Principles of Corticocortical Communication: Proposed Schemes and Design Considerations

Nearly all brain functions involve routing neural activity among a distributed network of areas. Understanding this routing requires more than a description of interareal anatomical connectivity: it requires understanding what controls the flow of signals through interareal circuitry and how this communication might be modulated to allow flexible behavior. Here we review proposals of how communication, particularly between visual cortical areas, is instantiated and modulated, highlighting recent work that offers new perspectives. We suggest transitioning from a focus on assessing changes in the strength of interareal interactions, as often seen in studies of interareal communication, to a broader consideration of how different signaling schemes might contribute to computation. To this end, we discuss a set of features that might be desirable for a communication scheme. Corticocortical communication is a fundamental aspect of brain function. Flexible behavior suggests a need for modulating interareal signaling from moment to moment.Several schemes for modulating corticocortical communication have been proposed. These include altering the structure of activity within a source network, the sensitivity of a target network to the input it receives, or gating signals during the relay between areas.We review these schemes and highlight new proposals that suggest communication may be determined by how source population signals align with interareal communication subspaces.We propose a set of design considerations for evaluating the relative merits of different communication schemes. When examining interareal communication, we suggest moving beyond merely characterizing changes in the strength of interareal interactions, to a wider consideration of the computational benefits and limitations of different communication schemes.