Brain development

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Chapter 2


Literature on adolescent brain development is minimal as this has been an interest area of research for only the past ten years. The use of the research has gone beyond justification of adolescent behaviors to help explain possible reasons for risk-taking actions, addictions, and legal responsibility of adolescents. Pioneers of adolescent brain development research include Dr. Paul Yakovlev and André Lecours as early as 1967. Since that time many researchers have followed suit to discover the links between behavior and the brain.

Early Research

The earliest hints of brain research dates back to the Egyptians and a papyrus found by archaeologist Edwin Smith in 1862. The translated papyrus revealed descriptions of physical injuries including head injuries. The brain was described as “the marrow of the skull” (Finger, 2000, p.13). The unknown author of the papyrus offers further description of various parts of the brain and reveals the discovery of early Egyptians realizing injury to this organ effects function of other areas of the body.

In the early nineteenth century, researches faced obstacles in conducting brain research. The microscopes used could not magnify at a high enough resolution for specimens to be seen without distortion, something was needed to aid the cell bodies to stand out from the background, and researchers needed to become open minded enough to want to put specimens of the brain on slides for viewing. (Finger, 2000, p. 197) By the late nineteenth century some of these obstacles had been removed. New theories had developed, improvements to the microscope had been made, investigators created new terms, and neuroanatomy was discovered. By the mid nineteenth century, nuclear medicine had evolved creating the ability to view inside the body without surgery through magnetic resonance imaging. In 1977, Hugh Clow and Ian Young would produce the first NMR image of the human head. (Rinick, 2008, p. 9) This lead to improvements and advanced research capability using technology and brain research began branching out into other areas.

In 1967, two researchers, Paul I. Yakovlev and André Lecours would expound on the link between brain development and behavior. (Write more about this here when you get the book)

Research Findings

Dr. Jay Giedd, a neuroscientist at the Institute of Health, Dr. Frances Jensen Professor at Harvard Medical School and senior assistant in Neurology at Children's Hospital Boston, and Dr. David K. Urion, also an associate professor of neurology at Harvard began their research in 1991 on brain development from childhood through adolescence. The introduction of the MRI scanning allowed Dr. Giedd to scan images of the brain during different development periods of participants.

The participants were screened in order for the research to be based on those participants were found to be the most psychiatrically and medically healthy. From a pool of 624 candidates, 55 males and 49 females were chosen for the study. Candidates that did not meet the criteria were excluded because of learning disorders, medical problems or behavioral problems. The pool was narrowed down again by excluding any candidate that did not meet certain criteria after psychiatric and familial assessment. The remaining candidates were then academically assessed, then narrowed down based on academic ability. Of the remaining pool, exclusions were also made if subjects had first or second degree relatives who were found to have learning disabilities or a history of psychiatric problems. The remaining subjects were eligible for MRI scanning, but of that number, four subjects were unable to participate due to anxiety and or claustrophobia created from the scanning procedure. The last four exclusions from the pool of candidates were due to bad MRI results because of movement during scanning. The mean age of the 104 subjects ranged from 4.7-17.8 years.

The images revealed differences in the size of frontal gray matter from one developmental stage to another.