The neurobiology of sentence production has been largely understudied compared to the neurobiology of sentence comprehension, due to difficulties with experimental control and motion-related artifacts in neuroimaging. We studied the neural response to constituents of increasing size and specifically focused on the similarities and differences in the production and comprehension of the same stimuli. Participants had to either produce or listen to stimuli in a gradient of constituent size based on a visual prompt. Larger constituent sizes engaged the left inferior frontal gyrus (LIFG) and middle temporal gyrus (LMTG) extending to inferior parietal areas in both production and comprehension, confirming that the neural resources for syntactic encoding and decoding are largely overlapping. An ROI analysis in LIFG and LMTG also showed that production elicited larger responses to constituent size than comprehension and that the LMTG was more engaged in comprehension than production, while the LIFG was more engaged in production than comprehension. Finally, increasing constituent size was characterized by later BOLD peaks in comprehension but earlier peaks in production. These results show that syntactic encoding and parsing engage overlapping areas, but there are asymmetries in the engagement of the language network due to the specific requirements of production and comprehension.
Commonalities and asymmetries in the neurobiological infrastructure for language production and comprehension
Stimulus presentation. A: Example of the screen that participants would see for each condition (identical in production and comprehension) with the corresponding expected output. The boxes clarified the type of output that was required. B: Screen sequence for each trial. The length of the fixation cross presentation was based on jittering optimized for contrast detection. In comprehension, during picture and verb presentation, a sound recording of the sentence started after 1000 ms.
Max Planck Institute for Psycholinguistics
