Psychology 110-04 Other Senses Lesson 3

  1. Chemical Senses
    1. Olfactory System
      1. Oldest sense, plays through olfactory bulb, direct connection
      2. Receptive cells olfactory cilia/mucus capture and dissolve scents
      3. Sensitivity is measured in ppm, only a few molecules are required to operate
      4. Tied to memory, mash episode, Windsong ads
    2. Taste
      1. Receptors located in clusters of cells located on tongue in bumps, taste buds
      2. 4 primary, non-uniform distribution, dissolve in solution
      3. cravings for particular tastes driven by body states
      4. genetic factors PTH chemical
      5. cultural factors Cajun hot or Indian curry
      6. taste influenced by smell, color, and expectations
    3. Mechanical Senses
      1. Auditory System
        1. Nature of Sound
          1. Simple form of energy from which we extract subtle information
          2. Physics Perception
            1. Frequency = Pitch
            2. Amplitude = Loudness
            3. Purity/Mixture = Timbre
      2. Measure of Loudness
        1. SPL perception is not linear, larger JNDs at higher amplitudes
        2. Function is logarithmic, measured in decibels, step of 90-100kHz = ~3x SPL
      3. Low Frequency
        1. Threshold U shape function, lowest around 2kHz, >10 dB, range from 10-20khz
        2. Many more animals have lower thresholds, lower & higher frequencies
        3. Bat Sonar
      4. High Frequency
      5. Pain at 120-130 dB, level of rock concert in front of speaker wall
        1. Current mil a/c = 140dB, SS/generation F-119 engines 150dB, only SV louder!
        2. Loud noise exposure effects
          1. Minimal temporary threshold shifts
          2. Pain and permanent hearing loss
        3. Auditory Process
      6. Gathering physical properties, pinna, auditory canal with two bends
        1. Eardrum, 7 cell thick membrane
        2. Ossicles: hammer, anvil, stirrup, set of levers mechanically amplify
        3. Cochlea: oval window, basilar membrane, round window
          1. Hair cells sheared by sound propagating down the basilar membrane
          2. Place vs. Frequency theory,
          3. Helmholtz place theory, Rutherford frequency theory
          4. Von Bekesy finds mostly for place, but some frequency effect present.
          5. LF = freq, MF = both, HF = place
      7. 3-D Audio perception
        1. Pinna, canal, temporal differences allow localization via HRTF
        2. Stereo permitted localization, poorly employed
          1. Dolby 5.1+, THX try to exploit 3 dimensionality
          2. Subwoofers move into vibration.
    4. Skin: Touch, Temperature, and Pain
      1. Mechanical deformity, pressure, Capucian Corpuscles amplifies pressure
        1. Receptive fields and JNDs
      2. Body sensitivity heterogeneous, sensitivity greater in some places than others
        1. Homunculus in medial brain sensory areas
      3. Complimentary heat and cold receptors
        1. Pain receptors open nerve endings
        2. Worst is electricity applied to the dental pulp
        3. Fast path, localized pain, mylinated A fibers
        4. Slow path, unmylinated C fibers
      4. Extensive work in pain pathways
        1. SC to midbrain, thalamus, ventrobasal nucleus relay to somatosensory cortex
        2. Cortex adjacent to motor areas
        3. Gate Control Theory
          1. Block pathways by inhibition, basis for acupuncture
        4. Chemicals, natural endorphins, artificial anesthetics
                1. Phantom Limb phenomenon
      5. Pain management is big business
    5. Kinesthetic senses
      1. Tightly coupled to motor control, where is our limb, feedback control system
      2. Degrades quickly with alcohol consumption, touch your nose test.
    6. Vesibular system
      1. Variation on hearing hair cells, augmented with gravel
      2. Maintains balance, orientation
      3. Easily fooled, death spiral and Birney chair
  2. Summary, sensation and perception
    1. Our knowledge of the world is indirect
    2. Although remarkably accurate, still can be flawed by pathology or by exploitation
    3. Veridical perception is attributed to highly evolved processing of sensory inputs
    4. Conflicting theories, can both be true at different levels o processing
    5. Everyone doesn't experience the world in the same way, process and culture
    6. Highlights biological underpinnings, know more because fewer synapses in

 

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