BIO 132

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BIO 132

• Neurophysiology

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Lecture Goals

• Course overview - syllabus tentative schedule

• How to succeed in Bio 132

• Historical perspective of Neuroscience

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Course Overview
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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?

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• 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.

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• 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.
• Aristotles view one out over Hippocrates view,
  which was held for about 500 years.

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• 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.

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• Renaissance (1500-1600)
• Galens 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.

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1750

• 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.

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Central NS
Peripheral NS
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1751

• 1751
• Ben Franklin publishes paper on electricity which
  gives scientist a new tool.
• Others found that shocking muscle causes
  twitches.
• Shocking limbs elicits sensation.
• Galens fluid theory replaced with one stating
  nerves use electrical pulses to carry info.
• It wasnt known if the same nerve carried both
  sensory and motor information.

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1810

• 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.

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1810

• 1810
• Gall, an Austrian, developed phrenology which
  correlates skull bumps with personality traits.
• Scientists didnt believe Galls theory since
  skull bumps dont follow brain bumps (gyri).
• Mainstream public bought 100,000 copies of Galls
  book.

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1820

• 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.

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1859

• 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.

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1860

• 1860s
• Broca, a neurologist, had a patient who could
  understand speech but couldnt speak.
• The patients words were jumbled together and
  didnt make sense.
• After patient died, Broca examined his brain and
  saw a lesion in a brain area.
• Today the area is called Brocas area and it is
  responsible for communication.
• This was the first evidence that a specific brain
  area had a specific function.

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1870

• 1870s
• Scientists could apply a small shock to the brain
  and elicit movement.
• Destruction of the same brain area caused
  paralysis.
• Mapping of the brains functions begins.

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1870

• 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.

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1950

• 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.