Duke University Medical Center researchers have discovered the brain region that automatically watches for patterns in sequences of events.
In an article posted online April 8, 2002 in Nature Neuroscience, researchers Scott Huettel, Beau Mack and Gregory McCarthy reported experiments in which they asked subjects to watch simple random sequences of a circle or a square flash onto a screen. During the experiments, the scientists imaged the subjects’ brains using high-resolution functional MRI (fMRI), enabling high-resolution mapping of blood flow to a particular region, triggered by increased activity of the brain cells in that region.

“We simply asked the subjects to press a button in their left hand when they saw a circle, and the right hand for a square,” said Huettel. “We purposely
kept the experiment very simple.

“Then, in analyzing brain activity during those responses, we took advantage of the fact that when you present a large number of random events, some of the time there will be short patterns, like a series of circles or a sequence of alternating circles or squares,” he said. “We concentrated on discovering whether the subjects’ brain activity in the prefrontal cortex changed when these occasional patterns were violated, as when a square would appear after a series of circles, or an alternating circle-square pattern would be disrupted.

“And even though our subjects knew they were seeing random sequences, and they didn’t behave in any explicit way when they saw these occasional patterns, their brains still reacted when the patterns were violated. So, their brains couldn’t help but look for these patterns,” said Huettel.

What’s more, he said, in behavioral studies, the subjects generally showed increased reaction time to violations of longer patterns. This finding confirmed the fMRI results revealing that the subjects were, indeed, perceiving patterns in the sequences.

“These findings suggest that the prefrontal cortex is really actively and dynamically processing information about the environment,” he said. “It’s preparing the organism to change its behavior in response to something that’s happening, not just passively rehearsing.”

Further studies, said Huettel, will seek to map how the prefrontal cortex interacts with other areas of the brain in processing such information. According to Huettel, the scientists’ findings reveal how brain functions that evolved to cope with the natural world might not be optimal in today’s technological environment.

Compulsive pattern-perception evolved to enable humans in the natural world to escape danger, but it today’s artificial world, it may lead to maladaptive superstitions such as the gambler’s belief that a pair of dice is “due” to roll a seven, the researchers said.

Perceiving patterns in random series: dynamic processing of sequence in prefrontal cortex,
S A Huettel, P B Mack & G McCarthy, Nature Neuroscience, 8 April 2002, DOI:10.1038/nn841