Core Faculty Profile

Julius P. A. Dewald

Associate Professor, Joint appointment with
Medical School - Physical Therapy & Human Movement Science, Chair
Ph.D, Neurophysiology, Loma Linda University

Phone:  (312) 238-2210, (312) 908-6788
Fax:  (312)908-2208
E-mail: j-dewald@northwestern.edu

Website(s):  http://www.feinberg.northwestern.edu/nupthms/faculty/dewald.html

Research Interests

Neurotherapeutic research, Neurophysiology, Physical therapy, Pathophysiology of stroke, Neuroimaging,Transcranial magnetic stimulation, Functional MRI, EEG, Spasticity, Abnormal Coordination. As both an assistant professor at Northwestern University and Senior Research Scientist at the Rehabilitation Institute of Chicago, I have the opportunity to combine clinical experience, neurophysiology and biomedical engineering to advance the scientific understanding of the pathophysiological mechanisms underlying movement disorders following central nervous system lesions in man. My work is funded largely through awards from the NIH and the Department of Education (NIDRR).

Ongoing Projects in the Neuroimaging and Motor Control Laboratories:

• Investigation of basic mechanisms of movement disorder following stroke. This is done using a 6 degrees of freedom loadcell to measure torques generated at the elbowand shoulder during isometric contractions. In this way, we can quantitatively record movementdisabilities following stroke.
• Investigation of possible roles of cortical reorganization in the emergence of abnormal movement patterns after stroke using EEG, fMRI, and Transcranial Magnetic Stimulation (TMS). By using multiple techniques, we hope to overcome their individual disadvantages. EEG and fMRI are used to understand brain organization during voluntary movments. EEG allows us to investigate in depth, any temporal changes in the movements and also has the great advantage of allowing large isometric exertions at the elbow and shoulder that are not possible in the MRI environment. TMS activates the arm muscles by stimulation of the brain while the subject is at rest, thereby allowing the study of the cortical connections without any additional input by other areas as would happen during voluntary movement. Both EEG and TMS are used in coordination with a 6 degree of freedom load cell and 12 channels of electromyographic(EMG) recording to accurately measure arm movement and muscle activity for a highly controlled experiment. We are currently working on ways to quantitatively measure movements and/or muscle activity in the MRI environment.
• Investigation of new neurotherapeutic rehabilitation which takes advantage of the knowledge we've gained about the disabilities in the stroke arm: that there are problems in coordination between shoulder abducters/adducters and elbow flexors/extensors. Using our 6 degree of freedom load cell and feedback, we train patients to successively work beyond those constraints in coordination.
• Spasticity quantification at the elbow and shoulder in stroke subjects using a Biodex motor.
• Quantification of torque patterns under dynamic conditions in the upper limb following brain injury. Using a 3-D HapticMASTER robot, we can quantitatively monitor endpoint forces and calculate shoulder torques during dynamic arm movements using a 6 DOF load cell. Feedback is provided to the subject via a virtual arm displayed on a monitor in front of them. The robot creates a virtual environment for the subject to interact with, and can be programmed to provide varying levels of support (making it easier for the subject to lift their limb against gravity), or to require a greater shoulder torque to lift the limb (as if the subject were lifting an object), or prescribe alternate planes of motion. This gives us unprecedented ability to look at the expression of synergies following stroke during dynamic reach and retrieval movements, as well as a new tool to train subjects to work outside of these debilitating synergies.

Selected Publications

1. Ellis MD, Acosta AM, Yao J, Dewald JP. Position-dependent torque coupling and associated muscle activation in the hemiparetic upper extremity. Exp Brain Res. 2007 Feb;176(4):594-602.

2. Krainak DM, Parrish TB, Dewald JP. A method to capture six-degrees-of-freedom mechanical measurements of isometric shoulder and elbow torques during event-related fMRI. J Neurosci Methods. 2006 Dec 27; [Epub ahead of print]

3. Yao J, Acosta AM, Dewald J. "A Biomechanics-based Method for the Quantification of Muscle Selectivity in a Musculoskeletal System," J. of Biomechanics, J Biomech. 2006;39(8):1527-30. Epub 2005 Jun 15).

4. Ellis, M., Holubar, B., Acosta, A., Beer, R., & Dewald, J. Modifiability of Abnormal Isometric Elbow and Shoulder Joint Torque Coupling After Stroke. Muscle & Nerve. 2005 Aug;32(2): 170-8.

