Increases in white matter volume may be correlated to improvements of fine motor performance, auditory processing, as well as sensory information transfer between language areas of the brain. In contrast, cortical gray matter increases in early life, peaks in preadolescence, and declines through adulthood, with the exception of occipital lobe gray matter. For example, parietal lobe gray matter peaks at age 10 in girls and 12 in boys, while frontal lobe gray matter peaks at age 11 in girls and 12 in boys. Such changes might reflect overproduction of synapses in the preadolescent years; in subsequent years, there seems to be pruning dependent on environmental context, corresponding to increased synchronicity of neuron firing. A key caveat from these imaging studies, however, is that there exists significant variability in the timing and characteristics of neurological change in preadolescents. Neurological changes, particularly in the prefrontal cortex, appear to be highly dependent on environmental input. Toxins, hormones, and lifestyle factors including stress and nutrition impact neurological maturation, demonstrating the importance of early lifestyle health interventions in preadolescence with regards to neurological and psychological development.
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