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Language and…


									      The Brain

Impairment as a Window on
 Normal Brain Functionality
Study of the Brain

Until quite recently, the only way to study
 the workings of the brain was by
 studying the connections between
 physical damage to the brain and
 changes in behavior.
Phineas Gage

Perhaps the most famous and striking
 example is Phineas Gage, who in 1848
 had a metal rod shot through his head in
 an accident. He survived, but with
 massive changes to his personality.
Reconstruction of Gage’s Accident
Damage to the Brain and
Language: Aphasia
Aphasia is the neurological term for any
 language disorder that results from brain
 damage caused by disease or trauma.
It is through study of aphasia that many
 of our insights into the connections
 between brain and language have come.
Broca’s Aphasia

Patients with Broca’s aphasia (with
 damage of Broca’s Area) show
 difficulties organizing the articulatory
 patterns of language, and controlling the
 use of inflectional and function
Speech Sample: a patient with
typical Broca’s aphasia
Examiner: Tell me, what did you do before
 you retired?
Aphasic: Uh, uh, uh, pub, par, partender,
Examiner: Carpenter?
Aphasic: (nodding) Carpenter, tuh, tuh,
 twenty year.
Wernicke’s Aphasia

Patients with Wernicke’s Aphasia, on
 the other hand, may speak fluently but
 have difficulty with the comprehension
 and selection of words.
Jargon Aphasia

Patients with damage to Wernicke’s area
 often show jargon aphasia, the
 substitution of one sound for another,
 saying sable for table, for example.
In extreme cases, the patient’s speech
 may be made up almost entirely of
 nonsense words.
Speech Sample: a patient with
typical Wernicke’s aphasia
Examiner: Do you like it here in Kansas City?
Aphasic: Yes, I am.
Examiner: I’d like to have you tell me something
  about your problem.
Aphasic: Yes, I, ugh, can’t hill all of my way. I
  can’t talk all of the things I do, and part of the
  part I can go is alright, but I can’t tell from the
  other people.
Conduction Aphasia

 Conduction aphasia results from damage to
  the arcuate fasciculus, the area that transmits
  information between Broca’s and Wernicke’s
 Patients with this disorder may show fluent but
  meaningless speech, or be able to understand
  utterances but not repeat them.

Of course, no patient has damage only
 to Broca’s or Wernicke’s (or any one
 other) area of the brain; it is through
 analysis of a large number of patients
 with similar problems that the areas
 have been isolated.

   The Brain: Language and
Speech: Broca’s and Wernicke’s
What does all this tell us about
 The very-selective impairment we see in
  aphasics provides information about the
  organization of grammar.
 Patients that produce long strings of nonsense
  that sound like sentences but make no sense
  show that knowledge of our language’s
  phonology and syntax may be disassociated
  from word meaning, for example.
An example: Aphasic language as
evidence for the existence of word classes

One patient with a type of Broca’s
 aphasia was unable to read function
 words at all.
When presented with function words to
 read, he would respond with “no!” or “I
 hate those little words.” But he could
 read lexical homophones:
Responses to a word-association
stimulus   response   stimulus   response
witch      witch      which      no!
bean       soup       been       no!
hour       time       our        no!
eye        eyes       I          no!
hymn       bible      him        no!
wood       wood       would      no!
So what?

 This is compelling evidence that our mental
  lexicon is compartmentalized; lexical and
  function words are treated differently in our
 That is, grammatical category is not simply a
  label we have applied to words, but is a “real”
  thing in our use of language.
Recovery from Damage and the
  Critical Period Hypothesis
         Video: Story of a
In short:

 The younger the individual is when damage to
  language areas takes place, the more likely he
  or she is to recover; children younger than the
  girl in the video can recover completely, while
  adults undergoing the same procedure would
  never speak again.
 The cutoff period seems to be at about 10-12
  years of age.
The Critical Period Hypothesis

As we shall see when we look at
 language acquisition, one of the
 arguments for innateness of language is
 the existence of a critical period, after
 which language may not be learned at
The Autonomy of Language and the
Innateness Hypothesis
There is also excellent evidence that
 language ability and general intelligence
 are not connected; more suggestions
 that language is to some degree innate.

There are many examples of savants,
 individuals with severely impaired
 cognitive abilities, who possess normal
 or above-average facilities with language.
Specific Language Impairment

On the other hand, there are cases of
 children (without brain lesions) who have
 difficulties in acquiring language
 normally; this is called Specific
 Language Impairment, or SLI.
Heritability of SLI

 A number of studies have pointed to SLI as a
  heritable disorder, including one famous study
  of a multigenerational family, more than half of
  whom had the same very specific grammatical
 Similarly, identical twins are much more likely
  to both suffer from SLI than are fraternal twins.
The Evolution of Language
This leads to a question:

If language is a heritable, innate ability
 possessed by humanity, when and how
 did it arise in the species?
First, two views:

The continuity view: Namely, that
 language ability is a difference of degree
 between humans and other primates.
The discontinuity view: That the onset
 of language ability is a qualitative leap.
Physical Problems

In nonhuman primates (including,
 according to some studies, Neanderthal
 man), the vocal tract is simply
 anatomically incapable of producing a
 very-large inventory of speech sounds.
But it’s not only speech:

Humans who are born deaf and learn
 sign language (and studies of their
 brains) show that it is language, and not
 just speech, that the brain is
 neurologically wired to learn.
Three Views on the Emergence
         of Language
Noam Chomsky:

“It could be that when the brain reached
 a certain level of complexity it simply
 automatically had certain properties
 because that’s what happens when you
 pack 1010 neurons into something the
 size of a basketball.”
Stephen Jay Gould:

 “The Darwinist model would say that language,
  like other complex organic systems, evolved
  step-by-step, each step being an adaptive
  solution. Yet language is such an “all or none”
  system, it is hard to imagine it evolving that
  way. Perhaps the brain grew in size and
  became capable of all kinds of things which
  were not part of the original properties.”
Stephen Pinker:

“All the evidence suggests that it is the
 precise wiring of the brain’s
 microcircuitry that makes language
 happen, not gross size, shape, or
 neuron packing.”

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