Neurogenesis: how are new neurons created?

Neuroscience explains how our brain regenerates its stock of neurons.

It is a well-known fact that certain experiences and habits kill neurons. 

Drinking alcohol, suffering blows to the head, following an inadequate diet and a long etcetera of situations translate into losses among the neuronal population of our brain, which means that every day we could be losing a few nerve cells.

Neurogenesis: the process of neuronal regeneration

However, not everything is death and destruction in the everyday life of the typical adult human brain: the birth of new neurons also takes place, a phenomenon known as neurogenesis.

Neurogenesis, changing the conception of the brain

For many years it has been believed that the human brain is an artifact that develops during the first months of life and that, upon reaching adulthood, it stops changing. This conception of the brain left the door open to the belief that the only possible modifications in our nervous system come through the death of neurons. Obviously, a person's brain changes after the removal of a part of the neocortex, just as it is not exactly the same after having suffered a small stroke.

However, neurogenesis is a sign that the brain continues to form once a part of the neocortex has been removed. the brain continues to form once childhood is behind us.. The birth of new cells by neurogenesis, which has been proven in an area of a brain structure called the hippocampus and around the lateral ventricles filled with cerebrospinal fluid, implies that new neurons can appear at any time and after a few days they will migrate to other parts of the brain.

What is neurogenesis for?

Things that happen in the brain at the microscopic level are always very difficult to study, and the phenomenon of neurogenesis is no exception. We know that new neurons appear in adult humans, but we do not know very well in what situations they appear. we don't know very well in what situations they appear or what exactly they are used for.. However, in general terms most neuroscientists agree that the birth of new nerve cells plays a role in brain plasticity. brain plasticitythat is, the brain's ability to adapt to new experiences and change over time.

The case of neurogenesis in the hippocampus is particularly interesting in this regard. This brain structure acts as a hinge between present experiences and memory, and is therefore fundamental in the formation of memories and learning.

The birth of more neurons in this part of the brain could mean a greater capacity to link past and present, i.e. to be able to adapt better to an environment based on previous knowledge. As past experiences are predictors of the future, it is adaptive for the hippocampus to always have new neurons ready.

If brain plasticity refers to the practically infinite combinatorial possibilities with which neurons send signals to each other, neurogenesis adds more carbon to this whole succession of changes, as it it brings more neurons into play, compensating to some extent for the effects of neuronal death..

In what contexts are new neurons born?

Neurogenesis does not only affect the processing of novel experiences: it is also subject to the changes that the organism undergoes in real time. Some situations enhance the birth of neurons, while others put the brakes on it. Of course, it is very difficult to define exactly which situations facilitate neurogenesis and which do not, since the infinite number of experiences that each of us may have and the individual differences that exist between us complicate this study.

However, in general terms, it can be said that stress, sedentary life and sleep deprivation reduce the appearance of neurons, while the practice of voluntary exercise, exposure to cognitively stimulating environments and in general, goal-oriented behaviors enhance neurogenesis.

Tips for enhancing neurogenesis

All this, translated into daily life, means that to boost neurogenesis in your hippocampus you should:

• Sleep well and enough hours so as not to feel tired the rest of the day.
• Do moderate exercise and, in general, keep boredom at bay. Neurogenesis seems to be oriented towards adaptive purposes, so try to set realistic and interesting goals.
• Do not expose yourself to more sources of stress than you can bear and try not to let it get to you too much. You can try meditation.

These are simple steps and relatively easy to follow. The complicated things will be taken care of by your brain's automatic processes..

Bibliographical references:

• Hanson, Nicola D.; Owens, Michael J.; Nemeroff, Charles B. (December 1, 2011). "Depression, Antidepressants, and Neurogenesis: A Critical Reappraisal". Neuropsychopharmacology.
• Rakic, P (October 2009). «Evolution of the neocortex: a perspective from developmental biology.». Nature reviews. Neuroscience.