Neuroscience of Pain and Reward Flashcards
What is psychological hedonism?
perspective arguing that peopl are motivated to act in ways to inc and maximize pleasure and minimize and avoid pain
Reward vs. pleasure
Reward: something an animal will work to achieve
Pleasure: the subjective hedonic value of rewards
Primary vs secondary reward
Primary: naturally rewarding stimuli and biologically essential
Secondary: learned rewards that gain importance through repeated associations
Punishment vs pain
Punishment: something an animal will work to avoid
Pain: the subjective hedonic and motivational response to a punishing stimuli
Primary vs secondary punishment
Primary: painful stimulus itself, naturally aversive
Secondary: leaned punishment through experience
What is subjective utility?
the idea that rewards don’t always produce pleasure and punishments don’t always cause pain, the personal value and satisfaction an individual assigns to an outcome based on their preferences and circumstances
What is alliesthesia?
The subjective hedonic value of a stimulus is tied to extent to which a stimulus contributes or disrupts homeostasis
What is the difference between pain and nociception?
pain is an unpleasant sensory or emotional experience and nociception is a neural processing of tissue damage (detection and transmission of info)
Can have pain without nociception (ie. phantom limb) and nociception without pain (withdrawal reflex)
What are the two components of pain?
1) sensory-discriminative component
- provides info about intensity, quality and location
- processed in primary and secondary somatosensory cortices and posterior insula
2) affective-motivational component
- relates to the emotional experience of pain and drives motivation to escape the pain
- processed in the dorsal anteior cingulate cortex (dACC) and anterior insula
What is some evidence of shared sensitivity to physical and social pain?
- greater baseline sensitivity to physical pain predicts greater sensitivity to social exclusion
-a genetic variant related to greater physical pain sensitivity is related to greater trait rejection sensitivity, greater self-reported subjective and neural reactivity to cyberball, and more sensitivity to hurtful partner behaviour
What is some evidence of the social pain hypothesis?
- Cyberball study: neuroimaging showed INC activation in dACC and anterior insula where the magnitude of neural activation correlates with both self-reported feelings of social exclusion and observer-rated social distress
-Photos of rejecting ex-partner, also shows inc activation of dACC and AI
What is the evidence that factors that increase/decrease one type of pain have the parallel effect on the other type of pain?
factors that decrease social pain also dec physical pain
ex) social support decreases physical pain (during labour) This is reflected in decreased signalling in dACC and AI in response to pain tas l
Factors that inc social pain are more complex
ex) cyberball exlcusion has been shown to lead to pain hypersensitivity, most excluded feel the most pain, also premeditated pain hurts more than accidental pain
But social exclusion has also been linked to hypoalgesia (reduction in pain) , emotional numbing –> less pain
factors that dec physical pain have parallel effects on social pain ex) Tylenol takers report lower levels of hurt feelings than placebo placebos
factors that increase physical pain have parallel effects on social pain ex) inflammatory challenge INC interpersonal sensitivity
What are behavioural consequences of social pain?
Neuropsychological evidence: in animals, dACC lesions lead to decreases in separation distress and deficits in social behaviour (maternal behaviour, social interest, proximity seeking)
Experimental evidence: social pain drives affiliative behaviour
- inc desire to work with others vs alone
-more effort on group task
- more likely to sign up for friend match-making
-more social monitoring
provide more positive evauations of a new partner
What is the caveat of behavioural responses to social pain?
we are likely to engage in affiliative behaviour only to the extent to which we see the target as a viable source of social connection
This means people whoa re fearful of negative evaluation are less likely to reach out post rejection
Sometimes social pain leads to aggressive behaviour
What is the difference between wanting and liking?
Liking is described as the subjective feeling of pleasure we experience when we receive a reward
Wanting is the motivation to pursue something
how do we measure liking and wanting?
liking: typically measured by asking, and sometimes by physical indicators (facial expression)
wanting: typically measured by amount of effort an individual is willing to exert to obtain the reward
How is beauty a reward?
Beauty is a primary reward because it signals health, fertility, genetic fitness
The brain processes facial attractiveness similarly to how it processes other rewarding stimuli
How does dopamine play in processing reward?
