Lecture 1 Adolescence
Brain keeps developing at least till the age of 25. Development of prefrontal cortex (top-down
control), responsible for self-control, not yet fully developed at young age. More driven by emotions
and impulses in adolescence.
The boundaries of adolescence; aren’t clear, depends on which criteria used (biological/ emotional/
cognitive/ social etc.). Biological; onset of puberty. Cognitive; emergence of more advance thinking
abilities. Social; transition into certain roles. In the book; beginning of adolescence is the start of
puberty (biological criteria), end of adolescence is transition into adult roles (social criteria).
This period had lengthened on both ends in the last century.
Period of transition; ages are not fixed
- Early adolescence; 10 -13 (pre-pubescence)
- Mid-adolescence; 14 -17 (pubescence)
- Late adolescence; 18 – 21 (post-pubescence)
- Emerging adulthood; 18 - 25
Ecological perspective on human development (Brontfenbrenner); we cannot understand
development without examining the environment in which it occurs. Even brain development depends
on environmental input.
Current view; nature and nurture. Spectrum of theories on perspectives on adolescence. From
extremely biological (biosocial, organismic), to learning theories, to extremely environmental
(sociological, historical/anthropological).
Stereotypes and myths;
- Adolescence is a distinct stage of development -> more a gradual process, period of
transition
- A period of universal storm and stress -> only 20 to 25% report significant problems, of
those 80% also experienced problems in childhood. So only 10% develop problematic
behavior during adolescence. Most of them adolescence-limited deviance.
- When new hormones develop -> hormonal levels increase, but are already present during
infancy. Brain development in adolescence influenced by prenatal hormonal levels. Around 8
weeks after gestation, testosterone levels masculinize the brains of males. Before that all
females brains.
- When relationships with parents become less important -> friends and romantic partners
become more important. Parent-child relationships are transformed, because needs change.
Importance of parental relationships remains.
Adolescence is a period of (semi-) continuous biopsychosocial transition, not typically characterized
by storm and stress, when levels of existing hormones increase, when peer relationships supplement
parent-adolescent relationships, they do not supplant them.
,Lecture 2 Adolescence
Puberty is the period during which an individual becomes capable of sexual reproduction. During that
period hormones regulated by the endocrine system trigger changes in the body. No new hormones
are being produced, no new bodily systems develop, everything is already there. Testosterone
increase in boys. It is a gradual, universal process resulting in reproductive capability and physical
maturation. Growth spurt (dramatic increase in height and weight). Development of primary and
secondary sex characteristics. Changes in percentages muscle and fat, and in circulatory and
respiratory systems (sweat glands).
The endocrine system; produces and regulated hormone levels in the body. GnRH neurons in
thalamus, functioning as a thermostat. Hormonal feedback loop; when hormones increase, fed back to
thalamus in the brain, signals pituitary gland and gonads to either increase or decrease hormonal levels
(HPG-axis). Responsible for hormonal changes during puberty.
Hypothalamus; maintaining the right balance. Responsible for vital functions, such as heart rate, blood
pressure, temperature, body weight etc. linked with endocrine system. Right above the pituitary gland
in the brain. Linked to behavioral features (aggression, anxiety, mood). It has a regulating function for
the body. Acts on thyroid and adrenal glands (maturation is called adrenarche). Cortisol also under the
influence of adrenal glands. Adolescents are more sensitive to stressing factors.
Triggers of puberty;
- environmental factors (presence of mature sexual partners, supply of sufficient nutritional
resources, physically healthy enough to begin reproducing).
- Brain chemicals; kisspeptin, leptin, melatonin (sleep).
- Other factors; genes, more fat cells, more exposure to light also triggers
Prenatal hormones program the brain to become masculine or feminine. Patterns of behavior in
adolescence can be the results of prenatal hormonal levels. Not only prenatal hormones, but also
current changes in hormones.
Somatic development; body height, mature sexually, changes in brain size, structure and function.
Growth spurt for girls; about age 12. For boys a bit later (14). Can be related with body dissatisfaction
(for girls more about body fat, for boys more about muscular mass).
Sexual maturation; increase in sex hormones, stimulates development of sexual characteristics. System
that is used to indicate in which stage a person is in terms of sexual maturation; Tanner stages. Timing
and tempo of puberty can depend on amount of fat cells.
Psychological and social impact of puberty. Impact of physical changes on psychosocial functioning.
May change self-image, and in turn behavior. Moodiness; decreases from 13 to 18.
Adolescent is not consistently impulsive, does not always make bad choices. Peer pressure and the
mere presence of peers makes them less cautious. Prefrontal cortex is one of the last to mature
(considering consequences of actions, top-down control). Limbic system is looking for a thrill
(reward-seeking hyperdrive). Disbalance in the brain between those systems in adolescence.
Prefrontal cortex is slowly becoming stronger as adolescents grow up, whereas the limbic system is at
its full force in puberty. So the limbic system has a bigger influence on behavior. This could partly
explain risk taking and impulsivity in adolescence. Risk taking doubled in the presence of peers,
than without the presence of peers. So, adolescent do not take more risk than adults per se when alone.
But they do in the presence of peers. Not sure yet of a causal link between brain development and risk
taking behaviors in adolescence.
, Dual system model; prefrontal cortex is still developing, and it can’t keep up with the limbic system,
which goes into reward-seeking hyperdrive. Systems compete with each other for priority.
In model C; maturation of prefrontal cortex a little bit earlier than the other models, due to new
research. But all models; during adolescence, the limbic system has a relative stronger influence
on choices and behavior than the cognitive control system. (age 10 till 25)
Cognitive control (neurobiological) -> self-regulation (psychology)
Reward-sensitivity (neurobiological) -> sensation seeking (psychology)
Pfeifer and Allen; evidence not clear that changes in brain are the cause of risk taking behavior seen in
adolescence.
Crone and Dahl; dual system model (limbic system and cognitive control). Propose that the cognitive
control (prefrontal cortex) can be flexibly used by adolescence, depending on how motivated an
adolescent is. They choose how much cognitive control.
Social influence on risk perception; young adolescents are more influenced by people their own age,
than people in any other age group are. Hypersensitive to social cues. They pay more attention to peers
than to adults. 12 to 14 year old let themselves to be informed by peers than others on risk perception.
