Herman I. Krebs, PhD

Contribution to Science (selected publications)

Design and Development of robotic tools for the field of neurorehabilitation

I have a self-serving tendency to think of myself as one of the “fathers” of the field of rehabilitation robotics, I have been intimately related with its development since I started my PhD at MIT in 1989 and developed multiple robotic tools with my students: the MIT-Manus, wrist, hand, anti-gravity, anklebot, pediatric anklebot, and MIT-skywalker. These robots have provided most of the clinical data supporting the use of robotics to the upper extremity (American Heart Association, Veterans Administration, Dep of Defense Guidelines for stroke care) and are the most cited papers in the field.

1. Krebs, H.I.; Hogan, N.; Aisen, M.L.; Volpe, B.T.; “Robot-Aided Neuro-Rehabilitation”, IEEE –Transactions on Rehabilitation Engineering, 6:1:75-87 (1998), PMCID 2692541. 
2. Krebs, H.I.; Volpe, B.T.; Williams, D.; Celestino, J.; Charles, S.K.; Lynch, D.; Hogan, N; “Robot-Aided Neurorehabilitation: A Robot for Wrist Rehabilitation,” IEEE Transaction Neural Systems and Rehabilitation Engineering 15(3)327-335 (2007), PMCID 2733849.
3. Roy, A, Krebs, HI, Williams, D, Bever, CT, Forrester, LW, Macko, RM, Hogan, N, “Robot-Aided Neurorehabilitation: A Robot for Ankle Rehabilitation,” IEEE – Transaction Robotics, 25:3:569-582 (2009).
4. Susko, T; Swaminathan, K; Krebs, HI; MIT-Skywalker: A Novel Gait Neurorehabilitation Robot for Stroke and Cerebral Palsy, IEEE –Transactions on Neural Systems and Rehabilitation Engineering, 24:10:1089-1099 (2016).

Translational Effort: rehabilitation robotic and stroke 

Throughout my research career, I have been fortunate to be involved with high caliper clinical investigators that educated me on the scarcity of evidence demonstrating that therapy outcomes. We tested the impact of rehabilitation robotics on stroke recovery in multiple studies. We published the first ever controlled clinical study in 1997 and continue to pursue the fundamental question on how to optimize care to a particular patient’s need. Our clinical studies are among the most cited in the literature.

5. Aisen, M.L.; Krebs, H.I.; McDowell, F.; Hogan, N.; Volpe, B.T.; “The Effect of Robot Assisted Therapy & Rehabilitative Training on Motor Recovery Following a Stroke”; Archives of Neurology; 54:443-446 (1997).
6. Volpe, B.T., Krebs, H.I., Hogan, N., Edelstein, L., Diels, C.M., Aisen, M.; “A Novel Approach to Stroke Rehabilitation: Robot Aided Sensorymotor Stimulation”, Neurology, 54:1938-1944 (2000).
7. Lo A, Guarino P D, Richards L.G., Haselkorn J.K., Wittenberg, G.F. Federman, D.G., Ringer R.J., Wagner T.H., Krebs H.I., Volpe B.T., Bever C.T., Bravata D.M., Duncan P. W., Corn B.H., Malffucci A.D., Nadeua S.E., Conroy S.S., Powell J.M., Huang G.D., Peduzzi P. “Robot-Assisted Therapy for Long-Term Upper-Limb Impairment after Stroke.” New England Journal of Medicine; 362:1772-1783 (2010).
8. Forrester, LW, Roy, A, Krebs, HI, Macko, RF, “Ankle Training With a Robotic Device Improves Hemiparetic Gait After a Stroke,” Neurorehabilitation and Neural Repair 25:4:369-377 (2011).

Translational Effort: rehabilitation robotic and cerebral palsy

The scarcity of data on habilitation of children with cerebral palsy dwarfs stroke.  To my knowledge, myself and colleagues were the first to test the impact of rehabilitation robotics on CP habilitation. We published the first set of studies in 2008 and continue to pursue the fundamental question on how to optimize care.

9. Fasoli, S.E., Fragala-Pinkham, M., Hughes, R., Hogan, N., Krebs, H.I., Stein, J., “Upper Limb Robotic Therapy for Children with Hemiplegia,” American Journal of Rehabilitation 87:11:929-936 (2008), PMID:18936558.
10. Krebs, H.I., Landenheim, B., Hippolyte, C., Monterroso, L., Mast, J., “Robot-Assisted Task Specific Training,” Journal of Developmental Medicine & Child Neurology, 51:S4:140-145 (2009).
11. Krebs HI, Fasoli SE, Dipietro L, Fragala-Pinkham M, Hughes R, Stein J, Hogan N, “Motor Learning Characterizes Habilitation of Children with Hemiplegic Cerebral Palsy,” Neurorehab Neu Repair 26:7:855-860 (2012), PMCID 4688005.
12. Michmizos K, Rossi S, Castelli E, Cappa P, Krebs HI. "Robot-Aided Neurorehabilitation: A Pediatric Robot for Ankle Rehabilitation." IEEE –Transactions on Neural Systems and Rehabilitation Engineering 23:6: 1056-1067 (2015).

Ankle and Wrist psychophysics

Most psychophysical data focus on reaching movements and there is little data on wrist and ankle pointing movements. I have been systematically expanding our understanding of psychophysics related to wrist and ankle movement. To my knowledge, this is the first time we understand whether several findings for reaching movement hold for wrist and ankle pointing movement. This understanding is critical to go beyond evidence-based into model-based approaches to deliver therapy.

