Habits are controllable – more than we knew

The power of habit

Habits are repetitive behaviours that we do without thinking, and they’re an important asset in getting things done effectively. We use habits all day long, mostly without even being aware of it, such as driving a regular route, performing routine duties at work, cooking a meal we prepare often, household cleaning and personal hygiene. These repetitive actions are a valuable addition to our ways of getting things done, but sometimes we form some that don’t serve us well, such as smoking, drinking too much alcohol, taking drugs, or watching too much television without being selective.

We sometimes only realise the power of habit when we choose to make some personal changes by altering ourĀ habits. That’s when we find the power of habit is greater than we might have realised, and what was formerly seen as an asset shows that it can also be a liability.

Breaking habits

Are our actions so hard-wired that we cannot change? Obviously there are times when it seems to be the case, but usually, if we put our minds to it, we can break some repetitive procedures that are damaging. It takes will power and determination, but habits are not impossible to break (just sometimes very, very difficult!).

And sometimes they are really damaging. There’s the obvious culprits of smoking and drinking to excess, and also over-eating, but there’s also habitual actions such as the entirely pointless habit of pulling out your own hair and eating it (trichotillomania), scratching at your skin or cutting it (‘self-harming’), and performing actions that put the spine at risk without taking care to adopt a healthy posture. The slight pain you might get from bending to pick up a heavy box hardly warns you adequately that you are, in fact, endangering your spine, unless you’re very observant of such things.

A new study by neuroscientists at MIT has found that a small part of the prefrontal cortex is responsible for ‘switching’ habits on or off.

“We’ve always thought – and I still do – that the value of a habit is you don’t have to think about it. It frees up your brain to do other things,” says Institute Professor Ann Graybiel, a member of the McGovern Institute for Brain Research at MIT. “However, it doesn’t free up all of it. There’s some piece of your cortex that’s still devoted to that control.”

The research gives new hope to those close to despair in trying to kick a bad habit, says Graybiel, senior author of the new study, which appears in the Proceedings of the National Academy of Sciences. It shows that even though some actions may be deeply entrenched, the brain can still intervene and change things. It raises the possibility that in the future, the technology might exist by which we can physically change bad habits – particularly important in cases of damaging compulsive behaviours (such as the earlier mentioned trichotillomania, for example).

How to break habits – an experiment

To simulate such compulsive behaviour in their research methods, researchers trained laboratory rats to take a particular turn in a maze in order to receive a treat (chocolate milk). Once the action became ingrained, the treat was discontinued, but the rats kept habitually turning at the same junction. The researchers went further, making the chocolate milk available in the rats’ cages, but this time laced with lithium chloride, which causes light nausea. The rats still kept to the route they’d learned by habit, but stopped taking the chocolate milk treat.

At this point, knowing that the repetitive action was well and truly ingrained, the researchers wanted to see if it were possible to alter it by interfering with a part of the prefrontal cortex known as the infralimbic (IL) cortex. Although it appears that habit forming takes place deep in the brain, it is known that the IL cortex is also necessary for such behaviors to develop.

The researchers used optogenetics, a method that allows them to inhibit specific cells with light, and were able to turn off IL cortex activity for several seconds as the rats approached the junction. The rats almost immediately stopped turning the old habitual way (where once they had found the reward), suggesting that with the IL cortex disabled, the brain could turn once again to a more thoughtful approach, and make decisions based on logic rather than habit.

The rats formed a new discipline, of running in the opposite direction from the old ‘treat’ route, but this too was upset by the use of the optogenetic technique, and the rats readily assumed their old habit of heading in the direction where they’d been trained to run, towards the treat.

“This habit was never really forgotten,” Kyle Smith, a McGovern Institute research scientist says. “It’s lurking there somewhere, and we’ve unmasked it by turning off the new one that had been overwritten.”

The reseach findings suggest that the IL cortex determines, moment-by-moment, which habitual behaviors will be followed.

“To us, what’s really stunning is that habit representation still must be totally intact and retrievable in an instant, and there’s an online monitoring system controlling that,” Graybiel says.

Jane Taylor, a professor of psychiatry and psychology at Yale University, who was not part of the study, gave her comments on the findings: “We’ve always thought of habits as being inflexible, but this suggests you can have flexible habits, in some sense.”

The infralimbic cortex favours new habits

It also appears that the IL cortex favours new habits over old ones, consistent with previous studies showing that when habits are broken they are not forgotten, but replaced with new ones. A point worth keeping in mind when you’re busy trying hard to replace an old bad habit with a new, better one.

At this stage, it would be virtually impossible to use optogenetics on humans, since it is such an invasive technique, but with advancing technology it might one day provide an option by which to treat damaging and compulsive behaviours.

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