Development of Physiological Influences

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Development of Physiological Influences

• The brain
• Nerve function
• Visual perception
• Brain localization
• Psychophysics

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A. The Brain

• Australopithecus africanus
• Trephining

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Egyptians

• Threw away brain when mummifying

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Greek Doctors Are There Animal Spirits in There?

• dissected brains and optic nerves brain is organ
  of thought
• the soul is in the fourth ventricle and the
  "animal spirits" (intellectual, motor system) are
  in the brain itself (cerebrum)

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Galens Cell Doctrine

• Galen localized the mind to the ventricular
  system of the brain

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• First cell imaginativa (imagination) and
  "fantasia" (fantasy)
• Second cell "aestimativa" (judgment),
  "cognitativa" (thought) and "ratio" (reason)
• Third cell "memorativa" (memory)

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Pre-Renaissance

• Animal Spirits

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Renaissance - da Vinci

• da Vincis system
• Anterior ventricle 'intelletto' (intellect) and
  'imprensiva
• Middle ventricle 'volonta' (will) and 'senso
  comune
• Posterior ventricle 'memoria' (memory)

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Renaissance - Descartes

• Agreed with Galen about ventricles
• Nerves are tubes with valves connected at one end
  to the ventricles (animal spirits) to muscles at
  the other end (hydraulic theory)

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B. Nerve function (electricity view)
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Whytt's (b. 1714) Reflex

• Reflexive contraction of pupil to light
• Reflexes were involuntary and depended on spinal
  cord
• Nervous tissue contained a sentient principle

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Galvani-Volta Debate
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• Luigi Galvani (b. 1737) claimed that he
  discovered animal electricity (electrical body
  fluid)
• Count Alessandro Volta (b. 1745) said that all
  that happened was that the frog conducted static
  electricity

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• "Galvanic skin response" GSR
• Volta.. Volts, Voltage
• Giovanni Aldini provided basis for a novel
  written by a famous writer...

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du Bois-Reymond (b. 1818)

• Discovered the action potential
• He or Galvani the "Father of Electrophysiology?

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Sir Charles Bell (b. 1774)

• Experiments with rabbits
• Francois Magendie experiments with puppies ?

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Bell-Magendie Law

• dorsal roots of spinal nerves bring in sensory
  information
• ventral roots carry motor fibers down to the
  muscles

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Johannes Muller (b. 1801)

• Directly aware only of the activity in our
  nerves, not external reality
• Doctrine of specific nerve energies - same
  stimulus applied to different sensory nerves
  results in different sensations

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C. Research on Visual Perception
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Hermann von Helmholtz (b. 1821)

• Medicine, physics, math, psychology, music,
  philosophy

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• "On the conservation of force
• Metabolism
• Determined wavelength of ultraviolet light
• Optics
• Theory of velocity of air in open tubes
  (acoustics)
• Thermodynamics (Law of conservation of energy)

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Contributions to Psychology

• Measuring the speed of the nerve impulse
  (REACTION TIME)
• Young-Helmholtz trichromatic color theory
• Place theory of pitch perception

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Ewald Hering (b. 1834)

• Opponent-process theory of color perception

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Hering Illusions
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Hering bow
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Jan Purkinje (b. 1787)

• Shift from cone to rod vision in twilight
• Purkinje effect in stars - red source will cease
  to be visible before the yellow or white source

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D. Brain Localization
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Phrenology
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Franz Gall (b. 1758) his pupil Spurzheim

• The mysterious Miss Leisler
• "Neither sin nor friends will ever leave me."

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Galls Work on Nervous System

• Nervous system is like a tree
• Distinction between gray matter (neurons) and
  white matter (axons)
• CNS fibers terminate in the cortex, not the
  medulla
• Identified origins of cranial nerves I-VIII
• Pyramidal tracts crossing brain hemispheres

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Galls Claim

• Mental activities localized in the cortex
• Wanted to develop a functional anatomy and
  physiology of the brain, as well as a revised
  psychology of personality
• Led to theories concerning localization and
  cranioscopy

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The System of Organology

• Brain is organ of the mind
• Brain is a collection of organs representing
  various propensities, sentiments, faculties
• Size of each organ indicates its power
• Skull conforms to brain's shape
• Mind's functions located in different places in
  the brain

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How Many Faculties of Mind?

• Gall sez 27
• Spurzheim sez 37

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Napoleons Descartes Heads
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Phrenology taken over by Quacks

• Employment
• Marriage prospects
• Children's prospects
• 1920's - The Psychograph

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Problems with Phrenology

• Arbitrary choice of faculties
• Observations not fitting in explained away

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Contributions of Phrenology

• Established brain as the source of mind
• Mental functions localized in the brain

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Pierre Flourens (b. 1794)

• "An Examination of Phrenology" 1824
• Ablation technique- removal of one of six
  separate areas of brain

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6 Different Brain Functions

• Cerebral hemispheres - willing, judging, memory,
  seeing, hearing
• Cerebellum - motor coordination
• Medulla oblongata - mediation of sensory/motor
  functions
• Corpora quadrigemina (inferior/superior
  colliculi) - vision
• Spinal cord - conduction
• Nerves - excitation

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Flourens vs. Gall

• Flourens approach reflected localization, but he
  stressed the common action of the various parts
• Emphasis on the common unity of the entire system

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Recovery of Function

• Also observed recovery of mental function over
  time - forerunner of "neural plasticity"

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Brain Localization The Story of Phineas Gage
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• Sept. 13, 1848 - Vermont - a deadly day for
  Phineas
• Iron rod entered under left cheek, exited through
  top of head, landed 30 yards away.
• Dr. John Harlow
• MRI analysis by Damasio shows damage in
  ventromedial region on left side of brain

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http//www.offoffoff.com/theater/2002/phineasgage.
php3
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Language Localization in Brain
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Paul Broca (b. 1824)

• Patient named Leborgne
• Autopsy showed lesion to 3rd convolution of left
  frontal lobe
• Concluded this area important for speech
  articulation

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Brocas Brain!
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Karl Wernicke (b. 1848)

• Damage in top left temporal lobe causes poor
  language comprehension (Receptive aphasia)

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Psychophysics the Beginning of Psychology?
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Ernst Weber (b. 1795)

• Investigated 2-point thresholds for touch
• Jnd's investigated for various stimuli
• Jnd's vary by a constant ratio called Weber
  Fraction
• First to quantitatively measure the mind?

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Gustav Fechner (b. 1801)

• "Elements of Psychophysics" 1860

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• The term Psychophysics coined - science of
  studying the relation between the physical and
  the mental (stimulus and sensation)
• Fechner's Law
• Devleoped method of limits, method of constant
  stimuli, method of average error (adjustment)