Neurophysiological Development:
Across The Life Span
Yoon Suh Moh, Ph.D., NCC, CRC, LPC
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AGENDA
Prenatal Brain Development
Brain Development During Adolescence
Developmentally Informed Interventions
The Aging Brain
Brain Development During Infancy and Childhood
Prenatal Brain Developement
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Prenatal Brain Development
First Trimester
- The brain starts to develop the 3rd week of gestation
- Around Day 17 to Day 20, the embryo develops a neural plate that will eventually become the
nervous system (the brain and spinal cord) --> Neural tube
- Neural stem cells line the neural tube and eventually give rise to the many specialized cells
in the nervous system (neurons and glial cells)
- Week 5 or 6 postconception, the cranial nerves begin to develop
- Around 50 days of gestation, neurogenesis begins; 250,000 per minutes, 4,000 new neurons per second
- Brain-derived neurotrophic factor (BDNF) supports the growth, survival, and differentiation of neurons in the central and peripheral nervous system
- At approximately 60 days postconception, the presence of sex hormones (e.g., testosterone) initiates sexual differentiation of both the body and the brain
Abnormal Development of The Neural Tube
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Anencephaly:
Failure of anterior neural tube to close.
Spina Bifida:
Failure of posterior spinal cord to form or improper formation of meninges and vertebrae
a.
Differentiation of The Telencephalon and Diencephalon
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Telencephalon: cerebral hemispheres, olfactory bulbs, basal telencephalon
Diencephalon: thalamus and hypothalamus
Prenatal Brain Development
Second Trimester
- The start of the second trimester, at 3 months postconception, the telencephalon, or cerebral cortex, becomes the largest structure of the prenatal brain
- The cerebellum follows a similar process of regionalized development
Brain Development During Infancy and Childhood
How Children Can Build Core Capabilities for Life
Cont'
After birth, the brain continues to grow and becomes more tailored in its functioning, increasing fourfold and reaching nearby 90% of adult brain volume by age 6 years (Stiles & Jernigan, 2010 cited in Field et al., 2017)
These sensitive and optimal periods dependent on the learning process and are not inherently limited by time (Jonnson, 2005 cited in Field et al., 2017)
During this early period, the brain produces many more neuronal connections than one could even actually use, primed for rapid learning
Through learning, certain connections become reinforced, and others that are now used are pruned (synaptic pruning)
During the first few years, humans move from primarily using motor reflexes that are key to survival (e.g., crying and the rooting-sucking reflex) to using their senses and vocalizations to communicate (e.g., head turning, cooing, and reaching for objects)
Brain Development During Adolescence
Roughly age 11 years to the mid-20s
A second, notable sensitive period of brain development and the most critical period in development (Pass, Keshavan, & Giedd, 2008)
A period during which the onset of numerous mental health disorders is seen.
During this time, individuals experience volumetric changes in both gray matter and white matter in the brain that represent an increased refinement in brain functioning (Casey, Jones, & Hare, 2008)
Myths of The Adolescent Brain by Dr. Daniel Siegel
https://www.youtube.com/watch?time_continue=217&v=WDQaEx-0K6U
Cont'
Emotional Regulation
Social Development
Influence of Sex Hormones
In this image of a cross-section of a mouse nerve, myelin, labeled in red, can be seen surrounding the individual nerve cells in blue. Sex hormones are key to the production of myelin. This production continues to a person's 20s.
Brain Maturation in Adolescence
Image adapted from Gogtay et al. (2004)
Emotional Regulation in Adolescence
- With changes in cortical structures,
concurrent changes in the limbic and paralimbic regions of the brain
- The amygdala, hippocampus, anterior cingulate cortex, and nucleus accumbent subject to
progressive synaptic running during adolescence
- The limbic structures of the brain mature earlier than the prefrontal cortex
- This asymmetrical develop in part explains the emotional lability, self-consciousness, impulsiveness, and
risk-taking behavior often seen during adolescence
- Adolescents are not yet able to optimally regulate their limbic regions in emotionally charged situations
- Adolescents appear to demonstrate a capacity for self-control and impulse regulation in nonemotional
situations similar to that of adult (Casey & Caudle, 2013 cited in Field et al., 2017)
- As ages and the volume of white matter increases between the prefrontal cortex and limbic regions will become more firmly establish and become better able to self-regulate in emotional contexts
Emotional Regulation in Adolescence: HPA Axis
- Hypothalamic-Pituitary-Adrenal (HPA) axis goes through a second sensitive period of development
during adolescence
- Experience higher levels of cortisol in their systems
- Chronic or acute stress during this period may have pronounced
effects on the emergence of mental health disorders during
adolescence as well as an individual's ability to self-regulate
and cope with stress
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Social Development in Adolescence
- A period of differentiating from caregivers (e.g., parents) and developing stronger interpersonal
connections with friends
- The onset of developing romantic interests and relationships with potential partners
- A decisive period in the development of social cognition, the ability to "recognize others, and to evaluate
