We briefly review the current literature where optogenetics has been used to 
study various aspects of astrocyte physiology in vitro and in vivo. This 
includes both genetically engineered Ca(2+) sensors and effector proteins, such 
as channelrhodopsin. We demonstrate how the ability to target astrocytes with 
cell-specific viral vectors to express optogenetic constructs helped to unravel 
some previously unsuspected roles of these inconspicuous cells.