Once again optogenetics is changing science, and is now responsible for "shedding some light" on Parkinson's therapy. For those of you who have yet to be informed about optogenetics, it is a recently developed technique based on a group of light-sensitive proteins called channelrhodopsins, which are isolated recently from various species of micro-organisms. Although it is relatively new, this technique has proven to be very powerful, because channelrhodopsins can be targeted to specific cells, so that their activity can be controlled by light, on a millisecond-by-millisecond timescale.
Recently researchers from Stanford University now report a new addition to the optogenetic toolkit, and show that it can be used to control biochemical signalling pathways in a mouse brain and to manipulate complex reward-related behaviour, they also used the existing channelrhodopsins to probe the neural circuitry implicated in Parkinson's disease , and obtain a much better understanding of why deep brain stimulation is effective in treating the disease.

If this interests you check out: Scienceblogs.com/neurophilosophy/2009/03/optogenetics_controls_brain_signalling