300 Section - Cortical Modulation After Assisted Reaching: A post-stroke EEG Study

Motor rehabilitation increasingly relies on assistive technologies designed to enhance movement execution and promote neuroplasticity. Understanding short-term neuromodulatory effects induced by such devices is essential for optimizing neurorehabilitation strategies. In this study, we aimed to investigate how a single session of right-arm reaching, performed with and without an assistive device, modulates cortical activity in healthy adults and in post-stroke survivors.

Design:

We recruited 36 individuals post-stroke (18 with left-side impairment, 18 with right-side impairment) and a control group of healthy individuals. The Float exoskeleton was used to support arm weight during assisted upper limb reaching. High-density resting-state electroencephalography (EEG) was recorded before and after the reaching session to detect session-level neuromodulation. EEG power spectra were computed across standard frequency bands, and post–pre differences were analysed.

Results:

Healthy participants exhibited a characteristic increase in alpha-band power over the right centro-parietal cortex, suggesting localized modulation of sensorimotor networks. This pattern was absent in post-stroke participants. Instead, individuals with stroke showed a shift of alpha-power increases toward frontal regions. Notably, this frontal enhancement was unilateral in participants with left-side impairment (right frontal cortex) and bilateral in those with right-side impairment. In the low-gamma band, participants with left-side impairment exhibited overall higher post-session power, particularly over the left frontal cortex, indicating a distinct spectral signature of short-term cortical engagement.

Conclusion:

These findings reveal frequency- and region-specific neuromodulatory responses to assisted reaching and highlight qualitative differences between healthy and post-stroke populations.