Scientists decode how brain updates goals based on new info

Washington: Scientists have identified mechanisms that govern how the brain incorporates information about new situations into our existing goals.

Using brain scans of human volunteers, researchers at the Princeton Neuroscience Institute (PNI) found that updating goals takes place in a region known as the prefrontal cortex, and appears to involve signals associated with the brain chemical dopamine.

When the researchers used a magnetic pulse to interrupt activity in that region of the brain, the volunteers became unable to switch to a new task when playing a game requiring them to push a button after seeing letters pop up on a screen.

"We have found a fundamental mechanism that contributes to the brain`s ability to concentrate on one task and then flexibly switch to another task," said researcher Jonathan Cohen.

"Impairments in this system are central to many critical disorders of cognitive function such as those observed in schizophrenia and obsessive-compulsive disorder," he said in a statement.

Researchers also explored the theory that dopamine - a naturally occurring chemical involved in motivation and reward among other brain functions - tags new information entering the prefrontal cortex as important for updating working memory and goals.

Cohen and his team imaged a brain region called the midbrain, which contains clusters of nerve cells called dopaminergic nuclei that are the source of most of the dopamine signals in the brain.

Researchers probed the activity of these dopamine-releasing cells in the brains of volunteers engaged in the game described above.

They found that the brain activity in these areas correlated both with the activity in the right prefrontal cortex and with the ability of the volunteers to press the correct buttons.

"The remarkable part was that the dopamine signals correlated both with the behaviour of our volunteers and their brain activity in the prefrontal cortex," Cohen said.

"This constellation of findings provides strong evidence that the dopaminergic nuclei are enabling the prefrontal cortex to hold on to information that is relevant for updating behaviour, but not information that isn`t," Cohen added.

The study was published in the journal Proceedings of the National Academy of Sciences (PNAS).


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