AAV1 is the optimal viral vector for optogenetic experiments in pigeons (Columba livia)

Noemi Rook,John Michael Tuff,Onur Güntürkün,Olivia Andrea Masseck,Stefan Herlitze,Sevim Isparta,Roland Pusch

doi:10.1038/s42003-020-01595-9

Noemi Rook, John Michael Tuff + Show 5 more

Open Access

https://doi.org/10.1038/s42003-020-01595-9

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Abstract

Although optogenetics has revolutionized rodent neuroscience, it is still rarely used in other model organisms as the efficiencies of viral gene transfer differ between species and comprehensive viral transduction studies are rare. However, for comparative research, birds offer valuable model organisms as they have excellent visual and cognitive capabilities. Therefore, the following study establishes optogenetics in pigeons on histological, physiological, and behavioral levels. We show that AAV1 is the most efficient viral vector in various brain regions and leads to extensive anterograde and retrograde ChR2 expression when combined with the CAG promoter. Furthermore, transient optical stimulation of ChR2 expressing cells in the entopallium decreases pigeons’ contrast sensitivity during a grayscale discrimination task. This finding demonstrates causal evidence for the involvement of the entopallium in contrast perception as well as a proof of principle for optogenetics in pigeons and provides the groundwork for various other methods that rely on viral gene transfer in birds.

Highlights

Optogenetics has revolutionized rodent neuroscience, it is still rarely used in other model organisms as the efficiencies of viral gene transfer differ between species and comprehensive viral transduction studies are rare
The counterstaining was performed to allow for an equal comparison between the serotypes, as serotypes with the human synapsin gene (hSyn) promoter were tagged with eYFP, whereas serotypes with the CAG promoter were tagged with mCherry
In the current study, we investigated the efficiency of three associated viral vector (AAV) (AAV1, AAV5, and AAV9) in combination with two different promoter systems in their ability to drive ChR2 expression in neurons within the entopallium, the first visual input structure of the avian forebrain

Summary

Introduction

Optogenetics has revolutionized rodent neuroscience, it is still rarely used in other model organisms as the efficiencies of viral gene transfer differ between species and comprehensive viral transduction studies are rare. Transient optical stimulation of ChR2 expressing cells in the entopallium decreases pigeons’ contrast sensitivity during a grayscale discrimination task This finding demonstrates causal evidence for the involvement of the entopallium in contrast perception as well as a proof of principle for optogenetics in pigeons and provides the groundwork for various other methods that rely on viral gene transfer in birds. There is, cumulative evidence suggesting that, the avian and mammalian brains differ on the macroscopic level, the local circuitry within their sensory systems is highly comparable indicating conserved principles in sensory systems organization[13]. Finding those invariant properties can help to establish circuit–function relationships that highlight general principles of the brain. We provide a proof of principle for optogenetics in pigeons as well as further insights into the function of the entopallium

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