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The Neural Basis of Thought and Language

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What we present today is purely our opinion on what some of the important topics ... Psycholinguistics. Mirror Neurons. Color. Image Schemas. Regier System. Details... – PowerPoint PPT presentation

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Title: The Neural Basis of Thought and Language


1
The Neural Basis of Thought and Language
  • Midterm
  • Review Session

2
DISCLAIMER
  • We havent seen the test
  • We dont know whats on the test
  • What we present today is purely our opinion on
    what some of the important topics are

3
Administrivia
  • Midterm in class next Tuesday, March 7th
  • Be there on time!
  • Format
  • closed books, closed notes
  • short answers, no blue books
  • up to Feb. 28th lecture

4
The format for this evening...
  • Question
  • Work on it
  • Discuss
  • Repeat...

5
Whats been covered so far...
  • Learning and Memory
  • Connectionist modeling
  • PDP systems
  • Back-propagation
  • Brain imaging
  • Psycholinguistics
  • Mirror Neurons
  • Color
  • Image Schemas
  • Regier System

6
Details...
  • Neurobiology/ Chemistry
  • neural firing
  • axons, synapses
  • differences from the computer
  • spreading activation
  • triangle node
  • mutual inhibition
  • reaction time experiments
  • neural development
  • learning / memory
  • Computational Bridge
  • connectionist modeling
  • learning
  • Hebbian learning
  • supervised learning
  • unsupervised learning
  • recruitment learning
  • reinforcement learning
  • neural network
  • feedfoward network
  • recurrent networks
  • backpropagation algorithm
  • E, ?W, ?, ?, ?
  • gradient descent (local minimum)
  • shift invariance
  • Cognitive Linguistics
  • color experiment
  • categories / prototypes
  • basic level categories
  • image schemas
  • force-dynamics
  • frames
  • Word Learning
  • Regier model
  • structured connectionism
  • no negative examples

7
Hebbian Learning
  • How do the strengths of the weights change in
    Hebbian Learning if the following neurons fire?

8
LTP and Hebbs Rule
  • Hebbs Rule neurons that fire together wire
    together
  • Long Term Potentiation (LTP) is the biological
    basis of Hebbs Rule
  • Calcium channels is the key mechanism

9
Long Term Potentiation (LTP)
  • These changes make each of the winning synapses
    more potent for an intermediate period, lasting
    from hours to days (LTP).
  • In addition, repetition of a pattern of
    successful firing triggers additional chemical
    changes that lead, in time, to an increase in the
    number of receptor channels associated with
    successful synapses - the requisite structural
    change for long term memory.
  • There are also related processes for weakening
    synapses and also for strengthening pairs of
    synapses that are active at about the same time.

10
Questions?
11
Learning
  • What type of learning discussed in class solves
    the problem of assigning blame?

12
Back-prop
Questions?
13
The Brain
  • What areas of the brain would be active when
    picking up an object vs. seeing someone pick up
    an object?
  • How does this play into the embodiment debate?

14
The Mirror Circuit in Monkeys
  • top
  • monkey sees experimenter grasp an object
  • bottom
  • monkey sees experimenter reaches his hand behind
    a screen to grasp an object

this is what we see in a monkey measuring a
neuron in the parietal area
15
Somatotopy
  • top
  • humans watching foot , hand and mouth
    actions without an object
  • bottom
  • humans watching same actions with an object
  • What can we learn from these two experiments?
  • integrated, multi-modal representation of
    actions, along with the objects and locations

Buccino et al., 2001
16
Concepts
  • What Concepts Are Basic Constraints
  • Concepts are the elements of reason, and
  • constitute the meanings of words and linguistic
    expressions.

17
Concepts Traditional Theory
  • The Traditional Theory
  • Reason and language are what distinguish human
    beings from other animals.
  • Concepts therefore use only human-specific brain
    mechanisms.
  • Reason is separate from perception and action,
    and does not make direct use of the sensory-motor
    system.
  • Concepts must be disembodied in this sense.

18
The neural theory
  • Human concepts are embodied. Many concepts make
    direct use of the sensory-motor capacities of our
    body-brain system.
  • Many of these capacities are also present in
    non-human primates.
  • Let us look at concepts that make use of our
    sensory-motor capacities, ex. Grasp.

19
Questions?
20
Color
  • What is the biological basis of basic color terms?

21
The WCS Color Chips
  • Basic color terms
  • Single word (not blue-green)
  • Frequently used (not mauve)
  • Refers primarily to colors (not lime)
  • Applies to any object (not blonde)

FYI English has 11 basic color terms
22
Results of Kays Color Study
Stage I II IIIa / IIIb IV V VI VII
W or R or Y W W W W W W
Bk or G or Bu R or Y R or Y R R R R
Bk or G or Bu G or Bu Y Y Y Y
Bk G or Bu G G G
Bk Bu Bu Bu
W Bk Bk Bk
R YBk (Brown) YBk (Brown)
Y RW (Pink)
Bk or G or Bu R Bu (Purple)
RY (Orange)
BW (Grey)
  • If you group languages into the number of basic
    color terms they have, as the number of color
    terms increases, additional terms specify focal
    colors

23
Color Opponent Cells
  • These cells are found in the LGN
  • Four color channels Red, Green, Blue, Yellow
  • R/G , B/Y pairs
  • much like center/surround cells
  • We can use these to determine the visual systems
    fundamental hue responses

Mean Spikes / Sec
Wavelength (mµ)
(Monkey brain)
24
Questions?
25
Categories
  • Internal structure (classical, radial, family
    resemblance, prototype-based, essentially-contest
    ed, ad-hoc)
  • External structure (basic-level, superordinate,
    subordinate)

26
Categories
  • What are super- and sub-ordinate types to red?

27
Categories
Furniture
Superordinate
Sofa
Desk
Basic-Level Category
leather sofa
fabric sofa
L-shaped desk
Reception disk
Subordinate
28
Basic-Level Category
What constitutes a basic-level category?
  • Perception
  • similar overall perceived shape
  • single mental image
  • (gestalt perception)
  • fast identification
  • Function
  • general motor program
  • Communication
  • shortest
  • most commonly used
  • contextually neutral
  • first to be learned by children
  • first to enter the lexicon
  • Knowledge Organization
  • most attributes of category members stored at
    this level

Red? Maroon?
yes arguable
(expertise)
29
Categories Internal Structure
  • Classical Category
  • necessary and sufficient conditions
  • Radial Category
  • a central member branching out to less-central
    and non-central cases
  • degrees of membership, with extendable boundary
  • Family Resemblance
  • every family member looks like some other family
    member(s)
  • there is no one property common across all
    members (e.g. polysemy)
  • Prototype-Based Category
  • Essentially-Contested Category (Gallie, 1956)
    (e.g. democracy)
  • Ad-hoc Category (e.g. things you can fit inside a
    shopping bag)

30
Questions?
31
Image Schemas and Regier
32
Image Schemas
  • Trajector / Landmark (asymmetric)
  • The bike is near the house
  • ? The house is near the bike
  • Boundary / Bounded Region
  • a bounded region has a closed boundary
  • Topological Relations
  • Separation, Contact, Overlap, Inclusion, Surround
  • Orientation
  • Vertical (up/down), Horizontal (left/right,
    front/back)
  • Absolute (E, S, W, N)

LM
TR
33
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