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Neurological changes, Tanner staging, gender sexuality

The stages of puberty can be described with the Tanner scale, also known as the Sexual Maturity Rating, which incorporates measurements and characteristics of primary and secondary sex characteristics, for example genital and breast development, as well as pubic hair growth. Pubertal development is regulated by the hypothalamic-pituitary-gonadal (HPG) axis. Tanner staging ranges from 1 through 5 (with 5 being the most developed). With regards to pubic hair development, the scale goes as follows: Stage 1-no hair; 2-downy hair; 3-scant terminal hair; 4-terminal hair overlying the pubic triangle; 5-terminal hair extending to the thigh. With regards to male genitalia development, the scale goes as follows: 1-testes at the same size and proportion of early childhood; 2-enlargement of the scrotum/change in texture of scrotal skin; 3-growth of the penis length-wise; 4-growth of the penis in terms of length and circumference; 5-adult-sized genitalia. With regards to female breast development, the scale is as follows: 1-no palpable gland tissue; 2-palpable breast bud under areola; 3-breast tissue palpable outside of areola; 4-areola elevated above breast contour; 5-areolar mound recedes into single breast contour.

As with the other stages of life through early adulthood, there are significant neurological changes that are expressed during preadolescence. White matter refers to the region of the nervous system corresponding to neuronal axons, which form fibers that convey information across different regions of the brain. In contrast, grey matter refers to the region of the nervous system corresponding to neuronal cell bodies, which process and relay neuronal signals. White matter volume increases at a relatively linear rate from ages 4 through 22, at a rate of about 12%, specifically focused in the frontal, parietal, and occipital lobes. 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 context, 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.