Bilateral Prefrontal Cortex Activation During Sensorimotor Tasks in People with Subacute Stroke – An Exploratory Functional Near-Infrared Spectroscopy Study

BackgroundPost-stroke, damage to the prefrontal cortex (PFC) disrupts the neural circuits involved in motor control and sensorimotor integration, which contributes to impaired ankle sensorimotor function.ObjectiveApply functional near-infrared spectroscopy (fNIRS) post-stroke to investigate, 1) whether PFC activation differed among active and passive dorsiflexion/plantarflexion and somatosensory stimulation of the paretic ankle, 2) differences between hemispheres, and 3) interhemispheric asymmetry and functional outcomes.MethodsIn nine participants, bilateral hemodynamic responses of the PFC were collected with fNIRS during active and passive dorsiflexion/plantarflexion and somatosensory stimulation. Sensorimotor function and interhemispheric asymmetry were assessed using the Fugl-Meyer Lower Extremity (FMLE) assessment and laterality index.ResultsAcross the three tasks, no differences in PFC activation were found within or between hemispheres. There was a potential relationship between interhemispheric asymmetry with the sensory and motor portions of the FMLE, suggesting that greater asymmetry during passive and somatosensory stimulation tasks may be associated with poorer functional outcomes.ConclusionsOur results highlight that ankle sensorimotor functions may not generate different levels of PFC activation in a single hemisphere. The imbalance of PFC activation between the hemispheres from somatosensory and motor input may relate to clinical somatosensory function, which could be a useful measure of recovery.