brain development

what is the brain like at birth?
Areas of the brain controlling functions necessary for survival, such as the brain stem are fully developed at birth. At birth, the neonate’s brain has almost all the neurons of an adult brain.
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what rapidly changes during development?
It is the development of synaptic connections between neurons which rapidly changes during maturation.
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what does epstein say?
this process occurs in spurts between 3-10 months, 2-4years, 6-8years, 10-12+years, and 14-16+years.
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explain the growth after 1 and a half years?
Growth after 1 ½ years accounted for 30% of total brain development, and was largely explained by myelination of cells and dendritic branching.
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how was data gathered in epstein?
Data was gathered from measuring head circumference, post-mortem studies of the brain, and EEG (measures electrical activity of neurons), across a dozen countries. Much of his data came from reviewing other’s research as well as his own
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what is the brain still going through in adolescence?
processes of maturation.
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what did barnea- goraly et al 2005 use?
MRI scans
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what did barnea- goraly et al 2005 find?
white matter (myelinated cells which transmit signals more efficiently as electrical energy is insulated and can’t disperse into the brain) increases with age.
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what else did barnea - goraly et al find?
Areas such as the prefrontal regions, basal ganglia and thalamic pathways, the ventral visual pathways, and the corpus callosum show the greatest changes, relating to improved functions of attention, motor skills, cognitive ability, and memory.
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what have functional scans shown?
Functional scans have also showed changes in brain activity during maturation.
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what did chugan and phelps (1986) do?
used PET scans to study glucose metabolism in children
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what did chugan and phelps find?
For infants 5 weeks or younger glucose metabolism was highest in the sensori-motor cortex. By 3 months the glucose metabolism had increased in most other cortical regions showing evidence of the development of higher functions.
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what else did chugan and phelps find? 2
By 8 months further increases were being seen in the frontal and posterior association cortex, meaning children are developing the ability to learn and construct schema.
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what else did chugan and phelps find? 3
The cortex continues to the develop, for example after the primary cortical regions develop for sensory and motor function, then the parietal areas develop for spatial awareness and temporal regions for language.
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what did gogtay et al (2004) do?
carried out a longitudinal MRI study and showed that grey matter (contains synaptic connections) decreases as brain growth increases in frontal regions of the brain that control executive functioning,- self-regulation/impulse control/problem solving
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who was this observed in? gogtay et al
This is observed post-adolescence, meaning the brain has not finished maturing until young adulthood (age 30 in this study).
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what is stabalisation and where does it occur found by gogtay?
Stabilisation (an end to changes) occurs in parietal cortex first, between childhood and adolescence, meaning functions such as integrating sensory information, are fully matured
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what is the frontal region like in adolescences and what still happens?
In adolescence though, the frontal region is not fully matured: synaptic pruning and myelination of cells is still occurring in the frontal regions, improving reasoning and executive functioning (i.e. controlling impulses to attain long-term goals)
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effect on risk taking behaviour?
ernst et al 2005
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what was the aim of arnst?
To investigate, using fMRI, whether maturational differences in the amygdala of adolescents and adults predicts enhanced risk-taking behaviour in adolescents.
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what was the sample? arnst
Fourteen adults (6 females/8 males, aged 20-40) and sixteen adolescents (9 females/7 males, aged 9-17) were recruited using newspaper advertisements in the US.
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charactristics of the sample? ernst
They were all healthy, and the mean IQ and socio-economic status was similar between the 2 conditions. All signed consent forms, and parents were asked for consent for adolescent group
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what was the method? ernst
quasi experiment
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what was the procedure ernst?
Participants were given a risk-making task where they could win real money, in an fMRI scanner. They were presented with a ‘Wheel of fortune’ type tas
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procedure 2?
They were all presented with a high-risk/reward wheel, where they had to choose between a 10% chance of winning $ 4.00 and a 90% chance of winning nothing, versus a ‘safer’ wheel with a 90% chance of winning $ 0.50 and a 10% chance of winning nothing
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procedure 3?
and a low-risk/reward condition, where subjects had to choose between a 30% chance of winning $ 2.00 and a 70% chance of winning nothing, versus a ‘safer’ wheel with a 70% chance of winning US$ 1.00 and a 30% chance of winning nothing.
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results ernst?
Risky choice selection was associated with significantly greater activation in the Orbital Frontal Cortex in adults compared to adolescents. Reduced activity in the Orbital Frontal Cortex correlated with greater risk-taking performance in adolescents
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results 2? ernst
Adults and adolescents however, performed similarly on the risk-taking task: they made similar numbers of risky choices and won similar amounts of money. However, the younger participants were, the more likely they were to take moderate risks
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conclusions ernst?
adolescents engage prefrontal self-regulatory/impulse control structures to a lesser extent than adults when making risky economic choices, suggesting this area may function less efficiently
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why would the area be functioning less efficently?
because processes of myelination or synaptic pruning are not complete
