Brain and Language

Here, SEO Anyaran will present about the meaning about Brain and Language. What are the interconnection between them? What happens if one of them injured? Below is the explanation.

Objectives

This chapter presents about: 

1. The survey of the organization of the human brain as it pertains to language
2. The basic structure and functioning of the parts of the brain used for language. 
3. The various language disorders. 
4. Critical age for language acquisition.

Introduction of Human Brain

Human being does not have the largest brain of any creature in the world. The largest is blue whale, the average brain mass of about 9,000 grams (compared to 1,375 grams for human). Human brain contains an average of ten billion neurons, or nerve cells, each of which is linked with one thousand to ten thousand other neurons. The functions of nerve cells is that make possible thought, perception, communication, and other types of mental activity.

Cortex is the outside surface of the brain. It consists of thin wrinkled mantle of grey tissue made up of millions of neurons. The function of cortex, as the layer of the brain which represents a relatively recent evolutionary step in neurological development and is not present a comparable degree in any other species.

The brain is divided into:

• Two roughly symmetrical hemispheres (Left and Right brains). Left hemisphere has primary responsibility for language. Right hemisphere, controls visual and spatial skills (the perception of non-linguistic sounds and musical melodies). 
• Two cerebral hemispheres. The largest of which is the corpus callosum.

Both hemispheres of the brain are involved in control over muscular activity as well as in sight and hearing. The right side of the brain is responsible for movement of the left arm and leg, while the left hemisphere controls the right arm and leg. That’s why someone who suffers damage to the right side of the brain (as the result of a stroke) will exhibit paralysis on the left side of the body. The control of one side of the body by the opposite side of the brain is known as contra-lateralization, while lateralization is the localization of cognitive and perceptual functions in a particular hemisphere of the brain.

Brain and Language

Paul Pierre Broca (1961, 1965) observed that an area in the left frontal lobe (Broca’ s area) appeared to be responsible for the ability to speak. He noted that an injury to the left side of the brain was much more likely to result in language loss than was an injury to the right side.

The conclusion is that the portion of the left brain that is the crucial to language is larger in fetuses than is the corresponding portion of the right brain. This asymmetry is maintained throughout life.

The role of the right brain.

The left brain is not dominant for the perception and analysis of all types of sounds. The right brain activity includes perception and production of melodies. Someone who suffered from damage to the right hemisphere may be able to understand the literal meaning of a sentence but fail to recognize whether it is spoken in an angry or a fearful way.

Coordinating the two brains.

Although most people’s language centers are localized in the left brain, both hemispheres are required for the fully natural use of language.

The Language Centers

Here are the language centers part:

1. Broca’s area is located in the front of part of the left hemisphere and is responsible for organizing the articulatory patterns of speech. 
2. Wernicke, identified a nearby area which is adjacent to the part of the cortex that processes reception of auditory input (Wernicke’s area) are also being central to language processing. 
3. The angular gyrus is the language center responsible for converting a visual stimulus into an auditory form and vice versa.

Language use; speaking, listening, writing, and reading requires the coordination of these language centers. If the language centers or the connections between them are damaged, the ability to use language deteriorates.

Language disorders

The most dangerous language disorders is aphasia. This language disorders resulting from brain damage. Below are kinds of aphasia.

• Broca’s Aphasia, characteristics; poor articulation, phonemic paraphasia, agrammatism, and deficits in syntactic knowledge. 
• Wernicke’s Aphasia, it is responsible for the representation of meaning, as well as the interpretation of words during comprehension and selection of words during speech production. Patients with this language disorders may suffer from some phonemic paraphasia, but the most striking feature of this disorder is an inability to comprehend spoken language and to construct meaningful utterances. This language disorders make their speech is nonsensical.
• Conduction Aphasia, Damage to the arcuate fasciculus affects transmission of information from Wernicke’s area and Broca’s area. Characteristics; semantically process is not coherent, the comprehension of language is impaired. Patients with this language disorders do not have articulation problems, because this aspect of speech is controlled by broca’s area, which is undamaged. Their ability to repeat words and sentences, however, is severely impaired. 
• Alexia, impairement to reading ability. It sometimes occurs by itself. An alexic patient may therefore be able to write but not to read what he or she has witten. 
• Agraphia, loss of the ability to write. 

The Critical Period Hypothesis

Lenneberge, 1967, proposed that children had only a limited number of years during which they could acquired their L1 flawlessly if they suffered brain damage to the language areas; brain plasticity in childhood would allow other areas of the brain to take over the language functions of the damage areas, but beyond a certain age, normal language would not be possible. This is the Critical Period Hypothesis.

References

Scnitzer. 1976. The Role of Phonology in Linguistic Communication: Some Neurolinguistic Consideration. (Eds) Whitaker, H and Whitaker, H., A. New York: Academia Press.

Lenneberg, Eric. 1967. Biological Foundations of Language. New York: John Wiley & Sons.

Dennis, H and Whitaker, H. “Language Acquisition Following Hemidecortitation: Linguistic Superiority of the Left Over the Right Hemisphere” in Brain and Language 3: 404-33.

Molfese, D., Freeman, R., and Palermo, D., 1975. “The Ontogeny of Brain Lateralization for Speech and Nonspeech Stimuli” in Brain and Language 2: 356-68