Submillimeter fMRI reveals an extensive, fine-grained and functionally-relevant scene-processing network in monkeys

Abstract

Primates are endowed with a dedicated cortical network for processing visual scene information, which is critical for navigation and object retrieval. Previous studies showed that this scene network encompasses three to maximally five cortical regions in humans and monkeys. Using submillimeter resolution fMRI (0.22 mm³ voxels), and two entirely different but carefully controlled stimulus sets, we demonstrate a robust, fine-grained, yet three-fold more extensive scene-processing network in macaques compared to previous studies. The core network, selective for both familiar and unfamiliar scenes, encompasses eleven patches distributed over all cerebral lobes and is surprisingly elaborated in frontal cortex. Five additional non-core scene-selective patches show scene selectivity, but only for places familiar to the monkeys. Notably, resting-state fMRI revealed that the frontal and temporo-parietal scene-selective patches form an intrinsically-connected network, largely segregated from other category-selective networks. Moreover, the strength of the functional connectivity across nodes of the network is a predictor of functional scene responses of nodes belonging to this network. Hence, this scene processing network is functionally-relevant. In summary, the scene-processing system is considerably more complex than previously documented, consisting of functionally interconnected patches throughout all cortical lobes.

Keywords: Category-selectivity; Frontal cortex; Functional connectivity; High-resolution fMRI; Rhesus monkey; Scene processing.