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HS-03-ScientificContext1week2.pptxContemporary Issues: Historical Framework of Contemporary Psychology
Unit 3
The Scientific Context
Science in the Age of Enlightenment
Enlightenment:1650s -1780s (Western Europe)
emphasized reason, analysis & individualism vs. traditional lines of authority.
Science can “shed light” on dark corners of human ignorance
Science can yield “objective truth”
Scientists are unbiased
Progress is something to be valued
Isaac Newton (1643-1727)
physicist, mathematician, & greatest scientist of his era
Cambridge Univ: mathematics, optics, physics & astronomy
fellow of Trinity College; Lucasian professor of mathematics (1669)
Ordination not required. Stephen Hawkins recently held this post
fellow of the Royal Society (1672); President 1703-death
Principles of Natural Philosophy (1687) Mechanics & Gravity
also published in history, theology and alchemy.
'The Opticks' (1704) - fundamental nature of light
Functioning of the Nervous System
Early Knowledge of CNS
Pre 1600s:
Neuroanatomy: da Vinci, Galen, & others
thought brain is organ for purification & refinement of animal spirits
typically studied poorly preserved brains (degraded into the formless mass)
Sir Christopher Wren (artist) developed preservation techniques
Thomas Willis (B. Med – Oxford, 1646)
Practicing Physician
Returned as Professor of Natural Philosophy, 1660
Focus: neuroanatomy of Brain (1664 Cerebri Anatome)
Moved to London to practice (at request of Archbishop of Canterbury)
Became wealthy, lots of pro-bono work
Thomas Willis (1621-1675)
Neuroanatomists
Cerebri Anatome (1664) (Anatomy of the Brain)
Circle of Willis
basic neuroanatomy, anatomical nomenclature, & comparative neuroanatomy
Coined important terms
Reflex
Neurology
Cranial Nerve #
Founder of Clinical Neuroscience
Longitudinal studies in his patients
dissecting and studying them after their death
would relate altered behavior he observed during their life to neurological deficits and deformities discovered during autopsy
Functioning of the Nervous System
Reflex Action
Robert Whytt (1714-1766)
Studied Art & then Medicine
Prof: theory of medicine at Edinburgh
Physiology: voluntary and involuntary activity of nervous system
spinal nerves in involuntary responses to stimuli
set the scene for the study of reflexes in the nineteenth century
Stimulated frog legs
If spinal cord separated from brain reflex occurred
If nerve disconnected from spinal cord no reflex
Therefore, spinal cord necessary for reflexes
Voluntary (requires brain) vs. involuntary (only requires spinal cord) actions
Habit formation: starts as voluntary, becomes more involuntary
Later, William James spoke of this
Reflex implies existence of a sensory component and a motor component
Bell-Magendie Law
Spinal Nerves
Orig: nerve fibers indiscriminate re: sensory/motor function
dorsal roots (#12) afferent/sensory fibers
if cut, movement but no sensation in corresponding limb
ventral roots (#11) efferent/motor fibers
if cut, sensation but no movement in corresponding limb
Naming Controversy
1811 Bell reported motor function ventral roots; did not mention sensory functions of the dorsal roots (due to method of dissection, he was an anatomist)
A dead, or rendered unconscious, animal would not register pain
11 years later, Magendie (a physiologist) reported motor neuron fibers exit the anterior root and the sensory neuron fibers from the dorsal root
NOTE: also national rivalry – English (Bell) vs French
Specific Nerve Energies
Johannes Peter Müller (1835)
(Bell had done some of this; Locke & others implied this)
perception is defined by the pathway over which the sensory information is carried.
(Eye Press Demo)
attributed the quality of an experience to some specific quality of the energy in the nerves
1912: Edgar Adrian showed all neurons carry the same electrical energy (i.e., action potentials)
1945, Roger Sperry showed that location in the brain to which nerves attach determines experience (Nobel 1981)
Sperry: Nobel for Split-Brain work at CalTech (tidbit: Sperry was denied tenure at U Chicago)
KEY: We do not perceive the world directly, we perceive the action of our nervous system
After Müller, the two problems of mind and body, the relationship of mind to brain and nervous system and the relationship of mind to world were inextricably linked. Although Müller did not himself explore the implications of his doctrine for the possibility that the ultimate correlates of sensory qualities might lie in specialized centers of the cerebral cortex or develop a sensory psychophysics, his principle of specificity lay the groundwork for the eventual localization of cortical function and his view of the epistemological function of the nervous system helped define the context within which techniques for the quantitative measurement of the mind/world relationship emerged in Fechner's psychophysics
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Hermann von Helmholtz (1821-1894)
10 interest was Science
couldn’t afford Univ; studied medicine on military grant
1849 Prof of (anatomy &) Physiology
Wilhelm Wundt was his assistant (1858-1863)
Studied Human Eye
1851 invented the ophthalmoscope
Young-Helmholtz trichromatic color vision theory
Studied Human Ear
Pitch & Tone (he was a musician)
1852 Speed of Neural Impulse (1/10 speed of sound)
Stim frog's nerve: 1st near a muscle, then farther away;
when the stimulus was farther from the muscle, it contracted just a little slower
1870 Changed focus – Prof of Physics
Hermann Ludwig Ferdinand von Helmholtz
Whoever, in the pursuit of science, seeks after immediate practical utility, may generally rest assured that he will seek in vain.
(All that science can achieve is a perfect knowledge and a perfect understanding of the action of natural forces.)
