Recurrent networks of the cerebral cortex: Circuits, neural computations, and sequence processing using two-photon optogenetics

Authors

• MH Histed
• B Akitake
• Y Deng
• C Deveau
• N Friedman
• P LaFosse
• J O'Rawe
• C Phillips
• V Scott
• R Yovanno
• Z Zhou

Abstract

The brain is a highly interconnected system, with extensive connectivity both between brain areas and also within areas. Inside cortical areas and layers, neurons receive a majority of their inputs from other local neurons within a few hundred microns' distance. These recurrent connections, mostly excitatory-excitatory connections, can dramatically shape neurons' responses: their ongoing activity, their individual responses, and how the network responds to input. That is, recurrent connectivity can have dramatic effects on neural computation. The Histed group uses cellular-resolution brain stimulation in vivo to understand how patterns of activity interact with neural circuits to create brain computations and control behavior.

We have made progress understanding how single cells transform their inputs (single cell response functions, activation functions, or f-I curves) in vivo, and how the cortical recurrent network transforms dynamic inputs which change over time. We have also developed viral tools for stable and consistent expression of a calcium indicator and opsin to enable cell-specific optogenetic experiments and shared these with the community. One important finding is the upper cortical layers of V1 in the mouse have dynamic responses, created by recurrent interactions, which filter static visual inputs and produce sparse, reliable responses during natural visual experience. This work shows how natural visual responses, often stronger, sparser, and more reliable than responses to edges or gratings, can be created by interaction of inputs with the cortical local circuitry. Some of the functions we find for recurrent circuits in the brain parallel functions for recurrent circuits in machine learning/AI systems.

Scientific Focus Area: Neuroscience

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