Brain technology can reveal differences in brain activity between a serial killer and a Buddhist monk, a music prodigy and a novice, or a top athlete and a couch potato.  But why do some brains develop differently?  Here are three views on the brain, each of which was believed to be true at one time.  Which view do you agree with?

A.  You brain is largely determined by your genes.  You are born with a certain brain, and is there isn't much you can do to change how your brain works.

B.  You brain is largely determined by genes and early childhood experiences.  How your parents treated you when you were a child can have a lasting effect on your brain.  But after the age of 6, your brain is largely fixed.

C. Your brain continues to change and adapt throughout your life.  Although your genes do provide a "first draft" of your brain, this is continuously edited by your life experiences.

Now, take a look at the video below to see what the latest science has to say on this matter.
Video Activity

Watch the video below on neuroplasticity, and take notes on the following:

  • What was the "old view" of the brain?

  • What is the current view?

  • Write down 3 examples of neuroplasticity from the video
How neuroplasticity works

The evidence is now clear:  the brain is not fixed at birth or in childhood, but continues to adapt throughout one's life.  Neuroplasticity refers to the brain's ability to adapt by forming new connections as a result of experience, learning, or following an injury.  Here were some examples of neuroplasticity from the video you watched:

  • The brains of ballet dancers change to keep them from getting dizzy. Regions of the cerebral cortex that process the signal (from the inner ear) to get dizzy actually shrink.

  • High level athletes who focus on precision develop thicker outer layers of the brain.  Scientists can predict how long an athlete has been training based on the thickness of outer layers

  • Just practicing playing the piano for five days (or even just thinking about practicing!) causes changes in the motor cortex region of the brain

How does the brain actually change?  The brain is made up billions of cells called neurons, and each neuron is connected to thousands of other neurons through its dendrites - tree like branches that carry signals from one neuron to the next.  Whenever you learn something new, your neurons form new connections with other neurons, and a new pathway in the brain is established.  Dendritic branching is the process by which the dendrites of one neuron branch out to establish connections with other neurons.  Watch this happen in the video below, and see how learning physically takes place in the brain!

​The sum total of all your brain's neurons, and the connections between them, can be thought of as an enormous neural network.  Every thought, memory, emotion or behavior is linked to a certain neural pathway in the brain.  The more often you engage a certain neural pathway, the stronger this pathway becomes, and the more likely this pathway will become activated in the future.  That's where habits come from.  On the other hand, stop using a pathway - for instance, give up practicing a musical instrument - and the pathway will weaken.  For more on the brain's pathways, take a look at the video below.
What is the evidence for neuroplasticity?  Two relevant studies will be summarized below:  one on animals, the other on humans.
Research: Rosenzweig & Bennet

Aim: Investigate neuroplasticity in rats

Procedure: Rats were randomly placed in one of two different environments.  In the enriched environment, rats were placed in a cage with other rats, toys, games, and a maze to explore.  In the deprived environment, rats were placed alone in a cage, with no other rats or toys.  Rats spent either 30 or 60 days in their environments, and then were killed in order to examine changes in brain structure.

Results: The rats in the enriched environment had a heavier frontal lobe and thicker cortex compared to the rats in the deprived environment.  A thicker cortex indicates more connections between neurons, while the frontal lobe is important for decision making, executive function, and self-control (remember Phineas Gage and Raine's study on killers)

Conclusion: Being in a more stimulating environment causes new connections to form in the brain, changing brain structure.  This supports neuroplasticity, the brain's ability to change as a result of experience.


  • This is was a laboratory experiment, allowing for a high degree of control over variables.  By randomly assigning rats to different conditions, this establishes a cause-and-effect relationship between being in a stimulating environment and brain development

  • As this study was performed on rats, it is questionable whether these results apply to humans.  Although rats and humans share a great deal of genetic similarity, there are obviously important differences.  More research involving human participants is needed to confirm neuroplasticity occurs to the same extent in people

  • This study involved killing rats, which raises ethical issues.  Is it right to kill animals in the name of science?  Some argue that animals deserve to be protected from harm

Research: Maguire

Aim: Investigate whether neuroplasticity occurs in London cab drivers, who must memorize 25,000 street names, landmarks, restaurants and hotels in order to earn a cab license

Procedure: A sample of 16 healthy, right-handed London cab drivers had their brains scanned using an MRI, and this was compared with MRI scans of 50 non-cab driving right-handed males of the same average age.  MRI uses magnets to track the flow of oxygenated blood in the brain, revealing brain structure.  The cab drivers had been driving for various lengths of time, ranging from 1.5 to 42 years.

Results:  The posterior (rear) of the hippocampus was significantly larger in the taxi drivers, while the anterior (front) of the hippocampus was larger in the control group.  Furthermore, there was a positive correlation between years of experience driving a taxi and the size of the posterior of the hippocampus.

