Rejuvenating the Brain With Chronic Exercise Through Adult Neurogenesis

TLDR

Aging reduces hippocampal neurogenesis and delays new neuron development, diminishing brain plasticity. The study aims to determine whether exercise‑induced neurogenic benefits persist over time and affect neurons generated across extended periods. The authors compared long (3–4 weeks) versus short (1 week) voluntary running on 3‑week‑old neurons, observing accelerated development only with prolonged exercise. Long‑term voluntary running accelerates maturation of 3‑week‑old neurons, with effects lasting up to three months and persisting across cohorts born during the exercise period, but not on neurons born after exercise cessation, leading to rapid integration and potentially more complex neural networks.

Abstract

The aging brain presents a general decline in plasticity that also affects hippocampal neurogenesis. Besides the well-known reduction in the rate of neuronal generation, development of new neurons is largely delayed in the aging brain. We have recently shown that this slow development is accelerated when middle-aged mice perform voluntary exercise in a running wheel. It is unclear whether the effects of exercise on neurogenic plasticity are persistent in time in a manner that might influence neuronal cohorts generated over an extended time span. To clarify these issues, we examined the effects of exercise length in three-week-old neurons and found that their development is accelerated only when running occurs for long (3–4 weeks) but not short periods (one week). Furthermore, chronic running acted with similar efficiency on neurons that were born at the onset, within, or at the end of the exercise period, lasting until 3 months. Interestingly, no effects were observed on neurons born one month after exercise had ended. Our results indicate that multiple neuronal cohorts born throughout the exercise span integrate very rapidly in the aging brain, such that the effects of running will accumulate and expand network assembly promoted by neurogenesis. These networks are likely to be more complex than those assembled in a sedentary mouse due to the faster and more efficient integration of new neurons.