Posts tagged optogenetics
Articles and news from the latest research reports.
Controlling Brains With a Flick of a Light Switch
Using the new science of optogenetics, scientists can activate or shut down neural pathways, altering behavior and heralding a true cure for psychiatric disease.
Stopped at a red light on his drive home from work, Karl Deisseroth contemplates one of his patients, a woman with depression so entrenched that she had been unresponsive to drugs and electroshock therapy for years. The red turns to green and Deisseroth accelerates, navigating roads and intersections with one part of his mind while another part considers a very different set of pathways that also can be regulated by a system of lights. In his lab at Stanford University’s Clark Center, Deisseroth is developing a remarkable way to switch brain cells off and on by exposing them to targeted green, yellow, or blue flashes. With that ability, he is learning how to regulate the flow of information in the brain.
Deisseroth’s technique, known broadly as optogenetics, could bring new hope to his most desperate patients. In a series of provocative experiments, he has already cured the symptoms of psychiatric disease in mice. Optogenetics also shows promise for defeating drug addiction. When Deisseroth exposed a set of test mice to cocaine and then flipped a switch, pulsing bright yellow light into their brains, the expected rush of euphoria—the prelude to addiction—was instantly blocked. Almost miraculously, they were immune to the cocaine high; the mice left the drug den as uninterested as if they had never been exposed.
One biotech startup wants to restore vision in blind patients with a gene therapy that gives light sensitivity to neurons that don’t normally possess it.
The attempt, by Ann Arbor, Michigan-based Retrosense Therapeutics, will use so-called optogenetics. Scientists have used the technique over the last few years as a research tool to study brain circuits and the neural control of behavior by directing neuron activity with flashes of light. But Retrosense and others groups are pushing to bring the technique to patients in clinical trials.
The idea behind Retrosense’s experimental therapy is to use optogenetics to treat patients who have lost their vision due to retinal degenerative diseases such as retinitis pigmentosa. Patients with retinitis pigmentosa experience progressive and irreversible vision loss because the rods and cones of their eyes die due to an inherited condition. If the company is successful, the treatment could also help patients with the most common form of macular degeneration, which affects nearly a million people in the United States. The U.S. Food and Drug Administration hasn’t approved any therapies for either condition.
Controlling Monkey Brains and Behavior With Light
ScienceDaily (July 26, 2012) — Researchers reporting online on July 26 in Current Biology, a Cell Press publication, have for the first time shown that they can control the behavior of monkeys by using pulses of blue light to very specifically activate particular brain cells. The findings represent a key advance for optogenetics, a state-of-the-art method for making causal connections between brain activity and behavior. Based on the discovery, the researchers say that similar light-based mind control could likely also be made to work in humans for therapeutic ends.
(Credit: © Eric Isselée / Fotolia)
"We are the first to show that optogenetics can alter the behavior of monkeys," says Wim Vanduffel of Massachusetts General Hospital and KU Leuven Medical School. "This opens the door to use of optogenetics at a large scale in primate research and to start developing optogenetic-based therapies for humans."
In optogenetics, neurons are made to respond to light through the insertion of light-sensitive genes derived from particular microbial organisms. Earlier studies had primarily validated this method for use in invertebrates and rodents, with only a few studies showing that optogenetics can alter activity in monkey brains on a fine scale.
In the new study, the researchers focused on neurons that control particular eye movements. Using optogenetics together with functional magnetic resonance imaging (fMRI), they showed that they could use light to activate these neurons, generating brain activity and subtle changes in eye-movement behavior.
The researchers also found that optogenetic stimulation of their focal brain region produced changes in the activity of specific neural networks located at some distance from the primary site of light activation.
The findings not only pave the way for a much more detailed understanding of how different parts of the brain control behavior, but they may also have important clinical applications in treating Parkinson’s disease, addiction, depression, obsessive-compulsive disorder, and other neurological conditions.
"Several neurological disorders can be attributed to the malfunctioning of specific cell types in very specific brain regions," Vanduffel says. "As already suggested by one of the leading researchers in optogenetics, Karl Deisseroth from Stanford University, it is important to identify the underlying neuronal circuits and the precise nature of the aberrations that lead to the neurological disorders and potentially to manipulate those malfunctioning circuits with high precision to restore them. The beauty of optogenetics is that, unlike any other method, one can affect the activity of very specific cell types, leaving others untouched."
Source: Science Daily