Until about twenty years ago, the prevailing theory was that the brain stops generating new neurons once it reaches maturity. Now neurologists believe that the brain has some ability to create new neurons, in a process called neurogenesis, throughout our adult lives.
This is exciting because it opens up the possibility that our adult brains, and by extension our personalities and learned behaviours, can continue to develop indefinitely.
Neurogenesis, combined with techniques to enhance neuroplasticity – which refers to the process of “rewiring” the brain so that it learns a new electrical pathway or response to external stimuli i.e. we might teach our brain that someone crossing the street means that they are taking a faster route, rather than anxiously believing that they are choosing to avoid us – means that our brains can be reprogrammed. Consequently, unhappy, anxious or mentally ill people may be able to build greater mental resilience. Moreover, the scientists believe that we have the ability to influence this process.
Fig 1. Neural connections or pathways in the brain can be “rewired” (neuroplasticity)
In order to understand what is going on here, it helps to understand the basic structures of the brain. (I should mention at this point that I have no formal medical training, so the following is based on my own research and understanding.)
Neurologists often refer to the “three brains” – namely the reptilian brain, the mammalian brain (limbic system) and the neocortex.
Fig 2. Showing regions in the brain and their functions
The most primitive of these is the reptilian brain, which controls our need for safety and survival. The lizard brain makes sure that we eat, stay warm and avoid danger. It also controls our vital body processes like breathing, heart rate and temperature regulation.
The mammalian brain houses the limbic system which is functionally concerned with processing memories, emotions, desires, fears and sexual impulses. The mammalian brain is our “feeling” centre: it remembers past experiences and makes emotional judgments in reaction to new stimuli. Because of this, this area of the brain is also believed to be strongly causally linked with depression and anxiety.
Finally the newest part of the brain the “neo” cortex, governs our higher functioning, such as sensory perception, abstract thought and reasoning, social behaviours, language and the ability to learn.
Currently the evidence suggests that neurogenesis occurs in two areas in the brain: the subventricular zone and the hippocampus (located in the mammalian brain).
Fig. 3 Showing the limbic system, including the hippocampus.
As previously noted, the limbic system is believed to be causally linked to cognitive pathologies such as addiction, depression and anxiety, as well as other diseases such as Parkinson’s and Alzheimer’s. The upshot is that if we can control our rate of neurogenesis, we could stand a chance of improving, preventing or even curing these conditions.
The following are believed to increase the rate of neurogenesis:
Exercise helps to counteract stress (endorphins and testosterone act as an antidote to the stress hormone cortisol and to general psychological stress). Some scientists believe exercise can become addictive because it increases the production of dopamine and serotonin to significantly higher levels than party drugs like cocaine.
The brain is largely comprised of fat and it needs good fats and other healthy foods as building materials. Good fats support brain function, but conversely excessive sugars are thought to reduce the rate of neurogenesis.
omega 3 rich foods – especially containing docosahexaenic acid (DHA), such as oily fish hemp, algae
Avocado, walnuts, pumpkin seeds
turmeric (contains curcumin – increases BDNF levels in the brain and has similar effects to an antidepressant without the side effects)
alcohol (sugar content)
excessive carbohydrates (convert to sugar)
Meditation and devotional practices
Studies have shown meditation, mindfulness practices, yoga, expressing gratitude, charity and spiritual or devotional practices have a positive effect on the hippocampus.
Sleep deprivation has been shown to significantly inhibit cell proliferation and impair brain function. Many studies have also been done on REM sleep and its positive impact on brain physiology.
Exposure to sunshine increases levels of the neurotransmitter serotonin, which promotes feelings of happiness and well-being.
Sex releases an intoxicating cocktail of positive neurotransmitters (including serotonin, which makes us feel happy, dopamine, the “reward and addiction” chemical, oxytocin, the love chemical, and adrenaline). It also helps promotes healthy brain functioning and neuronal growth, while reducing anxiety. It can also be good exercise (see above for the effects of exercise).
If we can use science to understand brain function and leverage this knowledge to continually improve the health of our brains and our rates of neurogenesis, this could have enormously exciting implications for the field of mental health.
Not only does it firmly reestablish autonomy in the hands of the mentally ill by giving them control over their mental states, it also opens the pathway for humans to take an active role in the future of our species by giving us a measurable road map by which to universally enhance our cognitive abilities.