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It was once thought that, in adulthood, the brain stops growing new neurons. It has since been discovered that this is not the case; adult brains can grow new neurons in a process called neurogenesis. While there is still much to be discovered about this phenomenon, a particular area of interest in this field is neurogenesis in the hippocampus, the part of the brain responsible for learning and memory.

 Neurons with an active synapse in the brain

Image source: Maciej Frolow

Research on different mammalian species has shown that environmental factors can influence the rate of neurogenesis in the hippocampus, and this is associated with changes in behavior and cognition. In a recent review article, Princeton University scientists Maya Opendak and Elizabeth Gould discussed the research that has been done on this subject.

The environment can influence hippocampal neurogenesis in various ways. Stressful events, such as sleep deprivation and social defeat, suppress neurogenesis. This is associated with worsened performance on hippocampus-related cognitive tasks and an increase in hippocampus-related anxiety-like behaviors. Rewarding events, such as mating and exercise, increase neurogenesis, which is associated with enhanced cognitive performance and decreased anxiety-like behaviors.

While it is known that the environment can have a significant impact on the brain, the functional significance of newly formed neurons is not yet fully understood. However, it has been suggested that neurogenesis in the adult hippocampus may help animals adapt to their environment. Increased neurogenesis brought on by a rewarding environment could lead to more learning and exploring in that environment, thus increasing reproductive success. Decreased neurogenesis and increased anxiety due to a stressful environment could discourage exploration in that environment, thus aiding survival. Prolonged stress, however, is maladaptive and can lead to depressive symptoms and more anxiety.

The researchers stressed that these results are often obtained in laboratory settings, and in order to have a more complete understanding of the relationship between neurogenesis and the environment, it is necessary to conduct research in more natural environments that better represent the complexity of the wild.

The findings discussed are significant because they give us a better understanding of how our daily experiences shape our brains and suggest that we can make positive changes, such as managing stress and being more physically active, to better our well-being.

Feature Image Source: stress by disenoterapia

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