13. Vaisman L, Dipietro L, Krebs HI, “A Comparative Analysis of Speed Profile Models for Wrist Pointing Movements,” IEEE –Transactions on Neural Systems and Rehabilitation Engineering, 21:5:756-766 (2013), PMCID 4689593.
14. Michmizos K, Krebs HI. “Pointing with the Ankle: the Speed-Accuracy Tradeoff,” Experimental Brain Research, 232:2:647-657 (2014), PMCID 3919136.
15. Michmizos K, Krebs HI. “Reaction Time in Ankle Movements: a Diffusion Model Analysis,” Experimental Brain Research, 232:11:3475-3488 (2014), PMCID 4697767.
16. Michmizos K, Vaisman L, Krebs, HI. "A Comparative Analysis of Speed Profile Models for Ankle Pointing Movements: Evidence that Lower and Upper Extremity Discrete Movements are controlled by a Single Invariant Strategy." Frontiers in Human Neuroscience 8:962 (2014), PMCID 4692803.
17. Lee H, Rouse E, Krebs H I, “Summary of Human Ankle Mechanical Impedance during Walking,” IEEE- Journal of Translational Engineering in Health and Medicine 4:1-7 (2016).

Biomarkers in neurorehabilitation

I have developed one of the most comprehensive set of biomarker that has been validated with stroke patients. I expect this biomarker to significantly impact our understanding of stroke recovery and potential facilitate testing of multiple interventions including pharmacological one.

18. Krebs, H.I.; Hogan, N.; Aisen, M.L.; Volpe, B.T.; “Quantization of Continuous Arm Movements in Humans with Brain Injury”, PNAS, 96:4645-4649 (1999), PMCID 16386.
19. Levy-Tzedek, S., Krebs, H.I., Song, D., Hogan, N., Poizner, H. “Non-Monotonicity on a Spatio-Temporally Defined Cyclic Task: Evidence of Two Movement Types?” Exp Brain Res, 202:4:733-746 (2010), PMCID 2858809.
20. Bosecker, C., Dipietro, L., Volpe, B., Krebs, H.I., “Kinematic Robot-Based Evaluation Scales and Clinical Counterparts to Measure Upper Limb Motor Performance in Patients with Chronic Stroke,” Neurorehabilitation and Neural Repair 24:62-69 (2010), PMCID 4687968.
21. Dipietro L, Krebs HI, Volpe BT, Stein J, Bever C, Mernoff ST, Fasoli SE, Hogan N, “Learning, Not Adaptation, Characterizes Stroke Motor Recovery: Evidence from Kinematic Changes Induced by Robot-Assisted Therapy in Trained and Untrained Task in the Same Workspace,” IEEE Trans Neural Sys and Rehab Eng 20:1:48-57 (2012).
22. Krebs HI, Krams M, Agrafiotis DK, DiBernardo A, Chavez JC, Littman GS, Yang E, Byttebier G, Dipietro L, Rykman A, McArthur K, Hajjar K, Lees KR, Volpe BT. “Robotic Measurement of Arm Movements After Stroke Establishes Biomarkers of Motor Recovery,” Stroke 45:1:200-204 (2014), PMCID 4689592.

Imaging and Neuromodulation

We have employed multiple imaging and neuromodulation techniques. I expect these tools to significantly impact our understanding of the consequences of behavioral changes and potential expanding outcomes. 

23. Krebs, H.I.; Brashers-Krug, T.; Rauch, S.L.; Savage, C.R.; Hogan, N.; Rubin, R.H.; Fischman, A.J.; Alpert, N.M.; “Robot-Aided Functional Imaging: Application to a Motor Learning Study”; Human Brain Mapping 6:59-72 (1998).
24. Dipietro, L., Ferraro, M., Palazzolo, J.J., Krebs, H.I., Volpe, B.T., Hogan, N., “Customized Interactive Robotic Treatment for Stroke: EMG-Triggered Therapy,” IEEE Transaction Neural Systems and Rehabilitation Engineering, 13:3:325-334 (2005).
25.  Edwards DJ, Krebs HI, Rykman-Berland A, Zipse J, Thickbroom GW, Mastaglia FL, Pascual-Leone A, Volpe, B , “Raised Corticomotor Excitability of M1 Forearm Area Following Anodal tDCS is Sustained During Robotic Wrist Therapy in Chronic Stroke,” Restorative Neurology and Neuroscience, 27:199-207 (2009).
26. Dipietro L, Poizner H, Krebs HI. “Spatio-Temporal Dynamics of Online Motor Correction Processing Revealed by High-Density Electroencephalography,” Journal of Cognitive Neuroscience, 1966-1980 (2014).
27. Edwards DJ, Dipietro L, Demirtas-Tatlidede A, Medeiros AH, Thickbroom GW, Mastaglia FL, Krebs HI, Pascual-Leone A. “Movement-generated afference paired with Transcranial Magnetic Stimulation: an associative stimulation paradigm,” ,” J NeuroEngineering and Rehabilitation, 11:31 (2014).

Rehabilitation Robotics; Stroke; Biomarkers; Human-Robot Interactions; Mechatronic Systems; Computer Vision; Adaptive Control Algorithms; Human Factors; Human Motor Control