Brain reorganization in anticipation of predictable words

How is speech understood despite the lack of a deterministic relationship between the sounds reaching auditory cortex and what we perceive? One possibility is that unheard words that are unconsciously activated in association with listening context are used to constrain interpretation. We hypothesized that a mechanism for doing so involves reusing the ability of the brain to predict the sensory effects of speaking associated words. Predictions are then compared to signals arriving in auditory cortex, resulting in reduced processing demands when accurate. Indeed, we show that sensorimotor brain regions are more active prior to words predictable from listening context. This activity resembles lexical and speech production related processes and, specifically, subsequent but still unpresented words. When those words occur, auditory cortex activity is reduced, through feedback connectivity. In less predictive contexts, activity patterns and connectivity for the same words are markedly different. Results suggest that the brain reorganizes to actively use knowledge about context to construct the speech we hear, enabling rapid and accurate comprehension despite acoustic variability.