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
>
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