November 14, 2013…The developing field of optogenetics uses micro-LEDs and light activated genes to control individual brain cells. For example, scientists can take a light-activated gene targeted at a particular type of neuron and insert the gene into a mouse. Then, shining light into the animal’s brain can either get neurons to fire or inhibit their activity. Such research may one day provide improved treatments for depression, addiction and anxiety. Researchers at Washington University School of Medicine in St. Louis are using tiny, electronic devices to identify and map neural circuits in the brain with funding from a rare EUREKA grant from the National Institutes of Health. EUREKA stands for Exceptional, Unconventional Research Enabling Knowledge Acceleration. So EUREKA grants fund high-risk/high-reward projects. The National Institutes of Health (NIH) supports just 12 to 18 such grants each year.
With the award, Michael R. Bruchas, PhD, assistant professor of anesthesiology, and his colleagues will conduct studies with micro-LED devices that his group recently co-developed with a team at the University of Illinois in Urbana-Champaign. In a recent study, Bruchas and his colleagues used the tiny electronic devices, which are thinner than a human hair, to tap into specific sections of neurons in the brains known as the internal reward system in mice. Through light activation the neurons were prodded to release dopamine, a chemical associated with pleasure, when the mice poked their noses through a hole in a particular part of a maze.
“Optogenetics allows us to zero in on specific populations of neurons and understand which ones are involved in complex behaviors,” Bruchas said. “What we learn from these studies will make it possible for us to target specific populations of brain cells that malfunction in depression, pain, addiction and other disorders.”
The four-year, $1.2 million grant will allow Bruchas and his team to develop specialized, optically sensitive G-protein-coupled receptors on brain cells that will allow the researchers to control cell signaling in the brain with light. These new receptor tools will be combined with wireless micro-LED devices implanted in the mouse brain in an effort to uncover more information about molecular and cellular events that underlie stress, addiction and depression. For example, Bruchas hopes to isolate and map the brain networks involved in stress by studying how mice interact in their cages. A dominant mouse may limit a cagemate from moving about freely, creating stress that may be apparent in the mouse’s brain networks.
What makes Washington University research unique is that the micro-LEDs are portable and wireless. So unlike most other optogenetic techniques being used, the animals do not have to be tethered to wires and are able to move freely. With funding from the EUREKA grant, his team plans to make them even smaller and add sensing capabilities to measure dynamic changes in the brain’s chemical transmission.