Microbial rhodopsins in the spotlight

The discovery of the light-gated cation channel Channelrhodopsin-2 (ChR2) and the use of the rediscovered light-driven Cl-pump halorhodopsin (HR) as optogenetic tools — genetically encoded switches that enable neurons to be turned on or off with bursts of light — refines the functional study of neurons in larger networks. Cell-specific expression allows a fast optical scanning approach to determine neuronal crosstalk following plasticity at the single synapse level or long-range projections in locomotion and somatosensory networks. Both rhodopsins proved to work functionally and could evoke behavioral responses in lower model organisms, reinstall rudimentary visual perception in blind mice and were set in a biomedical context with the investigation of neurodegenerative diseases.