Neurolinguistics

1
Neurolinguistics

• Based on Libben (2000) Brain and Language

2
Brain and Language

• 1.The human brain
• 1.1.The cerebral cortex
• 1.2.The cerebral hemispheres
• 1.3.The lobes of the cortex
• 2.Investigating the brain
• 2.1.Autopsy studies
• 2.2.Images of the living brain
• 2.3.Learning from hemispheric connections and
  disconnections
• Dichotic listening studies
• Split brain studies
• 3. Aphasia
• 3.1. Non-fluent aphasia
• Brocas aphasia as a syntactic disorder
• 3.2.Fluent aphasia (sensory aphasia)
• -Wernickes aphasia
• -Jargonaphasia

4.Acquired dyslexia and dysgraphia 4.1.Reading
and writing disturbances in aphasia -paragraphia
4.2.Acquired dyslexia as the dominant language
deficit -phonological dyslexia -surface
dyslexia 5.Linguistic theory and
aphasia 5.1.Features, rules, and underlying
forms 5.2.Agrammatism 5.3.Function words 5.4.Loss
of syntactic confidence 5.5.Agrammatism in other
languages 6.Where is language?
3
Introduction

• Neurolinguistics How language is represented and
  processed in the brain.
• -survey of brain structure
• -methods to study the brain
• -language disturbances that result from brain
  damage
• -how phonology, morphology, syntax, and semantics
  may be represented in the brain
• -Where is language?

4
1.The human brain

• 1400 grs of pinkish-white matter
• Neuroscience how the breadth and depth of human
  experience is coded in the brain matter.
• Neurons basic information-processing units of
  the nervous system
• 10 Billion neurons
• Each neuron can link with 10 thousand others
• 1.1.The cerebral cortex
• Spinal cord VS Brain VS cerebral cortex
• Human VS animals
• Folded

5
1.The human brain (Continued)

• 1.2.The cerebral hemispheres
• Sulci (fissure)
• Gyri
• Longitudinal fissure, cerebral hemispheres,
  corpus callasum
• Contralateral responsibilities, Left hemisphere
  controls the right side and vice versa
• Left-hemisphere analytical tasks, such as
  arithmetics
• Right-hemisphere overall appreciation of
  complex patterns, such as face recognition,
  melodies
• But, complex mental activities involve the
  coordinated functioning of both hemispheres
• Right-handed and left lateralized for language
• Left-hemisphere is removed but still comprehends
  some language
• Right-hemisphere damaged, difficulty in
  understanding jokes and metaphors
• Left-handers are less lateralized for language
• 1.3.The lobes of the cortex
• Lobe substructures of the cortex
• Occipital lobe, plays an important role in
  reading

6
2.Investigating the brain

• Techniques to investigate what is going on in the
  brain when people are engaged in language
  behavior.
• 2.1.Autopsy studies
• Observe patients behavior and, once dead,
  examine his brain.
• Brocas research, Brocas area, Brocas aphasia
• 2.2.Images of the living brain
• Computerized Axial Tomography (CT scanning)
• Positron Emission Tomography (PET), glucose
  isotopes
• Functional Magnetic Resonance Imaging (fMRI)
• It was found that when people
• -speak, blood flows to left hemisphere and
  Brocas area
• -read, occipital lobe, angular gyrus, other
  areas of the left hemisphere
• -SL processing involves a wider variety of
  cortical sites, less automatic nature of language
  requires additional diverse mental processes

7
2.Investigating the brain (continued)

• 2.3.Learning from hemispheric connections and
  disconnections
• Examining behavior that can be associated with a
  particular brain hemisphere
• Dichotic listening studies
• -language is processed better through right ear
  (Right Ear Advantage, REA)
• Split brain studies
• -Studying effects of the removal of corpus
  callosum on cognition
• -blindfolded patients holding a key in left
  hand cannot name it

8
3. Aphasia

• -stroke (a cerebrovascular accident)
• -aphasia (language deficit caused by a damage to
  the brain)
• -Mosss experience
• 3.1. Non-fluent aphasia (motor aphasia)
• -damage to the front central sulcus
• -effortful speech production
• -global aphasia, completely mute
• -Brocas aphasia, some phonemes miss,
  dysprosody, phonemic paraphasias
• -Brocas area has a language specific
  responsibility
• Brocas aphasia as a syntactic disorder
• -function words are omitted telegraphic speech
• -disturbance of syntactic competence
• -omit inflectional suffixes
• -grammaticality judgment is difficult, The
  boy ate up it.
• -cannot interpret based on the syntax of the
  sentence, The cat chased by the mouse.
• -Brocas aphasia is not simply a production
  deficit
• -Brocas aphasics are acutely aware of their
  language deficit
• -Brocas area of frontal lobe does not seem to
  be involved in the semantic relationships between
  words

