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Published: June 1, 2009
If you're in the field of neuroscience and for some crazy reason haven't heard of channel rhodopsin-2 (ChR2) yet, you will. It has got to be the sexiest contemporary technique available for the neuroscientist, and one that will probably earn Karl Deisseroth a trip to Stockholm in the future.
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A relatively new technique, ChR2 allows for tight temporal control of neuronal activation via photostimulation (optically mediated inhibition can be induced via the halorhodopsin channel).
The ability to express ChR2 in specific cell populations via genetic targeting make it far superior to previous methods of neuronal activation. Thus far, ChR2 has mainly been used to study synaptic plasticity and to map functional connections between neurons. However, a new paper in Science is the first to show that ChR2 activation can actually drive behavioral changes in adult mammals. While this result is not all that surprising, it's surely a milestone in the field and a harbinger for many, many studies to come.
Bradley Monakhos said ...
11:56, 22 July 2009 (PDT)
I'm guessing these channels aren't ubiquitous in wild-type mammals? Are there mice models available that express halorhodopsin non-photoreceptor neurons?
Jeremy Biane said ...
11:56, 22 July 2009 (PDT)
Correct, the channels are not endogenously expressed in the mammalian brain. I doubt there are any mice expressing halorhodopsin channels that are not light activated, as you would pretty much lose the main power of the technique: the ability to focally and transiently inhibit neurons by shining light on them. There are, however, separate channels that drive neuronal inhibition through other means, and that can also be restricted to cell-specific populations (for example, the allatostatin system developed by Ed Calloway). Importantly, these usually act on a much longer time scale in vivo (hours), and thus may be better suited for behavioral experiemnts where reversible inactivation of a neuronal population is desired throughout learning, testing, etc.
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