our own and others' mental states" (Blakemore & Mills, 2014 cited in Field et al., 2017)
- Associated structures of the brain with this ability: a set of brain structures including the medial
prefrontal cortex, anterior cingulate cortex, inferior frontal gyrus, posterior cortex, anterior cingulate
cortex, posterior superior temporal sulcus, amygdala, and anterior insula (Sebastian, Viding, Williams,
& Blakemore, 2010)
- Adolescents can become more sensitive to social cues, especially facial expressions (L. A. Thomas, De Bellis,
Graham, & LaBar, 2007)
- ex) K. M. Thomas et al., (2001): differences between adults and adolescents in perceptions of facial
expressions
Influence of Sex Hormons in Adolescence
- Nearly every change in the brain that occurs during adolescence is in some manner influenced by
the deluge of sex hormones (i.e., estrogen and testosterone) manufactured in the gonads
- Cerebral blood flow, HPA axis functioning, and levels of neurotransmitters are all regulated by levels of sex
hormones
- Estrogen not only influences levels of serotonin, dopamine, and oxytocin
- Increased levels of both estrogen and testosterone enhance the functioning of the HPA axis and related
corticosterone release and negative-feedback loops
- The influx of hormones leads to a sex differentiation in the gut microbiome, which again influences mental
health (Jasarevic, Morrison, & Bale, 2016 cited in Field et al. 2017)
Further information on effects of sex hormones during adolescence: http://www.brainfacts.org/thinking-sensing-and-behaving/childhood-and-adolescence/2015/hormones-and-the-adolescent-brain-120915
The Aging Brain
- Nearly one in five older adults experience mental health challenges such as depression, dementia, and Alzheimer's disease. However, those mental health needs are not currently being met (Karel, Gatz, & Smyer, 2012 cited in Field et al., 2017)
- Various aspects of cognitive functioning (processing speed, executive functioning, and
difficulty with episodic declarative memory) have been found to decline with age (Grady,
2012)
- Other cognitive function (emotional regulation and crystalized tasks [vocabulary]) appear
to stay intact (Wright & Diaz, 2014)
- Changes in the volume and integrity of white matter seen in the healthy aging brain
- Declines in white matter volume seem to start gradually around age 50 and decline more steeply after age
70 (Fjell & Walhovd, 2010)
- The majority of this decline is seen in the frontal lobe, with notable loss also occurring in the corpus
callosum (Greerligs, Renken, Saliasi, Mauritis, & Lorist 2015; Gunning-Dixon, Brickman, Cheng, &
Alexopouos, 2009 cited in Field et al., 2017)
- Decreases in myelinated axons within and across various brain regions may underscore much of this
volumetric change, with a reduction in the length of myelinated axons by nearly 50% (Fjell & Welhovd, 2010)
The Aging Brain: White Matter
White Matter
A tractography reconstruction of the arcuate fascicles in the left hemisphere of a 40-year old man. This arcuate pathway is
a crucial pathway in the language system, linking the Broca's and Wernick's areas.
- A loss of the brain volume with aging, with different brain areas displaying different aging trajectories
- The most notable volumetric loss reported in the frontal and prefrontal cortices, temporal lobes,
and hippocampus, thalamus, and nucleus accumbens (Fjell & Walhovd, 2010)
- Rather the result of necrosis (neuronal death), gray matter changes appear to be related to the
shrinkage of neurons, reduction of synaptic spines, decrease in the number of synapses, and loss
of glial cells (Fjell & Walhovd, 2010)
The Aging Brain: Gray Matter
Alzheimer's disease
- Various degenerative disorders (e.g., dementia and Alzheimer's disease) have a prevalence
rate of around 11% among adults older than age 65. in the United States
(Alzheimer'sAssociation, 2013)
- Characteristics of Alzheimer's disease: reduced brain weight, cortical atrophy, associated
ventricular enlargement in addition to neurofibrillary tangles of tau protein filaments
typically occurring in the hippocampus and related limbic structures and amyloid plaques
typically found throughout the cortex (Rossini, Rossi, Babylon, & Polichm 2007 cited in Field et
al., 2017)
A video clip on Alzheimer's disease: https://www.youtube.com/watch?v=0GXv3mHs9AU&list=PLpsXQDgp0xpUfbOShHsoRbYcgg2Ydpwr_&index=17
Alzheimer's disease
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Infectious Theory of Alzheimer's Disease
Other Potential Causes of Alzheimer's Disease in the 21st Century
- Metallic iron imbalance
https://www.youtube.com/watch?v=NUjmwTwNCAI
Developmentally Informed Interventions
- Understanding brain development over the life span enriches case conceptualization and treatment
planning.
- Best practices for working with children: play therapy, providing a symbolic framework that does not
rely on linguistic production and declarative memory systems
-- A child does not have to tell a story in words but symbolically represents the feelings of the body
the implicit memory of events in an environment that is safe and secure, fostering relationship and
attachment
-- The Brain Architecture Game at the Center on Developing Child:
- Best practices for working with older adults: in addition to assessing for mild cognitive impairment,
the rehabilitative effects of training on the aging brain
-- practice active tasks lasting from 2.5 to 10 hours related to divided attention, episodic memory,
and working memory leading to cortical activation similar to that of younger adults in their prefrontal,
frontal, and temporal cortices (Grady, 2012 cited in Field et al., 2017)
Center on developing child at Harvard University: https://www.youtube.com/watch?v=y2-DMvcrTlk
