Language and the brain

Language and the brain

http://www.youtube.com/watch?v=eYVKxZszofE&NR=1&feature=endscreen http://www.youtube.com/watch?v=WK29RAKDzf8

Important facts of the brain

First, humans are born with the innate capacity to acquire the extremely complex, creative system of communication that we call language.

We are born with a language instinct. This language aptitude is completely different from inborn reflex responses to stimuli as laughter, sneezing, or crying. 

The language instinct seems to be a uniquely human genetic endowment:  nearly all children exposed to language naturally acquire language almost as if by magic.  › Only in rare cases are children born without this magical ability to

absorb abstract syntactic patterns from their environment.  › These children are said to suffer from Specific Language

Impairment. 

Second, there is a critical age for acquiring fluent native language.

The natural ability for acquiring language normally diminishes rapidly somewhere around the age of puberty.

This phenomenon seems to be connected with the left hemisphere of most individuals--the hemisphere associated with monolinear cognition (such as abstract reasoning and step-by step physical tasks) and not the right hemisphere, which is associated with 3D spatial acuity, artistic and musical ability. 

Unlike adults, children seem to be able to employ both hemispheres to acquire language. In other words, one might say that children acquire language three-dimensionally while adults must learn it two dimensionally.

Third and finally, in most adults the language organ is the perisylvian area of the left hemispheric cortex.

Language is usually housed in this specific area of the brain. Only the human species uses this area for communication.  The signals of animal systems of communication seem to be controlled by the sub-cortex, the area which in humans controls similar inborn response signals such as laughter, crying, fear, desire, etc.

Aphasia• Specific areas of the left hemisphere are involved in the production and processing of particular aspects of language.  •From a study of patients who have had damage to certain parts of the left hemispheric cortex. Damage to this area produces a condition called aphasia, or speech impairment (also called dysphasia). The study of language loss in a once normal brain is called aphasiology. •Nearly 98% of aphasia cases can be traced to damage of the left hemisphere of the cerebral cortex.

Language is a complex of interacting components--consonants and vowels, nouns and verbs, content words and function words, syntax and semantics. 

Could it be that these components are housed in particular sub-areas of the left hemispheric cortex? 

There is no conclusive proof that nouns are stored separately from verbs, or where the fricative sounds are stored. There is compelling evidence to believe that two special aspects of language structure are processed by different sub-areas of the language center. 

Paul Broca - 1861 He discovered Broca's area (located in the frontal

portion of the left perisylvian area). Seems to be involved in grammatical processing.

(While parsing sentences such as fat people eat accumulates, there is a measurable burst of neural activity in Broca's area when the last word is spoken.)

Broca's area seems to process the grammatical structure rather than select the specific units of meaning.  It seems to be involved in the function aspect rather than the content areas of language)

This area holds the grammatical glue which holds the context together.

Karla Wernicke - 1875 The Wernike controls comprehension, as well as the selection of

content words.  When this area is specifically damaged, a very different type of aphasia usually results, one in which the grammar and function words are preserved, but the content is mostly destroyed. 

Wernicke's aphasics often talk incessantly and tend to utter whole volumes of grammatically correct nonsense with relatively few content words or with jibberish words like "thingamajig"  or "whatchamacallit" instead of true content words.

Wernicke's area houses the elements of language that have specific meaning--the content words of prefabricated, meaningful elements which a speaker selects when filling in a context.

The normal human mind uses both areas in unison when speaking. Apparently, normal adults use the neurons of Wernicke's area to select sounds or listemes.  We use the neurons of Broca's area to combine these units according to the abstract rules of phonology and syntax--the elements in language which have function but no specific meaning-- to produce utterances

Broca’s &Wernicke's areas

Both seem to be telling us about the way language is stored in the brain.  Language obviously consists of these two aspects working together in unison:1) a very large but finite number of elements with specific form and meaning (words, phrases). Stored in Wernicke's area.     2) a fairly small number of patterns with virtually no limit on the specific meaning they can express (the grammar of language). Stored in Broca's area.

Roman Jakobson Russian born linguist who made extensive studies of

aphasia in the 1950's, noted that both types of the aphasic lose language in the exact reverse order that language is acquired by a children’s of play. Progressive degeneration of the language centers in the mirror image of the acquisition of elements in childhood.

 These two areas have been implicated even more broadly with the human abilities to deal with signs.

Roman Jakobson also noted that normal language function involves an interaction of two different associative properties of meaning: association by similarity.

 Recent studies have shown that Broca's and Wernicke's areas are actually contiguous portions of the brain--part of a single area-- rather than separate areas.

These areas are connected by a dense set of neurons and so are really extensions of one another. The complex interaction of the neurons gives us our complete language faculty.

Yale class http://www.youtube.com/watch?v=Uf9t

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