thanks, Maryse, I've been trying with no success to copy this article re fiber optics Ray Rayilyn Brown Director AZNPF Arizona Chapter National Parkinson Foundation [log in to unmask] -------------------------------------------------- From: "mschild" <[log in to unmask]> Sent: Friday, March 20, 2009 10:15 AM To: <[log in to unmask]> Subject: more light > http://www.medgadget.com/archives/2009/03/fiber_optics_activate_neurons_axons_to_answer_parkinsons_questions.html > > Thursday, March 19, 2009 > Fiber Optics Activate Neurons, Axons to Answer Parkinson's Questions > > > Scientists at Stanford's lab of Dr. Karl Deisseroth developed a novel > technology that not only sheds new light on pathophysiology of > Parkinson's, > but may even one day become a therapeutic modality for this disease. The > research involves deep brain stimulation of the brain's subthalamic > nucleus > region, which is already a common therapy for people suffering from > Parkinson's. Until now the mechanism by which electrical signals lead to > an > improvement in symptoms has been a mystery in the medical community. So to > understand what's going on, Dr. Deisseroth et. al. developed thin, > flexible > fiber-optic cables, and compatible rodents with light sensitive neurons. > By > stimulating cells within the subthalamic nucleus using a fiber optic probe > the > researchers found little effect. Yet, when the axons that lead from the > region > to the outer regions of the brain were illuminated, the mice lost the > symptoms > of Parkinson's. > > To perform the research, Deisseroth’s team, which included students and > faculty from bioengineering, neuroscience and neurosurgery, used a > technique > his lab has pioneered called “optogenetics.” They genetically engineered > specific types of cells, or neurons, in the subthalamic nucleus regions of > different rodents to become controllable with light. A blue-colored laser > pulse makes the neurons more active, while a yellow laser light suppresses > activity. > > “Using the technology allowed us to separate the different circuit > elements by placing them under optical control,” Deisseroth said. “It > allowed > us to systematically move through the circuit, turning on or off different > elements and finding out which modifications of the circuit corrected the > symptoms.” > > This result also required a complementary method invented in the > Deisseroth lab, namely delivering light via a thin, flexible fiber-optic > cable > deep into the brain of the animals, so that they can move and behave > freely > during the experiment. > > The team tried every kind of neuron they could think of within the > brain > region itself, and found no effect. Out of persistence and desperation, > like a > person who has searched the whole house for the keys and finally finds > them in > the doorknob, the team decided to investigate the incoming axons. In > rodents > with cells that had been made light-sensitive, the researchers found > dramatic > results both with high-frequency and low-frequency pulses. > > “The [high-frequency stimulation] effects were not subtle,” the > researchers wrote in the Science Express paper. “In nearly every case > these > severely Parkinsonian animals were restored to behavior indistinguishable > from > normal, and in every case the therapeutic effect immediately and fully > reversed…upon discontinuation of the light pulse.” > > Low-frequency stimulation, meanwhile, caused the Parkinson’s symptoms > to > become worse. > > Here's more details about optogenetics from the New Scientist: > > Called optogenetics, the technology relies on light-sensitive proteins > called channel rhodopsins that are normally produced by algae. > > Deisseroth's team previously found that inserting a channel rhodopsin > into > neurons allows them to be activated with blue light. Similarly, an > engineered > protein called halo-rhodopsin can silence brain cells when flashed with > yellow > light. > > The proteins do this by pumping charged ions into or out of cells in > response to light, creating the electrical potential that is the native > language of neurons. > > Full story: Stanford study improves insights into Parkinson's disease and > possible treatments > > ---------------------------------------------------------------------- > To sign-off Parkinsn send a message to: > mailto:[log in to unmask] > In the body of the message put: signoff parkinsn ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn