y, Chen L, Wang Y, Wolpaw JR, and Chen XY “Operant Conditioning of Rat Soleus H-Reflex Oppositely Affects Another H-Reflex and Changes Locomotor Kinematics.” J Neurosci 2011 Aug 3; 31(31): 11370-5 doi: 10.1523/JNEUROSCI. 1526-11.2011.

Chen Y, Wang Y, chen L, Sun C, English AW, Wolpaw, JR, Chen XY. “H-Reflex Up-Conditioning Encourages Recovery of EMG Activity and H-Reflexes After Sciatic Nerve Transection and Repair in Rats.” J Neurosci, 2010 Dec 1: 30(48): 16128-36 doi: 10.1523/JNEUROSCI.4578-10.2010.

Chen XY, Chen Y, Wang Y, Thompson A, Carp JS, Segal RL, and Wolpaw JR. “Reflex Conditioning:  A New Strategy for Improving Motor Function after Spinal Cord Injury.”  Ann N Y Acad Sci, 2010 Jun; 1198 Suppl 1:E12-21. Doi: 10.1111/j.1749-6632.2010.05565.x

Wang Y, Pillai S, Wolpaw JR, Chen XY. “H-Reflex Down-Conditioning Greatly Increases the Number of Identifiable GABAergic Interneurons in Rat Ventral Horn.” Neurosci Lett, 2009 Mar 13; 452(2): 124-9. Doi:10.1016/j.neulet.2009.01.054.

Thompson AK, Chen XY, and Wolpaw JR. “Acquisition of a Simple Motor Skill:  Task-Dependent Adaptation Plus Long Term Change in the Human Soleus H-Reflex.” J Neurosci, 2009 May 6; 29(10):5784-92. Doi: 10.1523/JNEUROSCI.4326-08.2009.

Pillai S, Wang Y, Wolpaw JR, Chen XY. “Effects of H-Reflex Up-Conditioning on GABAergic Terminals on Rat Soleus Motoneurons.” Eur J Neurosci, 2008 Aug; 28(4):668-74. Doi: 10.1111/j. 1460-9568.2008.06370.x.

Chen XY, Pillai S, Chen Y, Wang Y, Chen L, Carp JS, Wolpaw JR. “Spinal and Supraspinal Effects of Long-Term Stimulation of Sensorimotor Cortex in Rats.” J Neurophysiol, 2007 Aug; 98(2):878-87, Epub 2007 May 23.

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Thompson AK, Stein RB, Chen XY, Wolpaw JR. “Modulation in Spinal Circuits and Corticospinal Connections Following Nerve Stimulation and Operant Conditioning.” Conf Proc IEEE Eng Med Bio Soc, 2006; 1:2138-41.

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Chen XY, Carp JS, Chen L, Wolpaw JR. “Sensorimotor Cortex Ablation Prevents H-Reflex Up-Conditioning and Causes a Paradoxical Response to Down-Conditioning in Rats.” J Neurophysiol, 2006 Jul; 96(1):119-27. Epub 2006 Apr 5.

Wolpaw JR, Chen XY. “The Cerebellum in Maintenance of Motor Skill:  A Hierarchy of Brain and Spinal Cord Plasticity Underlies H-Reflex Conditioning.”  Learn Mem, 2006 Mar-Apr; 13(2):208-15.

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Mazzocchio R, Kitago T, Liuzzi G, Wolpaw JR, Cohen LG. “Plastic Changes in the Human H-Reflex Pathway at Rest Following Skillful Cycling Training.” Clin Neurophysiol, 2006 Aug; 117(8): 1682-91. Epub 2006 Jun 21.

Chen XY, Chen L, Chen Y, Wolpaw JR. “Operant Conditioning of Reciprocal Inhibition in Rat Soleus Muscle.” J Neurophysiol, 2006 Oct; 96(4):2144-50. Epub 2006 Jun 28.

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Thompson AK, Doran B and Stein RB. “Short-term Effects of Functional Electrical Stimulation on Spinal Excitatory and Inhibitory Reflexes in Ankle Extensor and Flexor Muscles.”  Exp Brain Res, 2006 Apr; 170(2): 216-226  Epub 2005 Nov 30. DOI 10.1007/s00221-005-0203-y

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