9
3. Aphasia (continued)

• 3.2.Fluent aphasia (sensory aphasia)
• -damage to the left cortex behind the central
  sulcus
• -language production is OK but difficulty in
  selecting, organizing, and monitoring the
  production
• -Wernickes aphasia
• -generally unaware of their deficit
• -everything seems normal except rarely make
  sense
• -comprehension deficit
• -no coherent trains of thought
• -Jargonaphasia, Severe case of Wernickes
  aphasia, intonational charecteristics of the
  language is OK, but very few actual sentences

10
4.Acquired dyslexia and dysgraphia

• Dyslexia impairment of reading ability
• Dysgraphia impairment of writing ability
• Acquired VS developmental dyslexia dysgraphia
• 4.1.Reading and writing disturbances in aphasia
• -whatever impairment the patient has in
  listening and speaking will be matched in reading
  and writing.
• -most Brocas aphasics show writing
  disturbances that are comparable to their
  speaking deficits
• -the resulting error is paragraphia
• -production deficit at a very deep level of
  language planning
• -Wernickes aphasia, like Brocas aphasia
  involves a central disturbance of language
  competence

11
4.Acquired dyslexia and dysgraphia (continued)

• 4.2.Acquired dyslexia as the dominant language
  deficit
• -damage in and around the angular gyrus of the
  parietal lobe
• -theory readers maintain a set of
  spelling-to-sound rules that enables them to read
  new words aloud.
• -phonological dyslexia loosing
  spelling-to-sound rules not able to read unknown
  words
• -surface dyslexia the opposite, processing
  words only spelling-to-sound rules, regularly
  spelled words are OK, but irregularly spelled
  words are poblematic worm is perceived as
  opposite of cold.

12
5.Linguistic theory and aphasia

• For aphasia researchers
• -Not simply what the patients can or cannot do
• -but the deficit in terms of the loss of
  semantic features, phonological features,
  phonological rules, and syntactic tree structures
• For Theoretical linguists
• -distinctions between derivational and
  inflectional suffixes
• 5.1.Features, rules, and underlying forms
• -phonological features and rules may be good
  tools to characterize how language is represented
  and produced (with vs /wit/)
• -morphology inflectional is dropped,
  derivational is retained
• -illegal ? inlegal
• -semantics deep dyslexia father ?mother.
• -abstract words are more difficult to produce
  than concrete ones
• -concrete words are more difficult than
  abstract words selective inability inability to
  produce names for fruits and vegetables

13
5.Linguistic theory and aphasia (continued)

• 5.2.Agrammatism
• -agrammatism telegraphic speech, grammar is
  lost, omission of function words and inflectional
  affixes
• -comprehension deficit where correct
  interpretation solely depends on syntax
• -characteristics of the syndrome and
  characteristics of particular languages
• 5.3.Function words
• -prepositions are they function words or
  lexical words?
• 5.4.Loss of syntactic confidence
• -is hierarchical representation lost? Assigning
  meaning to first noun rather than the NP
• 5.5.Agrammatism in other languages
• -true nature of agrammatism is not dropping
  function words and inflectional affixes.
• -Hebrew kotev (writes) VS katev (wrote)
• -so, it is not simply an economy effort,
  misselection of linguistic forms

14
6.Where is language?

• Brocas area -articulation of speech
• -create syntactic representation
• Wernickes area -language comprehension
• Right above Wernickes area, angular gyrus
  reading
• Normal language use involves the integrated
  functioning of the entire cortex.
• Storage and retrieval of word forms may be
  diffusely represented in the brain.
• What is language is a more important question.

15
Summing up

• Left-hemisphere of the brain carries most of the
  responsibility for language processing.
• Most of our knowledge about language
  representation comes from the study of
  aphasialanguage disturbance resulting from
  damage to the brain.

16
Questions

• 1.What distinguishes the human brain from a
  non-human brain?
• 2.In what ways can the cerebral hemispheres be
  considered to be two separate brains?