5. Keller T, Ellis MD, Dewald JP. Overcoming abnormal joint torque patterns in paretic upper extremities using triceps stimulation. Artif Organs. 2005 Mar;29(3):229-32.

6. Deng J, Yao J, and Dewald J. "Classification of Shoulder Abduction and Elbow Flexion Using a Brain-Computer-Interface Approach," J. of Neural Engineering, (2005) vol. 2, pp. 131-138.

7. YaoJ, Dewald J."Evaluation of Different Cortical Source Localization Methods Using Simulated and SEP Related EEG Data," Neuroimage (2005) vol. 25, pp. 369-382.

8. Beer RF, Dewald JP, Dawson ML, Rymer WZ. Target-dependent differences between free and constrained arm movements in chronic hemiparesis. Exp Brain Res. 2004 Jun;156(4):458-70.

9. Ricamato AL, Dhaher YY, Dewald JP. Estimation of active cortical current source regions using a vector representation scanning approach. J Clin Neurophysiol. 2003 Sep-Oct;20(5):326-44.

10. Koo TK, Mak AF, Hung L, Dewald JP. Joint position dependence of weakness during maximum isometric voluntary contractions in subjects with hemiparesis. Arch Phys Med Rehabil. 2003 Sep;84(9):1380-6.

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

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

13. 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.

14. 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.

15. 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.

16. Schmit BD, Dewald JP, Rymer WZ. Stretch reflex adaptation in elbow flexors during repeated passive movements in unilateral brain-injured patients. Arch Phys Med Rehabil. 2000. Mar;81(3):269-78.

17. 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. 1999 Sep;22(9):1209-21.

18. 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.

19. Beer, RF, Given, JD, Dewald, JPA. Task-dependent weakness at the elbow in patients with hemiparesis. Arch Phys Med Rehabil. 1999 Jul;80(7):766-72.

20. Schmit BD, Dhaher Y, Dewald JP, Rymer WZ. Reflex torque response to movement of the spastic elbow: theoretical analyses and implications for quantification of spasticity. Ann Biomed Eng. 1999 Nov-Dec;27(6):815-29.

21. Reinkensmeyer DJ, Dewald JP, Rymer WZ. Guidance-based quantification of arm impairment following brain injury: a pilot study. IEEE Trans Rehabil Eng. 1999 Mar;7(1):1-11.

22. Dewald JP, Given JD, Rymer WZ. Long-lasting reductions of spasticity induced by skin electrical stimulation. IEEE Trans Rehabil Eng. 1996 Dec;4(4):231-42.

23. Review. Given JD, Dewald JP, Rymer WZ. Joint dependent passive stiffness in paretic and contralateral limbs of spastic patients with hemiparetic stroke. J Neurol Neurosurg Psychiatry. 1995 Sep;59(3):271-9.

24. Dewald JP, Pope PS, Given JD, Buchanan TS, Rymer WZ. Abnormal muscle coactivation patterns during isometric torque generation at the elbow and shoulder in hemiparetic subjects. Brain. 1995 Apr;118 ( Pt 2):495-510.

Recent Conference Poster Presentations

Neuroscience Conference, Society for Neuroscience, 2003 Poster Session, Poster 71.4. 'Reduced constraints in elbow/shoulder joint torque patterns in hemiparetic stroke using a multi-DOF isometric strengthening protocol'. M.D. ELLIS, B.G. HOLUBAR, A. ACOSTA, J.P.A. DEWALD.

Neuroscience Conference, Society for Neuroscience, 2003 Poster Session, Poster 71.17. 'Upper extremity multi-degree of freedom torque generating abilities in able-bodied individuals'. A. ACOSTA, J.L. BENES, B.H. HAUT, T.L. GUDUKAS, J.J. LAUGHLIN, S.M. SALTZMAN, J.P.A.DEWALD.

Neuroscience Conference, Society for Neuroscience, 2003 Poster Session, Poster 77.3. 'Optimal interpulse interval in dual pulse TMS for maximal facilitation of proximal muscles after stroke'. S.C.SCHWERIN, J.P.A. DEWALD.

Neuroscience Conference, Society for Neuroscience, 2003 Poster Session, Poster 918.5. 'The source localization of controlled torque-related cortical potentials using an EEG current density localization method'. J.YAO, J.P.A. DEWALD.