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S. Ali1, M. Bhat2, H. Palanisamy2, S. Ramachandran1, A. Arumugam3, S. Kumaran D1
1Manipal College of Health Professions, Manipal Academy of Higher Education, Department of Physiotherapy, Manipal, India, 2Manipal College of Health Professions, Manipal Academy of Higher Education, Department of Speech & Hearing, Manipal, India, 3College of Health Sciences, University of Sharjah, Department of Physiotherapy, Sharjah, United Arab Emirates
Background: Action observation and imitation (AOI) of a normal goal-oriented movement task in patients with stroke is found to improve their motor function. The major attributes of motor learning in this population are error detection and correction of the observed movement.
Purpose: The study was aimed at assessing whether brain cortical activity and upper limb muscle activity associated with a normal imitation of an upper limb reaching task differ following observation of normal and erroneous movement conditions.
Methods: In this cross-sectional study, participants diagnosed with a unilateral stroke were asked to observe an upper-limb reaching task performed under two conditions (normal and erroneous movement conditions shown with pre-recorded videos), and then imitate the normal movement condition. Electroencephalographic (EEG) mu (8–13 Hz) activity as a measure of mirror neuron system activation and normalized electromyographic (EMG) root mean square (RMS) amplitudes of the supraspinatus, biceps brachii, triceps brachii and extensor carpi-radialis of the paretic upper-limb were recorded separately during observation of the task and imitation of the task under both normal and erroneous movement conditions. The data were skewed, and the Wilcoxon signed rank test was used for comparing the outcomes (EEG mu frequency and EMG RMS amplitudes) across the movement conditions and AOI of the task.
Results: Twenty-five participants (21 males and 4 females; age 55.00 ± 14.49 years, median post-stroke duration is 13.0 [6.50, 180.5] days) were recruited. Analysis of mu rhythm in the C3 and C4 EEG electrodes revealed a statistically significant difference in mu suppression scores between normal and erroneous movement conditions (p ≤ 0.01) irrespective of observation or imitation of the task with significant mu suppression noted during AOI of the task under normal movement condition. Analysis of normalized mean RMS muscle activity of hemi-paretic upper limb muscles revealed no significant difference between normal and erroneous movement conditions irrespective of observation or imitation of task (p>0.05). Conversely, we noticed a significant difference between observation and imitation of the task (p ≤ 0.01) regardless of the movement conditions in all four muscles with an increased activity noted during imitation of the task.
Conclusion(s): AOI of the task under the normal movement condition produces better mirror neuron system activity compared to that of the erroneous movement condition and associated changes are evident in upper limb muscle activity.
Implications: Normal movement condition can be incorporated in AOI treatment module to improve upper limb function in patients with stroke. Incorporating observational component of daily activities in a stroke rehabilitation program should augment the therapeutic effects.
Funding, acknowledgements: No funding was received for conducting this study
Keywords: Movement error, Movement observation, Mu suppression
Topic: Neurology: stroke
Did this work require ethics approval? Yes
Institution: Manipal College of Helath Professions, Manipal Academy of Higher Education
Committee: Kasturba Medical College and Kasturba Hospital Ethics Committee
Ethics number: IEC:66/2018
All authors, affiliations and abstracts have been published as submitted.
