Language in context: MEG evidence for modality general and specific responses to reference resolution

ABSTRACT

Successful language comprehension critically depends on our ability to link linguistic ex-pressions to the entities they refer to. Without reference resolution, newly encountered language cannot be related to previously acquired knowledge. The human experience in-cludes many different types of referents, some visual, some auditory, some very abstract. Does the neural basis of reference resolution depend on the nature of the referents or do our brains utilize a modality general mechanism for linking meanings to referents? Here we report evidence for both. Using MEG, we varied both the modality of referents, which consisted either of visual or auditory objects, and the point at which reference resolution was possible within sentences. Source localized MEG responses revealed brain activity as-sociated with reference resolution that was independent of the modality of the referents, localized to the medial parietal lobe and starting around 415 ms after onset of reference resolving words. A modality-specific response to reference resolution in auditory domains was also found in the vicinity of auditory cortex. Our results suggest that referential lan-guage processing cannot be reduced to processing in classical language regions and repre-sentations of the referential domain in modality-specific neural systems. Instead, our re-sults suggest that reference resolution engages medial parietal cortex which supports a mechanism for referential processing regardless of the content modality.

Significance Statement Reference resolution is an elementary mechanism for language comprehension, connecting language meaning to pre-existing knowledge. It is unknown whether reference resolution depends on brain mechanisms specific to the modality of the referents, for example whether they are visual or auditory objects, or whether our brains utilize a modality gen-eral mechanism for linking meanings to referents. Here we show using source localized MEG that reference resolution is associated with a response in the medial parietal lobe, in-dependent of referent modality, supporting a modality-general mechanism for reference resolution. An additional response associated with resolving reference to auditory objects in auditory cortex suggests that modality-specific representations of the referents are also involved.