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					  BIO 132
Neurophysiology
                Lecture Goals:
   Course overview - syllabus & tentative schedule

   How to succeed in Bio 132

   Historical perspective of Neuroscience
Course Overview
      History of Neuroscience: A
              Perspective
Where in the body are memories stored; do
 commands to move come from; is sensory
 information processed; do consciousness, logic
 and emotion stem from?

What evidence do you have to support your
 answer?
       -500        0          500        1000        1500        2000




The Ancient Egyptians
 Greatly interested in physiology and how the body and
  mind worked.
 Thought the heart was seat of consciousness, and the
  brain did nothing important.
       When embalming the dead they would take great care to
        preserve the heart but the brain was pulled out through the
        nose and thrown out.
       -500      0        500       1000     1500      2000




The Ancient Greeks (~400b.c.)
 Hippocrates claims that the brain is the center of
  sensation and movement.
      Why would he come to this conclusion? He had
  no scientific tools like microscopes or MRI machines.

 Aristotle claimed that the heart “seethed” with emotion
  and that the brain was just a radiator to cool the body.

   Aristotle’s view one out over Hippocrates’ view, which
    was held for about 500 years.
       -500        0          500        1000       1500        2000




Ancient Romans (~150 ad.)
 Galen was a writer and physician to the gladiators.
      He saw the effects of brain and spinal injuries.
      By poking on the brain he noticed that the front was soft and
       back was hard, and concluded that the front dealt with
       memories and back dealt with movement.
      He dissected sheep brains and noted they had hollow cavities
       filled with fluid.
      He proposed that information was sent via the fluid traveling
       through nerves, which he considered just hollow tubes.
      This view was held for about 1,500 years.
       -500       0         500        1000      1500       2000




Renaissance (1500-1600)
 Galen’s views were strengthened by invention of
  hydraulics.
 Philosopher Rene Descartes ("I think therefore I am.“)
  developed a dualistic view of the human mind: soul and
  body were separate entities
      Claimed the soul communicated with the body through the
       pineal gland in the brain.
       -500        0          500        1000       1500   1750   2000




1700-1750
 Scientists took a closer look at the brain doing careful
  dissections.
      Grey and white matter found.
      White matter continuous with nerves of the body so assumed
       that it carried information.
      Found that there was a central nervous system and peripheral
       nervous system.
      Found that bumps (gyri) and fissures (sulci) on the brain are
       universal among people.
Central NS
                             Bump      Fissure
                             (gyrus)   (sulcus)
             Peripheral NS
       -500        0          500        1000       1500   1751   2000




1751
 Ben Franklin publishes paper on electricity which gives
  scientist a new tool.
      Others found that shocking muscle causes twitches.
      Shocking limbs elicits sensation.
      Galen’s “fluid theory” replaced with one stating nerves use
       electrical pulses to carry info.
      It wasn’t known if the same nerve carried both sensory and
       motor information.
       -500        0           500        1000        1500    1810   2000




1810
 Two scientist in different labs showed that neurons
  carry sensory or motor information, but not both.
      Nerves branch at the spinal cord, connecting with the front
       and back.
      If front branch is cut, movement is lost; if back branch is cut,
       sensation is lost.
        -500        0           500        1000   1500   1810   2000




1810
   Gall, an Austrian, developed
    “phrenology” which
    correlates skull bumps with
    personality traits.
       Scientists didn’t believe Gall’s
        theory since skull bumps don’t
        follow brain bumps (gyri).
       Mainstream public bought
        100,000 copies of Gall’s book.
         -500          0            500          1000          1500    1820   2000




1820
   Scientists look to see if different brain areas have specific
    functions using “experimental ablation method” which
    destroys a brain area to see what function is lost.
        Only large crude destruction was possible.
        Found that cerebrum is for sensation and perception, cerebellum is
         for movement coordination.
   Johannes Muller realizes that sensory systems and not the
    stimuli themselves produce sensations.
        Recognized that perceived sensations depend on the sensory organ
         type.
       -500       0         500       1000      1500   1859   2000




1859
 Charles Darwin publishes On the Origin of Species
      Darwin includes behavior among heritable traits.
      He observed that many mammals show similar behavior
       when frightened.
      Concluded animal nervous system probably share
       common wiring and underlying mechanisms.
       -500        0           500         1000        1500    1860   2000




1860s
 Broca, a neurologist, had a patient who could
  understand speech but couldn’t speak.
      The patient’s words were jumbled together and didn’t
       make sense.
      After patient died, Broca examined his brain and saw a
       lesion in a brain area.
      Today the area is called Broca’s area and it is responsible
       for communication.
      This was the first evidence that a specific brain area had a
       specific function.
     -500       0        500       1000      1500   1870   2000




1870s
 Scientists could apply a small shock to the brain and
  elicit movement.
 Destruction of the same brain area caused paralysis.

 Mapping of the brain’s functions begins.
         -500       0          500         1000        1500    1870   2000




1870s
 Nissl invents the Nissl stain and is able to see cell
  bodies under the microscope.
 Golgi invents the Golgi stain which shows the
  outline of neurons.
      He proposes the "Reticular Theory" - all neurons are one
       big net.
   Cajal uses Golgi stain to advance histology of brain to
    unprecedented heights and proposes "Neuron Doctrine" -
    each neuron is separate.
   Golgi and Cajal, bitter rivals, must share the Nobel Prize (1st
    time ever) in 1906.
       -500        0         500        1000       1500      1950 2000




1950s
 Electron microscope invented and shows that Cajal
  was correct (*usually).
 Hodgkin and Huxley use giant squid axon to test
  action and membrane potentials.
      They pioneered the use of the voltage clamp technique to
       change and measure the potential (charge) inside a
       neuron.
      They developed a model for activation and threshold
       energies.
      They shared the Nobel Prize in 1952.

				
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posted:2/25/2013
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