Schedule of Events | Symposia

The human brain's functional connectome specifies hierarchical and non-hierarchical visual cortical processing

Poster Session F - Tuesday, April 1, 2025, 8:00 – 10:00 am EDT, Back Bay Ballroom/Republic Ballroom

Alexandros Tzalavras^1,2 (at1159@rutgers.edu), David E. Osher³, Carrisa Cocuzza^1,2, Lakshman N.C. Chakravarthula^1,2, Ravi D. Mill¹, Kirsten L. Peterson^1,2, Michael W. Cole¹; ¹Center for Molecular and Behavioral Neuroscience, Rutgers University Newark, ²Behavioral and Neural Sciences PhD Program, ³Department of Psychology, The Ohio State University

The human brain utilizes complex visual representations even in simple everyday tasks. Understanding how these representations emerge requires delineating how brain network interactions generate task-relevant information. Previous research in our lab explored these interactions by investigating how the brain generates visual category selectivity through functional connectivity. Building on this, we sought to determine how connectivity shapes V1-initiated processing of visual stimuli in the early visual system, crucial for the emergence of task-relevant visual representations. Current theories suggest that cortical visual processing proceeds hierarchically, starting in V1 and progressing to V2, V3, V4, and beyond in a semi-serial manner. However, the contributions of hierarchical pathways versus direct, non-hierarchical connections remain unclear. We developed a novel functional connectomics approach yielding a confound-controlled whole-cortex connectome. To quantitatively define the visual system’s hierarchical structure, we utilized a graph theoretical metric, communicability, with the confound-controlled connectome to establish a connectivity-based hierarchy among early visual areas. We then applied V1-initiated activity flow modeling to test models of network information flow. Surprisingly, our activity flow model reveals that non-hierarchical flows directly from V1 suffice to generate visual representations throughout the early visual system. Incorporating hierarchical connections enhances the prediction of visual responses, suggesting the involvement of both hierarchical and direct pathways. This highlights the distributed and parallel nature of information flow in the visual system. These insights underscore the crucial role of activity flows over functional connections in shaping visual representations, demonstrating how interplay between hierarchical and direct pathways enables the brain to effectively represent visual inputs.

Topic Area: PERCEPTION & ACTION: Vision