Speak, Memory: Language and the Brain

“In the field of neuroscience, we know far less about language than about other brain mechanisms like emotion, memory, or sensation. The inherent difficulty of studying language is that it is so closely linked to thought. There are certainly parts of the brain in which language is concentrated, but it is hard to differentiate these areas from those involved in non-language cognitive processes. Language areas also appear to be quite fluid, occupying different parts of the brain among different individuals. And because language is a strictly human phenomenon, researchers can’t use animal studies to investigate brains at the neuron level.

Paradoxically, language-specific areas were the first localized areas to be discovered in the brain. As discussed earlier in our Going Mental series, French physician Paul Broca and German neurologist Carl Wernicke independently discovered two important language areas in the 1860s. Based on their brain damage studies, a cohesive picture of language processing emerged: stimuli from the auditory cortex (speech) or the visual cortex (reading) travel to Wernicke’s area in the left posterior temporal lobe, where it is processed and comprehended. From there, a bundle of nerves called the arcuate fasiculus connects to Broca’s area in the frontal lobe, which is responsible for language production. From there, the message is sent to the motor cortex for translation either into speech or writing. This succinct language circuit was the prevailing model for over a century; the only problem is that new tests show it to be inaccurate.

“Neither nature nor the brain always fits into discrete boxes,” writes Dr. John Ratey, author of “A User’s Guide to the Brain.” “Recent MRI and PET studies and highly specific clinical tests of language abilities and impairments show that the ability to move the face and tongue in the sequence necessary to produce speech sounds like ‘da’ and ‘ta’ and the ability to hear and decode the same sounds are in Broca’s area of the brain. This indicates that speech production and comprehension are not independent systems,” he says. ”

Read more at Big Think