History of Neuropsychology

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History of Neuropsychology
Psychology 315 Introduction to Neuropsychology 200
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• 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.

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• 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

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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)

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• 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

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

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

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• 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?

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• 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

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Localization of Function Phrenologists

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

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• 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

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

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• 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

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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

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• 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

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• 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

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• 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

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• In 1874, electrical stimulation in humans began

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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

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• 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

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• 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

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• 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

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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?

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(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

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(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

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(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

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

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• 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

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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

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• 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