Herman von Helmholt Academic Discourse, Heidelberg (1862)
Hermann Helmholtz (cont)
Advocated a strongly materialist philosophy
All life reduces to physical and chemical processes
Opposed the vitalism of his mentor (Müller)
Speed of the neural impulse
Assumed speed too fast to ever be measured
organisms powered by innate "vital force" rather than energy
1791 Galvani demonstrated electrical properties
Relative slowness demonstrated that physical/chemical processes involved
Would later provide the basis for the development of reaction time methodology
Helmholtz: Sensory Physiology
Research on Vision
Trichromatic theory (Young-Helmholtz)
Receptors for three primary colors
red, green, blue/violet
Other colors involved combinations of receptors
Retinal level
Opponent Process theory (Hering) applies later in the visual pathway (LGN)
Opponent process cells (R-G, B-Y, B-W)
Research on Hearing
Resonance theory / Place theory
Different frequencies detected by receptors in different locations on the cochlea
Helmholtz The Problem Of Perception
Remarkable capabilities to perceive
Yet poor optics
Poor quality info on space, distance, motion, etc.
Unconscious inference
Based on experience
e.g., person approaches us – we infer that they are getting closer, not bigger (we have learned that people don’t grow that fast)
Consistent with specific energies doctrine (Muller)
Congenial to British Empiricist thinking (Locke)
Honors
- 1873, elected member of the American Philosophical Society.
- 1881, elected Honorary Fellow of the Royal College of Surgeons in Ireland.
- 1881, awarded the Légion d'honneur: au grade de Commandeur, or Level 3 – a senior grade.
- 1883, Emperor, raised to the nobility, or Adel - now styled: von Helmholtz. The distinction was not a peerage or title, but conferred a certain social cachet.
- 1884, Honorary Member of Institution of Engineers and Shipbuilders in Scotland
Localization of Brain Function
Franz Joseph Gall (1758-1828)
Studied Medicine: neuroanatomist & physiologist
study of the localization of mental functions in the brain
1800 Craniometry; later called Phrenology
First serious localization theory
collected human and animal skulls and made wax molds of brains
relations between head shape & personality or ability
Basic principles of phrenology
Brain is the organ of the mind
Mind composed of a number of “faculties”
Intellectual, affective (emotional), personality
Each faculty located in a specific place on the cortex**
Strength of a faculty reflected in proportional brain size
Doctrine of the skull (skull reflects brain contour)
Enables measurement of faculties by measuring skulls
Discovered diff grey (neuron) vs. white (axons) matter
Phrenology – Little Scientific Acceptance
Rejected in Austria & France
Relied too much on anecdotal evidence
Avoided falsification
Apparent disproof explained away
Adopted by quacks & frauds
Popular in England & U.S. (1820s-1850s)
Eng. Used to justify inferiority of colonies
US slavery
Johann Spurzheim influence
biological explanation of mental processes
Big business
Fowler & Wells: social reformers,
publishers, lecturers
Lavery’s “psychograph”
Phrenology –Scientific Disproof
Pierre Flourens (1794-1867)
Physician: ablation & stimulation
Cortex, Cerebellum & Vestib system
Direct attack on phrenology
brain acts as functional entity (integrated whole)
although specific functions are controlled by specifics parts of the brain
Destroy some portion of brain
Make inferences based on the outcome
Specific locations had functions different from those proposed by phrenologists
e.g., cerebellum (motor coordination, not “amativeness”/sexual attraction)
Clinical Localization of Brain Function Case of Phineas Gage (1848)
Phineas P. Gage
American railroad construction foreman
large iron rod driven completely through head
destroying much of his brain's left frontal lobe
"entered on the [left] side of his face... passing back of the left eye, and out at the top of the head.
personality and behavior changes
friends saw him as "no longer Gage”
frontal lobe damage altered rational control over emotions
1st case: damage to specific parts of the brain might affect personality
Clinical Localization of Brain Function Case of “Tan”
Broca’s (motor) aphasia
Louis Leborgne lost the ability to speak at 30 yo
Admitted to Paris Hospital – could only say “Tan”
No other cog or language defects
21 yrs later (1861), autopsy of brain:
large lesion in the frontal area
posterior inferior frontal gyrus (Brodmann’s 44 & 45)
Lelong: 84-year-old being treated for dementia
Could only speak 5 words
autopsy showed similar brain lesion
Speech Function Was Localized
specific functional areas
Phrenologists had good insight
“Scientific Phrenology”
Electrical stimulation of the cortex
Fritsch (1860):
Military Hospital, Open Skull Injury, Elect Stim of Brain
Rear of brain eye movements
Fritsch joined Hitzig (1870)
German neurologist and neuropsychiatrist
Stim dogs specific body movements
Note: Univ wouldn’t allow so did at Fritsch’s home
Identified motor centers in the cortex
John Jackson – electrical discharge & epilepsy
David Ferrier (1873): electrical stim & ablation
Identified sensory and motor areas in primate cortex
Functions of the Brain (1876)
Wilder Penfield (1940): operating on epileptics
Mapped out motor cortex in human
London Times, Friday, March 25, 1887
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The Neuron & Behavior
Camillo Golgi (1844-1926)
Fixation & Staining procedures very poor in 1872: while an attending at hospital, developed staining techniques (Golgi stain) (published in 1875)
Visualize nerve cell body & all processes
Believed physically connected (stain crossed synapse)
Santiago Ramón y Cajal (1852-1934)
Believed they were adjacent but not physically connected
1906 Nobel Prize shared by Golgi & Ramón y Cajal
Sir Charles Sherrington (1857-1952)
Integrative Action of the Nervous System (1906)
Synapse must exist
RT of reflexes slower than expected from known neuron speeds
Temporal summation
Spatial summation
Nobel in 1921
