Neural connectomes of verbal fluency in post-stroke aphasia

OBJECTIVES: Verbal fluency tasks are widely used to assess language abilities and executive functions in both clinical and research settings. In post-stroke patients, prior research has indicated a significant hodological contribution to the neural basis of verbal fluency; however, this has largely been examined using lesion-based measures, predefined tractography approaches, and traditional diffusion metrics. METHODS: Quantitative anisotropy-based structural connectometry derived from correlational tractography was employed to determine the white matter circuits underlying semantic and phonemic fluency in 44 patients with post-stroke aphasia. RESULTS: Both task types were found to be linked to anterior frontal connections of left-hemisphere dorsal and ventral associative pathways, as well as domain-general projection pathways. However, visual inspection of the connectomes, supported by supplementary cross-control analyses, suggested differences in the relative emphasis and distribution of pathways, with phonemic fluency aligning more with the dorsal stream, while semantic fluency showed greater reliance on the ventral stream and a wider range of cortico-subcortical connections. CONCLUSIONS: The findings contribute to current understanding of the neural networks of verbal fluency in aphasia, with potential relevance for clinical practice and research.