PSYC 2011
Psychology: brain and brain behavior
Semester 1
2008
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Outline:
Abstract
1. Introduction.
2. Problems of the adolescent brain.
2.1. Adolescent brain structure.
2.2. Adolescent behavior influences final brain structure.
2.3. Changes in brain structure in adolescent schizophrenia.
2. The adolescent human brain and laboratory tests on animals.
3. Conclusion.
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Abstract
Current research has demonstrated that the adolescent brain is in a dynamic biological
state that is transitory due to the process of remodeling that involves about fifty percent of
neuronal connections. The main changes involve pruning of prefrontal cortex, grey matter
thinning, and restoring balance between the grey and white matter correlations through which
planned thinking and specialization are created. Specific activity of the adolescent brain is
assigned to some factors including the genetic and environmental influences; however, precise
mechanisms of the change are still unknown. From current research, the adolescent behavior can
be regulated by understanding how the adolescent brain grows and what causes its development.
The latest achievements of neuroscience can help develop cognitive control techniques, so that
vulnerability of the adolescent brain to various negative influences would be reduced, as well as
enhance the formation of neuronal connections that must be useful to continuous learning in
adulthood.
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1. Introduction
Peculiarities of adolescent behavior such as depression, addiction, and eating disorders
have been observed by many people who deal with adolescents. Current research on the
adolescent brain has revealed that it is different from the adult brain. The problem is important
because adolescence is considered to be at-risk stage in human development that needs special
investigation. The present paper argues that adolescent problems are mainly due to the process of
remodeling the adolescent brain.
2. Problems of the adolescent brain
2.1. Adolescent brain structure
Magnetic resonance imaging (MRI) has indicated that the adolescent brain undergoes the
process of restructuring caused by the overproduction of grey matter (Adolescent brain
development, 2003). At the age of twelve the human brain reaches the size of the adult brain.
However, adolescent brain structure is different from final brain structure. The adolescent brain
has the grey matter thinning that radiates in a wave from the back of the brain. Due to grey
matter thinning, layers of myelin are added to the axon connectors, so that the balance of grey
and white matter in the brain is restored. In adolescence, the formation of the upward curve of
myelination begins. As a result, the frontal brain regions of the adolescent brain integrate into
other areas of the brain (Powell, 2006). The frontal lobes of adolescents are less active than those
of adults, while adolescent amygdale is more active than that of adults (Adolescent brain
development, 2003). Thus, the adolescent brain remodels the correlation between the grey and
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the white matter. This dynamic process can be traced by the trajectory of the grey matter
thinning (Powell, 2006).
J. Giedd pointed out that the adolescent brain is involved in the process of “the brain
sculpting”. During this “pruning-sown phase” cells and connections are selected for survival,
while others will wither. The neuroscientist claimed that at this building-up stage the excess
connections are eliminated in the process of remodeling the grey matter as “thinking part of the
brain”. Giedd expressed the opinion that the adolescent brain is a transitory one whose main task
is to prepare the adult brain functioning by specializing selected connections and shaping the
frontal lobe area that is responsible for planning, strategizing, and organizing (Giedd, nd).
Weinberger, Eveval, & Giedd (2005) claimed that during adolescence dopamine inputs
grow substantially as well. Such growth increases the capacity of adolescents to develop impulse
control techniques and mature judgment. The dopamine reward signal is responsible for helping
adolescents pursue a goal rather than function on instinct. However, dopamine neuron growth is
vulnerable to drug abuse that destroys the potential of the brain to learn throughout adulthood.
Impulse control is connected with the hippocampus, the amygdale, and the caudate nucleus. For
example, the amygdale processes emotional information while the caudate nucleus is important
for automatic learning.
Weinberger, Eveval, and Giedd claimed that the adolescent brain is “a work in progress”.
They emphasized the advantages of magnetic resonance imaging (MRI) over other instruments
of scientific research. In their opinion, MRI marks “a new era of adolescent neuroscience” for
the following reasons. First, it shows that the adolescent brain is remarkable for a dynamic
biological state due to which the branches of neurons in the prefrontal cortex are getting more
complicated than they used to be in childhood. Second, the adolescent brain experiences the
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process of grey matter pruning in a back-to-front sequence and increases in white matter in a
front-to-back waves. Third, the adolescent brain is a developing one that grows and changes its
“wiring diagram” of neural connections. At the same time, current research still has no answer to
the question what cellular processes account for the cortex’ volume. Also, the role of such
influences as bacteria, viruses, nutrition, education, peers, school, parenting, addictions, and
some others needs to be clarified (Weinberger, Eveval, & Giedd, 2005).
