Sunday, 21 February 2016

Part 2: Neuroplasticity myths debunked

This post is the second in a three-part series on neuroplasticity. If you haven’t already read the first part, please click here. This blog post is going to explore some of the facts and myths surrounding neuroplasticity. Similar to the previous post, if you click on the links you will be directed to further information on the topic. Feel free to use these to learn more about the topic!

As we covered in the previous post, neuroplasticity is the idea that our brains are not hard wired, and that aspects of our brain's function can be reshaped or changed with experience and training. This reorganisation can also occur in response to losing an aspect of brain function – deaf and blind people can sometimes experience heightened ability in their other senses, as a direct result of losing their sight or hearing.

The purpose of this post is to challenge some of the most commonly believed myths surrounding neuroplasticity and the brain; some of which I’m sure you will have heard before! Whilst reading, feel free to test yourself – read the heading and guess its authenticity before scrolling down to see if the statement is true or not. Let me know how you get on in the comment section.



1. Neuroplasticity is a new idea

Two drawings of a dog brain shown from different angles. 
Drawing 1 is a view of the brain from above. Drawing 2 is a view from the side. The cerebellum is labelled Ce.
Source: taken from Hermann Munk (1884) Popular Science Monthly, 25, p612 

FALSE

In fact, neuroplasticity as a concept has been around since the 1700s! The first experiments regarding plasticity appear to have been carried out by the Italian anatomist Michele Vincenzo Malacarne and the Swiss naturalist Charles Bonnet, published in 1793. These experiments explored whether training and exercise could enlarge the brain, and were carried out on two groups of dogs. One group were kept in an environment with lots of entertaining stimuli and intense training, and the other none. Malacarne then compared the brains of the groups of dogs, and found that in the trained group the cerebellum (an area of the brain associated with coordination of movement) was more folded than those who were not trained. An average dog brain would look something like in the image above. The image is from 1884, demonstrating the scientific view of a dog brain around the same time. In the image, some of the normal level of folding of the cerebellum can be seen. Extra folding, as in the trained group of dogs, is a process that increases the surface area of a brain region, without taking up extra room in the skull.

This early experiment was the first to find a link between training and physical changes in the brain. However, this ground breaking experiment was largely forgotten, and the general consensus among scientists until relatively recently has been that the brain cannot be modified.

It wasn’t until the 1900s that the idea of neuroplasticity really came to prominence, after a series of experiments by a number of scientists that proved, in one way or another, that the brain really is malleable.


2. Our intelligence is fixed


This image shows some of the words and experiences we associate with intelligence. 
Source: CC0, Wikimedia Commons
 FALSE

The idea that intelligence is not fixed is essential to neuroplasticity. In fact, intelligence is not fixed because of neuroplasticity – learning new information and how to process it, which contributes to our intelligence, can change the structure and wiring of our brain.

One study demonstrating this was conducted in Scotland. In 1932, Scotland’s Mental Survey Committee decided to test the intelligence of nearly all (95%) children attending school in Scotland and who were born in 1921 - 89,498 children at the time. Intelligence was tested using the cognitive ‘Moray House Test’, which has a maximum score of 76.

In 1998, a team of psychologists led by Ian Deary and Lawrence Whalley tracked down 101 of the children tested in 1932 (now aged 77) and asked them to take the same intelligence test. The correlation between intelligence at age 11 and 80 was high (0.73). This means those that scored highly at age 11 mostly did well in the test again at age 80. However, individually, the score people got at age 80 was significantly higher than their own score at age 11. This demonstrates the fact that whilst intelligence for a group stays relatively the same, it changes for an individual.

This study contributed highly to the idea that intelligence is not fixed. Your own intelligence level at age 11 will differ greatly to that at age 40. However, you will probably stay in the same ranking of intelligence level amongst a group for your lifetime. The change in individual intelligence is what demonstrates that our brain is plastic – the malleability of our brain reflects the fact our intelligence can change.

3. After painting the ceiling of the famous Sistine Chapel, Michelangelo could not view things normally for a period of time


The ceiling of the Sistine Chapel, as painted by Michelangelo in 1508-1512
Source: Qypchak, Creative Commons

TRUE

Ascanio Condivi, an Italian painter and writer, is most famous for his biography of Michelangelo, published in 1553. The biography covered some of Michelangelo’s experiences during his painting of the Sistine Chapel, and notably described how the painting affected his vision.

Michelangelo painted the entire ceiling of the Sistine Chapel standing looking upwards, painting above his head. After four years of this, Wohl’s (1976) translation of Condivi’s account states, “…because he had spent such a long time painting with his eyes looking up at the vault, Michelangelo then could not see much when he looked down; so that, if he had to read a letter or other detailed things, he had to hold them with his arms up over his head.” After four years, Michelangelo’s eyes and brain had adapted to a new way of looking at the world.

This account depicts a phenomenon called perceptual adaptation, an ability of the brain to change the way it perceives information. In the case of Michelangelo, his eyes became accustomed to always looking upwards at a strange angle, causing them to undergo a level of visual plasticity. This effect has been produced in more recent experiments, such as those by Erismann and Kohler in the 1950s, which involved subjects wearing goggles that turned vision upside down. Kohler wore the goggles for 10 days, and became completely adjusted to the new way of viewing the world. This kind of study has been repeated in more recent years, with the same results.


