Modulation of brain activity by psycholinguistic information during naturalistic speech comprehension and production

Language processing requires the integration of diverse sources of information across mul-tiple levels of processing. A range of psycholinguistic properties have been documented in previous studies as having influence on brain activation during language processing. How-ever, most of those studies have used factorial designs to probe the effect of one or two in-dividual properties using highly controlled stimuli and experimental paradigms. Little is known about the neural correlates of psycholinguistic properties in more naturalistic discourse, especially during language production. The aim of our study is to explore the above issues in a rich fMRI dataset in which participants both listened to recorded passages of discourse and produced their own narrative discourse in response to prompts. Specifically, we measured 13 psycholinguistic properties of the discourse comprehended or produced by the participants, and we used principal components analysis (PCA) to address covariation in these properties and extract a smaller set of latent language characteristics. These latent components indexed vocabulary complexity, sensory-motor and emotional language con-tent, discourse coherence and speech quantity. A parametric approach was adopted to study the effects of these psycholinguistic variables on brain activation during comprehension and production. We found that the pattern of effects across the cortex was somewhat convergent across comprehension and production. However, the degree of convergence varied across language properties, being strongest for the component indexing sensory-motor language content. We report the full, unthresholded effect maps for each psycholinguistic variable, as well as mapping how these effects change along a large-scale cortical gradient of brain function. We believe that our findings provide a valuable starting point for future, confir-matory studies of discourse processing.(c) 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

This study examines the neural correlates of psycholinguistic properties in language processing, specifically during language production. Using fMRI data, the researchers found convergent patterns of brain activation across comprehension and production, with the strongest convergence observed for sensory-motor language content.