Intersubject Synchronization of Cortical Activity During Natural Vision

TLDR

The study asks whether all brains behave similarly during natural viewing conditions. Five participants watched a 30‑minute movie while fMRI recorded their brain activity, and the authors used a reverse‑correlation approach to let brain signals identify optimal stimuli for each cortical area. Voxel‑by‑voxel intersubject synchronization was observed across visual, auditory, and association cortices, with widespread activation linked to emotionally arousing scenes and regionally selective components, indicating that individual brains tend to tick collectively during natural vision.

Abstract

To what extent do all brains work alike during natural conditions? We explored this question by letting five subjects freely view half an hour of a popular movie while undergoing functional brain imaging. Applying an unbiased analysis in which spatiotemporal activity patterns in one brain were used to "model" activity in another brain, we found a striking level of voxel-by-voxel synchronization between individuals, not only in primary and secondary visual and auditory areas but also in association cortices. The results reveal a surprising tendency of individual brains to "tick collectively" during natural vision. The intersubject synchronization consisted of a widespread cortical activation pattern correlated with emotionally arousing scenes and regionally selective components. The characteristics of these activations were revealed with the use of an open-ended "reverse-correlation" approach, which inverts the conventional analysis by letting the brain signals themselves "pick up" the optimal stimuli for each specialized cortical area.