Optogenetics and its application in sleep research
I must admit, if I hear about something new, flashy and fancy I can’t help but get enthusiastic about it! Optogenetics, chosen method of the year 2010 by Nature Methods, is one of those fancy things that recently caught my attention.
Optogenetics is a technique which allows you to precisely control activity in one cell type by the use of light. In the video below you can see a nice overview of the technique and there are some great primers/introductions as well (see below for references; free content).
Also see this great talk by Ed Boyden on TED:
Rolls et al. (2011) have now applied optogenetics to study the effect of sleep disruption on memory consolidation. By using optogenetics in rats they were able to manipulate one aspect of sleep (i.e. sleep fragmentation) while keeping other sleep parameters such as sleep duration, intact. This way they could isolate the effect of sleep fragmentation on memory consolidation.
Memory consolidation was measured by using an object recognition task. When faced with a familiar object and a new object, rats spend more time exploring the unfamiliar object. This is taken as an indication that the rat “recognizes” the object and thus memory for that object has been consolidated. Sleep fragmentation resulted in impaired performace in such a task as compared to control rats. An additional interesting finding was that the effect of sleep fragmentation could be quantified. When sleep fragmentation was limited to a minimum of about 65%, memory wasn’t affected, while more sleep fragmentation resulted in disrupted memory consolidation.
This research nicely illustrates how optogenetics can be applied to study sleep mechanisms and the role of sleep in cognition. I’m looking forward to see this technique and its applications evolve, and hope it can further guide and direct future research.
References (resources freely available)
- Rolls, A. et al. Optogenetic disruption of sleep continuity impairs memory consolidation. Proceedings of the National Academy of Sciences (2011).
- Yizhar, O., Fenno, L.E., Davidson, T.J., Mogri, M. & Deisseroth, K. Optogenetics in neural systems. Neuron 71, 9–34 (2011). Very elaborate and extensive primer on the use of optogenetics. Opsin genes, opsin targeting, light deliverery and behavioral readout is discussed.
- Pastrana, E. Optogenetics: controlling cell function with light. Nat Methods 8, 24–25 (2011). Brief primer on optogenetics. Less technical than the paper of Yizhar.