The Beam of Light That Flips a Switch That Turns on the Brain

A new technique is floating through the medical world that may be able to control neurons in the human brain. The technique was founded by Dr. Karl Deisseroth along with Feng Zhang and requires fiber-optic wires with laser light to stimulate certain neurons. Dr. Deisseroth is shown to the right with two fiber-optic cables. A protein called channelrhodospin-2 (found in pond scum) allows the laser light to control altered cells.

Other studies have been done using channelrhodospin. The channel protein lets positive ions stream into cells when exposed to blue light, this can be very helpful with cell diffusion. The cool thing about these proteins is how they have shown there ability to function in different parts of the body.

German researchers teamed up with Dr. Deisseroth and Mr. Zhang in 2005 and found a way to "silence" neurons. The experiment showed that by using a bacterial protein, halorhodospin, and placing it in the brain that and shining yellow light on it would cause the cell to shut down. The image on the left shows there experiment with a roundworm.

A study at the University of California, Berkeley, preformed by Dr. Ehud Isacoff and Dirk Trauner, was done similar in technique but instead used a channel protein that anchors in the cell membrane of most human brain cells. The scientists then attached the protein to a molecular chain that contained glutamate (a neurotransmitter). When light was shined on the chain, the violet light was absorbed then the glutamate connected with the protein receptor and an electrical impulse was generated.

Research is being down in the medical field trying to implement this technology and grasping its fully potential in medicine. A study is being done trying to help rats with spinal cord injuries breathe independently using the channelrhodospin protein. Using the technique to help blindness and depression.

There are still several kinks to fix before the technique can become fully operational in humans. These problems included how to pipe the light into the brain, the gene-therapy required to put in the proteins, and how the immune system will react to foreign agents. However, the research thus far has been very promising.

I feel this article really connects medicine and engineering thus encompassing the concept of biomedical engineering. The fact that these scientist can control the movement of mice and roundworms shows that possible cures for paralyzed patients or other disorders aren't far off. I found this to be really interesting and I hope others do as well.



http://www.nytimes.com/2007/08/14/science/14brai.html?pagewanted=1&_r=1