Mind Control

How scientists use light to manipulate the brain—and treat illness

A mouse crouches on the ground of atiny low rectangular enclosure. It sniffs the air curiously. Then, atiny low light-weight hooked up to the highest of its head glows blue. The mouse begins running round the enclosure. the sunshine turns off. The mouse stops. By flipping a switch, scientists square measure dominant the a part of the mouse’s brain that creates it run.

A breakthrough technology referred to as optogenetics created this experiment potential back in 2007. Optogenetics lets scientists modify neurons, or brain cells, to form them answer light-weight. They shine light-weight on the cells to activate them. Since some neurons have totally different roles than others, targeting a selected cluster of neurons lets scientists management specific behaviors. “If we tend to wished to, we tend to might produce a mouse that we tend to might run sort of a device automobile,” says Eric Turner, a neurobiologist at city Children’s research facility in Washington.

But Turner and different scientists learning optogenetics have larger ideas. They’re victimization it to know however the brain creates our thoughts, emotions, and behaviors—and the way to treat devastating brain disorders.

BRAIN BASICS

How the brain works is essentially a mystery, even to doctors and scientists. The human brain contains concerning eighty six billion neurons. Electrical signals whiz throughout the brain on pathways that connect multiple neurons, inflicting each behavior from tasting to texting, and each feeling from happiness to worry. working out the one network of neurons that controls every of those responses isn’t straightforward.

Optogenetics is that the 1st tool that might reveal these secrets. Using it, scientists could finally be able to make out what causes psychiatrical disorders like depression and anxiety and diseases like Parkinson’s and brain disorder. higher therapies might then be developed to treat these sicknesses.

A BRIGHT plan

Optogenetics all began with Associate in Nursing unlikely source: chlorophyte. In 2004, Karl Deisseroth, a neurobiologist at Stanford University in Calif., became fascinated by a algae referred to as genus Chlamydomonas. The alga don’t have brains, however they are doing have proteins referred to as opsins. Opsins square measure sensitive to light: once the sun hits one, it sends a blast of electricity through the alga that signals it to maneuver toward or faraway from the sunshine. genus Chlamydomonas uses daylight to form energy, like what plants do throughout chemical action. Moving toward the sun permits them to gather a lot of energy.

Deisseroth puzzled if he might use opsins to “talk” to neurons within the brain. He thought that it would be potential as a result of each opsins and neurons use a similar language: electricity. If he inserted Associate in Nursing protein into a nerve cell, he could be able to modification however the nerve cell behaves by exposing it to light-weight.

No somebody had tried it before as a result of nobody thought it absolutely was potential. “I thought it in all probability wouldn’t work absolutely,” Deisseroth says. “But it absolutely was value a trial.” In 2006, Deisseroth and his team tested their plan on a mouse. They inserted the opsin’s gene—the opsin’s hereditary material—into neurons that management sleep and wakefulness. Then they place a skinny fibreoptic cable into that space of the brain. The cable was connected to a really little optical device, permitting it to shine light-weight directly into the brain.

The team tried the experiment on a sleeping mouse. after they turned on the optical device, the mouse began to maneuver. the sunshine within its head was activating the neurons that tell the mouse, “Wake up!” The experiment was a hit.

MIND MAPPING

Optogenetics is currently one in all the fastest-developing fields in science. By inserting the protein cistron into totally different neurons and flipping on light-weight to check what the mice do, scientists will make out what totally different neural pathways square measure dominant. “You name it—any behavior, any cognition—you will study it with optogenetics,” says Deisseroth.

By bit by bit operating through the brain one neural pathway at a time, scientists hope to form the primary finely elaborate map of the human brain. It might show U.S. however emotions, behaviors, and brain disorders return to be.

HEALING WITH light-weight

One disorder that might enjoy optogenetics is epilepsy—an incurable condition which will cause seizures (uncontrollable shaking of muscles). Epileptic seizures happen once neurons go haywire, firing their electrical signals out of management.

To regulate some severe cases of brain disorder, doctors implant electrodes within the a part of the brain that’s defective. The electrodes emit pulses of electricity that stop the neurons from firing wildly. however electrodes aren’t precise—they will zap healthy neurons along side misfiring ones. With optogenetics, doctors might treat solely the neurons that square measure defective.

People who suffer from anxiety might conjointly profit. Current medicines expose the whole brain to a treatment, which may cause undesirable aspect effects like somnolence or confusion. therefore Deisseroth’s work determined to do to find the precise neurons concerned in anxiety. They place the protein cistron into a circuit of neurons in a very mouse’s basal ganglion, a district of the brain related to worry and anxiety. Then they constituted a cable into the basal ganglion and watched what happened after they flipped the sunshine on (see illustration, right).

Mice square measure petrified of open areas, wherever they can’t hide from predators. once Deisseroth’s team placed the mouse in a very maze, it spent most of its time in a vicinity protected by high walls, sometimes gesture its scent out to explore. however after they switched on the sunshine, the mouse suddenly ventured out, exploring the open areas without worrying.

The results recommend that the team situated Associate in Nursing anxiety circuit within the brain. Someday, doctors might facilitate individuals with anxiety disorders by treating that circuit with a lot of precise medication.

TOO MUCH CONTROL?

Optogenetics might facilitate several individuals. however is manipulating the brain ethical? Some individuals worry that if scientists will management the brains of mice with light-weight, what’s to prevent somebody from dominant people’s brains against their will?

Deisseroth says current optogenetic technology isn’t nearly refined enough to form this an overseas chance. Plus, he says, the advantages so much outweigh any issues. The potential rewards square measure great: Optogenetics could also be the key to the primary refined treatments for devastating brain disorders. It might conjointly facilitate answer one in all the largest queries of all: however our brains create U.S. World Health Organization we tend to square measure.

HOW TO management A MOUSE’S MIND

Deisseroth’s work used optogenetics to shut off neurons in a very mouse’s brain that cause anxiety. Mice square measure fearful of open areas, however optogenetics will create them live through that worry. the method below shows however it works. Steps two through four show the fundamentals of all optogenetics experiments.

1. Associate in Nursing untreated mouse lingers within the corner of the maze, too afraid to explore on the far side the protected  walls.

2. The protein cistron (the opsin’s hereditary material) is far from photosensitive alga.

3. The protein cistron is inserted into a harmless virus and injected into the brain of a mouse.

4. Neurons, during this case associated with a mouse’s worry response, become conscious of light-weight. 5. Scientists shine light-weight into the mouse’s brain through a cable. The neurons answer light-weight, stopping the mouse’s worry response.


6. The mouse, not fearful of open areas, courageously explores the maze. The animal doesn't expertise anxiety.