creierul de-a lungul anilor - adolescentii Flashcards
What are the main anatomical changes in the adolescent brain?
- Shrinkage of grey matter – synaptic pruning – you lose the connections that you don’t use
- Expansion of white matter – axons – increase in dendrites
Why does shrinkage of grey matter happen?
Due to synaptic pruning
At age 7 there is more neurones than at age 15
Females are said to experience maturation earlier than boys because this synaptic pruning begins earlier in females. They lose connections that they do not need which makes communications that are needed quicker and more efficient
Why does expansion of white matter occur?
Due to myelinisation – when axons are covered in a fatty layer to speed up connections
What happens in the prefrontal cortex in adolescents?
Prefrontal cortex functions include planning and reasoning
It grows until 25 yo
In teens, the PFC is immature which makes them more prone to risky behaviours
What happens in the amygdala in adolescents?
Emotional core for passion, impulse, fear and aggression
Adults rely less on this and use prefrontal cortex more
Teens rely more on this and are more impulsive
The amygdala matures faster than the prefrontal cortex
What happens in the parietal lobe in adolescents?
Responsible for touch, sight, language
Grows till early 20s
In adults it is fully developed
In teens- they do not process information effectively
What happens in the ventral striatum in adolescents?
This is the reward centre
In adults it is fully developed
In teens it is not fully developed hence why teens are more excited by reward than consequence
What happens in the hippocampus in adolescents?
Hippocampus is the hub of memory and learning
In adults it is fully functional and loses neurones with age
In teens it has a tremendous learning curve
How are teenagers more risky especially with peers?
Measured using the Stoplight driving game
The aim is to reach as quickly as possible the end of straight tracks with intersections
2 conditions: peers / no peers
RESULTS:
Adolescents made riskier decisions and had more crashes when in the presence of peers
Young adults made less riskier decisions and crashed less when with peers
Adults made more riskier decisions but crashed less with peers
But overall teenagers made the most risky decisions and crashed the most
what did the experiment find in terms of brain activations
Higher left lateral prefrontal cortex activation in adults than teens
Higher right ventral striatum and left orbitofrontal cortex in teens with peers than adults - so they activated reward centre suggesting they get a reward from showing they are riskier to their peers and don’t think about the consequence (crashes)
What are the risky tendencies in different cultures?
There is association between age and risk taking
Around the world risk taking is generally highest among late adolescence based on Spotlight task and BART
when does sensation seeking peak
at 19yo
when does self regulation peak
between 23 and 26
what is impulsivity
engaging in unplanned risky behaviours and being unable to inhibit behavioural impulses and thoughts
what is motor (behavioural) impulsivity
response inhibition, related to dorsolateral prefrontal lobe
what is cognitive impulsivity
inability to compare immediate and future consequences of events
related to ventromedial prefrontal lobe
what’s impulsivity like in the teenage brain
reduced myelin growth in frontal areas is linked to impulsivity traits
so less myelin means more impulsivity
In adolescents with high impulsivity, myelin growth in frontal areas is particularly reduced
what is lower cortical thickness associated with
lower cortical thickness is associated with impulsive choice in specific brain networks that are important for decision making
what is compulsivity like in the teenage brain
greatest myelin related growth in late adolescence/early adulthood in cingulate cortex and frontostriatal areas
reduced rate of this growth is linked to compulsivity traits
less myelin - more compulsivity
reward-related activities increase in teenagers
dopamine reactivity is enhanced
this may cause:
- sensation seeking behaviours
- selective focus on rewards rather than risks
- increased susceptibility to alcohol
why do many mental disorders appear in adolescence
the big changes the brain experiences may explain why adolescence is the time when many mental disorders emerge
what is the link between genetic and environmental effects in mental health and adolescence
genes interact with environment to affect behaviour
allele alone bring no additional risk
but allele plus stressful life events lead to increased risk of self-report depression symptoms
what is an example of when E and G interact
Anorexia which is a multi-factorial disorder
Traits in childhood such as negative emotion, perfectionism, drive for thinness, OCD interact with genetic changes in adolescence such brain development and hormones which leads to dieting
