Cutaneous Senses

• What are the three reasons why it is important to feel physical stimuli?

  Feedback from objects, body positioning, and warning signals to protect the body
• What are the main components of the cutaneous system?

  • The skin
  • Mechanoreceptors
  • Pathways from the skin to the brain
  • The somatosensory cortex
• What are mechanoreceptors sensitive to?

  Mechanoreceptors are sensitive to mechanical deformation such as pressure, stretching, and vibration
• How many types of mechanoreceptors are there?

  There are four types of mechanoreceptors
• Name the four types of mechanoreceptors.

  Merkel receptor, Ruffini cylinder, Meissner corpuscle, and Pacinian corpuscle
• What characterizes large receptive fields in mechanoreceptors?

  • Located deeper in the skin
  • Have larger receptive fields
  • Ruffini (SA2) and Pacinian (RA2) receptors have larger fields than Merkel (SA1) and Meissner (RA1)
• What is the response pattern of Merkel receptors?

  Merkel receptors are slowly adapting and provide fine spatial detail
• What does the medial lemniscal pathway carry?

  It carries signals representing limb positions and the perception of touch
• What is the function of the spinothalamic pathway?

  The spinothalamic pathway carries signals responding to pain and temperature
• How is the somatosensory cortex organized?

  • Signals travel to the somatosensory receiving area (S1) in the parietal lobe
  • Also includes the secondary somatosensory cortex (S2)
  • Organized into maps representing locations on the body (homunculus)
• What does the homunculus represent in the somatosensory cortex?

  The homunculus represents the body parts and their corresponding sensitivity in the somatosensory cortex
• What is experience-dependent plasticity in the context of the somatosensory cortex?

  Experience-dependent plasticity refers to the increase in cortical area devoted to body parts through use
• What is the tactile acuity measure?

  The tactile acuity measure involves determining if one or two points are felt when close together
• How does the density of Merkel receptors relate to tactile acuity?

  A higher density of Merkel receptors is associated with better tactile acuity
• What is the primary role of the Pacinian corpuscle?

  The Pacinian corpuscle is primarily responsible for sensing vibrations
• How does touch compare to vision in terms of texture representation?

  Touch provides a more accurate representation of surface texture than vision
• What is the duplex theory of texture perception proposed by David Katz?

  • Spatial cues (e.g., bumps)
  • Temporal cues (as skin moves across the texture)
• What happens to texture discrimination when fingers are moving compared to when they are static?

  When fingers are moving, one surface is perceived as much rougher than the other, improving texture discrimination
• What systems interact in haptic perception?

  • Sensory system: detects touch, texture, temperature, etc.
  • Motor system: involves moving fingers and hands
  • Cognitive system: integrates sensory and motor information and holds it in memory
• What are the exploratory procedures in haptic perception?

  • Lateral motion: texture
  • Pressure: texture
  • Enclosure: shape
  • Contour following: shape
• How do mechanoreceptors contribute to shape perception?

  Mechanoreceptors fire in response to objects, with the most response at the point of contact