Spontaneous Activity in the Visual Cortex is Organized by Visual Streams

TL;DR

This study reveals that spontaneous activity in the visual cortex is organized primarily by visual streams, with intrinsic parcellation aligned with myelination gradients and segregated along dorsal/ventral pathways, reflecting feedback interactions.

Contribution

The paper introduces a novel analysis of fine-scale spontaneous activity in the visual cortex, highlighting organization by visual streams and intrinsic parcellation based on myelination gradients.

Findings

Visual cortical parcels align with myelination gradients.

Spontaneous activity is organized into dorsal/ventral modules.

Retinotopy and cytoarchitecture have limited influence on activity organization.

Abstract

Large-scale functional networks have been extensively studied using resting state functional magnetic resonance imaging. However, the pattern, organization, and function of fine-scale network activity remain largely unknown. Here we characterized the spontaneously emerging visual cortical activity by applying independent component analysis to resting state fMRI signals exclusively within the visual cortex. In this sub-system scale, we observed about 50 spatially independent components that were reproducible within and across subjects, and analyzed their spatial patterns and temporal relationships to reveal the intrinsic parcellation and organization of the visual cortex. We found that the visual cortical parcels were aligned with the steepest gradient of cortical myelination, and organized into functional modules segregated along the dorsal/ventral pathways and foveal/peripheral early visual areas. In contrast, cortical retinotopy, folding, and cytoarchitecture impose limited constraints to the organization of resting state activity. From these findings, we conclude that spontaneous activity patterns in the visual cortex are primarily organized by visual streams, likely reflecting feedback network interactions.