Feinberg School of Medicine

Department of Physical Therapy and

Human Movement Sciences

NEUROPLASTICITY AND MOTOR CONTROL OF UPPER LIMB FUNCTION FOLLOWING STROKE

Julius Dewald, PT, PhD

Assistant Professor

PhD, Loma Linda University

MS, Vrije Universiteit Brussel

PT, Vrije Universiteit Brussel

Contact Information

Phone#: (312) 908-6788

Fax#: (312) 908-0741

Email: j-dewald@northwestern.edu

 Research in this lab is focused on understanding discoordination of the upper limb after stroke, in learning the involvement of brain plasticity in recovery, and in developing novel neurotherapeutic training programs to enhance motor control of the upper limb even years after a stroke.  Using multi-channel EMG and a 6 degree-of-freedom load cell, we can quantify discoordination in the impaired arm and begin to investigate the mechanisms underlying this reduction in muscle and torque combinations between the elbow and shoulder joints.  One main objective is in understanding the relationship between the reduction in movement capabilities and brain reorganization.  We are currently investigating this possible relationship with several neuroimaging modalities: 128 channel EEG, Transcranial Magnetic Stimulation, and MRI.  Determination of the nature of reorganization of motor cortices during controlled mechanical experiments in hemiparetic stroke subjects is expected to answer fundamental questions regarding brain plasticity and its effects on motor recovery. Additional research interests I am pursuing involve the development of novel neurotherapeutic training programs using quantitative computer driven feedback that seek to improve the ability to produce necessary muscle and torque combinations for reaching and retrieval motions with the impaired arm. I am also planning some future work on pharmacological interventions that seek to alter spinal interneuronal bias. Abnormal interneuronal excitability is believed to be the source of altered spinal reflex activity following brain lesions and may very well be an important contributor to movement discoordination.

Collaborators:

· Ana Maria Acosta, PhD; Michael Ellis, PT; Brad Holubar, MS; Thierry Keller, PhD; Dan Kraniak, PhD student; Susan Scherwin, PhD cand; Jun Yao, PhD; DPTHMS

· Randall F Beer, PhD; Sensory Motor Performance Program, Rehabilitation Institute of Chicago

Funding:

Current projects are funded by the National Institutes of Health, the Department of Education (NIDRR), and the American Heart Association

Selected Publications:

Dewald, JPA, Rymer, WZ, Schmit, BD. (2003). Reflex torque responses to multiple movement velocities in the spastic elbow: Evidence for changes in reflex threshold and gain. Submitted to: Muscle & Nerve.

Ricamato, AL, Dhaher, YY, and Dewald, JPA (2002). Electrical cortical activity associated with joint torque direction in the human arm. Submitted to the Journal of Neurophysiology

Dewald, JPA, Beer, RF. Evidence for abnormal joint torque patterns in the paretic upper limb of subjects with hemiparesis. Muscle & Nerve  24 (2): 273-283,  2001.

Dewald, JPA, Sheshadri, V, Dawson, ML, Beer, RF. Upper limb discoordination in hemiparetic stroke: Implications for neurorehabilitation. Topics in Stroke Rehabilitation 8(1) 1-12, 2001.

Beer RF, Dewald JPA and Rymer WZ. Deficits in the coordination of multijoint arm movements in hemiparetic subjects. Evidence for disturbed control of limb dynamics. Experimental Brain Research 131 (3): 305-319, 2000

Dewald, JPA, Beer, RF, Given JD, McGuire, J.R., and Rymer, WZ. Reorganization of flexion reflexes in the upper extremity of hemiparetic subjects. Muscle & Nerve. 22 1209-1221, 1999.

Beer, R.F, Dewald, J.P.A, Rymer, WZ. Disturbances of Voluntary Movement in Stroke: Problems of Planning or Execution? Progress in Brain Research 123: 455-60, 1999.

Beer, RF, Given, JD, Dewald, JPA  Task-Dependent weakness at the elbow in patients with hemiparesis. Archives of Physical Medicine and Rehabilitation. 80(7) 766-72, 1999.