Whole-brain dimensions of intrinsic connectivity capture modality-specific and heteromodal language representations

Comprehension of spoken and written language involves a hierarchical sequence of modality-specific and heteromodal processes. While these have been localised to different regions, including areas of the temporal lobes, modality-selective responses extend beyond unimodal regions, implicating large-scale network organisation in language comprehension. Dimensions of whole-brain connectivity, derived from intrinsic activity, have been proposed as a general organising framework for cognition. Here, we test their utility in accounting for the spatial distribution of task-evoked activity during language comprehension. We investigated brain activity in human males and females in response to psycholinguistic variables linked to input processing and meaning in a sentence comprehension task presented both visually and auditorily. Macroscale patterns of brain activity were similar across modalities for sentence-level and semantic variables, but effects of orthographic and phonological distance were negatively correlated between modalities. The first dimension, which separates heteromodal and unimodal cortex, showed no differences across modalities for sentence processing and semantic variables, and opposite effects of word length and orthographic/phonological distance for spoken and written words, supporting the notion that higher-order processing requires heteromodal resources different to those linked to input processing. The second dimension, separating auditory-motor and visual processes, showed an asymmetry in the recruitment of the unimodal systems - listening to long and semantically dissimilar words involved stronger recruitment of primary auditory-motor regions and low visual engagement. These findings show that the language system is organised according to large-scale axes of intrinsic connectivity, with semantic, phonological and orthographic processes varying systematically along whole-brain functional dimensions. This supports the view that language comprehension reflects general principles of cortical organisation, offering a unified account of how modality-general and modality-specific computations are arranged across the cortex within and beyond the language domain.Significance statement Whole-brain dimensions of functional connectivity, derived from intrinsic activity, have been proposed as a general organising framework for cognition, yet their relevance to specific, ecologically meaningful tasks remains underexplored. Here, we show that these macroscale patterns account for key differences and commonalities in how the brain processes spoken and written language. Our findings reveal a principled division between modality-general semantic and sentence-level processes versus modality-specific input effects, structured along the first two axes of intrinsic connectivity. These results demonstrate that the language system aligns with domain-general principles of cortical organisation.