Saturday February 10, 2018

Turning off anxiety could be as easy as flicking on a light in your brain

Scientists have discovered a minimally invasive way to control specific brain functions with light.

Scientists have discovered a minimally invasive way to control specific brain functions with light. (Jose-Luis Olivares/MIT)

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The optogenetics technology

Optogenetics is a burgeoning field in the life sciences that scientists are very excited about. It's a tool that combines gene therapy and light to precisely control nerve cells. 

The way it works is through gene therapy, scientists add a protein that responds to light to specific nerve cells they want to control. By implanting fibre optic cables directly into those targeted areas in the brain, scientists can shine visible light through the cable to reach the proteins that respond to light to turn the neurons on or off. 

This is an extremely valuable tool for neuroscientists because it allows them to target specific neurons in the brain to remotely control behaviours. Optogenetics also has tremendous therapeutic potential. Scientists are looking to use versions of this tool to control Parkinson's, restore sight, and even to one day remotely control our brain's responses to things like fear, pain, and anxiety. 

Shutting down anxiety in mice

Scientists were looking to pinpoint the nerve cells in the brains of mice that control anxiety. They wanted to study this in mice because they are anxious animals, especially when they go into open spaces. The scientists placed the mice onto a maze with two arms that were open to the environment. Then they used a special imaging technique to pinpoint the neurons that fired when the mice were forced into the open spaces. That study only proves there's a correlation between these neurons and anxiety, but scientists wanted to dig deeper to find out if these neurons were causing the anxiety. For that, they turned to optogenetics. 

Dr. Mazen Kheirbek, an assistant professor of psychiatry at the University of California, San Francisco, and one of the senior authors of this study, says of the neurons they targeted in mice, "If we turned down their increased activity, the animals should become less anxious. And surprisingly, that's what actually happens.' 

New minimally invasive optogenetics 

One of the biggest limitations of optogenetics is how invasive it is with the fibre optic cables that have to be inserted directly to the neurons they want to target. This can cause tissue damage, especially when scientists are trying to control neurons deep within the brain.

Now scientists, led by Dr. Thomas McHugh, in Wako, Japan have developed a way around this invasiveness. He is the senior team leader at the RIKEN Brain Science Institute. The key to their new minimally invasive approach is to inject specially designed nanomaterials into the targeted regions. That allows the them to shine near infrared light from the outside of the skull, which unlike visible light used in current optogenetics methods, which can penetrate tissue. Once the near infrared light reaches the nanomaterials in the targeted regions of the brain, it causes them to shine in visible light inside the brain, which then controls nerve cells with the flick of a switch.