Dorsal and ventral streams in the evolution of the language-ready brain: Linking language to the world

Abstract Many studies in neurolinguistics focus on the dorsal and ventral streams of the auditory system in language comprehension, but few address the production of language (whether spoken or signed). Moreover, almost no neurolinguistic studies addresses how language use is situated with respect to our perception of and action in the world around us, functions which depend (in part) on the dorsal and ventral streams of the visual system. The aim of this paper is to lay the foundations for an integrated account of situated language processing in the human brain that incorporates the dorsal and ventral streams for both vision and audition. Our further aim is to do so in a way which lays bare the challenges of offering an account of brain evolution in which the macaque brain is used as a surrogate for the brain of LCA-m (the last common ancestor of human and macaque). In particular, we assess the challenges to the mirror system hypothesis (MSH) of the evolution of the language-ready brain when data on auditory dorsal and ventral streams are taken into account. To this end, we compare two accounts of language comprehension and one account of language production (for the special case of describing a visual scene). It will be argued that much of syntactic and semantic processing is fed by ventral processes, that both operate at the level of words-as-signifiers, and that the dorsal path and its role in the perception and production of words-as-articulatory actions plays only a secondary role in such processing.