# Iso-orientation bias of layer 2/3 connections unifies spontaneous, visually and optogenetically driven V1 dynamics

## TL;DR

The paper shows how a moderate bias in visual cortex connections explains various brain activity patterns, including spontaneous waves and responses to light stimulation.

## Contribution

The study introduces a unified model showing how iso-orientation biased connectivity explains multiple V1 activity regimes.

## Key findings

- A moderate iso-orientation bias in layer 2/3 connections explains diverse V1 activity patterns.
- The model predicts slower and isotropic spontaneous waves in layer 4.
- Optogenetic responses show non-monotonicity with larger illumination disks.

## Abstract

Functionally specific long-range lateral connectivity in layer 2/3 of the adult primary visual cortex (V1) supports the integration of visual information across visual space and shapes spontaneous, visual and optogenetically driven V1 activity. However, a comprehensive understanding of how these diverse cortical regimes emerge from this underlying cortical circuitry remains elusive. Here we address this gap by showing how the same model assuming moderately iso-orientation biased long-range cortical connectivity architecture explains diverse phenomena, including (i) range of visually driven phenomena, (ii) modular spontaneous activity, (iii) the propagation of spontaneous cortical waves, and (iv) neural responses to patterned optogenetic stimulation. The model offers testable predictions, including presence of slower and iso-tropic spontaneous wave propagation in layer 4 and non-monotonicity of optogenetically driven cortical response to increasingly larger disk of illumination. We thus offer a holistic framework for studying how cortical circuitry governs information integration across multiple operating regimes.

Here, the authors show a moderate iso-orientation bias of layer 2/3 lateral connections enables functionally specific spontaneous cortical waves and optogenetic stimulation response, and modular spontaneous activity in a large-scale spiking model of primary visual cortex.