Psychology - Applied - Pre-Adult Brain Development

background

what is grey matter?

neurones and synapses that cover the white matter, processing information - involved in movement, memory, emotional regulation, sensory processing , personality and intelligence (higher brain functions)

how much of the adult brain is grey matter?

40%

what is white matter?

located at the deeper parts of the brain it acts as a communication network allowing information to be transmitted around the brain and body - affects learning - subcortical in cerebrum and cerebellum but surrounds grey matter of spinal cord,

what is a myelinated neurone?

neurones conduct nerve impulses and are covered in a myelin sheath that prevents the impulse from one interfering with another whilst also speeding up their conduction - the breaking off leads to Parkinson’s, MS, Alzheimer’s etc

what is the pre-frontal cortex responsible for?

initiating higher-level functioning, contains Broca’s area that controls language - decision-making, problem-solving, intelligence and emotional regulation - social skills/personality,

what is the limbic system responsible for?

structures such as the amygdala, hippocampus, thalamus, hypothalamus etc - processing and regulating emotions (+ responses), survival instincts, social bonding, memory consolidation, arousal and learning, risk-taking

what is the ventral striatum responsible for?

reward gratification drive, impulsivity

what is synaptic pruning?

removal of neurones and synapses that are unnecessary - between 2-10 yrs and at ~20 yrs,

how do motor and visual skills develop?

0-5 months - reach and grasp items,

12-17 months - throw objects, place objects in container, point at objects,

24-29 months - bend and pick up objects, go up stairs with 2 feet per step,

36-41 months - sort shapes, go up stairs with 1 foot per step,

5 years - draw a person with 6 or more body parts,

how does brain weight change during childhood?

grows in spurts - ages 2-4, 6-8, 10-12 and 14-16 - by 5-10% over each 2 year period,

at 2 yrs brain = 55% of adult weight, at 6 yrs = 90%,

in adolescence grey matter reaches peak and then synaptic pruning begins, pre-frontal cortex last area to mature,

what is the role of serotonin and dopamine on behaviour?

dopamine - coordination, movement, feelings of pleasure and reward, mood, sleep, learning, blood flow, urine output,

serotonin - sleep-wake cycle, mood, emotions, metabolism and appetite, cognition and concentration, hormonal activity, body temperature and blood clotting.

what affects risk-taking behaviour in adolescents?

limbic system develops before pre-frontal cortex,

maturation of ventral striatum earlier,

reduction in serotonin in cerebral spinal cord (stress) can lead to impulsivity,

higher dopamine triggers V.S.

Eshel et al (2007)?

adults and adolescents were asked to choose between low probability/high reward and the opposite,

adults who made riskier decision showed activation of pre-frontal cortex - rational choice,

adolescents showed decreased activation - less likely to be rationalised choice,

Barkley-Levenson et al (2014) aim?

To see whether adolescents attach more value to rewards than adults do

to identify if there is a difference in neural activity between adolescent and adult brains when given a risk-taking scenario with different expected values of the outcomes of those gambles

Barkley-Levenson et al (2014) method + IV/DV?

Quasi lab experiment

IV = age (adult/adolescents)

DV = differences in enural activation and behavioural responses

Barkley-Levenson et al (2014) participants?

Adults:

• 19 (17 used)

• 25-30 yrs

• mean = 27.9 yrs

• 8M/11F

Adolescents:

• 22 (20 used)

• 13-17 yrs

• mean = 15.6 yrs

• 11M/11F

all healthy, right handed, no metal in body

self-select from poster and internet advert

university of california

participants from previous research

Barkley-Levenson et al (2014) pre-procedure?

all gave informed/parental consent

all acclimated to fMRI before with a mock scan

prior-information collected to control for novelty of reward as to income per month

each given $20 to play with

told there was an opportunity to receive up to $20 more but that they could also lose the $20

Barkley-Levenson et al (2014) procedure?

each trial they decided whether to gamble

told one of the trials they accepted would be selected and played, at the end of the scan for real money and the amount won/lost would affect the real $20

trained to use computerised gambling programme before testing

presented with a series of gambles across 144 trials

on screen they saw a ‘spinner’ with ½ probability of a win on one side and then lose on the other ($5-20)

had 3 secs to respond

Barkley-Levenson et al (2014) data collection?

Neural Activation

focused on activity in the ventral striatum and pre-frontal cortex

medial prefrontal cortex - involved in decision making, memory and emotion

dorsolateral prefrontal cortex - involved in the manipulation of information before an event

insula - involved with turning perceptions into emotions and preparing for action - linked with arousal and awareness of self

Behavioural

accepting/rejecting the gamble

Barkley-Levenson et al (2014) neural activity results?

Neural Activity:

• more activation in VS of adolescents as the EV increased

• when EV was high, risk seems worse taking, then adolescent brains are more active than adults

• even with similar gambling shown, adolescents still had greater VS activation

• adults had greater activation in Medial and Dorsolateral Prefrontal Cortex and adjacent cortical regions during EV computations

• adolescents had decreased activation in Insula when EV increased (might be less aware of what is going on around them)

Barkley-Levenson et al (2014) behavioural results?

Behavioural Differences:

• in trials when no risk was involved both groups made similar judgements

• for both groups an increased EV leads to an increased likelihood of accepting the gamble

• higher EV had a greater influence on adolescents

Barkley-Levenson et al (2014) overall results?

Overall:

• adolescents focused more on higher amounts they could win and less concerned with relatively small amounts they could lose

• both adults and adolescents virtually never accepted a gamble with more to lose and less to win

• adolescents are just as good as adults at avoiding disadvantageous choices and better than adults on advantageous chances

Barkley-Levenson et al (2014) conclusions?

adolescents place greater value on rewards than adults do

risk-taking shown in neural activity

the brain undergoes significant maturation during adolescence that influences reward sensitivity and risk-taking behaviour

application: intervention for neglected/abused children?

stressful childhoods/ACEs - less serotonin in cerebral spinal fluid increasing impulsivity

Olds et al (1998)

• identified families where possible neglect/abuse is likely to occur

• sent care workers/social workers/nurses etc in whilst also giving parenting training and skills

• children with support were less impulsive in school, less likely to get in trouble, led to fewer mental health issues

application: age appropriate curriculum

covering risky behaviours to highlight dangers

PSHE - drug awareness, sex education etc

application: conversation with positive role models?

talking about risky behaviours and their consequences to alter the cost/benefit analysis which occurs in the decision making

application: driving in adolescents

drivers age 16-19 in the UK are twice as likely to have a fatal car accident than drivers age 40-49

1 in 4 drivers age 18-24 will be involved in a car crash in their first 2 years of driving

Graduated Driver Licensing Scheme:

• programme implemented so adolescents aren’t given their full license for a probation period

• could save on average 4471 casualties and £224 million each year in the UK