Cortical Control Mechanisms of Auditory Comprehension and Verbal Expression Deficits in Post-Stroke Aphasia Patients Based on the Naturalistic Paradigm

<bold>Objective</bold>To explore the cortical control mechanisms of auditory comprehension and verbal expression deficits in post-stroke aphasia (PSA) patients based on a naturalistic paradigm that closely mimics real-world scenarios. <bold>Methods</bold> A total of 26 PSA patients (PSA group) treated in the Second Rehabilitation Hospital of Shanghai from March 2024 and February 2025 were enrolled, along with 21 gender-, age-, and education-matched healthy controls (control group). All participants completed an auditory comprehension-verbal expression task under functional near-infrared spectroscopy (fNIRS) monitoring. A block-task paradigm was designed based on a natural question-answer language model, consisting three phases, including listening to questions embedded in short narratives, thinking, and responding, with the entire paradigm repeated six times. fNIRS monitoring encompassed bilateral temporal, parietal, and prefrontal lobes. The Western Aphasia Battery (WAB) and the Boston Diagnostic Aphasia Examination (BDAE) were used to evaluate language function. The fNIRS system was used to assess cortical activation levels in various channels and brain regions, including the superior temporal gyrus (STG), middle temporal gyrus (MTG), supramarginal gyrus (SMG), fusiform gyrus (FG), angular gyrus (AG), somatosensory association cortex (SAC), primary somatosensory cortex (PSC), primary motor cortex (PMC), pre-motor and supplementary motor cortex (PMSC), pars triangularis of Broca's area (PT), pars opercularis (PO), dorsolateral prefrontal cortex (DLPFC), and frontal eye fields (FEF), during auditory comprehension and verbal expression tasks. To analyze the correlations between WAB auditory comprehension/verbal expression scores, WAB-AQ scores, BDAE scores, and cortical activation levels in the PSA group during auditory comprehension and verbal expression tasks.<bold>Results</bold>In the auditory comprehension task, the control group showed significant bilateral brain activation, with higher activation levels in the right hemisphere than the left, including the superior temporal gyrus (STG) (P=0.041), middle temporal gyrus (MTG) (P=0.002), and supramarginal gyrus (SMG) (P=0.028). In contrast, the PSA group primarily relied on the right-hemisphere homologue of Wernicke's area, including the STG (P=0.030) and MTG (P=0.024), with significantly reduced activation in the left hemisphere (P&lt;0.05). During the verbal expression task, the control group showed pronounced activation in the left Broca's area and related regions, including the PT (P=0.036), PO (P=0.001), and PMC (P=0.002), with symmetrical activation in the right hemisphere. The PSA group demonstrated compensatory activation in the right hemisphere, including the PT (P=0.035), PO (P=0.002), and PMC (P=0.017), while activation in the left hemisphere(particularly Broca's area) decreased significantly(P&lt;0.05). WAB auditory comprehension scores in patients with PSA correlated with the degree of activation in the bilateral DLPFC (r=-0.401, P=0.047), PMSC (r =-0.417, P=0.038), and PMC (r=-0.414, P=0.040). WAB spontaneous speech scores correlated with activation in the left DLPFC (r =-0.423, P=0.035), PMC (r =-0.400, P = 0.048), and PSC (r =-0.481, P = 0.015), as well as with activation in the right STG (r=-0.404, P = 0.045). <bold>Conclusion</bold> The degree of cortical activation during auditory comprehension and verbal expression tasks in PSA patients is significantly correlated with language function impairment scores, emphasizing the crucial role of the right hemisphere in PSA recovery.