Somatosensation (P2) and pain

Question 1

What is nociception?

Answer 1

Nociception is the neural process of encoding noxious stimuli, including extreme heat and cold.

Question 2

What is the primary function of nociception?

Answer 2

It alerts the body to potentially harmful stimuli, such as temperature extremes, pressure, or injury-related chemicals.

Question 3

Where are nociceptors located?

Answer 3

They are found in the skin, muscles, joints, bones, and internal organs (viscera).

Question 4

What are A-delta fibers?

Answer 4

Small, myelinated fibers that transmit sharp, immediate pain.

Question 5

What are C fibers?

Answer 5

Unmyelinated fibers that transmit dull, burning pain.

Question 6

What does “noxious” mean?

Answer 6

Perceived as harmful, such as poison or pain.

Question 7

What does “exogenous” mean?

Answer 7

Originating externally.

Question 8

What is a ganglion?

Answer 8

A collection of nerve cell bodies.

Question 9

What does the spinothalamic somatosensory system include?

Answer 9

Thermoception and nociception.

Question 10

What are thermoreceptors?

Answer 10

Receptors found on the tips of free nerve endings that detect subtle temperature changes.

Question 11

What do free nerve endings detect?

Answer 11

Pain, heat, and cold.

Question 12

What are mechanoreceptors?

Answer 12

Receptors, such as Merkel’s disks, Ruffini, and Meissner, that detect mechanical pressure, vibration, and texture.

Question 13

What is the function of TRP (Transient Receptor Potential) channels?

Answer 13

They are ion channels that pass Na+ and Ca2+ and are temperature-sensitive.

Question 14

David Julius - Nobel Prize - why?

Answer 14

David Julius (1997), who used capsaicin to identify the receptor sensitive to heat and capsaicin.

Question 15

What is chemaesthesis?

Answer 15

Activation of free nerve endings by chemical substances, typically in facial skin.

Question 16

What is the difference between chemaesthesis and chemosensation?

Answer 16

Chemaesthesis involves chemical stimuli causing irritation, while chemosensation refers to taste and smell.

Question 17

What cranial nerve is involved in chemaesthesis?

Answer 17

Cranial Nerve V (Trigeminal), which innervates facial skin, nasal cavity, mouth, and eyes.

Question 18

What is the spinothalamic tract?

Answer 18

A pain pathway where the first-order neuron projects to the spinal cord, decussates, and then travels to the thalamus and somatosensory cortex.

Question 19

What happens in thalamic relay?

Answer 19

Sensory input travels via dorsal column nuclei, crosses at the medulla, and is routed through the thalamus before reaching the parietal lobe.

Question 20

What is the pain matrix?

Answer 20

A network of brain areas involved in pain perception, including S1, S2, ACC, insula, and thalamus.

Question 21

What is the role of the anterior cingulate cortex (ACC) in pain?

Answer 21

It is involved in the emotional and motivational aspects of pain.

Question 22

How is empathy for pain different from experiencing pain?

Answer 22

Empathy for pain activates the ACC and insula, but not S1/S2, indicating an emotional rather than sensory experience.

Question 23

What did Singer et al. (2004) find in their fMRI study on pain empathy?

Answer 23

Empathy activates the ACC and insula, but not the somatosensory cortices (S1/S2).

Question 24

What factors influence pain perception?

Answer 24

Past experience, setting, beliefs, attention, affect, gender, and culture.

Question 25

Is pain perception subjective or objective?

Answer 25

Pain perception is subjective and multidimensional.

Question 26

What is a consequence of chronic pain in terms of referred sensations?

Answer 26

Pain may be felt in non-injured areas of the body.

Question 27

What ethical concerns are raised by the pain experience in minimally conscious state (MCS) patients?

Answer 27

MCS patients may still experience pain, despite being unable to communicate.

Question 28

What did Boly et al. (2008) study in relation to pain and consciousness?

Answer 28

they studied pain responses in patients in a minimally conscious state (MCS) vs. persistent vegetative state (PVS) and found that MCS patients show cortical responses to pain.

Question 29

What is the difference between nociception and pain?

Answer 29

Nociception is the physiological process of detecting harmful stimuli, while pain is the subjective, conscious experience of discomfort from nociception, influenced by cognitive and emotional factors.

Question 30

What factors influence an individual's pain threshold?

Answer 30

Biological (e.g., genetics), psychological (e.g., attention), social (e.g., empathy), and cultural factors (e.g., expression and tolerance).

Question 31

What happens in a bilateral dorsal lesion at T12?

Answer 31

Sensory loss occurs below the lesion bilaterally, affecting the dorsal columns (fine touch, proprioception) and possibly the spinothalamic tract (pain and temperature).

Question 32

What happens in a right-sided hemisection at C5-C6 (Brown-Séquard Syndrome)?

Answer 32

It causes sensory loss of fine touch and proprioception on the right side and pain and temperature loss on the left side below the lesion.

Question 33

What brain area is responsible for localizing pain?

Answer 33

The primary somatosensory cortex (S1).

Question 34

What area is involved in the emotional and motivational aspects of pain?

Answer 34

The anterior cingulate cortex (ACC).

Question 35

Which brain area integrates the emotional experience of pain?

Answer 35

The posterior cingulate cortex (PCC).

Question 36

How is pain perception shaped?

Answer 36

Pain perception is not only influenced by sensory input but also by emotion, attention, social context, and belief.

Question 37

Is the pain matrix specific to pain?

Answer 37

No, the pain matrix encodes salience and emotional significance, not just nociceptive pain.

Question 38

The thalamus projects in two different direction with nociceptive information - what are they?

Answer 38

1. Medial thalamus projects to the frontal cortex - specifically the Anterior Cingulate cortex and the insula - emotional unpleasantness, empathy 2. lateral thalamus projects to the somatosensory cortices - specifically SI and SII - sensory discrimination of pain - location and intensity