From common to unique: connectivity changes in the anterior temporal lobe in semantic memory linked to semantic retrieval ability.

Poster Session C - Sunday, April 14, 2024, 5:00 – 7:00 pm EDT, Sheraton Hall ABC

Nicolas Deom^1,2 (nicolas.deom@mail.utoronto.ca), Omar Khalil^1,2, Irene Giannoylis², Mary Pat McAndrews^1,2; ¹University of Toronto, ²Krembil Brain Institute, Toronto Western Hospital

Retrieval of semantic knowledge about unique entities relies on a network of regions with a key hub proposed in the left anterior temporal lobe (ATL). Individuals with left temporal lobe epilepsy (L-TLE) are impaired at proper name retrieval, but the interaction of this ATL hub with other regions in the semantic network and how differences in connectivity might relate to behavior remain open questions. To address them, we recruited a sample of 25 L-TLE patients and 17 healthy controls. In an MRI scanner, participants performed a semantic decision task where they were presented with a cue (e.g., Albert Einstein) and two target words (e.g., Physics and Biology) and had to select which target was more related to the cue. Some trials involved common nouns as the cue instead. L-TLE patients had more difficulty with unique entities but were like controls on all the connectivity measures. All participants showed increased functional connectivity between the left ATL and the left medial prefrontal cortex (MPFC) during proper noun retrieval. Increased connectivity between these two regions was also associated with slower performance during the proper trials but not the common. We previously showed increased activation of the left ATL and MPFC during retrieval of information about unique entities and here we demonstrate their interactivity is also enhanced. This suggests a different engagement of the semantic network that may reflect personal significance of proper nouns. However, an increased reliance on personally relevant information might also lead to slower performance on the task.

Topic Area: LONG-TERM MEMORY: Semantic