Question: What part of the brain produces speech?

Carolyn McGettigan answered on 18 Mar 2010:

Well, it would be an easy job for us if it were just one bit, but there are loads of bits of the brain that get involved in producing speech.

I hope you can find a cartoon of the brain online with some of the areas labelled so these bits I mention make sense to you. There’s a bit of the brain known as ‘Broca’s area’, which has been associated with the planning and production of speech since the end of the 19th Century. Paul Broca had a patient who had a brain injury that rid him of the ability to speak (he could only say ‘tan’ over and over). After the man died, Broca looked at his brain and found that a part in the frontal lobe on the left had been destroyed in the brain injury.

We can find out a lot more using MRI. In our experiments we see activation during speech production in motor cortex and the cerebellum (the little walnut-like bit at the back of the brain), which control the actual movement of articulators and the buzzing of our voice box. There are parts that respond to the sensation of our articulators moving around (i.e. we can feel our mouth open and close and our tongue moving around). These are in the parietal lobe and sometimes respond more when the speech task is more difficult, for example if we ask someone to do an impression of someone else. Also, there are bits of the brain that we use to listen to speech that can become involved when we speak out loud – these are in the temporal lobe. And THEN there are brain areas underneath the surface of the brain in the ‘basal ganglia’ which do important things in speech output too. So, I’ve got plenty to work on!