“the pleasure molecule”
Now understood as playing a large role in WANTING rather than liking
The Dopamine-based reward circuit involves the VTA, NA, PFC, and OFC
VTA
Ventral tegemental area
where dopamine is made
NA
Nucleus Accumbens
the brain’s pleasure centre
PFC
Prefrontal Cortex
Involved in decision-making and self-regulation
OFC
Orbitofrontal cortex
Key to evaluating rewarding stimuli
How does the dopamine reward circuit work?
Dopamine is released when a reward is evaluated and a positive prediction error happens when an outcome is better than expected
Dopamine release is greatest when a reward is unexpected, and or under-predicted and is even greater during anticipation
What role do endogenous opioids play in reward processing?
Play a large role in LIKING (pleasure)
- the opioid system is closely related to the dopamine system
-Opioids mediate pleasure stemming from a variety of stimuli (ex. tasty foods, exercise, sex, drugs, alcohol, social play)
How can we examine the role of opioids?
By adminstering opioid antagonists (naltrexone or naloxone) to block the signals, we can use neuroimaging to look at opioid release and correlate extent of opioid release with subjective feelings
What is the Motivation-decision model of pain?
Subjective interpretation of a sensory event can be understood as a manifestation of the unconscious decision process
- main idea is that decisions are based on what is most critical for survival in the moment–> if something more important than pain is happening the brain can reduce pain signals
Involves 3 factors:
- internal state
-sensory input
-Threats and Rewards
When is the brain most -likely to reduce pain signals?
can be for fight or flight
Also a variety of rewarding stimuli have been shown to reduce pain in humans and non-human animals (sweet foods, pleasurable odours, sexual behaviour, pleasant music)
EXPECTATION of reward also reduces pain
ex) placebo analgesia
ex) hungry rats who learn a shock means food show attenuation of pain response
What biological mechanisms affect analgesia in the motivation-decision model?
Endogenous opioids produce both stress and pleasure induced analgesia
Hungry rat who attenuates pain response to shock that means food–> this can be undone with opioid antagonists.
Placebo analgesia is a classic example
- the magnitude of placebo analgesia correlates with opioid release in brain
What is placebo analgesia?
a (reduction in pain that occurs after a person is given a placebo, an inert substance which has no effect but which the person believeswill attenuate their pain
What is Anhedonia?
the inability to enjoy everyday pleasures
- often caused by inhibition of reward by pain, where pain decreases engagement in rewarding activities
ex) high co-morbidity between chronic pain and depression
At the neuroanatomical level, what are the points of overlap between pain and pleasure processing discussed in class
Opioids and dopamine are both important for regulating pain and pleasure. Neural regions like…
ACC: represents the size and probability of rewards as well as effort required
Insula: encodes taste and food craving, linked to felt satisfaction, and interoceptive signals
Amygdala: involved in both pain/threat processing as well as reward
Why do we sometimes seek out pain?
The relief of pain is itself a pleasurable experience. Sometimes negative stimuli can be experienced as pleasant when in the context of more negative stimuli
Experience of moderate pain can be reported as pleasant when compared to alterntative extreme pain
What is relative relief? What is evidence of this?
the experience of pain being pleasant when compared to other, more intense pain
LAB STUDY: Ps subjected to painful task (like skin irritant)
when painful sensation stops, a sense of relief and positive affect results
the more intense the pain the more intense the relief
What is the opponent process model?
Emotional reactions are regulated by the brain to maintain hedonic balance. Strong emotional reactions (both pleasure and pain)are countered by an opposite reaction
Involves state A and B:
- State A is an emotionally powerful stimulus, develops quickly and ceases when stimulus is removed. The brain is counteracting the fear
- State B is the ful lforce of relief and excitement is felt, it develops slowly after state A, state B then slowly fades until emotions return to baseline
According to opponent process model? what happens with repeated stimuli?
state B becomes more intense over time
Because steady State A = A –B, repeated presentations of stimulus that triggered State A will lead to a reduction in hedonic intensity of State
What is the Peak-end rule?
The most intense positive or negative moments or the final moments (peaks and ends) of experiences are most heavily weighted in our recollections of experiences
