Cutaneous senses

Question 1

Why is it important to feel physical stimuli?

Answer 1

Feedback from objects and as to how your body is positioned. Provide warning signals to protect your body

Question 2

What is the cutaneous system made up of?

Answer 2

Skin, mechanoreceptors, pathways from the skin to the brain and the somatosensory cortex

Question 3

What are mechanoreceptors?

Answer 3

Receptors within the skin sensitive to mechanic deformation, such as pressure, stretching and vibration.

Question 4

What are the 4 types of mechanoreceptors?

Answer 4

Merkel receptor, ruffini cylinder, meissner corpuscle and pacinian corpuscle

Question 5

Which 2 receptors are slow adapting and which 2 are rapid adapting?

Answer 5

Slow - Ruffini cylinder and Merkel receptor
Rapid - Pacinian corpuscle and Meissner corpuscle

Question 6

Which receptors have the largest receptive field?

Answer 6

Ruffini (SA2) and Pacinian (RA2) receptors have larger receptive fields than Merkel (SA1) and Meissner (RA1) receptors. Located deeper in skin = larger receptive field

Question 7

What are the different perceptions of each receptor?

Answer 7

Merkel - fine spatial detail
Ruffini - stretching
Meissner - hand-grip control and light touch
Pacinian - vibration and pressure, texture

Question 8

What is the medial lemniscal pathway?

Answer 8

Carries signals representing the positions of the limbs and the perception of touch. High speed, important for movement control and responding to touch

Question 9

What is the spinothalamic pathway?

Answer 9

Carries signals responding to pain and temperature

Question 10

What happens in the somatosensory cortex?

Answer 10

Signals travel to the somatosensory receiving area (S1) in the parietal lobe, and the secondary somatosensory cortex (S2). Organised into maps representing locations in the body, called the homunculus.

Question 11

How do cortical body maps work?

Answer 11

Body parts like the hands have a large proportion of S1 devoted to it, relating to sensitivity.

Question 12

What is experience dependent plasticity?

Answer 12

Corresponding area increases by use

Question 13

How do Merkel receptors perceive detail?

Answer 13

Higher density of receptors (highest in fingertips) associated with better acuity but the cortex is also involved. Representation of body part in the brain is also responsible for tactile acuity

Question 14

How does tactile acuity work in the brain?

Answer 14

Areas of high tactile acuity gave a large area of cortex devoted to them so activity from 2 points is less likely to overlap

Question 15

How does the Pacinian perceive vibrations?

Answer 15

Pacinian corpuscle primary responsible for sensing vibrations so responds poorly to continuous pressure but well to high rates of vibrations. Role in texture perception

Question 16

How do we perceive texture?

Answer 16

Touch gives us a more accurate representation of surface texture than vision. Our perception of texture depends on how the surface is explored

Question 17

What did Katz (1925) come up with?

Answer 17

Proposed the duplex theory of texture perception. Needed spatial cues and temporal cues

Question 18

How is acuity for moving fingers measured?

Answer 18

Touch 2 surfaces. When fingers are moving one surface is perceived as much rougher than the other - better texture discrimination. When static, both surfaces about the same

Question 19

What is haptic perception?

Answer 19

Involves many systems interacting with one another - sensory systems which detect touch and temperature, motor system involves moving hands and fingers and cognitive systems which involves integrating info provided by the other 2 and holding it in memory

Question 20

What are the 4 exploratory procedures in haptic perception?

Answer 20

Lateral motion, pressure, enclosure and contour following

Question 21

How do mechanoreceptors and shape perception interact?

Answer 21

Objects typically stimulate multiple mechanoreceptors at once. Receptor at point of contact responds most and lessens the further away receptors and tells the brain about object curvature