From sensation to action: distributed mesoscale dynamics in the primate brain
Perceptual decisions engage distributed brain networks, yet how decision-related signals are organized across and within brain areas remains unclear. Mesoscale functional domains are established in visual cortex, but whether spatially distinct domains organize perceptual decisions across the brain is unknown. Here we used 7-T functional MRI at 1-mm isotropic resolution in two awake macaques performing a contrast-discrimination task to map brain-wide activity during sensation, decision formation and saccadic report. Voxel timecourses separated into three groups with distinct temporal profiles, associated with sensory, decision-related and action-related activity. Their spatial distributions formed a broad progression from visual cortex to parietal, prefrontal and motor regions, while revealing distinct response domains within these regions. Choice-related signals were distributed across sensory, associative, and motor systems before movement, including in visual cortex responses to physically identical stimuli that differed according to the animal's eventual choice. Moreover, within the intraparietal sulcus and other regions, mesoscale domains preferentially responsive to near-threshold conditions carried choice information under uncertainty, whereas domains responsive to high-contrast conditions carried choice information when evidence was strong. These findings reveal that perceptual decisions are organized across the brain through spatially differentiated mesoscale networks whose activity varies with task phase and sensory certainty. This spatial organization provides a framework for investigating how distributed neural signals support flexible choice.