lecture 9 - pain and social pain Flashcards
pain
An unpleasant sensory and emotional experience associated with actual or potential tissue damage
has intensity, implying that it can be measured
- Has character (ex. Sharp, Dull, Burning, Aching)
- Pain is subjective
list what pain can be modulated by
Ascending and Descending Pathways
o Salience Network (what to pay attention to)
o Modulation Network (top-down control, neurochemical pain killers)
o Physically manipulations (ex. medication, massage, etc)
what is acute pain
<6 months
immediate response from injury or disease (with limited duration)
responsive to pharmacological treatments
what is chronic pain
> 6 months
not responsive to pharmacological treatments
touch receptors come from …
hair (vibrational)
stretch receptors respond to…
pulling and condensing of muscles
wide, ridged receptors respond to…
vibration and pressure (texture)
list 3 types of sensory receptors
touch receptors
stretch receptors
wide ridged receptors
free nerve endings
pain receptors that are closest to the surface of the skin and don’t have caps that other nerve endings have
nociceptors
sensory neurons that respond to damaging / potentially damaging stimuli (specifically pain receptors)
transmit pain info to ipsilateral side of spinal cord (the side stimulated is the side that is received in spinal cord)
what are free nerve endings specific for
pain and temperature
what is the purpose of myelin in A-delta fibres
AP can be propageted down the axon faster thanks to the myelin
Why are C fibres different from A fibres?
C fibres have no myelin so the AP moves slower
specificity theory
causal relationship between pain stimulus and receptors
stimulus intensity is also called
pain intensity
issues with specificity theory
- there is no specific cortical location for pain
- pain fibres can be used for other purposes (like pressure and temperature)
- it doesn’t explain the diffs in peoples reports of pain
describe the spinothalamic tract process of pain
sensory neurons conduct and transmit painful stimuli from peripheral nervous system to CNS (the spinal cord)
nociceptors transmit pain information to ipsilateral (same) side of the spinal cord
pain signal crosses to the contralateral (opposite) side of spinal cord
transmission ascends spinal cord through brainstem VPL nucleus of thalamus
signal transmitted from thalamus to somatosensory areas of cerebral cortex
pain received on the right side of the body will be processed in the left hemisphere of the brain and vice versa
pattern theory
nociceptors generate repeated or very large signal in the spinal cord which gets passed to the brain to perceive the pain
the signal is only transmitted if it passes the threshold
flaws of pattern theory
doesnt explain deferred pain (like feeling period cramps in legs or back instead of uterus)
doesn’t explain pain without injury (or injury without pain) bc there is no stimulus to drive the APs
gate control theory
c fibre activates the inhibitory interneuron since no pain is observed. the signal therefore is not sent to the brain
c fibre inhibits the inhibitory neuron if pain is observed. signal is then sent to the brain.
pain can reactivate the inhibitory interneuron, partially allowing the inhibitory interneuron to do its job (block the pain signal ascension). the signal to the brain conveys slight pain.
- example of this is rubbing your knee after u bang it to make it feel better
pain modulators
can be physical or psychosocial
physical
- block pain from being transmitted up to brain (ex; medication)
psychosocial
- how much attention u have on the pain, how u interpret the pain, and diff coping strategies used
operant conditioning and pain
pain is a unpleasant sensation and leads to behaviour
classical conditioning and pain
pain is a particular situation or environment that is associated w pain/ anxiety/ depression
fear avoidance model
avoidance is associated w catastrophizing patients. if pain is interpreted as threatening, this fear evolves
avoidance behaviour leads to mainteneance or exacerbation of fear, hypervigilance to internal and external illness information, and muscular reactivity
confrontation leads to reduction of fear over time
list the cortical areas involved in pain and what they do
anterior cingulate cortex: pain unpleasantness
insular cortex: pain unpleasantness
S1(primary somatosensory cortex): pain sensation, location, modality
S2(secondary somatosensory): same as s1
prefrontal cortex: pain regulation
limbic areas: pairs pain with other aspects like emotion, fear, memory, etc
subjective pain experience study Coghill et al
purpose: explore conscious sensory experience from 3rd person observation and identify neural correlates of someones pain experience in relation to others receiving the same stimulus
method:
rated temp stimuli applied to their forearm and split into groups based on pain sensitivity
low= insensitive to pain, high = sensitive
fMRI was done while having paritipents forearm stimulated with heat
results:
- cortical regions related to sensation, attention and affect were most associated with pain sensitive ppl vs pain insensitive (prefrontal cortex, S1)
- all sensitive ppl had ACC activation, no activation for all of the insensitive ppl
- activation in thalamus was same for ALL subjects, showing everyone’s pain signal did make it to the brain via spinothalamic tract
pain reports resulted in real brain activations!
