Poster C127, Sunday, March 25, 1:00-3:00 pm, Exhibit Hall C
Instantiating new objects into the discourse: the role of hippocampus and prefrontal cortex
Zachary Ekves1,2, Pedro Paz-Alonso3, Nicholas Hindy4, Sarah Solomon5, Gerry Altmann1,2; 1University of Connecticut, 2Connecticut Institute for the Brain and Cognitive Sciences, 3Basque Center on Cognition, Brain, and Language, 4University of Louisville, 5University of Pennsylvania
We explore the potentially joint roles in language comprehension of the hippocampus – critical to encoding situation-specific episodic detail, and of left inferior frontal gyrus (LIFG) – critical for selection and inhibition. We analyzed functional connectivity in two prior fMRI studies (Hindy et al., 2012; Solomon et al., 2015). The first used sentences such as “John will chop the onion. And then he will weigh THE/ANOTHER onion” – these sentences manipulate whether the same token or a new token of the same type is referred to subsequently. We found increased connectivity between hippocampus and LIFG when instantiating a new token (“…ANOTHER onion”). This increased connectivity may reflect selection of canonical features associated with the new token, or inhibition of episodic features of the original token (i.e. the feature set in discourse focus), or both. To tease these possibilities apart we contrasted “John will chop the onion. AND THEN/BUT FIRST he will weigh the onion.” If the previously observed increase in connectivity between hippocampus and LIFG was due to suppression of the prior episodic feature-set, we should see this also in this 2nd dataset, where “but first” also requires such suppression. In fact, no difference was observed in connectivity between hippocampus and LIFG. We conclude that the increased connectivity observed between hippocampus and LIFG in the 1st study was due to selection of canonical features associated with the introduction of new tokens into the discourse and was not due to suppression of the episodic feature set in the current discourse focus.
Topic Area: LANGUAGE: Semantic