Life is distinguished from the inanimate by its ability to recreate itself and hold a pattern. Throughout our lives, The very material we are made up of is recycled or regenerated. Every few weeks we completely change out the cells that compose our skin. The body is constantly in a state of regenerating itself. Even the bones are borrowing or depositing calcium throughout our lives. The machinery of our cells are constantly disposing of waste, replacing damaged portions, killing cells that are old or dysfunctional and making new ones. All this processes are kept in order by our genetic information. In essence the only thing that holds our form and keeps it from weathering away and degenerating is our DNA. This is the master set of instructions that our cells use to replace, rebuild, and develop us into the body we now have. It is the ultimate difference between the collection of elements that is us, and a rock.
However, there is much more to what we are than just the DNA blueprints. I remember a moment at the beginning of my very first year of medical school that really brought this home to me. In anatomy we had to memorize every crater, every bump, every nodule, line and crevice in every bone in the body. As we learned about these landmarks, we learned that they form not as part of some genetic program, but as a reaction to stress forces from pulling tendons and ligaments, triggering a reaction that caused the cells in that part of the bone to duplicate and reinforce the bone as needed. In other words, our actions determine the shape of our bones every bit as much as our genes.
Our basic frame is in this way formed largely by our environment and experience. When a limb is paralyzed in children, the bones never gain that same shape. In fact, growth is less entirely, as evidenced in polio survivors with limbs that remain child sized.
While most of the cells in the body turn over several times within our lifetime, The neurons of the central nervous system are an exception. Like our skeletal frame, these cells provide the framework and wiring for our entire nervous system, and while the materials that make up the neuron may turn over, the neurons themselves do not (generally). We have recently discovered that the hippocampus, which forms and stores memories, actually continues to generate new cells throughout life.
While the cells have very little turnover, the connections they make are not permanent. They are culled back by lack of stimulation with the same developmental stunting occurring here as in the skeleton. The heart-wrenching evidence of this has been shown in studies of children who have suffered severe neglect and social deprivation. These children have smaller brains of CT scans, and usually lack capacity to develop language.
These children are the source for the of Tarzans or Mowglis in stories, children raised by apes or wolves. These children generally lack ability to develop language. One of the saddest cases in recent history is the horrifying story of Genie.
On November 4, 1970 a girl was discovered. She had been locked in a room alone for over ten years. She was tied to a potty chair and left to sit alone day after day. At night, she was tied into a sleeping bag which restrained her arms. She was put into an over-sized crib with a cover made of metal screening. Often she was forgotten. On those nights she slept tied to the potty chair.
Her Father suffered from paranoid schizophrenia, he locked her up from the age of three. Once rescued from this horrific situation, attempts were made to teach genie to speak, and she did. She picked up single words here and there. Sadly, she never was able to string together sentences. She scored perfectly on visual spatial IQ testing, but simply lacked the capacity for normal language. She lost it through simple lack of human contact.
The flip side of this is that stimulating our minds, learning to think in new ways and directions increases our brains capacity. We can make and strengthen new connections through our own experience and thought. We call this neuroplasticity. It means that we can, in some degree, increase our brain capacity through learning and study. Evidence seems to show that more education protects against developing Alzheimer’s disease later in life. It seems we can develop the brain through training just as we would a muscle.
One of the more revolutionary discoveries in the recent history of neuroscience is that not only are neurons plastic in their ability to make and strengthen new connections, but we do, in fact, actually produce new neurons throughout our life, even in adulthood. This idea has overturned over a century of dogma about neurons never replicating in grown brains. These discoveriea have led to a surge in the popularity of brain health in our culture.
These newly generated cells are critical for memory and preventing dementia. Evidence also seems to indicate they are central to recovery from major depression. Recovery from depression, from a cognitive behavioral standpoint, is all about taking the automatic thought pathways we have built through a lifetime of habit and challenging them. It is learning and understanding how these thoughts are intertwined with how we then feel, how these automatic thoughts trigger anxiety and tension, depression and pain. Then we learn how to challenge these thoughts and short circuit the tension and fear.
This is all incredible news if you think about it. We have to ability within ourselves to improve our memory and our own ability to think. We have the ability within ourselves to sculpt our brains the way we would like them. We have the ability within ourselves to learn how to overcome anxiety or depression, not instantaneously, and likely not on our own when in the throes of depression but over time with work and effort, and perhaps a boost from antidepressants. Each of us can be our own architect. We all hold the power to become the sculptor of our own brain.