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History of Neuropsychology

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Draws on many disciplines, including anatomy, biology, pharmacology, physiology, and philosophy ... Anesthesia, antisepsis, and localization of function ... – PowerPoint PPT presentation

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Title: History of Neuropsychology


1
History of Neuropsychology
Psychology 315 Introduction to Neuropsychology 200
8
2
  • Draws on many disciplines, including anatomy,
    biology, pharmacology, physiology, and philosophy
  • Donald Hebb first used the term in 1949, although
    it was not defined
  • By 1957, it was a field in the neurosciences
  • In 1960, it was again in the title of a book but
    still undefined.

3
  • The modern definition was influenced by two foci
    in brain research
  • The brain hypothesis brain is the sources of
    behaviour
  • The neuron hypothesis the unit of brain
    structure and function is the neuron

4
Brain Hypothesis
  • Earliest record occurred in 500 BC in which
    mental processes were thought to occur in the
    brain (i.e., brain hypothesis)
  • At the same time, Emedocles located mental
    processes in the heart (i.e., cardiac hypothesis)

5
  • Plato (420-347 BC) rational part of the soul in
    the brain because it was closest to the heavens
  • Aristotle (384-322 BC) heart was the source of
    mental processes because it was warm and active
  • Hippocrates (430-379 BC) and Galan (AD 129-199)
    argued for brain hypothesis

6
  • Following Galens observations, the cardiac
    hypothesis was largely refuted
  • Still has a mark on our language

7
  • Once the brain hypothesis had been accepted, the
    next stage was to understand how the brain
    controls behaviour

8
  • Modern thinking began with Rene Descartes
    (1596-1650)
  • He originated the mind-body problem What is
    relation between the mind and body? How do they
    interact?

9
  • Descartes believed movements/behaviours were
    caused by flow of animal spirits through nerves
  • Descartes thought the mind was an invisible
    substance, leading to 2 conclusions
  • (1) theories that subdivided brain function must
    be wrong, and
  • (2) because there was a mind-body distinction,
    complete understanding of the body would not
    fully explain human behaviour

10
Localization of Function Phrenologists
  • Gall (1758-1828) and Spurzheim (1776-1832) brain
    is the center of high mental activity
  • Function is localized

11
  • Important anatomical discoveries
  • (1) cortex is made of functioning cells that are
    connected to subcortical structures
  • (2) Spinal cord is made of gray and white matter
  • (3) Neural pathways crossover at the pyramids
  • (4) the 2 halves are connected by commissures

12
  • Gall associated behaviours with characteristics
    of the skull
  • Lead to the development of Phrenology the
    relationship between skulls features and mental
    faculties

13
  • Phrenology failed for several reasons
  • (1) faculties were difficult to objectively
    define
  • (2) assumed that superficial features of the
    skull could be used to estimate brain size and
    shape gyral patterns were random wrinkles

14
Localization of Function The First Experiments
  • Flourens (1794-1867) conducted the first
    experiments that refuted Galls ideas
  • Ablation technique removed part of brain and
    observed subsequent behaviours

15
  • Put forth idea that people never use more than
    10 of their brains (wrong!)
  • His science was flawed
  • (1) used animals with no neocortex
  • (2) behaviours he studied had no relationship to
    Galls faculties
  • (3) deficits he observed may have been due to
    other factors than localization

16
  • Fritsch (1838-1929) Hitzig (1838-1907)
    developed the technique for electrically
    stimulating the brain
  • Their results showed
  • (1) applying an electrical current to neocortex
    resulted in movement on the contralateral side of
    the body
  • (2) stimulation of small parts of neocortex
    resulted in movement of specific body parts
  • (3) stimulation of the posterior neocortex
    produced no movements

17
  • Studies by Fritsch Hitzig refuted 3 dictums by
    Flourens and showed that
  • (1) cortex is excitable,
  • (2) cortex plays an important role in movement,
    and
  • (3) function is localized

18
  • In 1874, electrical stimulation in humans began

19
Anti-Localization Movement Goltz
  • Henry Head some behaviours too complex to be
    located in only one area of the brain
  • Goltz provided important evidence for the
    anti-localization movement

20
  • Goltz ablated neocortex of 3 dogs
  • Dogs lived for 57 days, 92 days, and 18 months
  • Observed
  • (a) hyperactivity
  • (b) sleep -wake cycles
  • (c) responses to temperature changes
  • (d) walking, balance
  • (e) responses to environment
  • (f) able to differentiate between food/poison
  • (g) Respond to light/sounds

21
  • Hughlings-Jackson (1835-1911) explained Goltzs
    findings by proposing a hierarchical concept of
    brain function
  • Each successfully higher layer controlled more
    complex aspects of behaviour but does through so
    lower layers

22
  • H-J 3 layers
  • (1) spinal cord
  • (2) basal ganglia and motor cortex
  • (3) frontal cortex
  • Damage to higher layers would produce
    dissolution - simplified behaviours only

23
Neuron Hypothesis
  • Basis is that the nervous system is made of
    discrete, autonomous cells that interact but are
    not physically connected
  • Support comes from the answers of 3 questions
  • (1) How does the nervous conduct information?
  • (2) How is the nervous system constructed?
  • (3) How is the nervous system interconnected and
    connected with muscles?

24
(1) How does the nervous system conduct
information?
  • Early theories hydraulic system (balloonist
    theories)
  • Glisson (1677) tested this
  • Newton (1717) nerves were solid that worked by
    vibrating along an elastic aether
  • Grey (1731) bodies could be electrified

25
(2) How is the nervous sytem constructed?
  • 1833 development of achromatic microscope
    allowed for the description of nerves
  • Schwann (1839) cells are the basic structural
    unit of the nervous system
  • Development of staining important

26
(3) How is the nervous system interconnected with
itself and with muscles?
  • A brain net of physically interconected fibers or
    a collection of discrete units?
  • Former favours a holistic approach while latter
    favours localization of function
  • Von Leydig (1855) and Golgi nerve net
  • Cajal (1852-1934) axons have terminal bulbs

27
  • Hebb (1949) when cells activated at the same
    time form a mini-nerve net
  • These cell assemblies formed the structure for
    memory

28
  • Knowledge of development of behaviour influenced
    concepts of neuron hypothesis by
  • (a) knowing that CNS is a uniform substance and
    can be thought of as a uniform structure
  • (b) knowing that CNS can be electrically
    stimulated led to electrical experiments
  • (c) knowing gray vs. white matter lead to ideas
    about effects ofcell damage vs. fiber damage
  • (d) being able to see differences in cell
    structure under microscope allowed for the
    development of functional maps

29
Development of Modern Neuropsychology
  • Reasons why psychologists did not become
    interested in the brain before the mid 1900s
  • (1) strong arguments by Head and others refuting
    localization of precise behaviours
  • (2) World Wars interfered with development of
    science
  • (3) Psychology comes from philosophy and thus
    they directed attention to behaviourism and
    psychoanalytical movements

30
  • There have been 3 modern developments that have
    contributed to the discipline of neuropsychology
  • (1) neurosurgery
  • Anesthesia, antisepsis, and localization of
    function
  • (2) psychometrics and statistical evaluation
  • Binet, IQ development
  • Hebb and frontal lesions
  • (3) advances in technology
  • CT, MRI, fMRI, PET
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