# A real-time all-optical interface for dynamic perturbation of neural activity during behavior

## TL;DR

This paper introduces a system that uses real-time calcium imaging and holographic optogenetics to dynamically control neural activity in mice during behavior.

## Contribution

The novel contribution is an automated all-optical interface that enables real-time, closed-loop manipulation of neural activity based on ongoing brain activity patterns.

## Key findings

- Neurons can be automatically detected and recruited into photostimulation ensembles in real time.
- Closed-loop photoinhibition can be implemented immediately after mapping functional properties of cortical neurons.
- Targeted neuronal activation is guided by ongoing population activity patterns during decision-making.

## Abstract

We developed a strategy for implementing a dream experiment in systems neuroscience, where circuit manipulation is guided by the real-time readout of neural activity in behaving mice. The system integrates a state-of-the-art calcium imaging analysis package that achieves rapid online activity readout from two-photon calcium imaging, a custom hologram generation program that targets two-photon optogenetic stimulation of specific neuronal ensembles, and software modules that automate essential steps in running complex all-optical experiments. Proof-of-principle experiments demonstrate that neurons can be automatically detected and recruited into a photostimulation ensemble, closed-loop photoinhibition can be implemented immediately after fast mapping of the functional properties of cortical neurons, and targeted activation can be guided by readout of ongoing activity patterns in behaviorally relevant neuronal ensembles during decision-making.

•Holographic optogenetics guided by online analysis of two-photon calcium imaging•Automatic cell detection and recruitment into a photostimulation ensemble•Closed-loop activity suppression following fast functional properties mapping•Targeted neuronal activation guided by ongoing population activity patterns

Holographic optogenetics guided by online analysis of two-photon calcium imaging

Automatic cell detection and recruitment into a photostimulation ensemble

Closed-loop activity suppression following fast functional properties mapping

Targeted neuronal activation guided by ongoing population activity patterns

A fundamental question in neuroscience is how neural activity in the brain drives behavior. Recent advances in optical methods combining two-photon imaging and two-photon optogenetic stimulation have allowed simultaneous readout and manipulation of the activity of individual neurons in awake mice. Such an “all-optical” strategy has allowed neural interventions to be targeted to specific neurons based on their genetic and functional signatures, paving the way to probe their causal role during behavior. However, current all-optical experiments typically activate pre-defined neurons at pre-defined time points, irrespective of the ongoing activity in the local circuit. Since the activity of individual neurons and neural ensembles can be highly variable from trial to trial, it is essential to adjust photostimulation strategies based on real-time activity measurements during behavior.

Zhang et al. develop a system that reads activity from individual neurons in real time and uses holographic light patterns to control specific neurons in mice, enabling automated, all-optical experiments to study brain circuits during behavior.