Pre-adult brain development

Emily Barkley-Levenson

Background: Brain development and the impact of this on risk taking behaviour
Key Study: Barkley-Levenson & Galván (2008)
Strategy: Reduce risk taking behaviours using knowledge of brain development

Background: Brain development

Brain development is the process of how the brain grows from conception to old age.
It consists of the process of nerve cells (neurons) forming connections around different areas of the brain.
This generally happens during conception, development in the womb and from birth until around the age of 25 (although the brain continues to change into old age).

Background: Why is brain development difficult to study?

It would be practically very difficult and ethically completely wrong to artificially manipulate the brain development of a person for research purposes.
Instead what researchers can do first is measure how the brain develops naturally (through the use of brain scans like MRI) and then observe behaviour at the same time.
Researchers can then infer and hypothesise how the development of the brain can have an effect on behaviour.
This allows psychologists to explain the biological cause of different behaviours.

Background: Brain disorders

Another method for finding the link between brain development and behaviour is to look at brain damage or disorders.
For example, Maguire (2000) found that a lack of development in certain areas of the hippocampus (due to plasticity) can change the level of ability of people’s spatial awareness.
Brain damage in children can also reveal how certain areas of the brain relate to behaviour and also how this will affect the later development of the child.

Background: The nervous system

Another way to understand brain growth is by studying how the brain relates to the whole nervous system and researching the brain’s relationship with the rest of the body.
Neurons send electrical signals that connect the brain to certain regions. For example, Wernicke and Broca’s areas of the brain send information to the mouth, tongue and larynx indicating that it is active in controlling our language and speech abilities.

Background: Motor development

In your brain there are two types of matter: grey and white.
Grey matter makes up around 40% of your brain and is involved with processing information.
White matter is made up of long neurons that carry messages between the grey matter and other parts of the body.
It is the myelin sheath in the neurons that allows the white matter to effectively communicate messages. However, problems occur when the myelin sheath isn’t fully developed.
Disorders like multiple sclerosis are also associated with damaged myelin sheaths that hinder motor movement.
Babies do not have fully myelinated neurons which could explain why their early movements are awkward and uncoordinated.
Kolb and Whishaw (1996) are among some researchers who have shown that myelin formation in children relates to their development of movement (from crawling to toddling to walking).

Background: Language development

Language development relies on not only the physical skill of using your mouth to talk but also the cognitive understanding of words and grammar.
The frontal and temporal lobes of the brain have shown in scans to relate to language.
However, even though everyone biologically develops in the same way, there are of course individual differences in how quickly each person picks up language.

Background: Biological explanations of risk-taking behaviour

The prefrontal cortex area of the brain has been associated with high level reasoning and decisions. An underdeveloped prefrontal cortex could therefore explain impulsive and sudden risky actions.
As this area of the brain does not fully develop until the mid twenties, it could explain why adolescents are more likely to want to take an action immediately rather than weigh up the consequences of it.
In addition to the consumption of alcohol (more likely to be taken by adolescents), a lack of experience in dealing with certain situations could explain why adolescents might be more risky in their behaviour.

Background: Intelligence and risk taking

However, research suggests that rather than lacking something, it is actually having higher IQ that leads to risk taking.
Some research has shown that individuals with high IQ (better memory performance) often have high sensation-seeking behaviour (e.g. an adrenaline rush).
Zuckerman (1994) states that individuals who have high IQ and sensation-seeking are able to exert less self-control over their behaviour.
Eshel et al. (2007) carried out a study where participants had to choose between two options. One was a choice where they would probably receive a small financial reward and the other was a choice where they would be unlikely to receive a high financial reward (the risky choice).
Those who chose the risky option did not have a fully developed occipital frontal cortex – another possible explanation for their risky behaviour.

Aim = To identify if there was neural activity between adolescents and adults when giving risk-taking scenarios.

Sample

19 adults aged 25 to 30 (adult group)
22 adolescents aged 13 to 17 (adolescent group)
All participants were right-handed.
All were recruited by volunteer sample at the University of California.
No previous diagnoses of mental illness.
No metal in their bodies (e.g. pacemaker).
Only 20 adolescents and 17 adults’ data was used with the others not providing useful data.

Procedure

Participants all completed questionnaires about how they earn their money, how much they earn and how much they have to spend. This gave researchers an idea about their perceptions about winning and losing money.
Participants were also familiarised with an MRI scanner.
Participants then took part in a gambling task.

Gambling task

Participants were given a spinner with a number of dollars that can be won or lost (e.g. one side might say ‘gain $2’ the other side might say ‘lose $4’).
Using $20 that each participant was given at the start of the task, participants are told they could win another $20 or lose $20.
There were 144 spinners with different combinations of amounts.
Each participant had to take a risk with all 144 spinners.

Results

Both adults and adolescents accepted gambles if the negative outcome was $0 rather than losing money (e.g. lose $4).
The higher the amount that could be won, the more likely it was that the adolescent accepted the gamble.
Adolescents showed significantly more activity in the left ventral striatum as the amount available to win increased.
The right ventral striatum also showed greater activity in the adolescents.

Conclusions

Adolescents showed significantly greater activation in the ventral striatum than the adults (who showed barely any activity at all).
This could mean that the ventral striatum develops with age to decrease the amount of risk-taking behaviour.
This suggests that adolescent brains place more emphasis on potential rewards than adult brains and the ventral striatum seems to be significant in heightening sensitivity to rewards.
The brain then must undergo significant maturation in adulthood that reduces the sensitivity to rewards and therefore decreases the amount of risks adults take.

Application: Strategies to reduce risk-taking behaviours

There are many reasons why adolescents are more prone to risk-taking behaviour that could potentially be dangerous in the worst examples.
Providing adolescents who are most likely to give in to risky behaviour with good education and social support will help them control their ventral striatum.
Parents can talk to their children about the consequences of risk-taking behaviour and reduce risks for them (e.g. offering lifts in dangerous-to-drive roads).
Positive social networks (good friends, school and community) can also help reduce risky behaviour.

Application: Examples of applications

One of the causes of risky behaviour is when a pregnant mother who suffers a large amount of stress has too much cortisol in her blood when giving birth to her baby. This stress is often due to a stressful environment around her (poor income, bad neighbourhood, etc.).
Olds et al. (1998) carried out a programme that involved nurses visiting mothers before birth and providing training on how to cope with stressful situations. Results of this showed the children born at this time were more successful at school and showed lower rates of bad behaviour (possibly a reduction in risk-taking behaviour).
Another strategy used to help adolescents was an age-appropriate learning curriculum which was adopted to educate teenagers about how to drive safely.
New drivers were given a probationary period where their driving was restricted in certain ways (e.g. not being able to drive at night). This slow introduction to driving lowered the amount of new experiences to beginner drivers, therefore reducing the risk of starting driving than someone who could immediately drive with no restrictions.
The programme saw a significant reduction in the crashes of adolescent drivers after about six months (McCartt et al. 2003).