Neurogenesis: Benefits and Risks

While neurogenesis may have risks, it is beneficial to many because it boosts learning and memory, can alter stress response and emotions, and can help with rehabilitation of neurological disorders.

What is Neurogenesis?

Neurogenesis is known as the body’s ability to replicate neurons in the brain and spinal cord. Many researchers believed this only occurred in prenatal embryos. Scientists now realize this process can also occur in the adult brain. They are not sure how neurons can replicate and reintegrate into the circuits of the brain. Only a few areas of the brain can replicate neurons while most areas cannot. The three areas of the brain that can replicate neurons are the subventricular zone of the lateral ventricles, the dentate gyrus of the hippocampus, and the amygdala.

How Neurogenesis Works

Neurogenesis starts with a special neuron called a neurological stem cell. This stem cell can die off, become a neuron support, or begin the process to neurogenesis.

Neurogenesis occurs with changes that happen in the synapse of a neuron. The synapse is the space between an axon terminal and the dendrites where electrical signals travel. Synaptic plasticity is what helps the neurons integrate into the brain circuits.

The first stage is proliferation (aka mitosis) where the cell creates more neural tubes. The second stage is differentiation where the neuron develops a unique structure from other neurons. The third stage is migration where the immature neuron moves to its permanent location. The fourth stage is maturation where the neuron’s axon and dendrites develop and integrate. The fifth and final stage is synaptic integration where neurons connect to the brain circuits to start sending signals.

How to Stimulate Neurogenesis

Neurogenesis can be stimulated by everyday activities to a certain degree. Activities that can encourage and increase neurogenesis are diet, exercise, learning, meditation, and psychoactive substances. Healthy fats, such as the Omega 3’s, are important for brain function. Aerobic exercise increases growth hormones which are important for neurogenesis. Learning new skills, languages, and intellectually challenging yourself can be a stimulant for neurogenesis. Meditation can increase grey matter density which is valuable for neurogenesis. Psychoactive substances like mushrooms, cannabis, and some anti-depressants have shown to be beneficial to the brain and increase neurogenesis. All of these actions can play an important role in stimulating neurogenesis.

How Neurogenesis Affects Psychiatric Disorders

The hippocampus is a structure in the brain that controls many functions. It plays a significant part in psychiatric and neurological disorders. It also affects learning and memory. Studies have shown disorders such as major depression, schizophrenia, anxiety disorders, PTSD, and addiction have all shown decreased neuron count and density. For these diagnosis’s, doctors normally treat the patients with anti-depressants, anti-psychotics, and increasing exercise. These drugs as well as exercise have been known to increase neurogenesis. Genetics can also influence neurogenesis. This may explain why many psychiatric disorders are believed to have a genetic predisposition. Neurogenesis may soon be a key treatment in the future for psychiatric patients that have a decreased neuron count.

How Neurogenesis Affects Neurological Disorders

Diseased neurons are typically the culprit in neurological disorders. These diseased neurons are unable to transmit messages between each other. In neurogenesis, new neurons are able to reintegrate into the brain and make new connections. Some diseases experience early symptoms that then lead to the major symptoms. Pre-disease symptoms for Parkinson’s, Huntington’s, and Alzheimer’s, can include depression, anxiety, and cognitive or olfactory disfunction. These functions come from the same part of the brain where neurogenesis generally takes place. It is possible that decreased neurogenesis could be a possible cause to some of these symptoms. Many believe stimulating neurogenesis could help overcome neurological disorders in the future.

How Neurogenesis Affects Memory and Learning

If neurogenesis does not occur, memory encoding may encode in a way that disrupts previous memories. For example, episodic memory storage occurs in the hippocampus. Episodic memories are long term memories of personal recollections. These episodic memories have been locked up and unable to be recollected due to diseased neurons unable to transmit messages. This explains why individuals with Alzheimer’s may forget who their close family members are and of what importance they are.

“Mice housed in an enriched environment for 8 weeks showed promoted hippocampal neurogenesis concurrent with better performance in learning and short-term memory” (Yau, S. Y. Et. al.).

Risks of Neurogenesis

Research has found some risks to neurogenesis. Although neurogenesis has improved functions in some areas of the brain, that is not the case for all animals. Some animals increase spatial learning with neurogenesis while others do not. Results seem to vary among these animals. Animals that did not receive increased neurogenesis were able to recognize patterns better than those that did. This is surprising, given what is already known about the benefits of neurogenesis. In some research, neurogenesis resulted in inappropriate migration, differentiation, and integration which caused prolonged seizures. These examples show that neurogenesis may not always be the best option.

Neurogenesis is somewhat of a new idea that shows some good benefits to humans. There is research that supports this. However, there is also research that shows there may be risks involved with neurogenesis. It is definite that more research needs to be conducted concerning neurogenesis. There are positive signs that neurogenesis may play a more important role in treating humans in the future.

References

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Kang, B., Wen, Z., Hongjun Song, H., Christian, K. M., Ming, G. (2016). Adult neurogenesis and psychiatric disorders. Cold Spring Harbor perspectives in biology. https://cshperspectives.cshlp.org/content/8/9/a019026.full.pdf+html

Scharfman, H. E., & Hen, R. (2007). Neuroscience. Is more neurogenesis always better?. Science (New York, N.Y.). https://doi.org/10.1126/science.1138711 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2041961/

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(2018). 5 ways to boost your neurogenesis. Neurotracker. https://www.neurotrackerx.com/post/5-ways-to-boost-your-neurogenesis