Altered Cortical Activity During a Finger Tap in People with Stroke

Abstract This study describes temporal patterns of cortical activity during a simple finger movement in people with stroke to understand how temporal patterns of cortical activation and network connectivity align with prolonged muscle contraction at the end of a task. We investigated changes in the EEG temporal patterns in the beta band (13-26Hz) of people with chronic stroke (N = 10, 7F/3M) and controls (N = 10, 7F/3M), during and after a cued movement of the index finger. We quantified the change in beta band EEG power relative to baseline as activation at each electrode and the change in beta band task-based coherence (tbCoh) relative to baseline coherence as connectivity between EEG electrodes. Contrary to controls, finger tap cortical activity in the stroke group was spatially distributed bilaterally, and measurements from the post task period lacked a positive change in beta power relative to baseline, which has been described as event-related synchronization in controls. In addition, the stroke group exhibited no discernible reduction in tbCoh between the ipsilesional sensorimotor and frontal regions of the cortex during the post task period, which was a notable feature of tbCoh in controls. Our results suggest that divergent cortical activation patterns coupled with changes in connectivity between the sensorimotor and frontal cortices in the stroke group might explain clinical observations of prolonged muscle activation in people with stroke. This prolonged activation might be attributed to the combination of cortical reorganization and changes to sensory feedback post-stroke.