Neural structures associated with auditory short-term memory and sentence repetition following chronic left hemisphere stroke

Abstract

Introduction Prior evidence suggests auditory short-term memory (STM) and repetition share several processing elements. However, it remains elusive whether auditory STM capacity and repetition ability show overlapping neural correlates. We sought to identify the brain structures underpinning STM capacity and repetition outcomes in patients with chronic left hemisphere stroke and aphasia. Methods Fifty-four left hemisphere stroke patients with aphasia and 50 demographically matched healthy controls underwent digit span and language tasks. Structural and diffusion images were acquired in all participants. Support vector regression-based lesion-symptom mapping (SVR-LSM) analyses were conducted to identify critical brain regions associated with auditory STM capacity, as indexed by transformed digit span scores and word/sentence repetition performance. The relationships between direct and indirect arcuate fasciculus (AF) injury and behavioral performance were examined. Results Sentence repetition was associated with digit span performance by regressing out confounding variables. SVR-LSM identified the left parietal lobe, including the supramarginal gyrus and inferior parietal cortex, and the corresponding white matter regions were correlated with auditory STM capacity and sentence repetition after adjusting for control variables. Additionally, the direct lesional damage or the integrity of the left AF was associated with auditory STM and sentence repetition independent of the lesion load on the gray matter. When controlling for the damage of the left AF, the correlation with the left inferior parietal cortex with auditory STM capacity remained significant. Conclusion Our findings suggest that the AF, along with the inferior parietal cortex in the left hemisphere, is associated with auditory STM capacity and sentence repetition.