In this post I continue to present some topics from my book “Origin of the mind; From viruses to beliefs”. In this part I focus on the things that change our brain by changing the way of how genes express themselves inside the neurons.
Regardless of whether we are talking about people, drugs, activities or the things that we like, end up modifying the architecture of our brains by reinforcing the already existing synapses and creating novel synapses and new neurons. Contrary to the beliefs shaped a few decades ago, the development of the brain as an organ does not cease when reaching adolescence. It modifies its circuits in the course of a lifetime by adding novel neurons and creating new synapses and losing others. These long-lasting alterations represent the basis underlying the mental content that defines us as individuals, or what psychologists term “Self”. Furthermore, these alterations are responsible with the formation of novel memories. These changes occur by virtue of what are called epigenetic mechanisms that alter the DNA inside the neurons exposed to external information.
Epigenetic mechanisms are used to create and store cellular information in response to environmental signals – food, temperature, oxygen level. This informational storage is analogous to memory storage in the nervous system. More and more research has demonstrated the existence of a complex epigenetic mechanism responsible with regulating gene activity turning them on and off without altering the genetic code. So these epigenetic mechanisms act like a switcher. In the center of epigenetic processes lays the idea that genes have a “memory”. The lives of our grandparents – the air they breathed, food they ate or even the things they have seen – may influence us decades later, although we did not live those experiences directly. Subsequently, our experiences may affect the lives of our grandchildren. Therefore, the “memory” of an event can be passed from one generation to the other. A simple stimulus from our environment may turn on or off certain genes. One example relates to stress, which shuts down the genes involved in synaptic plasticity. Hence, chronic stress affects large areas of the brain. Essentially, it affects the connectivity between brain hubs, and thus informational exchange between distal areas. Moreover, it exerts a negative effect on non-emotional learning mechanisms, which are responsible with exploring and learning pieces of information ascertained as novel, more complex or different, compared to the already acquired ones. We might even say that what we call chronic depression is a degenerative disorder affecting the capacity to adapt to novelty. In addition, stress affects DNA, while memory consolidation processes are influenced by genes which encode the enzymes involved in DNA repair.
A fundamental thing is that epigenetic alterations may be transmitted to our children, what on long-term affect the genes of our species. This is how environment shapes the evolution. From the food we eat and the antibiotics we take to the technology we created, all these have the potential to change our species. And all these changes will remain recorded in our genes like in a data base.