Touch

Question 1

Name the four cutaneous mechanoreceptors.

Answer 1

Meissner corpuscle.
Merkel cell.
Pacinian corpuscle.
Ruffini endings.

Question 2

Name the two superficial cutaneous mechanoreceptors.

Answer 2

Meissner corpuscle.
Merkel cell.

Question 3

Name the two deep dermis cutaneous mechanoreceptors.

Answer 3

Pacinian corpuscle.
Ruffini endings.

Question 4

Which mechanoreceptor is RA1?

Answer 4

Meissner corpuscle.

Question 5

Which mechanoreceptor is RA2?

Answer 5

Pacinian corpuscle.

Question 6

Which mechanoreceptor is SA1?

Answer 6

Merkel cell.

Question 7

Which mechanoreceptor is SA2?

Answer 7

Ruffini endings.

Question 8

What size receptive field does a Meissner corpuscle have?

Answer 8

Small.

Question 9

What size receptive field does a Merkel cell have?

Answer 9

Small.

Question 10

What size receptive field does a Pacinian corpuscle have?

Answer 10

Large.

Question 11

What size receptive field does a Ruffini ending have?

Answer 11

Large.

Question 12

Which pathway of the spinal cord do peripheral nerve fibres travel along?

Answer 12

Dorsal column medial lemniscal pathway.

Question 13

Name the four peripheral nerve fibres.

Answer 13

C-fibres.
A-alpha fibres.
A-beta fibres.
A-delta fibres.

Question 14

What do columns D2, D3, D4 and D5 represent in the cortex?

Answer 14

Individual fingers.

Question 15

How many layers do the finger columns have?

Answer 15

Six.

Question 16

What is intercolumnar communication?

Answer 16

The finger columns communicate with each other.

Question 17

What is intracolumnar communication?

Answer 17

The layers within a finger column communicate with each other.

Question 18

Why does information become more complex in S2 compared to S1?

Answer 18

S2 is a higher order processing area.

Question 19

Where do the peripheral nerve fibres project to from the dorsal horn?

Answer 19

Up to the brain stem and/or thalamus.

Question 20

Where does sensory information travel to from the thalamus?

Answer 20

To subcortical structures and then to S2.

Question 21

Name the four Brodmann’s areas that active touch engages.

Answer 21

5, 7, 39 and 40.

Question 22

What is the role of Brodmann’s area 5?

Answer 22

Integrates postural and proprioceptive information with touch.

Question 23

What is the role of Brodmann’s area 7?

Answer 23

Integrates visual data with touch, such as hand-eye coordination.

Question 24

What is the role of Brodmann’s area 39?

Answer 24

Involved in language and number processing, spatial cognition, memory retrieval and attention.

Question 25

What is the role of Brodmann’s area 40?

Answer 25

Phonological processing and emotional response.

Question 26

What is the name of Brodmann’s area 39?

Answer 26

The angular gyrus.

Question 27

What is the name of Brodmann’s area 40?

Answer 27

The supramarginal gyrus.

Question 28

What is the role of the Meissner corpuscle?

Answer 28

Informs us about low frequency vibration and therefore slow movement.

Question 29

What is the role of the Merkel cell?

Answer 29

Informs us about edges, shape, size and pressure.

Question 30

What is the role of the Pacinian corpuscle?

Answer 30

It is highly sensitive to vibration.

Question 31

What is the role of Ruffini endings?

Answer 31

Informs us about the stretch of the skin, enabling us to interpret our hand shape when gripping an object and the 3D shape of the object.

Question 32

Describe the experiment that demonstrates how memory modifies our response to touch.

Answer 32

1. A monkey was exposed to two vibration signals on its fingertip (F1 and F2).
2. It was asked to report if F2 is larger or smaller than F1.
3. The response was recorded from an S2 neuron.
4. When F2 was larger than F1, the F2 response was larger.
5. When F2 was smaller than F1, the F2 response was smaller.
6. This shows that the responsiveness of the S2 neuron was altered by working memory.

Question 33

What is active touch?

Answer 33

When you deliberately touch something.

Question 34

What is passive touch?

Answer 34

When someone or something touches you.

Question 35

Describe how tactile information is processed in the central touch system.

Answer 35

1. Sensory afferent fibres transmit tactile information to the CNS through median, ulnar, and superficial radial nerves.
2. These nerves terminate ipsilaterally in spinal segments C6 to T1.
3. Other branches of these fibres project through the ipsilateral dorsal columns directly to the medulla where they make synaptic connections to neurons in the cuneate nucleus.