Alyahya et al. proposed a unified model of post-stroke language deficits that captures the multidimensionality of connected speech production. The authors explored this using various discourse genres (a simple and commonly used picture description, storytelling narrative, and a naturalistic procedural discourse) in post-stroke aphasia patients and in neuro-typical controls. Connected speech metrics alongside an extensive neuropsychological/aphasiological battery that assess a wide range of language and cognitive skills were submitted to a multivariate data-driven approach. In contrast to previous research, three unique orthogonal connected speech components were extracted, reflecting verbal quantity, verbal quality, and motor speech, alongside four core language and cognitive components: phonological production, semantic processing, phonological recognition, and executive functions. A whole-brain voxel-wise lesion-symptom mapping using these components provided evidence on the involvement of widespread cortical regions and their white matter connections with connected speech production. Specifically, left frontal regions and their underlying white matter tracts corresponding to the frontal aslant tract and the anterior segment of the arcuate fasciculus were particularly engaged with the quantity and quality of fluent connected speech production while controlling for other co-factors. The neural correlates associated with the other language domains align with existing models on the ventral and dorsal pathways for language processing.
The full article can be read here: https://academic.oup.com/brain/article/143/5/1541/5824903