The human brain has multiple regions to deal with different kinds of language. The two most important linguistic areas are Broca's Area and Wernicke's Area, as we talked about back in Topic 9. But just like the rest of the body, the brain is susceptible to damage, and if the parts responsible for various aspects of language can't do their regular work any longer, different varieties of aphasia, or inability to use language, result.
We have to be careful when we talk about the brain, or about aphasia, for a couple of reasons. Everyone's brain, even if you have an image in your mind of what a brain looks like, is actually different. The brain that we point to in pictures is an average brain, taken from a large number of scans of different brains that were then averaged together. The general layout of the brain might be the same from one person to the next, but the specifics differ, so we need to know about the brain in a particular person's head when we talk about neurolinguistics. We also need to be aware that brain injuries also are quite different from one to another, and can be small and just a part of one area, or quite large and covering large portions or all of multiple areas. We need to know the specifics of the injury before we draw any conclusions about what exactly that person's behaviour is expected to be.
But with this in mind, we do know a lot about aphasia. In this episode, we talk about Broca's aphasia, a form of expressive aphasia, where the ability to talk is severely reduced. Patients with Broca's aphasia struggle to speak, using broken, halting intonation in talking with others. They also have difficulties in getting out the sounds that they want to produce, swapping around sounds in their language, even if this leads to words that don't exist in the language. They also have problems with functional morphology, like tense, number and gender, and often omit them when speaking.
But they only omit them in languages where omitting them still leaves you with usable words! In languages like Italian or Hebrew, where you need to attach those functional morphemes, they just pick one up and stick it on, even if it's the wrong one. But they still know it's not okay to leave them out entirely! Patients with Broca's aphasia still retain a lot of knowledge about language, and their comprehension is often very good still, although they do have problems with some sentence types, as we'll talk about shortly. This pattern of loss, with good comprehension but poor fluency in speech and problems with sounds and morphemes, shows us that Broca's Area is responsible for speech planning, morphology, and phonology. But they still have words and understanding, so those must be somewhere else.
So how about it? What do you all think? Let us know below, and we’ll be happy to talk with you about neurolinguistics, what happens when things go wrong in the brain, and what other kinds of aphasia exist. There’s a lot of interesting stuff to say, and we want to hear what interests you!