Chapter 12: The body Sences

Question 1

proprioception

Answer 1

-muscle stretch and joint angle, for monitoring limb position and movement
-Three different types of sensory organs provide information about joint angles:
muscle spindles
Golgi tendon organs
joint receptors

Question 2

haptic

Answer 2

object shape, perceived through touch and proprioception together

Question 3

Specificity Theory

Answer 3

Feature detectors (grandmother cell)
Labeled lines - taste
Place theory – hearing
modular

Question 4

Pattern Theory

Answer 4

Distributed coding – trichromatic theory of colour vision

Population code

Question 5

Mechanoreceptors 4

Answer 5

Encapsulated receptors (Fast Adapting – FA)
fire at onset and offset of stimulation
Meissner corpuscles
Specialized endings of FAI mechanoreceptors
Pacinian corpuscles
Specialized endings of FAII mechanoreceptors
Non encapsulated receptors (Slow Adapting – SA)
fire continuously as long as pressure is applied
Merkel disks
Specialized endings of SAI mechanoreceptors
Ruffini endings (not called such in the text – see note on table)
Specialized endings of SAII mechanoreceptors

Question 6

Tactile Acuity

Answer 6

(Merkel Cell Endings (SA I))
-Specialized for the detailed perception of spatial patterns on surfaces
-Good acuity or spatial resolution
so small receptive fields
-Merkel receptors are densely packed on the fingertips - similar to cones in the fovea
-Both two-point thresholds and grating acuity studies show acuity was greatest on fingertips and that acuity is related to the spacing between Merkel (SA-punctate) receptors at each location

Question 7

Two-point threshold

Answer 7

minimum separation needed between two points to perceive them as two units

Question 8

Grating acuity

Answer 8

placing a grooved stimulus on the skin and asking the participant to indicate the orientation of the grating

Question 9

Grip Control

Answer 9

(Meissner corpuscles (FA I))

• respond most strongly to low- frequency vibrations
• convey information about very small motions of the skin
• ideally suited for perceiving slip and maintaining control over the force of one’s grip on an object.

Question 10

Skin Stretch

Answer 10

(SA II Mechanoreceptors… Ruffini endings)
-Very large receptive fields (poor spatial resolution)
-Important role in information about skin stretch
Critical to perception of hand conformation
Plays a role in perception of movement across the skin

Question 11

Vibration & Texture

Answer 11

(Pacinian Corpuscles (FA II))
-Onion-like structure
-Large receptive fields (poor spatial resolution, but high sensitivity)
-Very sensitive to vibration
Critical for perceiving texture of surfaces
The structure of the corpuscle is responsible for the response to vibration
without the corpuscle, FA II fibers respond when pressure is applied, as pressure continued, and when it was removed
with corpuscle, fibers only responded when pressure was applied and when it was removed

Question 12

duplex theory of texture perception

Answer 12

• Spatial cues are determined by the size, shape, and distribution of surface elements
• Temporal cues are determined by the rate of vibration as skin is moved across finely textured surfaces
• only the adaptation to the 250-Hz stimulus affected the perception of fine textures (adapt pacinian)

Question 13

Three general categories of pain:

Answer 13

Nociceptive
Inflammatory
Neuropathic

Question 14

two different types of fibers ( axons) transmit pain signals from the nociceptors to the spinal cord

Answer 14

Small Myelinated A- delta Fibers
-transmit action potentials relatively rapidly
-Associated with “first pain”
Unmyelinated C Fibers
-transmit action potentials relatively slowly
-Associated with “second pain”

Question 15

warm fibers

Answer 15

Thermoreceptors that fire at an ongoing moderate rate in response to sustained skin temperatures in the range of 29– 43° C.
Respond if skin temperature is abruptly warmed from a sustained neutral temperature