Study reveals that ageing affects brain dynamics, although not all changes have impact on cognitive functioning
The scientific article was published in the prestigious journal "eLife"
English version by Diana Taborda
A study conducted by the University of Coimbra (UC) and published in the prestigious journal eLife, reveals that not all changes in the brain caused by ageing affect cognitive performance. The brain changes significantly as we age, but some of those changes may not be relevant to its functioning.
The study – conducted by Maria Ribeiro and Miguel Castelo-Branco, researchers of the Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), ICNAS, and the Faculty of Medicine of the UC – shows that “an older brain presents a brain activity dynamics quite different from the one of a younger brain, with a decrease in the spontaneous fluctuations of neuronal activity, although this difference is not linked with a cognitive loss.”
According to both authors of the study, “Our brain never stops. Even when we are resting, our brain activity shows a lot of fluctuations. Periods of intense brain activity are followed by periods of lower activity, changing from one neuronal network to another, in a constant motion. This is called spontaneous brain activity.”
In other words, Maria Ribeiro and Miguel Castelo-Branco add that “with ageing, our spontaneous brain activity tends to become more stable. The brain activity pattern of older people suggests lower oscillations of neuronal activity and a decrease in the spontaneous activation of neuronal networks that include different distant areas of the brain. On the other hand, from a behavioural point of view, older people find it more difficult to keep a stable performance, i.e., when they repeat the same task over time, responses tend to vary more. This seems to be associated with a worse cognitive performance and is a predictor of cognitive decline and brain pathology associated with dementia.”
How can a more stable brain activity in older people be associated with a more unstable behavioural performance? This was the dilemma approached in the study. UC scientists compared brain activity patterns of older people with the brain patterns of young adults and studied the “connection between spontaneous brain activity and neuronal responses while the participants performed cognitive tasks.”
That was when they observed “a dissociation between spontaneous brain activity – which works as the background for all that happens in our brain – and the brain activity induced during cognitive performance. Although older people have a less variable spontaneous brain activity, their brain activity associated with cognitive performance shows the same level of variability as young adults.”
The scientific article is available at: https://elifesciences.org/articles/75722.