Lecture 9- Touch

Question 1

interoception

Answer 1

awareness of your own body

Question 2

exteroception

Answer 2

awareness of your immediate surroundings

Question 3

cutaneous

Answer 3

related to the skin

Question 4

proprioception

Answer 4

related to body position

Question 5

kinesthesis

Answer 5

related to body movements

Question 6

nocioception

Answer 6

related to pain and discomfort

Question 7

thermoreceptors

Answer 7

respond to heat or cold
- active between temps below 35C
-cool: responding when temp is below 5C “numb”
-warm: responding when temp rises to 35C, most active at 49C, then pain receptors start responding

Question 8

mechanoreceptors

Answer 8

respond to mechanical stimuli (stroking, stretching, or vibration of the skin)

Question 9

chemoreceptors

Answer 9

respond to chemical substances on the skin

Question 10

free nerve endings

Answer 10

send info related to skin temp… also send info related to pain

Question 11

free nerve endings are implicated as receptor cells for which 3 systems:

Answer 11

• cold perception
  -heat perception
  -pain perception

Question 12

polymodal

Answer 12

receptors that can code for a bunch of different things

Question 13

nociceptors

Answer 13

type of receptor that responds to stimuli that can damage skin tissue

Question 14

3 layers of skin

Answer 14

• epidermis
  -dermis
  -hypodermis

Question 15

epidermis

Answer 15

-provides a barrier for infection
-helps with thermoregulation
- has free nerve endings (noci/thermo) that send signals to the CNS

Question 16

dermis

Answer 16

has mechanoreceptors and thermoreceptors

Question 17

Merkel’s disks

Answer 17

mechanoreceptors that provide info about the shapes of the things you touch, and about how much pressure is being applied to the surface of your skin.
- found in dense clusters in fingertips and mammary glands

Question 18

Meissner’s corpuscles

Answer 18

mechanoreceptors; seem to react to light touch on the fingertips and the lips
- respond to the onset of touch, adapt quickly

Question 19

hair follicle receptors

Answer 19

mechanoreceptors that transmit info whenever the hair is moved

Question 20

hypodermis

Answer 20

where fat is stored, also sweat and mammary glands - - contains Pacinian and Ruffini corpuscles

Question 21

Pacinian corpuscles

Answer 21

about a mm long and are visible to the naked eye (with opening)
-mechanoreceptors; sensitive to vibrations, adapt quickly, not sensitive to constant pressure

Question 22

Ruffini corpuscles

Answer 22

mechanoreceptors that adapt slowly to pressure that results in stretching of the skin, so they record the sustained presence of pressure on the skin

Question 23

touch receptors can be categorized by 3 criteria

Answer 23

1. type of stimulation to which receptor responds
2. size of the receptive field
3. rate of adaptation (fast vs. slow)

Question 24

SA I (MERKEL)

Answer 24

respond best to steady and downward pressure
-texture and pattern perception (braille)

Question 25

SA II (Ruffini)

Answer 25

respond best to lateral skin stretch
-good for knowing the position of fingers when grasping

Question 26

FA I (Meissner)

Answer 26

respond best to low-frequency vibes,
-like slipping objects

Question 27

FA II (Pacinian)

Answer 27

respond best to high-frequency vibes,
-when an object contacts another

Question 28

Somatic reflex

Answer 28

an involuntary contraction of the skeletal muscles in response to stimuli

Question 29

2 major pathways from the spinal cord to the brain

Answer 29

1. spinothalamic pathway
2. dorsal column- medial lemniscal (DCML) pathway

Question 30

spinothalamic pathway

Answer 30

carries most of the info about skin temperature and pain (slower of the two)

Question 31

dorsal column- medial lemniscal (DCML) pathway

Answer 31

carries signals from skin, muscles, tendons, joints

Question 32

somatosensory cortex

Answer 32

this is the end of the path
“soma”= BODY

Question 33

why doesn’t the brain itself get any space in the somatosensory cortex?

Answer 33

the brain cannot feel pain

Question 34

insula

Answer 34

associated with processing affect

Question 35

C-tactile fibres

Answer 35

project to the insular cortex and code specifically for gentle caresses

Question 36

social touch hypothesis

Answer 36

• proposes that social touch is a distinct domain of touch
• C-tactile afferents form a special pathway that distinguishes social touch from other types of touch by selectively firing in response to touch of social-affective relevance
• socially relevent touch stands out from the rest as having positive emotional value and is processed further in affect-related brain areas such as the insula