Swallowing cortical network features under taste stimulation for patients with post stroke dysphagia—Insights from a fNIRS study

The alterations in the swallowing cortical network associated with taste stimulation in patients with post-stroke dysphagia remain unclear. The aim of the study was to investigate the alterations in brain functional activity among individuals with post-stroke dysphagia under taste stimuli using functional near-infrared spectroscopy (fNIRS). We recruited 28 patients with post-stroke dysphagia and 24 age-matched healthy controls in this study. Each of them completed swallowing evaluation, resting-state and swallowing task-related fNIRS test. We found that the brain activation of patients significantly decreased in the left and right supplemental motor area (SMA) for water swallowing task and the left SMA and right primary sensory area (S1) for salty water swallowing, compared with healthy controls, only the left SMA remained significant for salty water swallowing after False Discovery Rate (FDR) correction. Fourteen healthy controls and 13 patients were included in the subgroup analysis, to explore the influences of preferred taste on swallowing network, we observed that the brain activation in the right S1 was significantly reduced during water swallowing in patient group (p = 0.008, with FDR corrected), all channels showed similar strengths in the activation under preferred taste stimulus between the groups. Functional connectivity (FC) between hemispheric sensorimotor areas were significantly decreased in patients compared with healthy controls. Our investigation revealed a noteworthy reduction in the activation of the left SMA during the salty water swallowing task in patients with dysphagia when compared to the healthy control group. The dysphagic patients following stroke exhibited impaired interaction between hemispheric sensorimotor areas associated with swallowing. Sour, sweet, and preferred taste stimulation have the potential to enhance brain plasticity, which may offer new insights for developing novel strategies for post-stroke dysphagia.