Where the present gets remembered: Sensory regions communicate with the brain over the longest timescales.

Abstract

In natural contexts, the brain simultaneously processes sensory information over diverse timescales. Here we reveal how this is reflected in the organisation of asynchronous connectivity in the brain. In 86 individuals watching feature-length movies during functional neuroimaging, we calculated the delay at peak connectivity between brain regions. We found the longest delays in received whole-brain functional connectivity within sensory regions (:S 18 seconds). Two complementary dimensionality reduction approaches were used to probe the spatial organisation of connection delays and weights. First, clustering of received delays separated sensory, and transmodal/associative outputting regions, suggesting that putatively localised functions are associated with asynchronous local-to-whole-brain connectivity patterns. Next, we organised delayed connectivity maps by likeness, unveiling five orthogonal gradients of variation, each demonstrating associations between early-sensory and transmodal/associative regions. Together, these findings challenge contemporary conceptualisations of the brains temporal hierarchy by emphasising the role of sensory regions as sites of integration across timescales.