Lecture 25 Flashcards
What is pain?
a multimodal phenomenon containing a sensory component and an
affective or emotional component
What is inflammatory pain?
caused by damage to tissues and joints or by tumour
cells
What is neuropathic pain?
caused by damage to the central nervous system
* e.g. carpal tunnel syndrome, spinal cord injuries, etc.
What is nociceptive pain?
caused by
activation of nociceptors in the skin,
which signal impending damage
Describe the direct pathway model of pain
an early theory that assumed pain is simply the
result of nociceptors being stimulated and sending signals to the brain
* One kind of problem with the direct pathway model was various kinds of evidence for
many kinds of exceptions:
* Pain can be affected by a person’s mental state
* Pain can occur when there is no stimulation of the skin
* Pain can be affected by a person’s attention
* Phantom limbs
* etc.
Describe gate control model
gate control model still
assumes that pain signals enter the spinal cord from the
body and are transmitted to brain
Describe the network involved in pain perception
This network involves three types of signals processed in
the dorsal horn of the spinal cord, whose integrated
output is sent to what are referred to as transmission cells
(whose activity is directly related to our perception of pain)
Describe mechanoreceptors and the gate control model
receptors carrying information
about non-painful tactile-based stimuli
mechanoreceptors send inhibitory signals (-) to
transmission cells, closing the gate
Describe nociceptors and gate control model
receptors carrying information about
painful tactile-based stimuli
nociceptors send excitatory signals (+) to
transmission cells, opening the gate
Describe central control and gate control model
receive signals related to cognitive
function (attention, expectations distractions, etc.)
this module also sends inhibitory signals (-) to
transmission cells, closing the gate
Describe video game study
- Virtual reality technology has been used to keep patients’ attention on other
stimuli than the pain-inducing stimulation - When surgical patients are told what to expect, they request less pain
medication and leave the hospital earlier (Egbert et al., 1964) - Another example of expectations mediating pain can be seen with placebos,
which can be very effective at reducing pain (Finniss & Benedetti, 2005)
Describe the Bingel study
- Bingel et al. (2011) systematically varied expectations for pain
- The researchers then reapplied the same stimuli and asked participants to
again rate how painful they found it to be after manipulating expectations in
one of four conditions: 1. baseline, 2. no expectation, 3. positive
expectation, 4. negative expectation
(conditions described in more detail on next slide)
Describe Bingel results
- Baseline: No painkiller given, just saline solution
- No expectation: Saline solution switched to a painkiller (but participants were
not told about the switch) - Positive expectation: Saline solution switched to a painkiller (which participants were told about)
- Negative expectation: Saline solution switched to a painkiller (but participants were not told about), with warnings that their pain level may
increase
Describe the nocebo effect
negative placebo effect
the increase in
pain accompanying the
negative expectation
Describe top down processes and emotions
- Another kind of top-down effect on pain perception relates to emotions
- deWied and Verbaten (2001): Participants kept their hands in cold water
(~20C) for longer when they were shown positive pictures - Roy et al. (2008): Participants rated cold water as less intense and less
unpleasant while listening to pleasant music - These two kinds of ratings can be
thought of as tapping into distinct
dimensions of pain (i.e. sensory and
affective)
