How the Brain Develops
Because of the dramatic increase in studies of the mind and the brain’s development and deformities, the 1990’s is known to some as the decade of the brain (Siegel, 2012). Many of those studies have now been completed and new information about how the brain and mind are developed and traumatized is now available. In updating his book The Developing Mind (2012) Daniel Siegel M. D. and his researchers at UCLA read over 2,000 papers on those studies covering a twelve year period since his first edition was published in 1999. There is now more current information about the brain than ever before.
As Siegel’s (2012) research tells us, the brain is a complex system of interconnected parts that functions as an integrating system of subsystems that intertwines the functions of the brain and body. The activation of neural pathways directly influences how connections are made within the brain and how the regulation of genes is altered. Experience shapes the activity of the brain and the strength of neuronal connections throughout life. The brain is also dynamic in that it is continually in a state of change. “Cortical plasticity” is the process by which the brain shapes itself in response to various environmental stimuli (p. 22). New findings on the study of neuroplasticity reveal that the brain is open to further development throughout the lifespan. (Doidge, 2007)
The brain has an estimated one hundred billion neurons with each neuron having an average of ten thousand connections (synapse) that directly link itself to other neurons. There are thought to be about one million billion of these connections making it the most complex structure, natural or artificial, on earth (Green, 1998). The vast numbers of neural connections are not static as the brain continually changes its synaptic interconnections in response to experience (Doidge, 2007) (p. 15)
The neurons communicate with one another through a combination of electric and chemical impulses and because of the spider-web-like interconnections, the number of “on-off” patterns of neuronal firings is immense, estimated at ten times ten million one million times. The growth of myelin along the lengths of neurons increases the speed of nerve conduction by one hundred times and reduces the refractory period during which a just-fired neuron must rest before firing again by thirty times. Thus myelin functionally enhances the linkage among synaptically connected nerve cells by three thousand times (p. 23). This is an example of electrochemical energy flow. Because of this huge capacity and possibility of an immense variety of activity, no man made computer can come close to the organization and functionality of the human brain.
The brain is divided into two hemispheres, the right and the left. The left side is thought to be the “verbal” domain where activities such as language and arithmetic calculations take place and helps us listen carefully, be logical and stay calm (Karp, 2008). The right side of the brain controls many of our “non-verbal” functions including visual-spatial activities like reading a map and the more “imaginative” and “artistic” activities. The right half controls the rapid responses to the nervous system by making quick decisions and providing instant face recognition. Unlike the thoughtful left side, the right side is distractible, impulsive, and emotional. Some of these activities are interchangeable and can be performed by either side of the brain as in the case of people that are born where only one side of their brain has developed (Doidge, 2007).
The cerebellum, which means “little brain,” is found at the back of the brain underneath the two hemispheres. The cerebellum is responsible for the body’s balance and coordination which controls actions such as writing, walking, throwing a ball and speaking. At birth, the cerebellum is small which accounts for the lack of balance and coordination in infants but as the child grows so does the cerebellum and by the end of the first year the child can stand, reach and grab items, and contort the mouth muscles to make sounds (Karp, 2008).
The “lower structures” of the brain contain the circuits that regulate energy flow such as states of arousal, alertness, body temperature, respiration, heart rate and the survival reactions of fight-flight-freeze. The lower brain structure also contains the hypothalamus and pituitary which are responsible for body equilibrium, hormonal release and can be adversely affected by stress and trauma (p. 16).
The centrally located limbic region contain a cluster of neurons called the hippocampus that control emotions, motivation, goal-directed behavior, nitration of memory and the attachment system that enables young mammals to depend upon their parents for safety and security. This region also permits the integration of such mental activity as the appraisal of meaning, the processing of social signals, the activation of emotions and memory in the recall of facts, and the autobiographical details of an on-going experience. Included in this region is the cerebellum which links body motion, mental states and cognitive processing (p. 18).
The top of the brainstem is the thalamus which serves as a gateway for incoming sensory information and the mediation of conscious experience. The “higher structures,” such as the cerebral cortex, mediate “more complex” information processing functions such as perception, thinking and reasoning. These frontal neocortical areas are considered to be the most evolutionary “advanced” in humans and mediate the complex perceptional and abstract representations that make up our thought processes (p. 17).
The cortex matures from back to front with the frontal regions continuing active growth well into young adulthood. The prefrontal cortex is thought to play a major role in working memory (for example, where you left your keys) and the focusing of conscious attention. This region also links the perception of communication signals from other people creating a wide spectrum of integration from body functions to social awareness which includes self-awareness, empathy, emotion regulation and attachment (p. 18).
Prefrontal cortex of our brains is instrumental in managing what is called “executive function” which is our capacity for impulse regulation and attentional control; cognitive flexibility; task prioritization; organize plans and goal setting; and complex information processing (Anderson, 2002) (p. 42) Other research suggested that the prefrontal cortex of aggressive children actually haven’t developed, or are developing more slowly, so that they simply do not yet have brains capable of helping them regulate their behavior. But brains are changeable in that learning and repeated experience can actually alter the physical structure of the brain, creating new neuronal pathways as memory that may be stored in the synapses of our nervous system. (Green, R., 2012)
Self-regulation appears to depend upon neural integration. Relationships stimulate the growth of integrative fibers in the brain, whereas neglectful and abusive relationships specifically inhibit the healthy growth of neural integration in the young child (Teicher, 2010). Even impairments to health that are not experientially derived, such as autism, bipolar disorder, and schizophrenia, have now been shown to reveal impairments to neural integration (Zhang, 2010). Interpersonal experiences continue to influence how our minds function throughout life, but the major structures – especially those that are responsible for self-regulation – are initially formed in the early years. Impairments to self-regulation, held by the field of developmental psychopathology as central to mental dysfunction, may be fundamentally impairments to self-organization (p. 28).