Breaking habits with a flash of light
2012-10-30 0:00

By Ed Yong | DiscoverMagazine.com



In a lab at MIT, a rat enters a T-shaped maze, hears a tone, and runs down the left arm towards a piece of chocolate. It’s a habit. The rat has done the same thing over so many days that once it hears the tone, it’ll run in the same direction even if there’s no chocolate to be found. Humans are driven by similar habits. Every morning, I hear my alarm go off, put some clothes on, and shamble into the kitchen to brew some coffee.

Habits, by their very nature, seem permanent, stable, automatic. But they are not, and the MIT rat tells us why. Earlier, Kyle Smith had added a light-sensitive protein to one small part of its brain – the infralimbic cortex (ILC). This addition allows Smith to silence the neurons in this one area with a flash of yellow light, delivered to the rat’s brain via an optic fibre. The light flashes for just three seconds, and the habit disappears. The rat hears the tone, but no longer heads down the chocolate arm.

The experiment shows that even though habits seem automatic, they still depend on ongoing supervision from the ILC and possibly other parts of the brain. They’re ingrained and durable, but subject to second-by-second control. And they can be disrupted in surprisingly quick and simple ways.

“We were all stunned by how immediate and on-line these effects really are,” says Smith. “Changing the activity of this small cortex area could profoundly change how habitual behaviour was, in a matter of seconds.”

By cutting out bits of a rodent’s brain, or inactivating them with chemicals, other scientists had already identified parts of the brain, including the ILC, that are important for habits. But these are somewhat clumsy methods. Smith’s team wanted some more refined, something that could inactivate the ILC on demand for short bursts of time.

They turned to optogenetics. This revolutionary technique takes light-sensitive proteins from around the tree of life, and uses viruses to introduce them into an animal’s neurons. By choosing the right protein, and targeting the right part of the brain, scientists can now excite or silence a chosen group of neurons with astounding precision, using little more than flashes of coloured light.

Working with supervisor Ann Graybiel and optogenetics founder Karl Deisseroth, Smith filled his rats’ ILCs with halorhodopsin – a protein that comes from salt-loving microbes, and silences neurons when hit by yellow light.

Smith then trained rats to run down one arm of his T-shaped maze towards some chocolate, or down the other towards a sugary drink. One tone set them off, and a second one told them which arm to run down. After days of practice, the habits became ingrained. Even when Smith started “devaluing” one of the rewards by lacing it with a nauseating chemical, the rat would still run towards it the next time it was tested, even if it didn’t drink. That’s a habit – a behavioural reflex. The tone sets off a chain of actions, regardless of what the rat gets out of them.


[...]


Read the full article at: discovermagazine.com







Optogenetics (2010)






Related Articles


Latest News from our Front Page

Gunman Storms Dutch TV Station Demanding Airtime
2015-01-30 23:32
Dutch authorities have released few details about the bizarre case of 19-year-old Tarik Zahzah’s attack on the main news studio of television station NOS on Thursday. To get the obvious question out of the way first, the police say there is no evidence that Zahzah, who is half-Egyptian, acted on behalf of organized terrorism. The authorities always say that on the ...
How Alan Dershowitz bullied rape victims to protect a serial child molester
2015-01-30 23:40
Harvard law professor Alan Dershowitz always felt children were fair game for Israeli missiles. Now the question is whether he thinks they are fair game for the sexual exploits of his powerful associates and himself. Dershowitz and the UK’s Prince Andrew were accused in a recent court filing of raping a teenage girl who was forced into sexual slavery by ...
Alchemical Banksters
2015-01-30 22:39
This past week, the world's preeminent vultures, the economic power elite, met in Davos to discuss the maintenance of their global fiat hegemony. Highlights included furthering austerity, noting that the serf class can't have air conditioning and cars, as well as cheering on the death of privacy through the rise of technocracy. The degenerate elite, completely out of touch with ...
Men must prove a woman said ’Yes’ under tough new rape rules
2015-01-30 4:54
New guidance will be issued to all police forces and prosecutors as part of a ’toolkit’ to move rape investigations into the 21st century Men accused of date rape will need to convince police that a woman consented to sex as part of a major change in the way sex offences are investigated. The Director of Public Prosecutions said it was ...
4 beheaded in Saudi Arabia less than a week into King Salman's rule
2015-01-30 3:13
Comment: So when will the the "Human rights" promoting liberal west elite decide invade Saudi Arabia like they did Libya? Members of Magic Movement stage a mock execution scene in protest of Saudi Arabia beheading of eight Bangladeshi workers in October 2011. Four people have been executed in Saudi Arabia less than a week after 79-year-old King Salman assumed power following the ...
More News »