Schedule of Events | Symposia

Differential roles of frontoparietal regions in working memory and decision-making demand

Poster Session B - Sunday, March 30, 2025, 8:00 – 10:00 am EDT, Back Bay Ballroom/Republic Ballroom

Sophie E. Ack¹ (sophie.ack@northwestern.edu), Samantha M. Gray^1,2, Adam J. O. Dede¹, Jack J. Lin³, David King-Stephens^4,5, Peter B. Weber⁴, Kenneth D. Laxer⁴, Ignacio Saez^3,6, Fady Girgis^3,7, Stephan U. Schuele¹, Joshua M. Rosenow¹, Edward F. Chang⁸, Kurtis I. Auguste⁸, Eishi Asano⁹, Robert T. Knight¹⁰, Rodrigo M. Braga¹, Elizabeth L. Johnson¹; ¹Northwestern University, ²Stanford University, ³University of California, Davis, ⁴California Pacific Medical Center, ⁵Yale School of Medicine, ⁶Ichan School of Medicine at Mt. Sinai, ⁷University of Calgary, ⁸University of California, San Francisco, ⁹Children's Hospital of Michigan, ¹⁰University of California, Berkeley

Decision-making (DM) is a complex cognitive function with processes that rely on working memory (WM). DM and WM are both associated with a distributed network including regions of the posterior parietal cortex (PPC) and prefrontal cortex (PFC), but the shared and distinct roles of these regions and their coordination in DM and WM remain poorly understood. Here, we use intracranial EEG from 24 adult neurosurgical epilepsy patients with seizure- and artifact-free electrodes sampling PPC and/or PFC (n = 524) performing a delayed match-to-sample task. On each trial, patients memorized a sequence of three shapes (sample; WM demand) to compare to presentation of three more shapes (test; WM with additive DM demand). Sample and test sequences were followed by a 2-s delay with a randomly jittered star presented to disrupt ongoing processing. We compared high-frequency broadband activity (HFA; 70-150 Hz) between the sample and test delays to derive DM and WM effects in three PFC and three PPC subregions defined by sulcal boundaries. DM effects were defined by test-greater-than-sample HFA and WM effects by sample-greater-than-test HFA. Sustained DM effects in the inferior frontal gyrus disappeared following the star. Conversely, sustained WM effects in the middle frontal gyrus disappeared following the star and transient WM effects in the superior frontal and angular gyri appeared following the star. These results suggest an active inferior frontal DM process and diverging active vs. latent WM representations between frontoparietal subregions. Further analyses will use orthogonal, data-driven clustering to further characterize frontoparietal DM and WM functions.

Topic Area: EXECUTIVE PROCESSES: Working memory