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The brain in conversation: Mapping the neural correlates of turn-taking, production, and comprehension using fMRI

Poster B1 in Poster Session B and Reception, Thursday, October 6, 6:30 - 8:30 pm EDT, Millennium Hall

Caroline Arvidsson¹, Ekaterina Torubarova², André Pereira², Julia Uddén¹; ¹Stockholm University, Sweden, ²Royal Institute of Technology, Stockholm, Sweden

INTRODUCTION: Conversation is the most ubiquitous form of language use. A hallmark of conversation is turn-taking, in which speakers rapidly alternate between speaker and listener roles without conscious effort, while simultaneously planning their upcoming turn. Since previous neurolinguistic studies have mainly investigated single or few linguistic processes in isolated environments that lack resemblance to real-world language use, the neurobiology of turn-taking, production, and comprehension during real-time conversation is currently under-explored. In this fMRI investigation, we asked whether turn initiations would activate areas outside the classical perisylvian core language network and whether we would observe differences in activation during conversational production vs. conversational comprehension. METHODS: We utilized a publicly available fMRI dataset in which participants (N = 23) engaged in unscripted conversations via an audio-video link with a confederate outside the scanner. Each conversation (24 per participant) lasted for one minute. Conversational events were defined from the participant’s perspective. These events included turn initiations, defined as a 600 ms time window whose offset coincided with the onset of the participant’s turn. The duration of turn initiations was based on the reported minimum latency of speech preparation. The other events investigated in this study were production (defined as participant speech), and comprehension (defined as confederate speech). RESULTS: Turn initiations were associated with frontal regions outside of the classical perisylvian core language network. One cluster (2796 voxels, significant with FWE-correction used throughout) was observed in the medial prefrontal cortex bilaterally, spanning from the dorsal portion to the most ventral anterior cingulate cortex. Activation during turn initiations was also observed in the left middle frontal gyrus. Furthermore, both production and comprehension during conversation were associated with core language regions in the bilateral temporal lobes, but activation in the left inferior frontal gyrus (LIFG) was only present for production. Moreover, larger parts of the occipital cortex, and specifically the fusiform face area, were activated in comprehension than in production. DISCUSSION: We suggest that the observed frontal activation during turn initiations reflects sociopragmatic processes involved in intention processing and attentional control – processes that have not previously been localized outside the core perisylvian language network but have been hypothesized to play a crucial role in speech preparation during interaction. Furthermore, we interpret the fusiform face area activation during comprehension as an indication that listeners are aided by their interlocutor’s facial gestures specifically when comprehending speech input during real-time conversation. Finally, LIFG activation in conversational production but not comprehension may reflect the syntactic and semantic heuristics at play in conversational comprehension, minimizing the need for a full syntactic parse. The utilization of such heuristics may be a possible prerequisite for consistently meeting the expectations of timing in turn-taking.

Topic Areas: Meaning: Discourse and Pragmatics, Language Production