HEALTH NEWS

Study Title:

How the Aging Brain Can Use Experience to Its Advantage

Study Abstract

Some older individuals seem to use compensatory mechanisms to maintain high-level performance when submitted to cognitive tasks. However, whether and how these mechanisms affect fronto-striatal activity has never been explored. The purpose of this study was to investigate how aging affects brain patterns during the performance of a lexical analog of the Wisconsin Card Sorting Task, which has been shown to strongly depend on fronto-striatal activity. In the present study, both younger and older individuals revealed significant fronto-striatal loop activity associated with planning and execution of set-shifts, though age-related striatal activity reduction was observed. Most importantly, while the younger group showed the involvement of a “cognitive loop” during the receiving negative feedback period (which indicates that a set-shift will be required to perform the following trial) and the involvement of a “motor loop” during the matching after negative feedback period (when the set-shift must be performed), older participants showed significant activation of both loops during the matching after negative feedback period only. These findings are in agreement with the “load-shift” model postulated by Velanova et al. (Velanova K, Lustig C, Jacoby LL, Buckner RL. 2007. Evidence for frontally mediated controlled processing differences in older adults. Cereb Cortex. 17:1033–1046.) and indicate that the model is not limited to memory retrieval but also applies to executive processes relying on fronto-striatal regions.

From press release:

The brains of older people are not slower but rather wiser than young brains, which allows older adults to achieve an equivalent level of performance, according research undertaken at the University Geriatrics Institute of Montreal by Dr. Oury Monchi and Dr. Ruben Martins of the University of Montreal.

"The older brain has experience and knows that nothing is gained by jumping the gun. It was already known that aging is not necessarily associated with a significant loss in cognitive function. When it comes to certain tasks, the brains of older adults can achieve very close to the same performance as those of younger ones," explained Dr. Monchi. "We now have neurobiological evidence showing that with age comes wisdom and that as the brain gets older, it learns to better allocate its resources. Overall, our study shows that Aesop's fable about the tortoise and the hare was on the money: being able to run fast does not always win the race -- you have to know how to best use your abilities. This adage is a defining characteristic of aging."

The original goal of the study was to explore the brain regions and pathways that are involved in the planning and execution of language pairing tasks. In particular, the researchers were interested in knowing what happened when the rules of the task changed part way through the exercise. For this test, participants were asked to pair words according to different lexical rules, including semantic category (animal, object, etc.), rhyme, or the beginning of the word (attack). The matching rules changed multiple times throughout the task without the participants knowing. For example, if the person figured out that the words fell under the same semantic category, the rule was changed so that they were required to pair the words according to rhyme instead.

"Funny enough, the young brain is more reactive to negative reinforcement than the older one. When the young participants made a mistake and had to plan and execute a new strategy to get the right answer, various parts of their brains were recruited even before the next task began. However, when the older participants learned that they had made a mistake, these regions were only recruited at the beginning of the next trial, indicating that with age, we decide to make adjustments only when absolutely necessary. It is as though the older brain is more impervious to criticism and more confident than the young brain," stated Dr. Monchi.

Study Information

Ruben Martins, France Simard, Jean-Sebastien Provost, and Oury Monchi.
Changes in Regional and Temporal Patterns of Activity Associated with Aging during the Performance of a Lexical Set-Shifting Task.
Cereb. Cortex
2011 August
University of Montreal.