The law of specific nerve energies

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• The law of specific nerve energies
• Filtering(???????)
• Receptive field (???)
• Lateral inhibition(???)
• Efferent control of sensory processes
  (??????????)
• Topographic organization (???)
• Neural coding (???)
• Consciousness (??)

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The law of specific nerve energies
Chemical stimulus
Light stimulus

• Sensory organs are specialized to receive a
  particular stimulus.
• Nerve impulses are physically indistinguishable.
• A particular brain region interprets nerve
  impulses and assigns a particular type of
  sensation.

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The law of specific nerve energies(defined)
(Johannes Müller, 1838)

• When any given nerve (or neuron) is excited, the
  message it conveys is always the same no matter
  how it is stimulated.
• For example, neurons of the optic nerve only
  convey visual information.

• However, the physical signals in the nerve take
  the same form, action potentials, regardless of
  the type of sensations (later discovery).

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Synesthesia???

• The rare capacity to hear colors, taste shapes,
  or experience other equally startling sensory
  blending whose quality seems difficult for most
  of us to imagine.
• Curious about it? VisitSynesthesia
  Phenomenology And NeuropsychologyA Review of
  Current Knowledge

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Various Sensory Systems
sight hearing touch taste smell
balance hot/cold pain (itch)
electric magnetic humidity
ultrasound infrasound ultraviolet infrared
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Table 9-1. Receptor Cells and Sensory Neurons
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Filtering
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Receptive Field (1)
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Lateral Inhibition
??? lateral inhibition
Keffer Hartline (1967)
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Mach Band
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Mach Band
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Mach Band
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Mach Band
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Mach Band
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Mach band and lateral inhibition
Mach band Ernst Mach (1865)
Latelal inhibition Haldan Keffer Hartline
(Novel Prize in 1967)
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Lateral Inhibition
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Common Principles in Sensory Systems

• The law of specific nerve energies
• Filtering
• Receptive field (???)
• Lateral inhibition(???)
• Efferent control of sensory processes
  (??????????)
• Topographic organization (???)

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??????????

• Peripheral (???)
• Muscle spindle (???)
• Middle ear muscle contraction(?????)
• Neuromast cells in fish (?????????)
• Vestibulo-ocular reflex (??????)
• Central (???)
• Efference copy (??????????????)

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Efferent Control of Sensory Organs
inhibition
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Efferent Control of the Sensory Information
(Central)
Neurons in the superior colliculus (midbrain) of
monkey responds to a moving image presented on a
white screen.
When the monkey voluntarily move its eye, in
front of the same but stationary image, the
neuron show no response whatsoever.
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Efference Copy Experiment(Dont poke your eye!)

Gently press here to move your eye ball.
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Efferent control of sensory information(efference
copy)

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Common Principles in Sensory Systems

• Transduction
• The law of specific nerve energies
• Filtering
• Receptive field
• Neuronal code
• Efferent control of sensory processes
• Topographic organization (brain map)

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Topographic Organization(1)(brain map)
somatotopic organization
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???
retina
lateral geniculate nucleus
visual cortex
Figure legend in the textbook has an error.
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Topographic Organization(3)(brain map)

Tonotopic map
cat auditory cortex
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Topographic Organization(4)(auditory space map
in owl)
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Topographic Organization(5)(auditory space map
in bat)
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Topographic Organization(6)(auditory space map
in bat)
Suga, N. (1990) Biosonar and neural computation
in bats. Scientific American 262(6)60-68
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Brain MapsBrain loves to create maps of
outside world. Why? We dont know. But,
topographic maps are perhaps useful for brain to
deal with spatial information.