Topic 11: Cutaneous Senses

Question 1

proprioception

cutaneous senses

Answer 1

perception of position, movement and effort from muscles, joints and tendons
-perception of touch and pain from stimulation of skin

Question 2

skin

Answer 2

heaviest organ in body (12-15% of body weight)
-1.5-2 m2 of SA
protects body from external environment
hairy or glabrous (thicker)

Question 3

epidermis

dermis

Answer 3

• outer layer made up of dead skin cells

- lower layer containing mechanoreceptors responsive to pressure, stretching, vibration etc

Question 4

merkel receptors
meissner corpuscles
both on epidermis

Answer 4

• fire continuously while stim is present, percieve fine details (shape and texture), SA1 - slow adapting
• fire only when stim is applied/removed, precieves hand/grip control and motion, RA1 - rapid adapting

Question 5

Ruffini cylinders

pacinian corpuscles

Answer 5

fire continuously to stim, perceive stretching of skin, SA2 - slowly adapting
-fire when stim is applied/removed, perceive vibrations and fine texture, RA2 - rapid adapting

Question 6

medial lmniscal pathway

spinothalamic pathway

Answer 6

-large fibers, carries proprioception and touch into mechanoreceptors (decussates at brain)
-smaller fibers, carries temp and pain, deccusates at spinal cord
both arrive at ventrolateral nucleus of thalamus

Question 7

tactile acuity

two point threshold

Answer 7

• raised pattern ID, used to determine smallest size that can be recognized (braille)
• min separation between 2 points to perceive them as 2 units

Question 8

duplex theory of texture perception

spatial and temporal cues

Answer 8

• rough surfaces, determined by size, shape and distribution of larger surface elements (SA1)
• fine surfaces, determined by rate of vibration as skin is moved across finely textured surfaces (RA2)

Question 9

adaptation experiment - Hollins 2001

Answer 9

p’s skin was adapted for meissner or pacinian
tested on ability to ID fine texture surfaces
losing ra1 - didnt effect ID ability but RA2 dod
need RA2 for texture ID

Question 10

haptic perception

experiment - Lederman 1987

Answer 10

humans use active touch to interact with environment

• sensory, motor and cognitive systems
• we can ID in 1-2 sec, use exploratory procedures

Question 11

motion sensitive neurons
orientation sensitive neurons
direction sensitive neurons

Answer 11

• respond to any motion in receptive field
• respond to motion along particular axis
• respond to motion in single direction

Question 12

pain
inflammatory
neuropathic
nociceptive

Answer 12

unpleasant sensory and emotional experiences associated with actual or potential tissue damage
-pain from arthimitic joints
-carpal tunnel
chemical burn

Question 13

nociceptors
sensory component
affective component

Answer 13

• receptors in skin for different types of painful stimuli, separate from other receptors
• refers to intensity (sharp, dull)
• refers to unpleasantness of pain

Question 14

direct pathway model of pain
issues with direct pathway
phantom-limb phenomenon

Answer 14

• pain is due to nociceptive activation (skin to brain direct)
• soldiers and athletes experience no pain despite serious injuries (stim doesnt led to perception)
• loss of limb but retention of sensation, pain in area where limb is missing

Question 15

placebo effect

nocebo effect

Answer 15

• decrease in perceived pain due to treatment with no physiological effect
• increase in perceived pain due to treatment with no physiological effect

Question 16

gate control model of pain

Answer 16

nociceptor - spinal cord - brainstem (primary path)
-additional pathways control a gate between nociceptor and perception of pain
nociceptors - activate excitatory synapses (open)
mechanoreceptors - activate inhibitory (close)
central control - top-down cognitive input (open/close)

Question 17

moderators of pain perception

Answer 17

expectations - placebo/nocebo
attention - distraction and mindfulness
emotions - pleasant music and/or images

Question 18

attention and pain

Answer 18

pain can be moderated by attention, not in awareness it wont be as much of a problem

• VR games in hospitals to distract patients
• toys used for kids getting vaccines

Question 19

emotion and pain

Answer 19

looking at positive pictures can reduce experience of pain
how long can p’s hold hand in water, longest when looking at positive pics
lower pain ratings to heat stim when listening to pleasant music

Question 20

pain processing in the brain

Answer 20

s1, anterior cingulate cortex, PFC, amygdala and hypothalamus, insula

sensory: s1 and s2
affective: dorsal ACC and Insula

Question 21

observing pain in others : singer 2004

Answer 21

p was shocked or watch partner get shocked
s1 acc and insula activated when you were shocked
acc and insula activated when partner was shocked
empathy = acc activation