Peak Activation Shifts in the Sensorimotor Cortex of Chronic Stroke Patients Following Robot-assisted Rehabilitation Therapy

Loukas G. Astrakas1, Shasha Li2, 3, 4, Mark P. Ottensmeyer2, 5, Christian Pusatere3, 4, Michael A. Moskowitz2, 4, 6, A. Aria Tzika2, 3, 4, *
1 Medical Physics, Faculty of Medicine, University of Ioannina, Ioannina, Greece
2 Harvard Medical School, Boston, MA, USA
3 NMR Surgical Laboratory, Department of Surgery, Center for Surgery, Innovation and Bioengineering, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
4 Athinoula A. Martinos Center of Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
5 Medical Device & Simulation Laboratory, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA
6 Neuroscience Center, Departments of Neurology and Neurosurgery, Massachusetts General Hospital, Boston, MA, USA

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Creative Commons License
© 2021 Astrakas et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the NMR Surgical Laboratory, Department of Surgery, Massachusetts General Hospital, and Shriners Burns Institute, Harvard Medical School, 51 Blossom Street, Room 261, Boston, MA 02114, USA; Tel: (617) 371-4871; Cell: (617) 308-1958; Fax: (617) 720-3544; E-mails: and



Ischemic stroke is the most common cause of complex chronic disability and the third leading cause of death worldwide. In recovering stroke patients, peak activation within the ipsilesional primary motor cortex (M1) during the performance of a simple motor task has been shown to exhibit an anterior shift in many studies and a posterior shift in other studies.


We investigated this discrepancy in chronic stroke patients who completed a robot-assisted rehabilitation therapy program.


Eight chronic stroke patients with an intact M1 and 13 Healthy Control (HC) volunteers underwent 300 functional magnetic resonance imaging (fMRI) scans while performing a grip task at different force levels with a robotic device. The patients were trained with the same robotic device over a 10-week intervention period and their progress was evaluated serially with the Fugl-Meyer and Modified Ashworth scales. Repeated measure analyses were used to assess group differences in locations of peak activity in the sensorimotor cortex (SM) and the relationship of such changes with scores on the Fugl-Meyer Upper Extremity (FM UE) scale.


Patients moving their stroke-affected hand had proportionally more peak activations in the primary motor area and fewer peak activations in the somatosensory cortex than the healthy controls (P=0.009). They also showed an anterior shift of peak activity on average of 5.3-mm (P<0.001). The shift correlated negatively with FM UE scores (P=0.002).


A stroke rehabilitation grip task with a robotic device was confirmed to be feasible during fMRI scanning and thus amenable to be used to assess plastic changes in neurological motor activity. Location of peak activity in the SM is a promising clinical neuroimaging index for the evaluation and monitoring of chronic stroke patients.

Keywords: Stroke, Functional magnetic resonance imaging, Hand rehabilitation, MR compatible robotic devices, Brain plasticity, Fugl-meyer upper extremity scale.