phantom limb
sensation that an amputated or missing limb is still attached
can range from twitches to full range motion or control
can be painful
possible mechanism for phantom limb (there are 2 listed here)
mirror therapy
a person who can see their other limb moving in a mirror “in response to” the movement their nerves in the amputated limb want to do, this can bring relief to the phantom limb phenomenon.
- hyper excitability in peripheral nerves or CNS
mirror neurons
- found in animal studies which fire when animals perform or observe an action
- therefore, by receiving tangential visual input of perception and tactile sensations, the brain can limit the amount of pain u are experiencing from it
congenital universal insensitivity to pain (CUIP)
inability to perceive physical pain but can tell difference from diff amounts of touch, temp, etc
present from birth
can lead to injury or death as u cant tell if u are injured
what may cause CUIP?
SCN9 gene; responsible for instructions to make the alpha subunit part of the sodium channel (Na V1.7)
absence of functioning NaV1.7 channels impairs transmission of pain signals, causing those affected to be insensitive to pain
social pain + social exclusion: Macdonalds and Leary
Being socially excluded feels awful
- But more than that, it actually hurts
- English speakers tend to use physical injury-related terms to describe social injury
Jaak Panksepp - morphine
morphine calms distress of social isolation in animals
injections of morphine quieted the distress vocalizations of maternally isolate guinea pigs (fewer vocalizations of guinea pigs injected with morphine)
- Panksepp conjectured that the social distress system overlaps with the more ancient physical pain system
- The endogenous brain opioid system may be one of the neurochemical regulators of the distress associated with social separation, as well as the pleasure associated w/ social connection (Eisenberger, 2012)
does swearing cure pain? Stephens and Roberston
IVs: Type of swear words
o Conventional (Fuck)
o “New” (Fouch, Twizpipe, etc)
o Neutral (any word)
- DVs:
o Ratings of emotion, humour, distraction
o cold pressure pain threshold
o cold pressor pain tolerance
o pain perception score
o change from resting heart rate
- They were able to keep their hand in the cold water longer when they used the conventional swear words
- It’s the context of the emotion that influences pain (not necessarily the emotion itself)?
Eisenberger et al - cyberball task
Participants played a game of Cyberball under 3 conditions, while imaging brain activity with fMRI:
1. Excluded due to technical difficulties
2. Included
3. Excluded due to rejection by other players (who are actually not playing with you, they are part of the computer simulation)
- Found greater activity in the dACC and 2 regions of the right ventrolateral prefrontal cortex during exclusion than during inclusion
o These same brain regions are activated in response to physical pain
- Does depend on personality traits!
o More neurotic people are more sensitive to physical pain and more sensitive to rejection
o More extroverted people are less sensitive to physical pain and less sensitive to rejection
social pain implications - Dewall et al
experiment 1
Randomly assigned participants to receive:
* Daily dose of Tylenol (1000mg) OR…
* Placebo over period of 21 days
Each evening, participants recorded questions regarding degree to which they felt emotionally hurt during the day
o Results:
Placebo group: no change in hurt feelings over 21 day period
Tylenol group: significant decline in hurt feelings over the 21 day period
o People were physically experiencing less pain also experienced less social pain
experiment 2
Randomly assigned to take:
* 1000mg Tylenol Morning, 1000mg Tylenol at bed OR…
* Placebo of same dose (n=25)
*
3 weeks later –fMRI lab experiment, ball tossing game (social exclusion task)
o Results:
Compared to placebo group, participants who took acetaminophen showed less activity in dACC and anterior insula in response to cyberball exclusion
o By manipulating the ability to feel pain in the brain, you can also manipulate the ability of the brain to feel emotional pain
BUT dangerous path to addiction…
prevention of psychological and pain disorders with morphine
ppl given morphine immediately following a traumatic event are less likely to develop PTSD
how may opiates interfere with memory consolidation?
through a beta-adrenergic mechanism
also have to consider addiction
