Aging is often accompanied by memory decline and neurodegenerative diseases. While studies suggest that exercise can benefit brain function, how this happens remains unknown. To better understand the effects of physical activity on the aging brain, a group of researchers recently examined the effects of long-term running on the brains of mice.
Adult-born neurons are thought to contribute to hippocampus-dependent memory function. While they are considered temporarily important in mice between three and six weeks of age, it remains unknown whether they continue to be integrated into neural networks later on.
To understand more about how these neurons function in later life- and how exercise may affect this- the researchers examined the brains of mice split into two groups- one sedentary, and the other following a regular running regime. At the beginning of the study, they injected the mice with a rabies virus-based retrograde tracer to monitor adult-born neurons over time.
After six months- when the mice reached the equivalent of middle age'- the researchers identified and quantified differences between the previously tagged adult-born neurons within the hippocampus and subcortical areas.
They found that long-term running kept adult-born neurons wired into a network relevant for episodic memory encoding while aging.
“Long-term exercise profoundly benefits the aging brain and may prevent aging-related memory function decline by increasing the survival and modifying the network of the adult-born neurons born during early adulthood, and thereby facilitating their participation in cognitive processes,” said Henriette van Praag, Ph.D., corresponding author and an associate professor of biomedical science Florida Atlantic University, in a press release.
“We show that running also substantially increases the back-projection from the dorsal subiculum onto old adult-born granule cells. This connectivity may provide navigation-associated information and mediate the long-term running-induced improvement in spatial memory function," she continued.
The researchers noted that their findings provide insight into how regular exercise between early adulthood and middle age can maintain memory function during the aging process. The findings, they say, highlight the importance of daily exercise regimes.
Sources: Neuroscience News, eNeuro