Notes on Language and Brain

On a recent visit to the library, I came across How Language Works, by David Crystal. In chapter 27, How the brain handles language, Crystal simplifies how language is interpreted in the mind and how the mind constructs language. I will make notes on what he has to say in this chapter (the images are scanned and uploaded from the chapter as well):

Cerebrum: the largest region of the brain. It is divided into the left cerebral hemisphere and the right cerebral hemisphere.

Brain stem: connects the cerebral hemispheres to the spinal cord. The brain stem consists of the mid-brain, the pons, and the medulla oblongata.

Cerebellum: responsible for body posture and the smooth coordination of all body movements. The cerebellum is located at the back of the pons.

(Cerebral) Cortex / Gray Matter: Nerve cells found on the surface of the cerebrum. The cortex is involved in the control of voluntary movements and intellectual functions, and the decoding of information from the senses.

White Matter: fiber tracts that transmit signals between the different parts of each hemisphere, and between the cortex and the brain stem.

Median Longitudinal Fissure: separates the cerebral hemispheres.

The brain is divided into four main lobes:
1. frontal
2. temporal
3. parietal
4. occipital


Theory of Cerebral Localization: "The idea that a single area of the brain can be related to a single behavioural ability, such as vision or speech."

Support for this theory came from the work of Paul Pierre Broca and Carl Wernicke (both were neurologists who found that damage done to certain parts of the brain results in reduced linguistic and/or motor capabilities; please see my previous blog post about aphasia, the loss of language due to brain damage).

Other areas of the brain which are associate with speech, listening, reading, writing, and signing are located in the image below:


- The front part of the parietal lobe, along the fissure of Rolando, is primarily involved in the processing of sensation, and may be connected with the speech and auditory areas at a deeper level.

- The area in front of the central fissure (aka the fissure of Rolando) is mainly involved in motor functioning, and is thus relevant to the study of speaking and writing.

- An area in the upper back part of the temporal lobe, extending upwards into the parietal lobe, plays a major part in the comprehension of speech (This is Wernicke's area).

- In the upper part of the temporal lobe is the main area involved in auditory reception, known as Heschl's gyri, after the Austrian pathologist R. L. Heschl.

- The lower back part of the frontal lobe is primarily involved in the encoding of speech (This is Broca's area).

- Another area towards the back of the frontal lobe may be involved in the motor control of writing. It is known as Exner's centre after the German neurologist Sigmund Exner.

- Part of the left parietal region, close to Wernicke's area, is involved with the control of manual signing.

- The area at the back of the occipital lobe is used mainly for the processing of visual input.

NEUROLINGUISTIC PROCESSING (Here is the amazing part):

- Speech production: Wernicke's area (utterance structure) --> Broca's area (encoding) --> adjacent motor area (articulation)

- Speech comprehension: speech --> auditory cortex (speech reception) --> Wernicke's area (interpretation)

- Reading aloud: written form --> visual cortex (reception) --> angular gyrus --> Wernicke's area (auditory representation) --> Broca's area (processing)

Aphasia—Loss of Language

Aphasia is the loss of language due to damage to part or parts of the brain that are responsible for language. Damage may be brought about by head injuries, strokes, tumors, infection, or dementia.

Damage to the left or right temporal lobe (though normally in the left) results in Wernicke's Aphasia (fluent aphasia). A person with Wernicke's Aphasia will speak in long sentences that are hard for others to understand (it is also hard for such a person to understand others). They may add unnecessary or even invented words to their speech. Because the left temporal lobe is not close to any motor movement areas of the brain, Wernicke's Aphasia is not usually accompanied by weakness or paralysis of the body.


Broca's Aphasia, a type of non-fluent aphasia, occurs with damage to the frontal lobe. A person with Broca's Aphasia speaks in short, concise sentences that eliminate small words like "is" or "the." Though strained to speak, an affected person has no comprehension problem when listening to others. Broca's Aphasia is frequently accompanied by right-side weakness or paralysis, since the frontal lobe also controls motor movement.

Global Aphasia (non-fluent) is a result of damage in extensive areas of the brain's language areas, resulting in limited speech and comprehension abilities and extreme difficulties with communication.

Below are some examples of sentences that may be spoken by persons with aphasia. Remember, while Wernicke's is characterised by long, drawn-out speech with superfluous or made-up words, Broca's speech is identified by its brevity.

Wernicke's:

"You know that smoodle pinkered and that I want to get him round and take care of him like you want before.”

Broca's:

"Walk dog.” (meaning "I will take the dog for a walk.")
"Book book two table." (meaning "There are two books on the table.")

[Source for all above information: National Institute on Deafness and Other Communication Disorders' website, at this url: http://www.nidcd.nih.gov/health/voice/aphasia.asp]

As you can see, not every aspect of language is controled by one single area of the brain, in fact different aspects of language are controlled by parts of the brain that are separated from one another. I believe this to be an advantageous development, since in the event of a head injury causing a form of aphasia the chance of losing all language capabilities whatsoever is lessened. That is my best guess, not actually being a neurologist myself.

After reading about this I would also be interested to know 1. How do the mechanics of the brain work in regards to language and communication, and 2. How and to what effect do the language-areas of the brain correspond with motor skills? If you are reading this and you know anything about this, please feel free to share your knowledge.