The many facets of optogenetics. Introduction.

Abstract

We are pleased to present in this special issue of Experimental Physiology a set of papers which summarize experiences of a number of internationally recognized laboratories working with the technology currently known as optogenetics'. Contrary to popular belief, optogenetics is not all about using light-sensitive ion channels, such as channelrhodopsin, although this particular method has led to a flood of high-profile publications. Strictly speaking, optogenetics means experimentation which involves a combination of genetic manipulation and optics. Therefore, perhaps, its history should date back to the first days when scientists started experimenting with green fluorescent protein or even earlier. Genetic engineering enables targeted expression, in mammalian cells, of various constructs, which can be subdivided into reporters and effectors (or sensors and actuators, following Miesenbock & Kevrekidis, 2005). Unsurprisingly, this approach has been swiftly adopted particularly by neuroscientists. Brain represents a particularly difficult experimental target; there, the numerous cell types are intermingled and interconnected, they are hard to visualize and almost impossible to control selectively other than by using patch clamp on a cell-by-cell basis. Therefore, understanding the complex behaviours of neuronal networks is a formidable task. The recent appreciation of the active role of astroglia has added yet another dimension to it. At the same time, optogenetics deserves a wider application than only neuroscience, and we hope to excite our diverse readership with the possibilities it offers.