Lecture 17 - Introduction to Pain

Question 1

What is pain?

Answer 1

An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.

Question 2

Is pain always personal/subjective?

Answer 2

Yes.

Question 3

Are pain and nociception different?

Answer 3

Yes.

Question 4

Do people learn the concept of pain through their lives?

Answer 4

Yes.

Question 5

Should we respect people’s subjective reports of pain?

Answer 5

Yes.

Question 6

Those who have congenital insensitivity to pain have a reduced life span?

Answer 6

Yes. 20-25 years.

Question 7

Why do we have pain?

Answer 7

Pain directs our attention to danger and prevents further injury.

Question 8

What is the basic mechanism for how we feel pain?

Answer 8

Transduction - noxious agents (such as thermal, chemical, or mechanical) activate nociceptors.

Transmission - signals are sent from the peripheral nervous system to neurons in the dorsal horn of the spinal chord.

Perception - this information is then sent to the thalamus and onto other ares of the brain to generate a withdrawal response, as well as learning from the experience to prevent future or further harm.

Question 9

Define nociceptor.

Answer 9

A receptor capable of detecting and transmitting information about noxious stimuli.

Sensory receptors capable of transducing noxious stimuli.

Question 10

Are nociceptors the same as thermoceptors?

Answer 10

No. Thermoceptors respond to changes in temperature. Nociceptors (that are sensitive to heat/cold) only respond/fire when a temperature threshold is met and increase their firing with increased stimuli (e.g. heat/cold).

Thermoceptors will start to fire as soon as they detect change in temperature. Nociceptors will only fire when a threshold is met and then they indicate pain as the heat/cold is potentially going to/or is causing tissue damage.

Question 11

What type of nociceptor fibres sense noxious mechanical stimuli?

Answer 11

A-delta fibres.

Question 12

What type of nociceptor fibres sense noxious heat or chemical stimuli?

Answer 12

C-fibres.

Question 13

What type of fibres sense non-noxious mechanical stimuli?

Answer 13

A-beta fibres.

Question 14

Why does it help to apply deep pressure to spot that you have just hurt/hit?

Answer 14

When we apply deep pressure this is picked by other receptors and signals are sent to the spinal cord. In the spinal cord, only so many signals can be transmitted to the brain. Incoming new signals prevent as many signals from the nociceptors reaching the brain.

Question 15

What functions is the anterior cingulate cortex associated with?

Answer 15

The anterior cingulate cortex is known to receive signals from the thalamus about pain. It is also known to be important for the integration of pain with emotional and situational cues.

Question 16

What brain area is known as the primary control centre for descending pain modulation?

Answer 16

The periaqueductal gray (PAG).

Question 17

If we have experienced something painful before, but have not had a negative experience, then our subsequent responses to that pain may be dampened. An example would be going to the doctor and getting a vaccination. If we did not have a negative experience the next time we go it may not be as painful.

How are pain responses modulated?

Answer 17

The brain has a centre that modulates the degree to which we experience pain. This centre is known as the periaquaductal gray (PAG). This centre receives information about pain from the thalamus, but also information about prior experiences from the anterior cingulate cortex and amygdala for example. It then either sends descending signals down the spine to either amplify or dampen the response being sent to the brain from the nociceptors.

This can make originally painful experiences not as painful on subsequent occasions, or make not so painful experiences extremely painful on subsequent occasions, based on the consequences and emtotional/physical experiences had in the past.

Question 18

Pain is very complex and is not just about what the nociceptors pick up and send signals about.

T/F?

Answer 18

True.

Question 19

We discussed three components that make up our experience of pain. What are they, and what order do they occur in (temporal)?

Answer 19

1. The discriminative process - what is the pain? Where is it coming from?
2. The cognitive process - have we had this experience before? Do we know what is happening?
3. The affective process - how do we feel about the pain? What emotional experience have we had in the past?

Question 20

What is an example of how cognitive processes can change our experience of pain?

Answer 20

When we focus on pain it feels worse. When we are distracted from pain it feels less painful.

Question 21

What is an example of how the emotions can change our experience of pain?

Answer 21

When we are in a negative mood state pain feels more unpleasant. When we are in a positive mood state, pain feels less unpleasant.

Question 22

What are some genetic factors that influence how pain is experienced?

Answer 22

Gender.
People with red hair experience pain more easily and require more anaesthetic.

Question 23

What are some of the modifiable factors that influence our experience of pain?

Answer 23

Context.
Mood.
Prior experience.
Attention.
Sleep.

Question 24

What is an experiment that showed the painful experience of social exclusion?

Answer 24

In the computerised ball throwing game, when the computer stopped throwing the ball to the participant similar brain regions activated as when someone is being physically hurt.

When participants had tylenol for three weeks prior to the experiment, there was less activation in the pain brain areas compared to those who did not take tylenol.

Question 25

In an experiment that looked subjective feelings of “hurt feelings” each night for a control group that took a placebo pill and a test group that took tylenol (a painkiller), what did they find?

Answer 25

Those who were on tylenol reported reduced “hurt feelings” than those on the placebo.

Question 26

Are A-beta or delta and C fibres myelinated?

Answer 26

A-beta fibres are.