Model of a patient going through neurological testing

The future of neurorehabilitation will likely
involve a mix of molecular, cellular,
pharmacological, neuromodulatory,
and training interventions to maximize
neural plasticity and recovery.

Principle Investigator: Michael Dimyan, MD

The Dimyan Laboratory's mission is to understand how the nervous system controls movement and how brain injuries affect that control. Our goal is to help patients with neurological injury recover limb usage to engage in activities of daily living and improve their quality of life.

We are guided by compassion for individuals living with neurological disability, dedication to the integrity of human subjects research, and a conviction in robust empiricism as the guiding principle for the creation of new knowledge.

We collaborate with healthy and injured human volunteers to conduct scientific research on the basic neural mechanisms of motor control and the effects of brain injury, like stroke. Currently, the techniques we use include motor exercise, training, therapy, questionnaires, scales, robot-assisted training, neurophysiological measurement and stimulation, and neuroimaging.

Our current research focuses on:

  • Interhemispheric interactions between the two sides of the brain and their relationship to muscle control
  • The mechanisms of repetitive-training for post-stroke rehabilitation and the biomarkers that predict response to such treatment

Read Dr. Dimyan's publications on Orcid.

Ongoing Research

Modulation of Interhemispheric Interactions and Arm Activity After Stroke

Chart showing results of a test

We first demonstrated that there
is a lack of normal modulation of
interhemispheric interactions, rather
than over-inhibition, after stroke.

Even after comprehensive rehabilitation, 30% of stroke survivors are left with arm weakness. Chronic hemiparesis is significant because 50% of the reduction in quality of life for stroke survivors is due to arm weakness.

Current treatments of hemiparesis are based on different models of how the two arms interact after stroke. However, these models are limited by an incomplete understanding of interhemispheric competition. In particular, we do not know how interactions between the two arms are dynamically modulated during arm activity.

I will pursue this problem by:

  1. Defining normal interhemispheric interactions between the two arms during unilateral arm activity
  2. Discovering how aging and stroke impair those dynamics
  3. Determining how other brain areas influence the interaction between the two arms

This will be done by studying neurophysiological measures of corticospinal and interhemispheric interactions in hemiparetic patients and healthy controls performing an arm activity.

I will also use multimodal neurophysiological and imaging techniques to examine brain network interactions and their influence on corticospinal activity. The proposed research is innovative conceptually in its elaboration and addition to the model of interhemispheric interactions during movement and after stroke.

The results of this research may significantly contribute to our understanding of the interaction between the two arms. This is important because it will allow us to design therapies that take advantage of those interactions.

The impact of this proposal is that it will allow us to design interventions that target specific neurophysiological impairments at specific time-points during movement to enhance rehabilitation after stroke.

This research proposal addresses the NIH missions to reduce the burden of neurological disorders and enhance the quality of life of people with disabilities. This proposal also addresses the goals of the NIH BRAIN initiative to develop a dynamic picture of the human brain describing how neural circuits interact in time and space.

Neurological scan results

We are now investigating the dynamics of brain
and corticospinal networks during movement.

Neurophysiological and Kinematic Predictors of Response in Chronic Stroke

In collaboration with Dr. George Wittenberg, VA Pittsburgh and University of Pittsburgh

Picture of a brain scan

Baseline brain network interactions may
predict response to different therapies.

Stroke is the leading cause of neurological disability in the veteran population and upper extremity dysfunction is a major cause of functional loss. The costs of rehabilitation are significant and practically limit therapy to the first few months after stroke onset.

Recent results show clearly that patients with chronic stroke benefit from rehabilitation and that robot assisted therapy offers a more cost-effective approach to this patient group. An ongoing study has shown value in adding task related training to robotic training to improve functional recovery.

The proposed study will expand the current study to examine the ability to predict who will benefit from this optimized therapy approach as well as expand knowledge of what brain structures and activity are important for improvement.

Meet Dr. Dimyan's Team of Collaborators

Dr. Dimyan collaborates with experts in occupational and physical therapy, neuroimaging, neurophysiology, psychology, biomedical engineering, motor control, exercise physiology, stroke, and neurology.

  • Elsa Ermer, PhD | Senior Data Analyst
  • Stacey A Harcum, OT/RL | Research Occupational Therapist
  • Leigh Casey | Senior Program Specialist, Research

Principles We Live By

"Men ought to know that from nothing else but the brain come joys, delights, laughter and sports, and sorrows, griefs, despondency, and lamentations. And by this, in an especial manner, we acquire wisdom and knowledge…" – On the Sacred Disease, Hippocrates, 400BCE, translated by Francis Adams

"Plasticity, then, in the wide sense of the word, means the possession of a structure weak enough to yield to an influence, but strong enough not to yield all at once. Each relatively stable phase of equilibrium in such a structure is marked by what we may call a new set of habits. Organic matter, especially nervous tissue, seems endowed with a very extraordinary degree of plasticity of this sort…" – The Principles of Psychology, Williams James, 1890