Brain Diffusion for Visual Exploration: Cortical Discovery using Large Scale Generative Models

TL;DR

This paper introduces BrainDiVE, a novel data-driven method using large-scale diffusion models and fMRI data to synthesize images that activate specific brain regions, revealing detailed functional organization in the visual cortex.

Contribution

The study presents a new approach combining diffusion models with brain-guided image synthesis to explore cortical organization without relying on predefined stimuli.

Findings

Successfully synthesized images for category-selective ROIs

Characterized differences between ROIs within the same category

Identified novel functional subdivisions validated by behavioral data

Abstract

A long standing goal in neuroscience has been to elucidate the functional organization of the brain. Within higher visual cortex, functional accounts have remained relatively coarse, focusing on regions of interest (ROIs) and taking the form of selectivity for broad categories such as faces, places, bodies, food, or words. Because the identification of such ROIs has typically relied on manually assembled stimulus sets consisting of isolated objects in non-ecological contexts, exploring functional organization without robust a priori hypotheses has been challenging. To overcome these limitations, we introduce a data-driven approach in which we synthesize images predicted to activate a given brain region using paired natural images and fMRI recordings, bypassing the need for category-specific stimuli. Our approach -- Brain Diffusion for Visual Exploration ("BrainDiVE") -- builds on recent generative methods by combining large-scale diffusion models with brain-guided image synthesis. Validating our method, we demonstrate the ability to synthesize preferred images with appropriate semantic specificity for well-characterized category-selective ROIs. We then show that BrainDiVE can characterize differences between ROIs selective for the same high-level category. Finally we identify novel functional subdivisions within these ROIs, validated with behavioral data. These results advance our understanding of the fine-grained functional organization of human visual cortex, and provide well-specified constraints for further examination of cortical organization using hypothesis-driven methods.