DTI tractography image of a healthy brain

Do the sides of our brain do different things?

We help you separate scientific fact from brainy baloney

Another popular myth about the brain is that the left hemisphere is ‘logical’ and the right hemisphere is ‘artistic’.

This probably comes from early studies of people with brain damage and from work on ‘split-brain’ patients, in whom the connections between the left and right hemispheres were destroyed to prevent epileptic seizures from spreading throughout the brain. It’s true that the left and right hemispheres each contain areas that are specialised for different functions, but most things we do involve the coordinated activity of the two hemispheres.

Split-brain patients

A year or so after surgery, split-brain patients are often able to lead very normal lives and are generally not aware of a difference in their behaviours and abilities. However, in studies where information is conveyed to one side of the brain and not the other – for example flashing a word in front of the left eye and not the right – the lack of communication between the two brain hemispheres becomes obvious.

For example, the left hemisphere is largely responsible for producing language, so if a word is flashed in such a way that only the right hemisphere is able to perceive it, the patient will not be able to articulate the word they saw, but they are able to draw it. This demonstrates how each hemisphere has certain ‘specialisms’, but in no way supports the claim that either hemisphere is ‘creative’ or ‘logical’.

You can see some of these tests in action here.

Lead image:

Connections in the brain of a healthy adult viewed from the back. Brain cells communicate with each other through these nerve fibres, which have been visualised using diffusion imaging tractography. The corpus callosum – the bundle of fibres which connects the two brain hemispheres, allowing them to communicate – is visible in the centre. It is this that is cut in ‘split brain’ patients.

Henrietta Howells, NatBrainLab/Wellcome Collection CC BY

References

About this resource

This resource was first published in ‘Inside the Brain’ in January 2013 and reviewed and updated in November 2017.

Topic:
Neuroscience
Issues:
Inside the Brain, Thinking
Education levels:
16–19, Continuing professional development