Many therapeutic technologies, including Cochlear implants that enable the deaf to hear, or deep brain stimulators that treat some symptoms of Parkinson’s disease, use electricity to stimulate neurons in the brain. This method isn’t exactly precise, however, as the electrical fields stimulate neurons around the targeted area, which leads to side effects.
Researchers at Stanford wanted to use light to precisely stimulate targeted areas in the brain, but ran into one giant problem – neurons don’t respond to light. The workaround? Genetically engineer the brain by splicing in genes from simple algae that do respond to light, and therefore result in the neurons firing when exposed to light from a fiber optic cable. The method could be used to more effectively treat brain diseases such as Parkinson’s:
Many experts had thought the cure was to stimulate certain kinds of cells within the subthalamic nucleus, which coordinates motion. But when they tried that, it had no effect whatsoever. Then two of Deisseroth’s grad students began experimenting with a dark-horse idea. They stimulated neurons near the surface of the brain that send signals into the subthalamic nucleus — a much harder approach because it meant working at one remove. It was as if, instead of using scissors yourself, you had to guide someone else’s hands to make the cuts.
Their idea worked. The mice walked. In their paper, published in April 2009, they wrote that the “effects were not subtle; indeed, in nearly every case these severely parkinsonian animals were restored to behavior indistinguishable from normal.”
Over at MIT, Boyden was asking the obvious question: Would this work on people? But imagine saying to a patient, “We’re going to genetically alter your brain by injecting it with viruses that carry genes taken from pond scum, and then we’re going to insert light sources into your skull.” He was going to need some persuasive safety data first.
That same summer, Boyden and his assistants began working with rhesus monkeys, whose brains are relatively similar to humans’. He was looking to see whether the primates were harmed by the technique. They triggered the neurons of one particular monkey for several minutes every few weeks for nine months. In the end, the animal was just fine.
Read the entire fascinating article over at Wired.