Typ & Atyp - Week 9 - Adolescent Brain

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Adolescents and Risk

Although adolescents are more prone to risk taking behaviour - this is not always bad

Particularly relevant is stimulation of the Nucleus accumbens, part

of dopamine reward system which has the biggest signal related to reward

The bigger the response to reward the more likely you are to partake in risky behaviour.

- See Galvan

et al., 2007

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Triadic Brain

Ventral

striatum = short hand for dopamine response system

Amygdala = if active you feel fearful – turns on vigilance

However, Amygdala doesn’t just

sense fear, does other end of the spectrum, i.e. tells you if your safe or not

Prefrontal

cortex = assesses responses of ventral striatum and amygdala and decides whether to respond

In other words, deals with cognitive assessment of your emotional response

Model is a simple one and doesn't involve hippocampus - in

order to decide if something is risky you should compare to memory of previous events...

Red

and green work together, both might fire if something is both risky and

rewarding, e.g. bungee jumping

Teenagers are more sensitive to reward in green ventral striatum area and less sensitive to threat in red Amygdala area

The connections from the purple Prefrontal Cortex are also less strong than in adults, so for teenagers there is less regulation , more likelihood to

respond to your emotions than have a cognitive response

See - Somerville et al. 2011 go, no go task

Children perform the same as adults because typically they get response inhibition from adults, teenagers have to learn to do it

themselves – immature system

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Adolescent Brain Development

There is a difference in the way different parts of the brain develop in adolescents

e.g. The Prefrontal Cortex has a relatively linear development from child to adulthood, whereas the nucleus accumbens is not linear, it peaks sharply to adolescence and then flattens off completely

So cognitive control lags behind

our response to reward in teenage years

Impulsivity mixes up risk and reward

See - van Leijenhorst et

al., 2010 gambling study

and Dreyfuss et

al., 2014 go no go fearful faces

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Adolescent Specific vs Emergent

(Pertains to go - no go task)

Adolescent emergent effects happen in

places with cognitive control

Adolescent

specific effects in places where you get emotional responses

Males are more prone as teenagers to react to false alarms than females

Therefore, because teenagers have both increased propensity for risk taking and reward seeking, Ernst,

Pine & Hardin's 2006 Triadic brain model cannot be correct

Casey's assumption about discrepant development of prefrontal cortex and nucleus accumbens can't be right either....

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Imbalance Framework

What if, as you develop, you get more connections in the cortex than the sub cortex, and so become emotionally less responsive