Lecture 10

Question 1

Area of skin

Answer 1

1.8 m^2

Question 2

Weight of skin

Answer 2

5kg

Question 3

What is skin?

Answer 3

Largest sense organ in the body

Question 4

Two types of skin

Answer 4

Glabrous and hairy

Question 5

Where is glabrous skin found?

Answer 5

Palms of hands and feet

Question 6

Where is hairy skin found?

Answer 6

Everywhere but hands and feet

Question 7

Physiology of skin senses

4 stages

Answer 7

1) stimulus contacts skin
2) receptor in skin fires
3) signal travels to the brain via spinal cord
4) signal reached somatosensory cortex on opposite side of the body

Question 8

What 4 senses do skin receptors give sense to

Answer 8

Touch (mechanical stimuli)
Pain
Body sense (proprioception)
Temperature

Question 9

4 types of tactile receptor

Answer 9

Merkel’s disc
Meissner corpuscle
Ruffini organ
Paccinian corpuscle

Question 10

Merkel’s disc responds to

Answer 10

Fine details (e.g., braille)

Question 11

Meissner corpuscle responds to

Answer 11

Flutter (like an object slipping through fingers)

Question 12

Ruffini organ responds to

Answer 12

Stretching

Question 13

Paccinian corpuscle responds to

Answer 13

Vibration, fine texture (like using a tool)

Question 14

Why do we have multiple receptor types

Answer 14

Many receptors allows us to detect many types of information

A single stimulus can activate many different receptor systems

Question 15

Receptive fields

Answer 15

The area of skin that a particular cell receives information about

Question 16

Do meissener’s or Paccinian corpuscles have larger receptive fields?

Answer 16

Paccinian

Question 17

Two point threshold

Answer 17

The smallest separation of 2 separate but adjacent points that just produces two distinct impressions of touch

Question 18

fingertip 2 point threshold

Answer 18

2 mm

Question 19

arm 2 point threshold

Answer 19

3.5 cm

Question 20

what stops two points from being discriminated|?

Answer 20

both points of pressure are within the same receptive field

Question 21

where are we most sensitive?

Answer 21

lips, hands and face

Question 22

fovea of the skin, why is it named this?

Answer 22

fingertip

most receptors

Question 23

what happens to fingertip with experience

Answer 23

acuity can change

Question 24

active touch

Answer 24

active exploration of environment

Question 25

passive touch

Answer 25

body is stationary

Question 26

advantages of active touch

Answer 26

more parts of your body are in contact with the object you can search for the most diagnostic parts of objects to feel kinaesthetic senses are also engaged

Question 27

cues in perceiving texture

Answer 27

spatial | temporal

Question 28

spatial cues in perceiving texture

Answer 28

bumps and grooves when finger is stationary or moving

Question 29

temporal cues when perceiving texture

Answer 29

only when moving finger across a surface paccinian corpuscles: adaption to high frequencies impairs performance can perceive texture via a tool

Question 30

tactile agnosia

Answer 30

cannot identify objects by touch but have no problems with spatial processing (WHERE not what)

Question 31

tactile extinction

Answer 31

the. failure to detect a stimulus only in the presence of. another stimulus to certain parts of the body no problems in object recognition (WHAT not where)

Question 32

activity when determining what object was

Answer 32

activity in primary and secondary somatosensory cortex

Question 33

activity when determining where object was

Answer 33

activity in superior parietal areas

Question 34

top down influences on touch

Answer 34

must update as move body position emotional effect of touch- same sensation may be pleasurable or unpleasant expectation vs surprise (tickling)

Question 35

illusions of touch

Answer 35

Aristotle's illusion cutaneous rabbit illusion

Question 36

affect of the cutaneous rabbit illusion

Answer 36

activity in the primary somatosensory cortex as if more points than physically touched had actually been stimulated

Question 37

why cant you tickle yourself ?

Answer 37

can predict your own actions | same touch rates as more ticklish when produced by an experimenter rather than self

Question 38

nociceptor

Answer 38

receptors for pain

Question 39

two types of pain

Answer 39

A delta fibres- fast sharp pain | C fibres - slow dull pain

Question 40

a delta fibre pain examples

Answer 40

pin prick, pinches, extreme temperature

Question 41

C fibres pain examples

Answer 41

many types of pain | mild stimulation can be pleasurable

Question 42

can one stimulus activate both pain systems

Answer 42

yes

Question 43

what can pain be affected by?

Answer 43

a persons mental state | attention

Question 44

an example of pain in the absence of stimulation

Answer 44

phantom limb pain

Question 45

gating of pain in the spinal cord influences...

Answer 45

the degree to which painful information reaches the brain

Question 46

what can pain be reduced by?

Answer 46

non-painful tactile inputs (massage, rubbing) | top down input (expectations etc.)

Question 47

what is a phantom limb?

Answer 47

after a limb is amputated and a patient feels a phantom limb in its place there is no external stimulus but the patient still perceives the limb many patients feel phantom arms/ hands when touched on the face: missing hand is still represented in the brain

Question 48

what is proprioception?

Answer 48

where your body is in space

Question 49

what is proprioception reliant on?

Answer 49

signals from muscles vestibular system, tactile receptors... kinesthesis`

Question 50

kinesthesis

Answer 50

movement of limbs in space

Question 51

IW case study

Answer 51

lost proprioception, kinesthesis and touch age 19 from viral infection learned to compensate using visual system, unable to move if its dark

Question 52

physiological changes in IW

Answer 52

lost fast myelinated fibres, retained slow C fibres

Question 53

C tactile

Answer 53

pain, temperature, enjoy being cuddled