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233 Brain

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Title: 233 Brain & Behaviour: 1. Introduction Author: lauwerja Last modified by: Jan Lauwereyns Created Date: 2/26/2004 11:51:29 PM Document presentation format – PowerPoint PPT presentation

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Title: 233 Brain


1
Basic neuroscience Language Decision Making
J. Lauwereyns, Ph.D. Professor Graduate School of
Systems Life Sciences Kyushu University jan_at_sls.k
yushu-u.ac.jp
2
Language Unique to humans?
3
Evolution and Physiology of Language
  • Human language is different because it is more
    productive
  • can produce new signals to represent new ideas
  • Chimpanzees can learn to communicate using sign
    language or symbols, but different from human
    language
  • symbols used to request but rarely to describe
  • seldom recombine in new combinations
  • say more than they understand, the opposite of
    children

4
Language as a Special Module
  • Humans have evolved with something that enables
    them to learn language easily
  • Chomsky and Pinker a language acquisition device
  • children learn language with ease, including
    children of deaf parents
  • deaf children learn sign or invent one of their
    own
  • not likely a separate module since most language
    areas used for other functions, e.g., memory,
    music perception
  • intelligence may be by-product of language

5
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6
Broca vs Wernicke
7
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8
Brocas Aphasia
  • Also called non-fluent aphasia
  • severe deficits in language production caused by
    damage to Brocas area, and other cortical and
    subcortical structures
  • difficulty pronouncing, gesturing and writing as
    well as understanding complex speech
  • uses and understands nouns and verbs more easily
    than closed-class words, e.g., prepositions,
    pronouns
  • ignores grammar and relies on inferences
  • but, can usually recognize when something is
    wrong with sentence even if they cannot correct
    it

9
Wernickes Aphasia
  • Also called fluent aphasia
  • caused by damage to left temporal cortex
  • seriously impaired language comprehension
  • difficulty finding the right word and trouble
    recalling names of objects
  • grammatical but often nonsensical speech
  • perhaps because cant find words due to rapid
    speech
  • but, can pronounce clearly, fluently and rapidly

10
Wernicke Comprehension, Meaning
Broca Production, Syntax
11
What about language on the left?
12
What about language on the left?
  • Lateralization of Brain Function
  • Two hemispheres are not mirror images of each
    other
  • left hemisphere controls right side of body
  • right controls left side
  • taste and smell input to same side
  • Lateralization is the specialization of labor
    between the two hemispheres
  • left hemisphere specialized for language
  • right specialized for complex visual-spatial
    tasks and synthetic processing

13
  • Handedness and Language Dominance
  • Right handedness a heritage
  • 10 of people are left-handed or ambidextrous
  • 90 of prehistoric drawings show tools in right
    hand
  • most chimps and other primates are right handed
  • Left handers
  • have equal as well as left or right hemisphere
    dominance for speech
  • if right is dominant, left hemisphere contributes
    more to spatial perception
  • Corpus Callosum is thicker for greater
    communication

14
Not quite as famous as Sir Edmund Hillary,
but
15
Where does Corballis get his idea?
  • Corticol control of manual movements
  • Primates acquiring sign language
  • The mirror system in monkeys
  • Left hemisphere for speech and hands
  • Deaf use sign languages with full syntax
  • Nonverbal gestures during speech
  • FOXP2 gene mutated about 200,000 years ago

16
FOXp2
17
Where does Corballis get his idea?
  • Corticol control of manual movements
  • Primates acquiring sign language
  • The mirror system in monkeys
  • Left hemisphere for speech and hands
  • Deaf use sign languages with full syntax
  • Nonverbal gestures during speech
  • FOXP2 gene mutated about 200,000 years ago

18
The mirror system
Ventral premotor area monkey homologue of
Area 44 in frontal cortex, that is, Brocas
Area Studied by Rizzolatti and co.
19
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20
The mirror system
  • Neurons in ventral premotor area
  • activated both when the subject performs an
    action and when the subject observes someone else
    perform the same action
  • Abstract action representation
  • This system likely plays a role both in
    recognising and planning actions (thinking about
    actions)

21
Importance of the mirror system?
  • Understanding action?
  • Origins of language?
  • Empathy?
  • Morality?
  • (some other day)

22
On reasoning and decision making
23
On reasoning and decision making
  • More complex with language
  • Consider context
  • Imagine different scenarios

24
Most basic structure for decision making
Response
Stimulus
Stimulus Response Matrix
25
Signal detection theory
26
Bias
27
Consider different decision contexts
28
Consider different decision contexts
29
Consider different decision contexts
30
Bias
31
Sensitivity
32
Sensitivity
33
Ways to improve sensitivity
34
Ways to improve sensitivity
35
Ways to improve sensitivity
36
How does it really work?
37
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39
General increase
40
General increaseProspective, additive
  • Bias in anticipatory activity
  • Linearly enhances sensory activity
  • Response Input Reward Bias
  • Prefrontal cortex, basal ganglia
  • Superior colliculus

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43
Improved discrimination
44
Improved discriminationSynergistic,
multiplicative
  • Sensory properties
  • Non-linearly enhanced by reward
  • Response Input Reward Gain
  • Prefrontal cortex, parietal cortex
  • Superior colliculus

45
Dopamine
46
Dopamine
47
Excitation
Dopamine
Synergistic, multiplicative
Disinhibition
Sensitivity
Prospective, additive
Bias
48
How do we process conflicts?
  • Paradox
  • Immediate reward
  • versus Delayed gratification

49
The classic Stroop
  • James Ridley Stroop, inventive priest
  • Present participants with a word printed in a
    certain colour
  • GREEN
  • Name the colour
  • Interference from irrelevant word
  • RT Incompatible gt Neutral gt Compatible
  • Evidence of conflict

50
fMRI studyMcDonald et al
  • Using a cued Stroop task
  • Trial begins with
  • word read the word
  • colour name the colour
  • Task instruction changes trial by trial
  • Separate effects
  • Instruction-related activity
  • Response-related activity

51
Response- related activity
Congruent stimulus
Incongruent stimulus
RED
GREEN
COLOUR NAMING
Instruction- related activity
red
red
RED
GREEN
WORD READING
red
green
52
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53
Interpretation
  • In DLPFC
  • Stronger activity in colour trials than in
    word trials
  • Effects of task instruction, but not congruency
  • Especially before target onset (during
    preparation)
  • In ACC
  • Stronger activity in incongruent trials as
    compared to congruent trials
  • Effects of congruency, but not task instruction
  • Especially after target onset, or even after
    response

54
Conclusions
  • Dorsolateral prefrontal cortex
  • Seems important for representing the task
    instruction
  • Ordering what to do
  • Anterior cingulate cortex
  • Seems involved in situations of conflict
  • Performance monitoring
  • Evaluating what you do
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