Viral Vector-Based Techniques for Optogenetic Modulation In Vivo - Viral Vector Approaches in Neurobiology and Brain Diseases - page 278

Chapter 15

Viral Vector-Based Techniques for Optogenetic
Modulation In Vivo

Mathias Mahn , Shiri Ron , and Ofer Yizhar

Abstract

Optogenetics is a technical methodology that allows direct light-based manipulation of genetically specifi ed
cells. Optogenetic methods have provided novel insights into the role of defi ned neuronal populations in
brain function and animal behavior. An expanding palette of single-component optogenetic tools provides
powerful interventional strategies for modulating the function of targeted neurons in awake, behaving
mammals and for detailed interrogation of circuit physiology in vitro. Although several genetic methods
can be utilized for delivering these genes into target cell populations, the use of viral vectors for delivery of
optogenetic tools has several important advantages. In recent years, techniques for viral vector-mediated
delivery of optogenetic tools have improved and expanded signifi cantly. These techniques now allow mod-
ular use of optogenetic tools in defi ned cell types and circuits and dovetail well with genetic mouse models
and recombinase-based driver lines. Here, we review the use of viral vectors for delivering genes encoding
optogenetic tools into the rodent brain and provide a detailed protocol for viral transduction of mouse
cortical neurons and chronic implantation of a fi beroptic connector for light delivery in vivo.

Key words Optogenetics, Lentivirus, Adeno-associated virus, Circuit tracing, Fiberoptic cannula

1 Introduction

Microbial rhodopsins are light-sensitive, retinal-containing pro-
teins known for many years to be crucial for the survival and func-
tion of a wide range of microbial species [ 1 ]. Recently, with the
discovery of channelrhodopsin [ 2 , 3 ] and the fi rst application of
this microbial opsin for stimulating neurons [ 4 , 5 ], neuroscientists
began to realize the immense potential of these light-activated pro-
teins to serve as genetically encoded tools for manipulating the
activity of defi ned neural circuit elements with high spatiotemporal
resolution [ 6 ]. Optogenetics relies on the natural capacity of
microbial rhodopsins and other engineered light-responsive

Mahn and Ron contributed equally to this work.