Eventually, Michelangelo's eyes adjusted back to our normal way of viewing the world, but this case and the more recent studies demonstrate how easily our brains can adapt to new or different information, and how quickly this can become the new normal. 

4. Taxi drivers have different brains to those of the average person

The kind of taxi typically driven by a London taxi driver who has acquired ‘The Knowledge’ 
Source: Jimmy Barrett, Wikimedia Commons

TRUE

It may seem unbelievable, but this statement is actually true – although it’s only applicable in the case of taxi drivers who have acquired ‘The Knowledge’.

In London, cabbies must learn ‘The Knowledge’ before qualifying as a licensed black taxi driver. The purpose of this training is so that a taxi driver can decide a route to take immediately upon a passenger’s request, without using a map – taking into account one-way streets and likely traffic conditions.

The trainee taxi drivers must learn 320 main routes across London. This includes the 25,000 streets within a 6-mile radius of Charing Cross, as well as other commonly used journeys across the city. Aside from learning streets, taxi driver trainees must also know the ‘points of interest’ along all routes – including hospitals, railway stations, restaurants and theatres – amounting to around 20,000 landmarks!

Unsurprisingly, learning all of this information affects the brain. Taxi drivers who have passed ‘the Knowledge’ test have been found to have larger hippocampi than the average person. The hippocampus plays an important role in spatial navigation tasks and helps with cementing short-term memory to long-term.

This physical difference in the brains of taxi drivers is an example of neuroplasticity – their brains have adapted to the requirement that they must know and remember massive amounts of map-related/navigational information, showing that the structure of our brains can change with learning.

***

What do you think? Has this blog post changed your view of the brain and plasticity at all? The next and final post of this series will be a quiz on the knowledge you have gained from this and the previous post!

This blog post is part of my Final Year Project for my Neuroscience BSc at the University of Manchester. I would really appreciate if you could take the time to write a comment below detailing your opinion on neuroplasticity, and how it may have changed after reading this post – feel free to write this anonymously if you so wish.

Thank you, and I hope you enjoyed this post!

15 comments:

  1. Really interesting article! Do you know how much intelligence varied over age? Surely there are limitations to how intelligent one person can become?

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    1. Thanks for your comment!

      Interestingly, the study found that the IQ of one person was 100 in the first test, and dropped to 60 in the second. Some of this variation can be explained by external factors, such as the level of education the person received between the two tests. They also could have developed a neurodegenerative disease, such as dementia, in the gap between tests, which would affect IQ levels dramatically. This link describes the study (perhaps more clearly!) and includes an image from the study that illustrates the variance of intelligence quite well: http://www.creativitypost.com/psychology/why_iq_fluctuates_over_your_lifespan

      In regard to intelligence limits, the answer depends on the context of your question. For example, a limit to intelligence can be in evolutionary terms - will our future counterparts one day reach a limit to how much more their brain can be developed. We are more intelligent in this sense than our caveman ancestors, but some argue there is a possibility that our brains will reach a point where evolutionary development is no longer achievable. This paper explains the point of view that physics will limit how much smarter we can become: http://www.cs.virginia.edu/~robins/The_Limits_of_Intelligence.pdf

      However, in terms of the individual, you or I are perfectly capable of becoming more and more intelligent in our lifetime. There is no limit to the amount of languages you can learn or instruments you can learn to play, for example. Both of the types of intelligence limits are discussed in this article from the Guardian: http://www.theguardian.com/technology/2012/jan/08/thomas-hills-evolutionary-intelligence

      Hopefully that answers your question a little! Thanks again for your comment :)

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  2. Wow, that's fascinating about Michelangelo! Such an informative blog post, can't wait for part 3!

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    1. Thank you! The next part will be uploaded early next week so keep an eye out for it around then :)

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    2. Never knew that about Michelangelo, so interesting! bring on part 3!

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  3. That's really interesting about the Sistine Chapel. I have been there, and they never told us that.

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    1. Thanks for your comment. I was quite surprised to find out about Michelangelo too - it seems to be a pretty unknown fact. Glad you liked the post!

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  4. Oh this is fascinating!! I'm not surprised about the cabbies though!

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    1. Thanks! It's amazing that cabbies can retain so much information, and not that surprising that it would affect their brains in one way or another from the amount they have to learn!

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  5. Really enjoyed this, great read! It's amazing to see how easily our brains are able to adjust according to their environment. Also, would never have guessed neuroplasticity has been around for such a long time!

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    1. Thank you for your comment. Glad you enjoyed the post! Look out for the quiz post on this topic where you can test your knowledge of neuroplasticity :)

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  6. Really interesting post, although I still have reservations about the taxi driver myth - that might have something more to do with their desire for a bigger fare than knowledge though!

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    1. Thank you for your comment. So glad you find the post interesting! You could be right!

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  7. Woah! Brains!

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  8. Thank you for this piece. Leonardo Da Vinci is yet another example.

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