Optical bioimaging: from living tissue to a single molecule: optical detection of synaptically induced glutamate...

Since voltage-sensitive dyes (VSDs) change their optical properties in response to membrane potential changes, non-invasive optical measurements of membrane excitation using VSDs have been applied to various types of excitable tissue. This article deals with the authors' recent work using this technique in addition to basic and technical information about VSD imaging. By applying this technology to hippocampal brain slices, we have found that astrocytes play indispensable roles in sequestering glutamate, maintenance of synaptic transmission, and neuronal survival. Finally, the potential of VSD imaging for drug development was discussed.