A dorsal-pathway account of aphasic language production: the WEAVER++/ARC model.

It has long been assumed that a dorsal pathway running from temporal to inferior frontal cortex underpinned by the left arcuate fasciculus (AF) underlies both repetition and spoken language production. However, according to a recent proposal, a ventral pathway underpinned by extreme capsule (EmC) and uncinate fasciculus (UF) fiber tracts is primarily responsible for language production, whereas the AF primarily underlies repetition. Here, a computational implementation of the dorsal-pathway account of language production is presented, called WEAVER++/ARC (for WEAVER++ Arcuate Repetition and Conversation), which synthesizes behavioral psycholinguistic, functional neuroimaging, and tractographic evidence. The results of computer simulations revealed that the model accounts for the typical patterns of impaired and spared language performance associated with classic acute-onset and progressive aphasias. Moreover, the model accounts for recent evidence that damage to the AF but not the EmC/UF pathway predicts impaired production performance. It is concluded that the results demonstrate the viability of a dorsal-pathway account of language production.