http://www.insidebayarea.com/localnews/ci_11967017

In a new study, associate professor Dr. Karl Deisseroth and graduate students Viviana Gradinaru and Murtaza Mogri say they believe they've identified the specific part of the brain that is affected by that electrical stimulation.

In rodent tests, they found that instead of the subthalmic nucleus — the area of the brain where the electrical implants are typically implanted — it's actually the axons, or neural wires, that connect the subthalmic nucleus to other parts of the brain, that are most impacted by stimulation.

The researchers used a technique called "optogenetics," engineering rodents' brain cells so the cells are controllable by light. This allowed them to control different sections of the brain at different times, and they determined that by stimulating the axons the rodents' Parkinsonian symptoms seemed to stop.

"This insight leads to deeper understanding of the circuit and could even lead to new kinds of treatment,"
Deisseroth said in a news release. "Because these axons are coming from areas closer to the brain's surface, new treatments could perhaps be less invasive than deep-brain stimulation."

Their study was released Thursday in the online journal Science Express