Channelrhodopsin

Abstract

Channelrhodopsins can be readily expressed in excitable cells such as neurons using a variety of transfection techniques (viral transfection, electroporation, gene gun) or transgenic animals. The light-absorbing pigment retinal is present in most cells (of vertebrates) as Vitamin A, making it possible to photostimulate neurons without adding any chemical compounds. Before the discovery of channelrhodopsins, neuroscientists were limited to recording the activity of neurons in the brain and correlate this activity with behavior. This is not sufficient to prove that the recorded neural activity actually caused that behavior. Controlling networks of genetically modified cells with light, an emerging field known as Optogenetics., allows researchers now to explore the causal link between activity in a specific group of neurons and mental events, e.g. decision making. Using fluorescently labeled ChR2, light-stimulated axons and synapses can be identified.[8] This is useful to study the molecular events during the induction of synaptic plasticity.[31] Transfected cultured neuronal networks can be stimulated to perform some desired behaviors for applications in robotics and control.[32] ChR2 has also been used to map long-range connections from one side of the brain to the other, and to map the spatial location of inputs on the dendritic tree of individual neurons