High Mental Performance Demands Flexible Brain Activity
In high-performing older adults, brain activity increases with the difficulty of the task
According to a recently published study by the Max Planck Institute for Human Development, high mental performance requires that brain activity be adjusted to the difficulty of the task, a conclusion that applies equally to younger and older adults. In both age groups, participants whose brain activity increased as the difficulty of tasks rose achieved better performance than those whose brain activity levels held steady or declined. “The differences in adjustment of brain activity to the difficulty of the task were especially large among older adults. Future research should try to uncover the causes of these differences,” psychologist Irene Nagel recommends (PNAS, Vol. 106, pp. 22552–22557, 2009).
Show me whether your brain’s level of task-related activity increases with the difficulty of a challenge, and I’ll tell you how well you perform. That was the result of a study recently published in the Proceedings of the National Academy of Sciences (PNAS) by the Max Planck Institute for Human Development in Berlin. The study examined the differences in cognitive performance among younger and older adults. Psychologist Irene Nagel and an international team of researchers headed by Hauke Heekeren and Ulman Lindenberger used functional magnetic resonance imaging (fMRI) to observe brain activity levels in 30 younger (20–30 years) and 30 older (60–70 years) study subjects. Participants were supposed to memorize spatial patterns of differing levels of difficulty while undergoing MRI and recall them a short time later, a task that draws on a person’s visual and spatial working memory. Based on the fMRI images, the team of researchers was able to determine which areas of the brain were activated to perform these tasks, and how brain activity changed as the difficulty of the task varied.
Differences between individuals – especially with increasing age
The brain’s working memory capacity varies from person to person. Over the course of an adult’s life, these differences become more pronounced, because some people experience a sharper decline in performance than others. In previous fMRI studies, these differences had often been overlooked, since the results were generally averaged out among all of the people in a single age group.
It was precisely these previously neglected differences between individuals that Nagel and the team of researchers aimed to study. They used the correctness of subjects’ answers to determine their performance and investigate how adjustment of brain activity levels to the difficulty of a particular task varied between those with high performance and those who fared less well.
The outcome showed that among test subjects with high performance, brain activity rose as tasks became more difficult – regardless of age. The differences in brain activity levels with regard to performance were especially pronounced among older adults, meaning that older subjects with high performance showed increasing levels of brain activity as tasks became more difficult, like younger adults. Older adults with lower performance, by contrast, often showed decreasing brain activity, especially when faced with the most difficult tasks. The researchers at the Max Planck Institute for Human Development are currently conducting further studies to discover the causes of these differences.
Differences in brain activity: one key to maintaining mental abilities in advanced age
Under what conditions can mental performance capabilities be maintained in advanced age? The results of the newly published study show that high-performance brains of older adults work similarly to those of younger adults. “The similarities in the activation patterns between older and younger adults with high working memory performance provide us with initial clues as to how we may be able to preserve cognitive abilities over our adult lives,” Nagel says.
Nagel, I. E., Preuschhof, C., Li, S.-C., Nyberg, L., Bäckman, L., Lindenberger, U., & Heekeren, H. R. (2009). Performance level modulates adult age differences in brain activation during spatial working memory. Proceedings of the National Academy of Sciences of the United States of America, 106, 22552–22557.