Bradley Buchsbaum, Rotman Research Institute, Toronto, Canada
Cognitive theories of verbal working memory and speech production both posit the existence of an “inner loop” that is serves as a channel of communication between auditory and articulatory components of the speech network. In the context of speech production, this “inner loop” may serve a number of functions, including self-monitoring of speech output and as a mechanism supporting a forward model of speech. In verbal working memory, the inner loop is thought to serve a mechanism that allows for the reactivation of sensory/phonological speech codes in short-term memory. Here we propose that self-monitoring, short-term memory reactivation, and forward models are supported a common underlying neural mechanism. To examine this idea, we have designed an fMRI paradigm of verbal working memory and multivariate pattern analysis (MVPA) approach to examine distributed representations of speech features during the perception and short-term maintenance of syllables. Our results show that sustained memory representations in the lateral superior temporal gyrus are likely the result of motor-to-sensory signals originating in the premotor cortex. We discuss our findings in terms of existing functional neuroanatomical models of speech production and verbal working memory.