Poster Presentation

Poster C in Poster Session C: Wednesday, August 5, 9:30 – 11:15 am, Kimmel Center, Shorin & Rosenthal Rooms

Network Activity Flow Models Dissociate Local and Distributed Mechanisms of Visuomotor Hyperactivation after Concussion

Farzin Hajebrahimi¹, Michael W. Cole², Suril Gohel², Melissa Noble², Arlene Goodman³, Mitchell Scheiman⁴, Tara L. Alvarez¹; ¹New Jersey Institute of Technology, ²Rutgers University, ³Comprehensive Sports Medicine & Concussion Care, LLC., ⁴Pennsylvania College of Optometry at Drexel University

Presenter: Farzin Hajebrahimi

Persisting symptoms after concussion (PSaC) affect 10–30% of patients, with convergence insufficiency as the most prevalent visual symptom and predictor of poor outcomes. Task fMRI reveals aberrant brain activations, but it is unknown if they arise from disrupted network communication or local dysfunction. Activity flow mapping (actflow) models how these activations propagate across resting-state functional connectivity (FC) pathways, distinguishing network contributions from local ones. We applied this framework to fMRI data from PSaC patients (n=65) and healthy controls (n=45) during a visuomotor vergence task. Actflow accurately predicted whole-brain task activations in both groups (Control: r=0.731; PSaC: r=0.700; both p<0.0001). PSaC patients showed hyperactivation in Default-mode and Posterior-Multimodal network regions (pFWE<0.05), with activation correlating with the two primary clinical measures (pFDR<0.05). To test whether hyperactivation is network-generated, actflow predictions were recomputed by excluding dysfunctional regions from the sources. Whole-brain accuracy was preserved, yet predicted activations still distinguished PSaC from controls at all regions of interest (pBonf<0.05) and correlated with clinical measures (pFDR<0.05). Analysis of flow terms revealed excess inflow from Frontoparietal and Cingulo-Opercular networks, as well as excess within-Default-mode network inflow into the dysfunctional regions in PSaC. These findings reframe PSaC as a disorder of network communication, characterized by aberrant executive and default-mode activity flows into higher-order associative regions, resulting in hyperactivation that correlates with the severity of oculomotor symptoms.

Topic Area: Development, Individual Differences & Clinical Populations