Cortical Areas Interact through a Communication Subspace.

Summary Most brain functions involve interactions among multiple, distinct areas or nuclei. For instance, visual processing in primates requires the appropriate relaying of signals across many distinct cortical areas. Yet our understanding of how populations of neurons in interconnected brain areas communicate is in its infancy. Here we investigate how trial-to-trial fluctuations of population responses in primary visual cortex (V1) are related to simultaneously recorded population responses in area V2. Using dimensionality reduction methods, we find that V1-V2 interactions occur through a communication subspace: V2 fluctuations are related to a small subset of V1 population activity patterns, distinct from the largest fluctuations shared among neurons within V1. In contrast, interactions between subpopulations within V1 are less selective. We propose that the communication subspace may be a general, population-level mechanism by which activity can be selectively routed across brain areas. Highlights • Visual cortical areas interact through a communication subspace (CS) • The CS defines which activity patterns in a source area relate to downstream activity • The largest activity patterns in a source area are not matched to the CS • The CS allows for selective and flexible routing of population signals between areas Most brain functions require the selective and flexible routing of neuronal activity between cortical areas. Using paired population recordings from multiple visual cortical areas, Semedo et al. find a population-level mechanism that can achieve this routing, termed a communication subspace. [ABSTRACT FROM AUTHOR]