Booklet 2: Pre-adult brain development (Biological) (Brain Development…
Booklet 2: Pre-adult brain development (Biological)
Development of the brain occurs over a lifetime, developing from the back to the front. So the Prefrontal cortex doesn't fully develop until mid-20s.
Rapid growth of brain matter and formation of new connections. Aged 7-11.
Cutting away unused/unimportant connections. Aged 11+.
Insulation of brain pathways to make them faster and more stable.
Synaptic growth spurt:
Age 7-11, brain undergoes huge growth spurt of connections, similar to the one 18months - 2yrs. Most growth in temporal and parietal lobes.
First change in the synaptic growth spurt. Frontal lobes lose 3% of grey matter. Around age 11 'prunes' itself, sculpting away excess material and connections to make a more efficient adult brain.
Insulating frontal lobes, completes age 18-20 allowing it to operate more efficiently. Happens in temporal and parietal lobes before frontal. Teens moving from concrete to abstract thinking. Idealistic & cause orientated. Prefrontal lobes responsible for reasoning ability, planning and organisation of tasks.
Amygdala responsible for processing incoming sensory information, holds emotional memory, starts fight or flight response, develops before frontal lobes.
Resulting behavioural changes
: Teens demonstrate heightened level of self-consciousness. Believe everyone's concerned with their thoughts and behaviours. "Imaginary audience" and become overly dramatic in situations.
Adolscents ignore negative consequences as lack high level reasoning and judgement, controlled by prefrontal cortex.
Serotonin, neurotransmitter linked to mood, reduction in this leads to impulsivity of rheus monkeys, relating to children who abused/neglected showing more impulsivity. So may not just be this but also the environmental factors too.
Barkley-Levenson et al. (2014)
Identify difference in neural activity between adolescent and adut brains given risk-taking scenarios with different expected values of outcomes.
Prior to this research, unclear whether adolescent brain attributes greater value to rewards, or value money to greater extent than adults as have less experience with it.
Adolescents accept more gambles of increasing EV than adults.
Ventral striatum activation increase in proportion to increasing eV in dolescents.
Adults who behave like adolescents in gambling behaviour not exhibit hyperactive Ventral Striatal activation.
IV whether they were adult or adolescent. Quasi-experiment with Independent measures design, conducted in a lab. Performance measured on mixed gambles and DV difference in neural activation and behavioural responses to gambling, fMRI scan used.
19 healthy right-handed adults aged 25-30 (11 females & 8 males) and 22 healthy, right-handed adolescents aged 13-17 (11 females & 11 males). All volunteers responded to posters and internet adverts.
PP's attended lab for 'intake session' to give consent (themselves/parents). Asked about primary source and amount of spending money received a month. Pp's given $20 for completing but used it in task to win up to $20 more or lose it in gambling fMRI task. Whilst they were being scanned, 50% chance of gaining or losing amount shown, 144 trials. 24 were gain only and 24 were loss only. Pp's had to decide whether they'll gamble for real money.
3 pp's excluded from experiment. Acceptance rates didn't change between groups when no riks involved. No differences in reaction time. Higher the EV more likely adolescent was to gamble. Correlated with greater activation in ventral striatum. fMRI showed changes in amygdala (fear response) decreased activity and increased in medial prefrontal cortex (memory and desicion making).
Adolescents are more likely to engage in advantageous risk taking. Adolescents more attentive to value of available options than adults. Expected value used to bias reward-related behaviour during adolescence.
Stressful childhood means less serotonin strong case for intervening with parents at risk of neglecting/maltreating their children, e.g. sure start. Programme in 1998, nurses visiting expectant mothersbefore birth, providing training for parents on how to cope.
Educating parents working with children to provide age-appropriate curriculum covering risky behaviours.
Interventions reduce risk-taking designed alter knowledge, attitudes and beliefs. Risks of substance use, reckless driving or unprotected sex. This improved young people's knowledge but not effective in changing behaviour. Adolescents lack cognitive control to resist sensation-seeking.
Graduated driver licensing schemes
Driving programme US, Australia and China. Adolescent drivers likely to be risky and have more accidents, not allowed full license until completed probationary period.
Peers present make rewarding aspects of risk taking more appealing, increased activation in VS brain region. 1 or more probationary periods for new drivers qualified for their licenses. Age limits, no. of passengers and restriction on alcohol consumption or night-time driving.
Learning should be completed in lower risk and supervised conditions until skill fully mastered. Sig reduction in crashes of adolescent drivers after 6 months/1000 miles.
Adolescents learn to avoid maladaptive behaviours, if given information linked to effective reactions to those behaviours. For example, tracking drug use since 1974 in Monitoring the Future Study found drugs are dangerous to health, but media don't portray this correctly.
Intervention programmes delivered in elementary in US positive effects on acadmic development and health-risk behaviours of urban children. Produced greater commitment and attachment to school, less school misbehaviour, better academic achievement after 6 years. Especially with children from poor families and reduce violent criminal behaviour, heavy drinking, sexual intercourse and pregnancy.
The impact of brain development on risk-taking behaviour
Adolescence characterised by heightened sensitivity to rewards, ventral striatum exaggerated response to anticipation, expected or unexpected rewards.
Subjective value- value inidividual places on stimulus, determining the SV of each alternative and selects the one with the greatest SV.
Neural computation of SV hrough measurement of EV (expected value), sum of all possible outcomes of a certain choice multiplied by probabilities - risk vs reward. Adults, increasing EV gives activation increases in VS, midbrain, medial prefrontal cortex and dorsolateral prefrontal cortex.