The functional anatomy of self-generated and predictable speech

Abstract

Sensory attenuation refers to the cortical suppression of self-generated sensations relative to externally-generated sensations. This attenuation of cortical responsiveness is the result of internal forward models which make precise predictions about forthcoming sensations. Forward models of sensory attenuation in the auditory domain are thought to operate along auditory white matter pathways such as the arcuate fasciculus and the frontal aslant. The aim of this study was to investigate whether brain regions that are structurally connected via these white matter pathways are also effectively connected during overt speech, as well as as when listening to externally-generated speech that is temporally predictable via a visual cue. Using Electroencephalography (EEG) and Dynamic Causal Modelling (DCM) we investigated network models that link the primary auditory cortex to Wernickes and Brocas area either directly or indirectly through Geschwinds territory, which are structurally connected via the arcuate fasciculus. Connections between Brocas and supplementary motor area, which are structurally connected via the frontal aslant, were also included. Our results revealed that bilateral areas interconnected by indirect and direct pathways of the arcuate fasciculus, in addition to regions interconnected by the frontal aslant best explain the EEG responses to both self-generated speech, and speech that is externally-generated but temporally predictable. These findings indicate that structurally connected brain regions thought to be involved in auditory attenuation are also effectively connected. Critically, our findings expand on the notion of internal forward models, whereby sensory consequences of our actions are internally predicted and reflected in reduced cortical responsiveness to these sensations.\n\nHighlightsO_LIEffective connectivity of auditory attenuation to self-generated and predictable speech\nC_LIO_LIEEG and DCM were used to investigate several plausible network models\nC_LIO_LIStructurally connected brain areas of auditory attenuation are effectively connected\nC_LIO_LIInternal forward models modulate self-generated and predictable speech\nC_LI