This book precedes Dr. Perlmutter’s best-known books Brain Maker and Grain Brain, yet some of the science he shares in this book is the same in his two famous books. I have enjoyed the neuroscience part of this book and have largely ignored the part of enlightenment and shamanism. While I do read books about Buddhism and Stoicism, the talk about shamans in this book seemed very esoteric to me.
How our body deals with stress:
The HPA axis – which refers to three organs, the hypothalamus, the pituitary, and the adrenal glands – regulates our fight-or-flight system. The pituitary gland and hypothalamus are both located within the limbic brain, and the adrenal glands are located above the kidneys. If the amygdala perceives an imminent threat, the HPA axis, rather than passing the signal along to the neocortex for logical processing, releases stress hormones – cortisol and adrenaline – into the bloodstream. These steroids give us quick energy, increase our heart rate, direct blood away from digestion and other nonemergency body functions, and reroute blood to our extremities and muscles so we can fight or flee.
The stress hormone cortisol, which is produced in excessive amounts when the HPA axis is locked in a state of chronic stress, increases the damaging effects of free radicals in the neurons of the hippocampus. This causes damage to the mitochondria, which in turn causes even more free radical production. The final act in this tragic play is that the hippocampal neurons themselves perish through the process of apoptosis. And when hippocampal neurons die, learning and creativity become almost impossible.
Chronic stress can lead to a rut in which the wiring of our neural networks keeps us repeating the same dysfunctional behavior and hoping for a different outcome. As we experience depression and repetitive behaviors that stem from chronic stress, we’re less capable of analytic thought.
Focused Attention and Learning
The need for focused attention is further affirmed by Joe Dispenza in his book Evolve Your Brain: “They key ingredient in making these neural connections… is focused attention. When we mentally attend to whatever we are learning, the brain can map the information on which we are focusing.
Sharon Begley, an award-winning science writer summarized in a Wall Street Journal article in 2007: “The discovery that neuroplasticity cannot occur without attention has important implications. If a skill becomes so routine you can do it on autopilot, practicing it will no longer change the brain. And if you take up mental exercises to keep your brain young, they will not be as effective if you become able to do them without paying much attention.
Brain-derived neurotrophic factor (BDNF)
A major component in this gift of neurogenesis is a protein called brain-derived neurotrophic factor (BDNF), which plays a key role in creating new neurons. It also protects existing neurons, helping ensure their survivability while encouraging synapse formation – that is, the connection of one neuron to another – which is vital for thinking, learning, and higher levels of brain functions.
Calorie reduction and fasting
Biological benefits of calorie reduction and fasting are:
- Reduction in free radical production
- Enhancement of mitochondrial ability to generate adenosine triphosphate (ATP) energy
- Increase in the number of mitochondria through mitochondrial biogenesis
- Increase in the production of brain-derived neurotrophic factor (BDNF)
- Reduction of apoptosis (brain cell suicide)
- Activation of the Nrf2 pathway, which leads to reduced brain inflammation, enhanced detoxification, and increased antioxidant protection.
Our brain is able to utilize an alternative source of calories during times of starvation. Typically, we supply our brain with glucose from our daily food consumption. We continue to supply our brains with a steady stream of glucose (blood sugar) between meals by breaking down glycogen, a storage form of glucose primarily found in the liver and muscles. As glycogen stores are depleted, our metabolism shifts and we are actually able to create new molecules from amino acids harvested from the breakdown of protein primarily found in muscle.
But human physiology offers one more pathway to provide vital fuel to the demanding brain during times of scarcity. When food is unavailable, after about three days the liver begins to use body fat to create chemicals called ketones.
One ketone in particular beta hydroxybutyrate (beta-HBA) actually serves as a highly efficient fuel source for the brain, allowing humans to function cognitively for extended periods during food scarcity.
In a recent report in the journal Neurobiology of Aging, researchers stated that administering simple fats called medium-chain triglycerides (MCTs) as part of MCT oil significantly raised levels of beta-HBA in as little as 90 minutes after consumption. They also observed markedly improved cognitive function in patients who received MCT oil in comparison with those who received a placebo.