Adult-born neurons are believed to play a role in memory function and exhibit enhanced synaptic plasticity during a critical period between three to six weeks of age. However, it remained unclear whether neurons generated in early adulthood remain integrated into neural networks and whether their circuitry can be influenced by physical activity in middle age.
To answer these questions, researchers utilized a unique approach involving the use of a rabies virus-based circuit tracing method. They examined the neural circuitry of adult-born neurons in middle-aged rodents several months after the initial labeling process.
The study, published in the journal eNeuro, uncovered that long-term running establishes connections among adult-born neurons generated in early adulthood, forming a network crucial for the maintenance of episodic memory encoding during aging.
Henriette van Praag, Ph.D., an associate professor at FAU’s Schmidt College of Medicine and a member of the FAU Stiles-Nicholson Brain Institute, emphasized the profound benefits of long-term exercise on the aging brain. She explained that running substantially increases the back-projection from the dorsal subiculum onto old adult-born granule cells, which may provide navigation-related information and mediate the improvement of spatial memory function.
In addition to increasing the number of adult-born neurons, long-term running also enhances the involvement of presynaptic (sub)-cortical cells in their network. This improved connectivity rescues perirhinal connectivity and increases the contribution of the entorhinal cortices to the network of old adult-born neurons.
Carmen Vivar, Ph.D., from the Department of Physiology, Biophysics, and Neuroscience at Centro de Investigacion y de Estudios Avanzados del IPN in Mexico, highlighted that long-term running might improve pattern separation ability, which is closely linked to adult neurogenesis. Pattern separation ability is crucial for distinguishing between similar events or stimuli and is one of the cognitive functions that show early deficits indicative of age-related memory decline.
Overall, the study emphasizes the importance of regular exercise, starting in early adulthood and continuing throughout middle age, for maintaining memory function as individuals age. It underscores the relevance of incorporating exercise into our daily lives to preserve cognitive health and enhance memory performance as we grow older.