pre-adult brain development

Question 1

brain development in the first three months?

Answer 1

average growth of 1% / day

some of this due to synaptogenesis, connections being made between neurons

this process signals the development of conscious action, memories, thought and emotions

Question 2

synaptogenesis?

Answer 2

can be monitored using MRI as an increase in grey matter

starts in visual cortex and moves forward to areas responsible for higher cognition and emotional functioning

Question 3

myelination?

Answer 3

also occurs during childhood

process of coating axons with a myelin sheath, insulating and facilitating their function, helping coordination

can also be monitored with MRI as an increase in white matter

grey matter volumes peak at 11 years for girls and 13 years for boys and decline from there due to synaptic pruning

Question 4

synaptic pruning?

Answer 4

connections between neurons that aren’t used frequently are eliminated

allows brain to be more efficient in how it uses its energy

continues to operate until the early-mid twenties

follows a predetermined path going from the visual cortex and ending with the prefrontal cortex

Question 5

limbic system and risk taking in adolescence?

Answer 5

matures before the prefrontal cortex and is hypersensitive to ‘rewarding’ feeling of risk taking behaviour

makes risky behaviours more likely particularly in front of peers

Question 6

prefrontal cortex and risk taking?

Answer 6

can be argued that lack of maturation in prefrontal cortex is responsible for risk taking as risks cannot be adequately assessed

Question 7

ventral striatum and risk taking?

Answer 7

encourages adolescents to engage in more adult risky behaviours such as sexual promiscuity, drinking and driving

also drives process of seeking independence from family

without mature PFC, all these behaviours prove risky

Question 8

serotonin and risk taking?

Answer 8

reducing levels of serotonin in monkeys increases impulsivity

serotonin levels in humans can be reduced when one is abused or neglected as a child so risk taking is more prevalent for those with such a background

Question 9

dopamine and risk taking?

Answer 9

evidence that base levels of dopamine for adolescents are lower

so they require more stimulation so require higher levels of stimulation to acquire the same level of pleasure as an adult

also levels of dopamine released are also higher so potential positives more attractive

Question 10

barkley-levenson & galvan aim?

Answer 10

identify differences in neural activity between adolescents and adults when given risk-taking scenarios

in the form of gambles with outcomes of different expected values

Question 11

barkley-levenson & galvan method?

Answer 11

lab expt, imd, quasi

Question 12

barkley-levenson & galvan sample?

Answer 12

19 adults (25-30)

22 adolescents (15-17)

recruited through a database of past ps, an internet advert and posters

all right handed and healthy

Question 13

b-l & g procedure pre main task?

Answer 13

went to lab, adults gave informed consent and adolescents gave assent (informed consent given by parents)

information gathered about ps source of and amount of income

also gave chance to familiarise themselves with mock fMRI scanner

Question 14

b-l & g procedure main task?

Answer 14

ps told they have $20 spending money and could lose it, double it or something in between

in fMRI scanner, ps given a series of gambles presented on spinning discs, 50/50 chance either way

had values of +/-$5 to +/-$20

ps had to accept or reject the gambles on a keyboard and told one of them would be played out for real at the end (acc just given either $20+$5 or $20+$10)

Question 15

b-l & g procedure neural data?

Answer 15

neural activation in response to gambling task was observed and recorded using fMRI

focus on ventral striatum which is associated with valuation and reward

Question 16

b-l & g procedure behavioural data?

Answer 16

ps responses to gambles were recorded for each trial

to facilitate analysis, expected values were calculated for each trial

Question 17

b-l & g results neural activity?

Answer 17

as expected value of a gamble increased, there was greater activation in the adolescent’s ventral striatum, far more than for adults

vs activity was also higher when groups were matched on income or on acceptance rates

Question 18

b-l & g results behavioural differences?

Answer 18

when no risk, adults and adolescents had similar judgement

for both groups the higher the ev, the more likely they were to accept the gamble

adolescents more focused on the high amount they could win and less bothered by a small amount they could lose

both rarely accepted gambles with a - ev

Question 19

barkley-levenson & galvan conclusions?

Answer 19

adolescents value rewards more than adults reflected by higher activation in the ventral striatum

this explains their risk taking behaviour where they perceive potential significant rewards

Question 20

application: background?

Answer 20

17-19 year old drivers make up 1.5% of drivers but 9% of fatal/serious crashes

23% of 18-23 year olds crash within two years of passing their test

Question 21

application: past approaches?

Answer 21

trying to educate adolescents on the dangers and risks

ineffective as adolescents fully aware of risks but just accept a greater risk if the rewards are higher as the ventral striatum rewards

Question 22

application: graduated drivers licence schemes?

Answer 22

legally enforced probationary periods for drivers who have just qualified

Question 23

application: gdl in california?

Answer 23

no passengers under 20 unless with an older adult

no night driving (11pm-5am)

period of 12 months

Question 24

application: gdl in australia?

Answer 24

max speed of 90 kmph

zero blood alcohol permitted

night time driving limits to one passenger <21 (11pm-5am)

immediate suspension for speeding

3 year period with stages

Question 25

application: effectiveness of gdl schemes?

Answer 25

estimated that implementing a gdl scheme in the uk would save an average of…

4471 casualties and £224 million a year