Mapping distinct neural pathways associated with conceptual and lexical verb retrieval priming in aphasia: A preliminary study

This preliminary study examined the feasibility of using correlational tractography and differential tractography to identify white-matter mechanisms associated with conceptual and lexical verb priming in post-stroke aphasia. Participants with chronic aphasia due to left-lateralized ischemic stroke were recruited with age-matched controls. We showed that differential tractography was capable of mapping the affected neuronal pathways following stroke in each patient with a false discovery rate (FDR) of 0.0437. Correlational tractography analyses revealed potential white-matter tracts involved in conceptual and lexical priming, compared to baseline (FDR = 0.000217 conceptual priming; FDR = 0.000173 lexical priming). Specifically, both priming conditions were significantly associated with tracts of neurocognitive dual-stream models of language, including the ventral stream left inferior fronto-occipital fasciculus and portions of left projection pathways, including the corticostriatal and corticopontine tracts. The anatomical details provided by correlation tractography suggested that there are critically distinct pathways involved, such that the integrity of the left frontal aslant tract was linked to lexical priming, while the left inferior longitudinal fasciculus was associated with conceptual priming. These preliminary findings provide potential insights into how novel tractographic modalities may be used to inform personalized neurorehabilitation strategies for aphasia. Future research with larger samples must confirm these findings and explore the effects of behavioral and neuroanatomical characteristics on therapy outcomes from different cue types.