Post-stroke dysphagia is associated with abnormal gamma power and phase synchronisation during swallowing

Post-stroke dysphagia (PSD) has a series of complications that are associated with poor recovery and even mortality. Uncovering abnormal neural activities during swallowing bears critical implications for optimising treatment strategies for PSD patients. The current study was designed to identify the abnormal neural representations of swallowing in PSD. PSD individuals, stroke individuals without dysphagia, and healthy controls underwent a swallowing task while ongoing EEG was recorded. Compared to healthy controls, PSD patients demonstrated predominant gamma-band hypoactivity and hypoconnectivity during swallowing. We also identified an excessive gamma-band hyperconnectivity that was related to more severe dysphagia, possibly reflect inefficient neural effort or muscle recruitment during swallowing. As a secondary outcome, PSD patients demonstrated lower theta-band connectivity compared to those without dysphagia. These novel findings may help inform future research on potential neuromodulation approaches for PSD. However, this is considered as a pilot study, and these findings should be explained in the context of a small sample size.