This week I came across an interesting study from a group of Stanford scientists who have found a way to utilize the genes from a photosynthesizing cell and light to control neuron function. Unlike drugs which affect all neurons in the target area, this approach allows the targeting of specific neurons, meaning no side effects!
Better yet, it is speculated that this method of controlling neuron function can eliminate the symptoms of diseases like Parkinson’s.
How does it all work?
Here’s the brief, less-scientific explanation:
A gene from a photosynthesizing cell is injected into the area of the brain that house the targeted neurons. For example, someone having trouble walking would have this gene injected into the motor cortex (either left or right, or both depending on the motor impairment). Since this gene reacts to light, a light source is needed to activate the targeted neurons. So, they stick a little box in the brain with blue and yellow lights that turn on and off when you want the neurons stimulated. Blue is for on, yellow is for off. When the light is turned on the gene activates the neuron, but only the neuron/neurons that the gene is “marked” to activate.
More scientific explanation: Science Warning!
A light sensitive gene is taken from the cell membrane of Chlamydomonas (a type of algae). This light sensitive gene is responsible for making the proteins in the cell react. The retinal complex absorbs a photon, causing a change in the transmembrane protein, opening a cell pore to 6Å, releasing a flow of ions which lasts for a few milliseconds. The gene’s name is Channelrhodopsin-1, with a cousin gene of Channelrhodopsin-2. Blue light, light at a wavelength of 480nm, causes an optimal reaction from this gene, essentially turning whatever it is attached to “on.” Halorhodopsin is a bacterial gene that was found to turn attached neurons “off” when exposed to yellow lights (the discovery of this particular property of the gene is credited to Dr. Ed Boyden). The necessary combination of firing and inhibiting neurons is complete with these two genes.
The news of this research is wonderful, possibly leading to the suppression of debilitating disease symptoms as well as offering the blind, deaf, and physically impaired the chance to experience an easier lifestyle.
Here are some great resources concerning this study:
Wired Magazine Story
Wikipedia.org Channelrhodopsin Entry
Image Courtesy of Wikipedia.org