2.2. Adolescent behavior influences final brain structure
The processes of remodeling the adolescent brain are linked with adolescent behavior that
involves risk taking, inadequate responses, and readiness for new experiences. Frontal lobes are
responsible for self-control, judgment, and emotional regulation. The adolescent brain is specific
in sound judgment, control impulses, and effective planning, all of which cause adolescents
problems in communicating with the world of adults (Weinberger, Eveval, & Giedd, 2005).
Specific brain-based cognitive functions are cognitive control, learning and memory, and
reading. Cognitive control is the ability of the human brain to override negative thoughts and
behavior. This function is associated with the prefrontal cortex. Learning and memory are
associated with the hippocampus (Noble, Tottenham, & Casey, 2005). Adolescent behaviors are
influenced by brain restructuring; however, exact mechanisms that would contribute to taking
control over adolescent behavioral peculiarities are not known yet.
2.3. Changes in brain structure in adolescent schizophrenia
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Current research has shown a dynamic wave of grey matter loss that begins in parietal
association cortices and proceeds frontally to prefrontal cortex and temporal cortices in early
adolescent cases of schizophrenia. This points to brain change modulation in diseases that start in
adolescence. In schizophrenic patients more than 5 percent of grey matter can be lost annually,
which is observed in frontal eye fields, motor, sensorimotor, parietal, and temporal cortices in
both brain hemispheres. Right parietal and sensorimotor cortices undergo faster loss in younger
adolescent, while the temporal and dorsolateral prefrontal deficits begin in late adolescence
(Thompson, Vidal, Giedd. Gochman, Blumenthal, Nicolson, Toga, & Rapoport, 2001).
2.4. The adolescent human brain andlaboratory tests on animals
Studies with laboratory animals have shown that not only human adolescents but also
adolescent rodents, primates, and some birds face similar behavioral problems (Powell, 2006). In
his study of brain evolution, Eric Keverne compared mammalian brains. He claimed that
hippocampus is enlarged in species that store and hide food, while the neocortext is enlarged in
social primates that live in groups. In primates, hypothalamus, amygdale, and medial pre-optic
area are under hormonal and visceral influences. In the process of the evolution, mammalian
brains turned from biological to cognitive regulation of behavior (Keverne, 2004). The reptilian
brain is shared by humans with other animals that have a backbone; it controls body functions
relating to survival. The mammalian brain is shared by humans and mammals; it is responsible
for the automatic control of body functions, new experiences’ filing, and danger recognition. The
human brain is different from the mammalian brain due to neocortex (Davidmann, nd). In both
human and nonhuman primates, changes in the hippocampus; synaptic organization, dopamine
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wiring, and myelination occur in adolescence (Weinberger, Eveval, & Giedd, 2005). Laboratory
tests on animals have indicated that animals may develop behavioral deficits in adolescence. For
example, during the transition from adolescence to adulthood rats can experience reductions in
an index of cell packing density. What is mote, this period is marked by synaptic remodeling. In
rats, deficits in an index of neural activity may be traced in adolescence (Qiao, Seidler, Tate,
Cousins, & Slotkin, 2003).
In conclusion, the adolescent brain undergoes the transitory stage in which the grey and
white matter correlation is remodeled. The grey matter thinning is the key process in human
brain development that needs further investigation in order to fill in the gap between
neuroscience and educational theories.
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References
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Cornell University, University of Rochester, & the NYS Center for School Safety. Available
from: http://www.actforyouth.net/documents/may02factsheetadolbraindev.pdf
Davidmann. M. Howe the human brain developed and how the human mind works. Available
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Keverne, E.B. (2004). Understanding well-being in the evolutionary context of brain
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Noble, K.G., Tottenham, N., & Casey, B. (2005). Neuroscience perspectives on disparities in
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Powell, K. (2006). Neurodevelopment: How does the teenage brain work? Nation, 442: 865-867.
Qiao, D., Seidler, F.J., Tate, C.A., Cousins, M.M., & Slotkin, T.A. (2003). Fetal chlorpyrifos
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Thompson, P.M., Vidal, C., Giedd, J.N., Gochman, P., Blumenthal, J., Nicolson, R., Toga, A.W.,
& Rapoport, J. (2001). Mapping adolescent brain change reveals dynamic wave of accelerated
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Weinberger, D.R., Eveval, B., Giedd, J. (2005). The adolescent brain: A work in progress.
Available from: www.teenpregnancy.org/resources/reading/pdf/brain.pdf