The cognitive neuroscience of language comprehension

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The cognitive neuroscience of language
comprehension
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Uniqueness of language

• Separates humans from other animals
• Other unique human abilities have been found in
  other animals.
• Tool use
• Cooperation
• Use of symbols
• Theory of mind

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Animal language studies

• Parrots
• Dolphins
• Dogs
• Apes
• Orangutans
• Gorillas
• Chimpanzees
• Bonobos

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Chimpanzees

• Several researchers have attempted to raise
  chimpanzees as a member of the family (e.g.,
  Kellog, Hayes).
• Chimpanzee could learn to recognize more than 100
  words.
• Chimpanzees are not able to produce sounds used
  in human language.

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Bonobo language learning

• Kanzi and Sue Savage-Rumbaugh

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Language learning in Bonobos

• Learned a few hundred lexigrams.
• Also learned to comprehend some spoken English as
  well as a 2.5 year old child.

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Lexical vs. grammatical ability in children

• Lexical growth and grammatical ability strongly
  correlate (Bates and Goodman, 1997).

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Subcomponents of language

• Sound
• Phonemes
• Lexical access (semantics, word class of
  individual word,.
• Results Using eye tracking very few regressive
  eye movements.

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Classic model of language processing in the brain

• Wernicke-Lichthiem-Geschwind model

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Types of aphasia

• Brocas aphasiadifficulty producing words
• Wernickess aphasia difficulty comprehending
  words.
• Conduction aphasia difficulty repeating words or
  correcting mistakes.
• Global aphasia (transcortical aphasia)
  difficulty comprehending and producing words.

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Brocas aphasia

• The patient is talking about why he came to the
  hospital
• Yes ... ah ... Monday .... ah .... Dad and Peter
  Hogan, and Dad .... ah .... hospital .... and ah
  .... Wednesday .... Wednesday nine o'clock and ah
  Thursday ... ten o'clock ah doctors ... two ....
  two .... an doctors and .... ah .... teeth ....
  yah .... And a doctor an girl .... and gums, an
  I.
• From 'The Shattered Mind' by Howard Gardner.

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Wernickes aphasia

• "What brings you to the hospital? ... "Boy, I'm
  sweating, I'm awful nervous, you know, once in a
  while I get caught up, I can't mention the
  tarrripoi, a month ago, quite a little, I've done
  a lot well, I impose a lot, while, on the other
  hand, you know what I mean, I have to run around,
  look it over, trebbin and all that sort of
  stuff." ... "Thank you, Mr. Grogan. I want to ask
  you a few -" "Oh, sure, go ahead, any old think
  you want. If I could I would. Oh, I'm taking the
  word the wrong way to say, all of the barbers
  here whenever they stop you it's going around and
  around, if you know what I mean, that is tying
  and tying for repucer, recuperation, well, we
  were trying the best that we could while another
  time it was with the beds over there the same
  thing ..."
• From 'The Shattered Mind' by Howard Gardner.

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Modifications to W-G model

• Beyond the word level
• Brocas aphasics often have problems in
  comprehension of syntactically complex sentences.
• Reexamination of neuropsychological evidence

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Brocas aphasics and syntactic complexity

• The brown horse is chased by the white dog.
  (Caramazza Zurif, 1976)
• The brown horse chased the white dog.
• (Schwartz, Saffran, Marin, 1980).

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Brocas aphasia

• Two possibilities to explain syntactic deficits
• Loss of syntactic knowledge?
• Inability to access syntactic knowledge?

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Difficulty accessing syntactic knowledge

• Brocas aggramatic aphasics can judge
  grammaticality of sentences.
• The brown dog chase the white horse.
• The brown dog chases the white horse.

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Neuropsychological evidence

• Original model made before modern neuroimaging
  technology
• CAT scanning of Brocas patient Tans brain
  shows that lesion includes BA 44,45,47, anterior
  insula, basal ganglia, and white matter tracts.

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Neuropsychological studies

• Behavior based studies
• Lesions not including Brocas area can produce
  Brocas aphasia.
• Lesion based studies
• Patients with lesions in Brocas area without
  Brocas aphasia.
• Voxel-based lesion symptom mapping (Bates et al.,
  2003)

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Dronkers et al. (2004) VLSM study

• Tested 64 LH lesion patients in sentence
  comprehension battery (CYCLE-R) and compared
  results with RH lesion, and older control
  subjects.

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Behavioral stimuli
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Summary of VLSM mapping results

• 5 general areas involved in sentence processing
• Medial temporal gyrus
• Anterior BA22
• Superior temporal sulcus/BA39
• BA46
• BA47
• Neither Wernickes nor Brocas area implicated.

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Summary of Dronkers et al. (2004)

• Medial temporal gyrus important for word level
  comprehension.
• Anterior BA22 important for simple syntax, and
  basic morphosyntax.
• Frontal areas important for working memory used
  during sentence comprehension.
• Angular gyrus needed for verbal short term memory
  and auditory rehearsal.

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Neuroimaging studies

• Individual word level
• Sentence level semantics
• Sentence level syntax

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Semantics

• Number of propositions in a sentence (Caplan et
  al., 1998) (bilateral superior and medial
  temporal lobes)
• Jabberwocky versus sentences with content
• English Betsy can eat the apple at this park.
• Jabberywocky Bapfa can eeg the agger at this
  pilt.
• (source Neville lab, University of Oregon)
• Detection of semantic errors compared to
  detection of other errors

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Examples of sentence conditions used in
Friederici et al. (2003).

• Correct condition
• Das Hemd wurde gebügelt
• The shirt was ironed
• Syntactic violation condition
• Die Bluse wurde am gebügelt
• The blouse was on ironed
• Semantic violation condition
• Das Gewitter wurde gebügelt
• The thunderstorm was ironed
• Correct filler condition
• Der Rock wurde am Freitag gebügelt
• The skirt was on Friday ironed

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Syntax

• Kaan and Swaab (2002) review neural basis of
  syntax.
• Complex versus simple sentences.
• Simple The child spilled the juice that stained
  the rug.
• Complex The juice that the child spilled stained
  the rug.
• Sentences compared to word lists.
• Jabberwocky versus pseudoword lists.
• Detection of syntactic errors.

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Complex versus simple sentences
Jabberwocky versus pseudoword lists
(Indefrey Cutler, 2004)
Error detection
Sentences versus word lists
Black (syntax-correct) Blue(syntax-semantics) Gree
n(syntax-other) Pink (semantic-
correct) Red(semantic- syntactic)
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ERP studies

• Semantics
• N400
• Syntax
• LAN
• P600/SPS

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N400

• Kutas and Federmeir (2000)

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N400 (2)
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Summary

• The Wernicke-Geschwind model is being replaced by
  new models.
• New models focus on both neural basis and timing
  of language comprehension, and have moved beyond
  simplistic divisions of comprehension/production.
• rent priorities on cues for sentence
  comprehension.
• In Italian inflectional morphology word order
  ...
• In English word order inflectional morphology...