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key research?
Barkley-Levenson & Galvan (2014)
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aim Barkley-Levenson & Galvan (2014)?
To identify if there is a difference in the neural (nerve) activity between adolescent and adult brains when given risk-taking scenarios (gambles) with different expected values (outcomes).
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method Barkley-Levenson & Galvan (2014)?
Quasi-experiment with independent measures design, conducted in a laboratory. The IV was whether the participant was an adult or an adolescent. The DV was the activity observed during decision-making about gambles +the type of gambling decisions made
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sample Barkley-Levenson & Galvan?
19 adults (11F; 6M) aged 25-30, and 22 13-17 year old (11F; 11M) healthy, US volunteers were recruited. Consent was gained from Ps, or their parents, if under 18.
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procedure Barkley-Levenson & Galvan?
Data was collected on income, as a control. They were familiarised with a mock MRI scanner. Then they were given $20 for taking part, and told they would be able to gamble and win/lose another $20.
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procedure Barkley-Levenson & Galvan? 2
1wk later, they were called back for an fMRI scan, while they undertook the decision-making process about the gambles. Each P was showed a spinner with the number of dollars that could be lost or gained on each side.
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procedure Barkley-Levenson & Galvan? 3
They were asked to state if they’d be willing to make that gamble. They were told that one of the gambles they had been willing to make would be played, and they would keep the outcome of that gamble.
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materials used? Barkley-Levenson & Galvan
: There were 144 spinners, with a gain on one side and a loss on the other. * High expectancy is when the potential gain significantly outweighs the potential loss * Low expectancy is when the potential gain slightly outweighs the potential loss
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materials used? Barkley-Levenson & Galvan 2
Negative expectancy is when the potential loss outweighs the potential gain There were also 24 win/win spinners and 24 lose/lose spinners which were used as controls.
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results and conclusion Barkley-Levenson & Galvan?
The higher the expected value of the win, the more likely the adolescent was to accept the gamble. Expected value had a greater effect on adolescents than adults. This demonstrated that adolescents took risks which had the potential being rewarding
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what does finding 1 suggest?
suggesting they get more pleasure from rewards. The avoidance of risk where the potential cost was similar to or greater than what could be gained showed that adolescents do make a reasoned decision rather than acting impulsively, can choose
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finding and conclusion 2?
Scans showed that there was significantly more activity in the left ventral striatum of the adolescents, when gambling, than the adults. This area showed greater activity as the Expected value increased. This area is associated with gaining pleasure
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what was finding 2 suggest?
This suggests risk taking behaviour is more readily reinforced in adolescents by the pleasure they get at the prospect of a win/ reward.
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what does finding 2 also suggest?
It also indicates that connections between the frontal regions of the cortex responsible for supressing reward seeking behaviours (inhibiting activation of the ventral striatum) and the ventral striatum are not very efficient-
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what might the second suggestion be down to?
this may be due to processes of synaptic pruning occurring last in the frontal regions and continuing until age 25.
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3rd finding?
Activation in the Medial and Dorsolateral pre-frontal regions was observed as expected value of the gambles increased, in all participants, suggesting that adolescents do recruit (use) these areas of the brain
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what does the third finding support?
supports that they are capable of reasoning and understanding the consequences of their decisions but weigh the rewards more heavily than the potential losses
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application, biological strategies, Barkley-Levenson & Galvan (2014)?
demonstrated that when adolescents engage in particularly rewarding risk-taking behaviours (high expected value: greater expected win than loss), the activity in ventral striatum increases
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application, biological strategies, Barkley-Levenson & Galvan? 2
When teenagers are in groups of peers, they may be more inclined to take risks because the expected value (outcome) of the risk may be seen as more rewarding, i.e. the teenagers will achieve peer approval.
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application, biological strategies, Barkley-Levenson & Galvan? 3
a strategy to discourage teenagers from risk-taking may involve restricting unsupervised interaction with peers.
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application, biological strategies, Barkley-Levenson & Galvan? 4
Their research also showed that adolescents were likely to avoid risks with low expected values (with a greater potential loss than win), as they receive little pleasure from them, as activation of the ventral striatum is lowered.
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application, biological strategies, Barkley-Levenson & Galvan? 5
the cost of the risky behaviour could also be increased, i.e. harsher punishment.
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application, biological strategies, Gogtay et al. (2004)?
showed the pre-frontal cortex does not fully mature until post-adolescence, so teenagers may not successfully reason the consequences of their actions.
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application, biological strategies, Gogtay et al. (2004)? 2
educating teenagers about the dangerous consequences of risk-taking, by inviting speakers to deliver assemblies in schools and encouraging parents to discuss the dangers may help prevent risk taking
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what rapidly changes during development?

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It is the development of synaptic connections between neurons which rapidly changes during maturation.

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what does epstein say?

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explain the growth after 1 and a half years?

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how was data gathered in epstein?

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