Sensory Processing

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Sensory Processing

• What senses do you possess?
• Are there other senses in the animal kingdom that
  you do not possess?

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Five Senses?

• There are other senses of which we are unaware or
  are physiologically separate from the classic
  senses
• Kinesthetic senses (motor sense)
• Proprioception
• Muscle stretch
• Subsets of Somatosensory
• Temperature
• Pain
• Pressure
• Vibration
• Vestibular sense
• Pheremonal reception? (vomeronasal organ in other
  animals)

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Other animals have different senses that we do
not experience

• Some rodents can see ultraviolet light
• Sharks, eels and platypus can sense electrical
  changes in the environment
• Snakes sense infrared (heat)
• Bats and Dolphins echolocation
• Some birds may use magnetic energy for migration

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Sensory Transduction

• Law of Specific Nerve Energies (Transduction)
  (Muller, 1826)
• - Each sense has dedicated receptors and
  pathways within brain
• - Each sense is stimulated by specific
  physical events (e.g. light,
• air pressure changes)

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Signal Detection Theory
Used to determine the capabilities and limits of
sensory systems
Absolute threshold the minimum stimulus value
that can be detected Difference threshold the
minimum difference in stimulus value that can be
detected 50 of the time. (jnd just noticeable
difference)
Weber-Fechner Law - suggests that the just
noticeable difference (jnd) is a constant
proportion of the original stimulus.
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Quick Quiz (Sensation) Name ____________________
_

• 1. Which of the following senses can detect
  photons?
• a. audition d. olfaction
• b. vision e. somatosensation
• c. gustation
• Which of the following senses uses
  mechanoreceptors?
• a. audition d. olfaction
• b. vision e. somatosensation
• c. gustation
• The conversion of energy from the environment
  into a pattern of electrochemical responses
  in the nervous system is called a.
  acquisition d. perception
• b. accommodation e. learning
• c. transduction
• 4. What transduction mechanism is used for
  olfaction and gustation?
• a. nociceptors d. photoreceptors
• b. thermoreceptors e. chemoreceptors
• c. mechanoreceptors

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The Visual Sense

• Light consists of quanta (photons) that vibrate
  at a particular range in the electromagnetic
  spectrum

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The psychophysics of vision

• The visual system breaks down the visual world
  based on three basic variables
• Form
• Color
• Motion

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1. Form

• Higher processing involving cortical centers
  (e.g. inferior temporal lobe damage results in
  prosopagnosia the inability to recognize faces
  with preserved perception of facial features, see
  Fruit Face)
• Spatial frequency is primary determinant of form
  perception

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Fruit Face
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2. Color

• Coded via wavelength of photons
• Consists of
• Brightness created by brain, a relative
  measure based on context
• Hue subjective color
• Saturation depth of color
• Blue colors are short wavelengths Red is long
  wavelengths

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3. Motion

• Motion range of perception is limited to the
  speed of relevant organisms probably involves
  the convergence of cells coding spatial frequency
  and changes across spatial frequency

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Quick Quiz (Sensation) Name ____________________
_

• 5. What are the three variables processed by the
  visual system? What is the physical basis of
  each variable?

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The Eye
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The Retina
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How do we see color?
Trichromatic Theory vs. Opponent Process
Theory Three cone types (with different light
sensitive opsins) projecting to opponent
process ganglion cells.
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How does information from your eye get to your
brain?
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Visual information is separated by color, form
and motion in the brain
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Quick Quiz Vision (22)

1. What are the three defining characteristics of a
   sensory system? 3
2. What is the function of sensory transduction
   mechanisms? 1
3. What is the transduction mechanism for vision? 1
4. What is the difference between rods and cones? 4
5. Visual information is broken up into what three
   components? 3
6. What are the two theories of color vision? 2
7. Briefly describe the pathway for vision from the
   eye to the cortex. 6
8. What are the physical qualities of a waveform
   that are important for sensory processing? 2

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Audition

• What is sound?
• Air pressure changes (vibrations) of a certain
  frequency that are audible to an organism.

Pressure changes can be varied in amplitude
(loudness measured in decibels (dB)) or in
frequency (pitch measured in Hertz (Hz)
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The Psychophysics of sound

• In ideal circumstances, humans can hear within
  the range of 20-20,000 Hz
• The frequency range for human speech is 400-4000
  Hz
• We tend to lose our ability to hear higher
  frequencies as we get older
• Other species can hear outside the range of human
  hearing

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The anatomy of audition
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Transduction occurs in the cochlea
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Pitch is determined by the location of the
basilar membrane most vibrated and the number of
hair cells activated

• Place Theory
• Volley Theory

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How does information get from your ear to your
brain?
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Which vehicle appears to be larger? Why?
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