An overthinking brain can complicate simple tasks

Why do some people learn a new skill right away, while others only gradually improve? Whatever else may be different about their lives, something must be happening in their brains that captures this variation.

Danielle Bassett, the Skirkanich Assistant Professor of Innovation in the School of Engineering and Applied Science’s departments of Bioengineering and Electrical and Systems Engineering, and recent MacArthur Award winner, has started to answer this question by looking at the brain as a complex, dynamic network.

Along with Muzhi Yang, a graduate student in the Applied Mathematics and Computational Science Program in the School of Arts & Sciences and colleagues from Johns Hopkins University and the University of California, Santa Barbara (UCSB), she measured the connections between different brain regions as participants learned to play a simple game. Comparing the neural activity between the quickest and slowest learners suggests that recruiting unnecessary parts of the brain for a given task—akin to over-thinking the problem—plays a critical role in this difference.

Bassett’s co-authors from Hopkins and UCSB scanned the brains of study participants while they played a simple game—pressing a series of color-coded buttons in response to a pre-determined set of sequences of cues displayed on a screen. The participants returned to the scanner two, four, and six weeks later to see how well mandatory home practice sessions, remotely monitored by the researchers, had helped them to master the game.      

Some picked up the sequences immediately, while others gradually improved during the six-week period. Bassett, an expert in network science, analyzed patterns in these scans to see what might be at the root of this difference.

“We looked at the whole brain at once and saw which parts were communicating with each other the most,” she says.   

Through these comparisons, the researchers found overarching trends about how regions responsible for different functions worked together. Most striking was the way the parts of the brain associated with motor control and visual perception became increasingly independent as the participants learned the sequences.

“What we think is happening,” Bassett says, “is that they see the first few elements of a sequence and realize which one it is, then they can play it from motor memory.”

With the neurological correlates of the learning process coming into focus, the researchers could delve into the differences between participants, which might explain why some learned the sequences faster than others. The critical distinction seemed to be in parts of the brain not directly related to the task: the frontal cortex and the anterior cingulate cortex. The slower learners kept these parts of their brains active for longer.

These cognitive control centers are thought to be most responsible for making and following through with plans, spotting, and avoiding errors and other higher-order types of thinking. Those abilities are necessary for complex tasks but might actually be a hindrance to mastering simple ones.  

“It seems like those other parts are getting in the way for the slower learners. It’s almost like they’re trying too hard and overthinking it,” Bassett says.

Further research will delve into why some people are better than others at shutting down the connections in these parts of the brains, and how this dynamic influences early childhood learning, as the frontal cortex and anterior cingulate cortex are some of the last regions of the brain to fully develop in humans.

Danielle Bassett