The brain selects for the brain circuits that are most utilized throughout development
Much of the growth of the human brain occurs after birth.
Through this weeding out of unutilized cells and synapses, the selection of useful connections, and the formation of new ones, the specialized circuits of the maturing human brain emerge. This is what is refered to in ethology as imprinting. The imprinting process is highly specific to each individual person—so much so that not even the brains of identical twins have the same nerve branching, connections, and circuitry. In large part, our early years define how well our brain structures will develop and how the neurological networks that control human behavior will mature.
At any point in the process of imprinting you will have many potentials for either positive or negative stimulation to get in and set the microstructure of the brain. It is precisely here where the problem arises for young children who will, in adolescence and beyond, develop addiction and ADHD (ADHD and addiction can be traced to similar causes). Too much negative stimulation, and in many cases simply not enough positive stimulation. Our genetic capacity for brain development can find its full expression only if circumstances are favorable: Gene expression is highly contingent on the environment.
To illustrate this, just imagine a baby who was cared for in every way but kept in a dark room. After a year of such sensory deprivation the brain of this infant would not be comparable to those of others, no matter its inherited potential. Despite perfectly good eyes at birth, without the stimulation of light waves, the neurological units that make up our visual sense would not develop. The neural components of vision already present at birth would atrophy and become useless if this child did not see light for about five years. Why? Neural Darwinism. Without the requisite stimulation during the critical period allotted by Nature for the visual system’s development, the child’s brain would never have received the information that being able to see is needed for survival. Irreversible blindness would be the result.
References
- Mate, Gabor. (2010). In the Realm of Hungry Ghosts Close Encounters with Addiction Chapter 17. Their Brains Never Had a Chance (p. 232). Berkeley, CA: North Atlantic Books.
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Type:🔴 Tags: Biology / Neuroscience / Developmental Psychology Status:⛅️