Brain functions do not all develop at the same time or at the same rate for all children. A child may show advanced development in one area and be delayed in another. For example, a child in K-3 may read early but be physically clumsy. Thinking about human development and its relationship to the process of learning and memory, what conclusions can be drawn about a child's brain functions, developments, and learning?
From the observance of children, one can conclude that individuals develop at different rates; it stands to reason, then, that brain functions differ from child to child and that both pre-natal and post-natal influences affect brain development and functions. Studies, some of which involved MRIs, have demonstrated that brain development in the formation of dendrites--"a short branched extension of a nerve cell, along which impulses received from other cells at synapses, or junctions, are transmitted to the cell body"--begins before birth, but continues well afterwards. As axons grow faster than dendrites and are often able to affect what is called "dendrite differentiations" of cerebral circuits, differences in children can be established.
Further, over time there are other changes such as those in cortical thickness. Such changes can be effected by many experiences, along with gonadal hormones, and even stress. In fact, the cortex becomes thinner around age two and continues until a person is at least twenty years of age; moreover, this cortical thinning can be correlated to behavioral development. For example,
... the results of MRI studies of changes in cortical thickness have shown that increased motor dexterity is associated with a decrease in cortical thickness in the hand region of the left motor cortex in right-handers (O’Hare & Sowell, 2008).
In another MRI study, a thickening of the left inferior frontal cortex is correlated with enhanced understanding of speech sounds; yet, in contrast, development in vocabulary is associated with less cortical thickness in "diffuse cortical regions" (O’Hare & Sowell, 2008).
Thus, one child may grasp phonics in second grade, while another cannot; similarly one child may build vocabulary skills while another struggles. And, since cortical thinning can be connected to behavioral development which continues for at least eighteen years of a child's life, it is reasonable to assume that different children will develop skills and functions to different degrees and at differing rates of development from others. Clearly, changes in the brain produce changes in behaviors, and some changes are age dependent.
Researchers and scientists are constantly refining techniques which provide more detailed information on brain development beginning with very young children and into late adolescence. Researchers are able to track how changes in a developing brain might point to milestones in a child’s mental abilities, physical capabilities, and behavior changes.
According to the National Institute of Mental Health, "Scientists are conducting studies to determine what individual genes do in the brain and how changes in genes disrupt brain function. Already this work has led to the identification of candidate compounds to correct deficits associated with neurodevelopmental disorders like Fragile X syndrome; clinical trials are underway."
Some recent research on early childhood stress is showing and interesting parallel that might show how early trauma can alter the brain’s stress response system, which may contribute to possible risk of anxiety and mood disorders as an adult.
According to NIMH, "Studies of how the environment can turn genes on and off—a field called epigenetics—are providing clues to how early experience can have lasting effects on behavior, even across generations. Epigenetic changes are likely to be involved in the effects of the environment on development of the nervous system. Knowledge of epigenetic processes may offer targets for the development of new medications."