WIKIMEDIA, CHEMPETITIVETen years ago, optogenetics started out as a means to stimulate neuronal activity without the use of electrodes: a genetically introduced light-sensitive membrane channel and a blue light could do the job. At the Society for Neuroscience (SfN) meeting in Chicago this week, scientists announced new techniques for recording neurons optically, as well, obviating the need for invading cells or tissues with electrical probes altogether.
The basic approach is to express genes for a light-sensitive channel and an optical reporter in the same cell. For instance, researchers have succeeded in using genetically introduced calcium indicators, which signal action potentials, to record cell activity upon optogenetic stimulation.
To get an even more refined look at cell activity, particularly at the sub-action potential level, Adam Cohen’s team at Harvard University has developed an optical voltage indicator, called QuasAr, which glows in the near infrared upon changes in cellular voltage (voltage indicators act on a much faster time scale than calcium indicators). Along with Ed Boyden’s lab at MIT, Cohen developed a new channelrhodopsin that’s extremely sensitive to blue light and introduced it into cells along with QuasAr, allowing the researchers to stimulate ...
