Lecture 10a: Physical and Brain Development in Adolescence Flashcards
What happens to grey and white matter during middle childhood?
During middle childhood, developments in the brain include changes to white and gray matter volume, growth in the complexity of neural networks, and increased coordination across regions of the brain.
What happens to white matter?
White matter volume increases linearly throughout middle childhood and adolescence, reflecting the myelination of axons
Recall that myelin is the fatty white sheath that surrounds axons.
The growth in myelin helps strengthen brain connections by allowing faster transmission of neural signals.
What happens to grey matter?
Grey matter increases in childhood and then decreases in adolescence, reflecting the pruning of unused synapses.
Peaks to gray matter volume occur in different regions of the brain at different times in development.
How can we appreciate adolescent thinking?
To fully appreciate adolescent thinking and decision making, it’s helpful to consider the asymmetrical maturity of different brain regions across development. Notably, by adolescence, the prefrontal cortex is relatively immature in its development compared to the more complete maturation of the limbic system
What is the limbic system?
The highly active adolescent limbic system which includes the hippocampus, amygdala, and cingulate gyrus, among other structures is packed with neurons that are involved in motivation and emotions.
Simplified; The limbic system is a group of interconnected brain structures that help regulate your emotions and behavior
What is Puberty?
Period of lifespan in which individual becomes capable of sexual reproduction
What are the 3 chief physical manifestations?
- Rapid acceleration in growth (height, weight)
- Development of primary sex characteristics (gonads)
- Development of secondary sex characteristics
What is the Endocrine System
Produces, circulates, and regulates hormone levels in the body
- Hormones
- Glands
- Gonadotropin-releasing hormone (GnRH) neurons
What is the Hypothalamic-Pituitary-Gonads “HPG Axis”
Reproduction and fertility are regulated via hormones of the hypothalamic-pituitary-gonadal (HPG) axis.
**Controls production of
androgens and estrogens by
gonads
REVIEW SLIDE 8 CHART
What are Primary sex characteristics
Primary sex characteristics are associated with the reproductive organs, ovaries, uterus, and vagina in girls, and penis, scrotum, and testes in boys.
Primary sex changes result in the production of ova in girls and sperm in boys, which enable reproduction.
What are secondary sex characteristics?
Secondary sex characteristics include observable body changes such as a growth spurt, pubic hair, breasts in girls, and facial hair and changes to voice in boys.
What Triggers Puberty?
Puberty begins when several different signals – genetic, environmental – instruct the brain to change the “set
point” of the HPG axis
What signals the HPG axis to change the set point?
Increase in brain chemical called “kisspeptin” – initiates increased
secretion of GnRH from hypothalamus
[Gonadotropin hormone-releasing hormone (GnRH)]
Hypothalamus becomes less sensitive to androgens/estrogens
What products kisspeptin?
Leptin (protein produced by fat cells) stimulates production of kisspeptin
What are the 3 chief physical changes during Somatic Development?
- Adolescent growth spurt
- Development of primary sex characteristics (gonads)
- Development of secondary sex characteristics (breasts, body hair)
What is growth spurt?
One of the most noticeable outcomes of puberty is the growth spurt acceleration of growth in hands, legs, and feet followed by torso length
How do boys and girls differ in growth spurt?
Boys’ shoulders broaden relative to their hips, but girls’ hips broaden relative to their shoulders.
Girls also add fat to their limbs and torso, whereas boys reduce fat and add more muscle mass to their bodies than do girls
Moreover, the growth spurt occurs at a later age and lasts longer in boys than in girls. Thus, during middle school and the first year or two of high school, it is common to see girls towering over boys, with this pattern reversing a couple of years later.
What are the Sex Differences in Muscle and Fat?
Relative proportions of body fat/muscle change during puberty
Muscle-to-fat ratio at end of puberty is 3:1 (boys) vs. 5:4 (girls)
What is the timing of puberty for girls
Secondary sex characteristics: 10 years old on average
First period: 12-13 years old on average
What is the timing of puberty for men
Secondary sex characteristics: 11-11.5 years old on average
What are Secular trends?
Secular trends are nongenetic changes in human development that occur over extended time frames, further illustrate diet’s effect on pubertal timing. Worldwide improvements in nutrition and health over centuries have led to earlier and earlier onsets of puberty
What are the Individual Differences in Pubertal Timing?
- Genetic predispositions
Two key environmental influences:
* Nutrition
* Health
Protein/caloric deficiency, chronic illness, intensive exercise = Delayed puberty
What is ehe role of the pituitary gland in puberty?
The hypothalamus increases production of gonadotropin-releasing hormone, which stimulates the pituitary gland to release gonadotropin hormones, which trigger the production of testosterone and estrogen. The release of testosterone and estrogen from the pituitary gland causes a series of chemical changes that trigger the physical transformations of puberty
What does early maturation feel like for girls?
In general, early pubertal timing relative to peers may render adolescents susceptible to depression and behavior problems, although such negative effects have been most consistently documented for female adolescents
What does late maturation feel like for girls?
Adolescents who show asynchronous development in the physical changes associated with puberty, such as developing breasts very late are at greater risk of depressive symptoms at age 20
What are the Mechanisms of Influence on puberty? AKA Why does the timing of puberty relative to one’s peers matter?
- Peer influence hypothesis
- Maturational deviance hypothesis
- Readiness hypothesis
- Contextual amplification hypothesis
What is peer influence hypothesis?
Early puberty may instigate problem behaviors because of the influence of older peers.
Early maturing adolescents are likely to hang out with older teens who look like them physically. They are thus prone to earlier-than-usual exposure to risky behaviors, such as alcohol use and sexual activity, at a time when they are insufficiently mature to handle peer influences
Simplified: Influence of older peers
What is Maturational deviance hypothesis?
The adolescent’s physical deviation from his or her peer group, whether due to early or late maturation, is stressful and may increase vulnerability for mood and behavior problems.
Early maturing girls are the most physically “deviant” because they enter puberty before most other girls their age and before nearly all boys their age.
In contrast, late-maturing boys are the most physically “deviant” because they are the last to develop relative to boys and girls of their age
Simplified: Stress caused by being different from peers
What is Readiness hypothesis?
That early maturation may be problematic because of the asynchrony it creates between physical, cognitive, social, and emotional maturity
What is Contextual amplification hypothesis?
Adolescent adjustment to early pubertal timing, especially in girls, depends on social and cultural context.
Social messages about sexuality and body image interact with a teen’s experience of puberty to determine whether and to what degree early timing cascades to problem behaviors
How does the Home Context affect Puberty?
Environmental forces, such as social interactions in the family and foods available at home, also contribute.
Adolescents who experience prolonged, unpleasant conditions at home, including conflict and stress among family members, parental divorce, poor attachment relationships, child maltreatment, and low parental involvement, are prone to early pubertal onset
