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Scientists discover brain part that drives decision-making

A tiny part of the brain may be what’s behind your big decisions.

Canadian scientists say they’ve discovered that a part of the brain called the lateral habenula may help us make major cost-benefit decisions like buying a new house.

The study “suggests that the scientific community has misunderstood the true functioning of this mysterious, but important, region of the brain,” study author Dr. Stan Floresco, a behavioral neuroscientist at the University of British Columbia in Vancouver, said in a statement.

The new research was published Nov. 24 in Nature Neuroscience.

The lateral habenula is one of the smallest parts of the brain. Scientists previously linked it to depressive symptoms when they saw patients improve when the part was turned off through deep brain stimulation, a procedure where electrodes are implanted in the brain and controlled by a pacemaker.

The structure had also been thought to be involved in avoidance behavior.

Evolutionarily, the lateral habenula had been considered to be one of the oldest regions of the brain, according to the scientists -- they just might not have realized what it actually did.

In a lab experiment, scientists led by Floresco and UBC colleague Colin Stopper trained rats to pick between a task that gave them a consistent, but small reward of one food pellet or a task that took longer but could potentially give them a larger haul of four pellets.

The rats acted like people would: They tended to choose the larger rewards when the amount of time they had to wait before receiving the pellets -- the “costs” -- were low, but they picked the smaller rewards as the time lags increased.

Essentially they decided "what's better for me?" according to the researchers.

However when the scientists turned off the lateral habenula, the rats selected either option equally, no longer showing the ability to pick the best option.

That surprised the researchers, who expected the rats to choose the larger, riskier reward more often due to the previous research that has linked the brain region to avoidance behaviors.

Previous studies that found the depression benefits may have also been misinterpreted, they said. What may have been happening in those patients were changes in decision-making. 

“Our findings suggest these improvements may not be because patients feel happier. They may simply no longer care as much about what is making them feel depressed.”

It may sound surprising scientists are finding out new information about something so studied like the brain, but it’s not totally foreign for researchers to discover new functions for body parts.

In Nov., Belgian surgeons discovered a “new” ligament in the knee, the anterolateral ligament (ALL), that previously was thought to be a part of the ACL that may tear during knee injuries.

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