by Shirley Johanna on  August 29, 2016 at 7:07 PM Research News
How the Brains can Accurately Track Distribution of Probabilities
The brain constantly combines complicated observations from the surroundings into a simple assessment of the situation that aids our behavior and decisions, says a new research.

"Our implicit computations are so much better than our explicit computations," said study co-author Kenneth Norman, Professor of Psychology at Princeton University in the US.

The researchers found that our brains could accurately track the likelihood of several different explanations for what we see around us.

They traced these abilities to a region of the brain located just behind our eyes known as the orbitofrontal cortex.

To study these implicit computations, the team tracked the brain activity of participants as they explored a virtual "safari park" split into four zones -- blue, green, pink and yellow.

Each zone contained a different assortment of elephants, giraffes, hippos, lions, and zebras. The task forced the brain to use previous observations of these animals to decide in which colored zones various arrangements of the animals were likely to be found.

First, participants saw a series of pictures of the animals in each zone -- a collection of 30 to 40 animals shown one after the other.

After getting a sense of how the animals were distributed across the different zones, the participants viewed a new series of animal pictures that showed between one and six animals.

They were asked which of two zones the animals were more likely to have come from. Participants were consistently able to correctly choose the more likely of the two zones.

What is more, participants' accuracy did not suffer when choosing between two zones which were not the most likely overall, indicating that they could track the relative likelihood of all four zones.

To find out where the brain performs this feat, the researchers had participants perform the task while undergoing functional magnetic resonance imaging (fMRI), which reveals the regions of the brain that are most active at a given time.

The researchers expected the brain to track the situation as a series of four probabilities -- one for each zone -- so they looked for brain regions in which the pattern of activity changed together with the four probabilities.

The best match for this search was the orbitofrontal cortex, a brain region implicated in carrying out complex plans, learning how a setting or situation has changed since last seen, and high-order thinking.

The findings were published in the Journal of Neuroscience.

Source: IANS

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