PSY 210 pain Flashcards
definition of pain
an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage
multimodal means:
different areas of brain involved in processing pain
- physical stimulation
- emotional
- cognitive
indicators of damage to skin
nociceptors in skin
types of pain
inflammatory
- inflammation of joints
- tumor cells
neuropathic (damage to neurons)
- carpal tunnel syndrome (pain, numbness, and tingling in the hand and arm)
- spinal cord/ brain injury
nociceptive
- stimulation of specialized skin cells
physical aspects of pain
Meyer and Campbell (‘81)
- correlation between nociceptor firing and perception of pain
- monkey nociceptors go up as temperature goes up - similar in humans
- pain was thought to only go through nociceptors (only one path)
types of nociceptors
heat & cold
chemicals
severe pressure
- have different thresholds
- temp increases – damage COULD now happen; don’t feel pain every time
pain threshold… balanced to:
- warn of damage
- not be affected by normal activity
DIRECT PATHWAY MODEL OF PAIN
- oldest model
- nociceptors are stimulated and send signals to spinal cord – cortex
- not preferred
problems with DIRECT PATHWAY MODEL OF PAIN
- pain can be affected by a person’s mental state (bad mood = more pain)
- pain can occur when there is no stimulation of the skin
- pain can be affected by a person’s attention – distracting someone
- phantom limbs (phantom pain)
GATE THEORY
Melzak and Wall (‘65)
– gate = SUBSTANTIA GELATINOSA cells in dorsal horn of spinal cord
MECHANORECEPTORS/Large diameter (L-) fibers =
• gate closing
• directly to transmission cell
SG -
NOCICEPTORS/Small diameter (S-) fibers =
• gate opening
• directly to transmission cell
SG+
where are substantia gelatinosa (SG) cells
dorsal horn of spinal cord
central control
info from cognitive factors from the cortex stimulate SG cells
what happens when you get novocaine at dentist
they shake cheek to mitigate pain by stimulating mechanoreceptors
- mixture of signals from same part of body
gate theory… no pain versus pain
NO PAIN: central control/L-fibers – SG- – T-cell
PAIN: S-fibers – SG+ – T-cell
cognitive aspects of pain perception
PAIN EXPECTATION
• Discloser = patient told what to expect
• Placebo effects = Real! help w/ pain management; given fake “pain meds” – expectation thins
SHIFTING ATTENTION
• Virtual reality = HOFFMAN
— people in pain used VR to chase spider and smash it
(attention diverted; experienced less pain)
• de Wied and Verbaten
— males held hand in ice water - DISTRACTED
— positive distraction: pretty girls.. chose to experience more pain
— neg distraction: took arm out faster
Derbyshire et al
('04)
THREE conditions:
1- physically induced pain
2- hypnotically induced pain
3- control condition : IMAGINED PAINFUL STIMULATION
• hypnosis DID produce pain • both physical & hypnotically pain shown in cortical areas - direct model in pain - multimodel/dimensional - can produce in many ways • hypnotic DON'T USE SKIN RECEPTORS
Melzak and Wall
(‘65)
- gate theory
Emotional aspects of pain
Rainville (‘97)
– Neuropsychology - using patient studies (messy)
– lesions to anterior cingulate
• no problems detecting pain (intensity; physicalness)
— same as non-lesioned people
• decreases in emotional sensation of pain (unpleasantness)
•• suggests that anterior cingulate (subcortical) is associated with emotional aspect of pain
Rainville
‘97
- lesions to anterior cingulate
Hofbauer
‘01
- participants presented w/ potentially painful stimuli
- rated: intensity (sensory) + unpleasantness (affective)
- using fMRI (good spatial)
1 condition: hands in hot water (STIMULUS STAYS SAME)
- HYPNOSIS: independently increase/decrease sensory and affective components ((give suggestions to patients about what will change))
RESULTS:
SUGGESTIONS ABOUT INTENSITY:
• affected intensity and unpleasantness
• S1 involved in processing intensity of pain
SUGGESTIONS ABOUT UNPLEASANTNESS:
• changed ratings of unpleasantness and anterior cingulate activiation
— important in processing emotional aspect of chain
• NO intensity/S1 activiation
•• intensity & unpleasantness can be seperated
pain matrix
SUBCORTICAL • hypothalamus • limbic system • thalamus • anterior cingulate
CORTICAL
• S1 in somatosensory cortex
• insula = control processing, inhibition
• prefrontal cortices
pathway– not fully understood like others (not direct)
artificial opioids
heroin
oxycodon
morphine
what do opioids do
- many opiate receptor sites in brain
- stimulated (filled) – reduces pain and instills euphoria
naturally occurring morphine
ENDORPHINS
- endurance in athletes.. “runner’s high”
what does naloxone do
- blocks opiate sites, increasing pain
- decreased placebo effects
narcan aka
naloxone
Benedetti
‘99
• patients injected w/ capsaicin (chemical compound found in chilli’s that produces head/pain)
• some given topical cream to soothe
• others: placebo
RESULTS= pain perception decreased w/ placebo
– placebo effects are real
