Exploring Knowledge Integration: Insights from Angular Gyrus (AG) and Ventrolateral Prefrontal Cortex (vlPFC) HD-tDCS

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

Xuan zhang¹ (xzhang@research.baycrest.org), Michael Lochner^1,3, Karen Joseph⁴, Asaf Gilboa^1,2,3; ¹Rotman Research Institute, Baycrest Hospital, ²Department of Psychology, University of Toronto, ³Department of Psychology, York University, ⁴Holland Bloorview Kids Rehabilitation Hospital

Semantic knowledge refers to one's store of facts and information, which can be acquired through direct experiences or inferred from knowledge encountered across episodes. Self-derivation through integration is a form of semantic knowledge acquisition involving the generation of novel insights by connecting distinct yet relevant pieces of information. The prefrontal and parietal cortices have been shown to contribute to semantic integration, but the causal role of each region remains unknown. This study sought to uncover the specific causal roles of the AG and vlPFC during semantic integration using High-Definition Transcranial Direct Current Stimulation (HD-tDCS). Anodal or sham HD-tDCS was applied to the left AG or the left vlPFC before participants engaged in semantic self-derivation (Varga and Bauer, 2017). Participants read sentences that could be integrated to derive novel facts, and were later tested on their knowledge of these facts. Additionally, participants' IQ was assessed using WASI-II. The preliminary results revealed a distinct relationship between participants' integration ability, IQ, and stimulation condition. Specifically, a significant correlation between participants' IQ and integration abilities was identified. Interestingly, there was an interaction between IQ-integration correlation and stimulation condition, such that a strong correlation was present in both conditions for AG participants but was only present in the sham group and absent in the stimulation group for vlPFC participants. This study revealed an intricate relationship between IQ and the neural substrates of semantic integration, suggesting the extent of contribution of AG and vlPFC to semantic integration may depend on participants’ overall reasoning ability.

Topic Area: LONG-TERM MEMORY: Semantic