Conclusion:  The hippocampus is the region of the brain associated with memory, and the posterior is believed to be related to spatial memory and navigation.  Experienced cab drivers develop a "mental map" of London, involving thousands of streets and landmarks.  This causes an increase in the posterior of the hippocampus.


  • This study involved comparing two seperate groups of participants, with no random assignment into different conditions.  Therefore, the results are correlational, and it cannot be concluded with certainty that driving a cab caused changes in the hippocampus.  It is possible that cab drivers already tended to have a bigger hippocampus even before they started driving.

  • On the other hand, the study did find a correlation between years of taxi driving experience and size of the hippocampus.  This finding strongly suggests that the hippocampus did develop over time as a result of constantly navigating London's streets
  • The precise role of the posterior and anterior of the hippocampus remain speculative.  Although it is believed that the posterior of the hippocampus is linked to spatial navigation, more research is needed to confirm this.

Video Activity

In a number of cases, the extent to which the brain can re-organize itself (for instance, following a brain injury) is nothing short of remarkable.  Watch the video below, which tell story of a girl who functions with only half of a brain.  Try to answer the following:

  • What was wrong with Cameron?

  • Why did she need surgery?

  • When she first woke up from surgery, what had happened?

  • To what extent did Cameron recover from surgery?

  • Is this an example of neuroplasticity? Explain why or why not

IB Psychology Matters

When I was a child, I was convinced that I had no musical talent.  I easily became frustrated when practicing the piano, and quickly gave up, especially when it seemed like other kids were just naturally better than me.  In short, I had a fixed mindset, believing that talent in music was something that you either had or didn't have.

Many kids come to similar conclusions - if not about music, then perhaps about Math, or about sports, or anything else.  How many times have you heard someone say, "I'm just not good at sports" or "I'm just not a Math person"?

Research on neuroplasticity challenges the idea this fixed view of talent and intelligence.  If you can re-wire your brain through practice and experience, then anyone can train themselves to have the brain of an athlete, a musician, or a Mathematician.

Your task: Prepare a presentation (or write an article) for younger students (say, aged 13-15) on the brain's ability to change itself.  In your presentation, challenge the notion that anyone can be naturally "bad" at something, using brain science to back up your argument.  Here are some tips for doing so:

  • Start off with a quiz, discussion or activity to encourage students to reflect on their talents, and whether they believe them to be fixed or capable of growth
  • Make use of Scientific research, but be sure to adjust your language so that younger students will be able to understand

  • Encourage students to think of practical suggestions for how to stimulate the growth of new connections in the brain

  • I can explain the concept of neuroplasticity

  • I can describe how neuroplasticity takes place through dendritic branching and the formation of neural networks

  • I can outline a number of examples of neuroplasticity

  • I can discuss the Aim, Procedure, Findings, Conclusion and Evaluation of Rosenzweig & Bennet

  • I can discuss the Aim, Procedure, Findings, Conclusion and Evaluation of Maguire
Quiz Yourself!

1.  Which statement regarding brain development is false?

(a) The brain has largely completed developing by around the age of 6

(b) The brain can form new connections as a result of learning, injury, or experience

(c) The human brain continues to change throughout a person's life

(d) Both genes and the environment interact to affect brain development

2.  Dendritic branching is the process by which...

(a) Neurons multiply in number

(b) Unused connections between neurons become weakened over time

(c) An existing pathway in the brain becomes strengthened through practice

(d) Neurons form new connections

3.  Which is NOT an example of neuroplasticity?

(a) Men with enlarged hippocampuses are more likely to become taxi drivers

(b) Regions of the cerebral cortex (associated with dizziness) shrink in ballet dancers

(c) Training to become a professional athlete causes outer layers of the brain to thicken

(d) Rats placed in a stimulating environment develop more neural connections in the cortex

4.  In Rosenzweig and Bennet's research, some rats were placed in an enriched environment.  How did their brains change?

(a) Posterior of the hippocampus increased in size, anterior decreased in size

(b) Posterior of the hippocampus decreased in size, anterior increased in size

(c) Frontal lobe became heavier, and developed a thicker cortex

(d) Frontal lobe became thicker, and cortex became heavier

5.  Macguire's on taxi drivers is correlational, because it compares two groups of people (taxi drivers and non-taxi drivers) without randomly assigning them to different conditions.  Which of the following findings suggest that the brains of the taxi drivers actually changed?

(a) A positive correlation was observed between years of taxi driving experience and hippocampus size

(b) Both taxi drivers and the control group were right-handed males of a similar age

(c) The taxi drivers had a larger posterior of the hippocampus compared to the controls

(d) The taxi drivers had a thicker cortex compared to the controls


Quiz Yourself

​1- A, 2 - D, 3 - A, 4 - C, 5 - A