There’s no denying the pre-pubescent penchant for shenanigans. But how our developing brains grow by making us make stupid decisions is still up for debate.
Researchers have speculated that the adolescent brain eventually gets better at suppressing those cravings for stupid acts. But now a study on primates suggests that the brain can mature by getting better at forming alternative strategies.
By examining patterns of brain activity in male macaques before and after puberty, researchers found that their adult brains make smart choices not by suppressing foolish urges, but by getting better at forming wise, purposeful plans. The findings, published in the Proceedings of the National Academy of Sciencesmay provide insight into the treatment of patients struggling with social and mental health problems due to cognitive immaturity, the authors suggest.
For the study, the monkeys underwent a standard antisaccade task, commonly used in humans to test the brain’s ability to suppress reflexive jerks from both eyes — a saccade — to new visual cues. The monkeys were trained to focus on a green dot on a screen and not look at a distracting white square that would appear. Wherever the square appeared, the monkeys had to look in the opposite direction, suppressing the desire to look at the forbidden cue. In other words, if the white square appeared to the left of the green point, the monkeys had to briefly move their eyes to the right.
Suppressing the urge to peek at what you shouldn’t be looking at takes some mental skill and impulse control. For diabolically prepubescent people, who don’t have a fully developed prefrontal cortex (the front of the brain involved in decision-making), this is a tough test. But adults can usually manage.
In the study, the researchers found that the monkeys were the same. When they tested the primates before they hit puberty, they averaged an F — successfully looking away from the white square only about 57 percent of the time. When the researchers tested the same monkeys again in adulthood, they fared better, bringing their average score to 80 percent.
When the researchers analyzed how neurons in the prefrontal cortex of young and adult monkeys fired during the tests, they found clear patterns that could explain what changed. While the neural circuits of both young and adult monkeys lit up when the distracting signals appeared, the adults seemed to have brighter basal brain activity associated with the goal of focusing on the green dot.
So, the authors concluded, it wasn’t that the adult apes suppressed a childish mental response to ogle at the forbidden white square, but that they had formed a stronger mental determination to stay on task and stare at the green dot. before the distraction appeared.
While it’s still possible that other matured brain regions contributed to the improved test scores, and brain development may be different in humans, the researchers hope the finding could help understand and treat patients suffering from impaired cognitive maturity. .
Proceedings of the National Academy of Sciences2015. DOI: 10.1073/pnas.1518147113 (About DOIs).