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

Young Greeks flee abroad as crisis deepens
2015-07-03 2:28
Athens (AFP) - What does the future look like for young people in crisis-hit Greece, where years of hardship and sky-high unemployment were followed this week by bank closures? The answer: self-imposed exile. "I don't see a future in Greece," sighs Dani Iordake. The 21-year-old, who proudly sports self-styled tattoos on his arms, was forced to drop out of university to ...
Google driverless cars in accidents again, humans at fault - again
2015-07-03 2:28
San Francisco - Google's autonomous cars were once again involved in accidents while out mapping the streets of Mountain View, Calif. But in both instances, as with the dozen or so previous incidents over years of testing, humans in other vehicles were at fault, according to Google. The search company released its latest autonomous-car monthly report Wednesday, detailing two accidents in which ...
Boston University Professor Says White College Males are a Problem Population
2015-07-03 0:26
It seems like every day anti-White hate is being spewed from some hate filled professor without consequence. The trend of terrifying defamation has become unfathomable and intolerable. National Youth Front has already made a stand at ASU over their anti-White hate course entitled “The Problem With Whiteness.” Today we have continued to take a stand. Operation Grumpy Grundy was completed earlier ...
Capture the Flag: Rebels & Rainbows
2015-07-02 5:24
The White House turned into a rainbow as the Supreme Court declared same-sex marriage legal nationwide, bypassing state sovereignty. While the country is wooed with rainbow magic, have they now forgiven the government of their many trespasses? How concerned are they about human rights, while removing the Confederate flag in the south? Tearing down one symbol and lifting up another ...
Facebook looks to reduce white share of staff
2015-07-02 3:52
Facebook CEO Mark Zuckerberg has voiced a desire to transform the demographics of Facebook's employee base to better echo the company's billion-plus international users. However, Facebook's most recent diversity report revealed that white men continue to have a claim on positions at Facebook. The online social networking service claims that diversity is central to the company's mission, observing &"Our work is producing ...
More News »