Poster Session B, Sunday, March 24, 8:00 – 10:00 am, Pacific Concourse
An Intracranial EEG Study of Taxonomic and Thematic Relations
Melissa Thye1, Jason Geller1, Diana Pizarro1, Jerzy P. Szaflarski1, Daniel Mirman1; 1University of Alabama at Birmingham
The hub-and-spoke model of semantic cognition posits that the anterior temporal lobe (ATL) serves as a critical hub, integrating multimodal information from surrounding spokes to arrive at semantic representations. The dual-hub account suggests that although ATL is important for processing taxonomic relations [defined by shared features (e.g., dog - bear)], an additional hub in the temporo-parietal cortex (TPC) may be specialized for processing thematic relations [based on event-related co-occurrence (e.g., dog - leash)]. Previous studies of semantic cognition have been restricted to neuroimaging methods with limited spatial or temporal resolution. In the current study, we overcome this limitation by recording from 84 electrode channels from 5 participants with refractory epilepsy undergoing intracranial EEGs from an array of multi-contact depth electrodes. Participants completed a semantic relatedness judgement task where critical word pairs varied in semantic type (taxonomic vs. thematic) and relatedness strength (high vs. low). Data were epoched, bandpass filtered to extract the high gamma range (70-110 Hz), transformed to generate the analytic signal, smoothed, and baseline corrected. Peak high gamma power (HGP) was greater for taxonomic compared to thematic relations in ATL. The opposite pattern was observed in TPC with greater peak HGP for thematic relations. Peak HGP was relatively consistent across the regions for the relatedness strength manipulation with greater peak HGP in response to the highly related trials. Our data support a dual-hub account of semantic cognition, with ATL as a critical hub for processing taxonomic relations, and TPC as a secondary hub for processing thematic relations.
Topic Area: LANGUAGE: Semantic