The neural dynamics of speech perception: Dissociable networks for processing linguistic content and monitoring speaker turn-taking

• We measured brain activity elicited by naturalistic conversation stimuli.
• Speaker gaps activated a posterior pathway spanning sensorimotor regions.
• Speaker responses elicited an anterior pathway spanning the superior temporal gyrus.
• The posterior pathway is uniquely involved in monitoring speaker turn-taking.

The neural circuitry for speech perception is well-characterized, yet the temporal dynamics therein are largely unknown. This timing information is critical in that spoken language almost always occurs in the context of joint speech (i.e., conversations) where effective communication requires the precise timing of speaker turn-taking—a core aspect of prosody. Here, we used event-related potentials to characterize neural activity elicited by conversation stimuli within a large, unselected adult sample (N = 115). We focused on two stages of speech perception: inter-speaker gaps and speaker responses. We found activation in two known speech perception networks, with functional and neuroanatomical specificity: silence during inter-speaker gaps primarily activated the posterior pathway involving the supramarginal gyrus and premotor cortex, whereas hearing speaker responses primarily activated the anterior pathway involving the superior temporal gyrus. These data provide the first direct evidence that the posterior pathway is uniquely involved in monitoring speaker turn-taking.