Summary

Brain and Language
Summary

 

    The Human Brain

The brain is the most complex organ of the body. The surface of the brain is the cortex, often called “gray matter,” consisting of billions of neurons (nerve cells) and glial cells (which support and protect the neurons). The cortex is the decision-making organ of the body. It is the organ that most distinguishes humans from other animals. Somewhere in this gray matter resides the grammar that represents our knowledge of language.

  

The brain is composed by:

v  Right hemisphere:  Controls the left side of the body.

v  Left hemisphere:    Controls the right side of the body.

v  Corpus Callosum:  Allows the two hemispheres of the brain to communicate with each other. 

Sensory information from the right side of the body such as (e.g., right ear, right hand, right visual field) is received by the left hemisphere of the brain, and sensory input to the left side of the body is received by the right hemisphere, this function is called contralateral brain.

 

       The Localization of Language

In the early nineteenth century, Franz Joseph Gall proposed the theory of localization, this idea consists those different human cognitive abilities and behaviors are localized in specific parts of the brain. At first Franz Gall thought that language was located directly under the eye, but later, Paul Broca and Carl Wernicke determined that language is lateralized to the left hemisphere. Our capacity to use language is located in the left hemisphere of the brain, specifically in two areas: Broca's area (associated with speech production and articulation) and Wernicke's area (associated with comprehension).

• Lateralization: is the term used to refer to the localization of function to one hemisphere of the brain.

         Aphasia

The study of aphasia has been an important area of research in understanding the relationship between the brain and language. As we know, aphasia is the neurological term for any language disorder that results from acquired brain damage caused by disease or trauma.

Most aphasics do not show total language loss. Rather, different aspects of language are selectively impaired, and the kind of impairment is generally related to the location of the brain damage. Because of this damage-deficit correlation, research on patients with aphasia has provided a great deal of information about how language is organized in the brain.

 

         The Linguistic Characterization of Aphasic Syndromes

•            Broca’s aphasia: (also often called agrammatic aphasics) It is characterized by labored speech and certain kinds of word-finding difficulties, but it is primarily a disorder that affects a person’s ability to form sentences with the rules of syntax, and where they cannot rely on their real-world knowledge. 

•          Wernicke’s aphasia: People with Wernicke’s aphasia produce fluent speech with good intonation, and they may largely adhere to the rules of syntax. However, their language is often semantically incoherent.

 

        Split Brains

An extreme measure used to help people suffering from intractable epilepsy is a procedure of “splitting the brain” in which a surgeon severs the corpus callosum, the fibrous network that connects the two halves.

In people who have undergone split-brain surgery, the two hemispheres appear to be independent, and messages sent to the brain result in different responses, depending on which side receives the message. Experiments shown that the right brain does better than the left in pattern-matching tasks, in recognizing faces, and in spatial tasks. The left hemisphere is superior for language, rhythmic perception, temporal-order judgments, and arithmetic calculations.

 

        Dichotic listening

Dichotic listening is an experimental technique that uses auditory signals to observe the behavior of the individual hemispheres of the human brain. Subjects hear two different sound signals simultaneously through earphones.

These experiments have shown that subjects are more frequently correct in reporting linguistic stimuli (language, words, nonsense syllables, and so on) delivered directly to the left side of the brain, but are more frequently correct in reporting nonverbal stimuli (musical chords, environmental sounds, and so on) delivered to the right side.