Neuroscience Flashcards
1
Q
Modern field of “decision neuroscience” founded on 2 observations
A
- Human neuropsychology: patients with vmPFC lesions show poor judgment and risky decision-making in the real world
- Primate electrophysiology: during Pavlovian conditioning, dopamine neurons fire to unexpected rewards and conditioned stimuli that predict reward
2
Q
Damasio’s patient “EVR”
A
- Formerly a pillar of society, developed frontal lobe tumour, post-operative recovery seemed good (retained high IQ, no psychiatric symptoms, performed well on neuropsychological assessment)
- BUT made many poor real-life decisions (unreliable employee, fired from jobs, Questionable business ventures that led to bankruptcy, Erratic personal life)
- Brain damage to the ventromedial prefrontal cortex is linked to real-life decision-making deficits: choices offer immediate gratification but with long-term negative consequences; patients fail to learn from their mistakes (“myopia/shortsightedness for the future”)
3
Q
Iowa Gambling Task
A
- 100 choices from 4 decks of cards
- Decks A & B = risky; high immediate reward, very high long term punishment (net loss)
- Decks C & D = safe; low immediate reward, minimal long-term punishment
- Net score = safe choices – risky choices (if net score is positive, you prefer safe decks, and vice versa)
- EVR and other patients with damage to vmPFC show strong risky preference in their net scores, whereas normal people and patients with other types of brain damage show strong preference for safe decks
- this task is good at measuring the subjective value of goods
4
Q
Arousal and risky decision-making
A
- Measuring Skin Conduction Response (sweating from fingertips; index of sympathetic nervous system)
- SCR to wins and losses is similar for everyone (ie. VmPFC patients react), but SCR response during the decisions to choose risky vs. safe decks is different (ie. VmPFC patients don’t react; as if they don’t remember the emotional information about how these decisions played out in the past)
5
Q
Key neurotransmitters (esp. dopamine)
A
- Glutamate, GABA, serotonin, noradrenaline, acetylcholine, dopamine
- Dopamine is of interest to us here:
- 2 sets of cell bodies, both in midbrain:
1) Substantia nigra (movement)
2) Ventral tegmental area (reward)
- 2 sets of cell bodies, both in midbrain:
- Their axons project into the striatum: Nigro-striatal ; Meso-limbic (then into cerebral cortex, esp. frontal lobe)
- – Dopamine-receiving striatum is robustly activated by various types of rewards (Ex. Money, music, love, humour, etc.)
6
Q
Dopamine and Pavlovian Conditioning
A
- Dopamine neurons signal unexpected rewards
- With learning, dopamine neurons also signal conditioned stimuli (CSs) that predict reward
- After learning, the neuron only fires to the CS, not the reward
- Ex. Monkey sees random pictures, then gets fruit juice. Dopamine initially happens for fruit juice, but once he gets conditioned, dopamine only happens for the picture (CS) -> picture is the unexpected thing now, and fruit juice is predictable (so no dopamine for juice)
- Dopamine is NOT pleasure chemical
7
Q
Functional MRI (fMRI)
A
- Oxygenated and de-oxygenated blood have different magnetic properties; bloodflow changes in 2-7s -> good temporal resolution
- VmPFC is traditionally hard to image with fMRI (“signal dropout”)
8
Q
Reward system in social media use (2 studies)
A
- Meshia et al study:
- People see pictures of themselves and others paired with positive or negative reputations
- – Large overlap between areas that respond to monetary reward and seeing a positive reputational statement about yourself -> participants who activate this reputation response the most correlates with amount of FB use
- Sherman et al study:
- On Instagram, ventral striatum activity increases with number of likes, especially on posted photos supplied by the participants
9
Q
Theories of vmPFC function
A
- Damasio / Bechara “somatic marker hypothesis”: vmPFC retrieves emotional memories to guide decision-making
- Valuation perspective: “vmPFC contains info about the personal, subjective value (i.e. economic utility) of stimuli or actions” … “a common currency that would in turn support decision making”
- Other views: ‘affect regulation’ (“inhibiting maladaptive responses”) and ‘social cognition’ (“domain specificity to social stimuli”)
10
Q
Willingness to Pay
A
- Hungry people put in a brain scanner, see food items and have chance to bid for them (some of this bids will be honoured in real life)
- Saw that brain activated for foods they liked and deactivated with things they don’t like -> OFC correlates with economic “willingness to pay”
- – Good for measuring subjective value of different goods
11
Q
Elements of expected utility (“the common currency”)
A
- Subjective value: I prefer apples to oranges
- Expected value: reward size x probability you’ll get the reward (low probability reduces value)
- Delayed value: reward size x delay (delay reduces value)
12
Q
If vmPFC holds value/utility, what is the primary effect of vmPFC damage
A
Ex. Before study, showing puppy photos, you rank the puppies. Then during study you see puppies side by side and say which one you like more (if you switch preferences, that’s a “preference error” -> patients with vmPFC damage make more of those preference errors -> make less stable preferences)
13
Q
Stages of decision-making
A
Decision -> anticipation -> outcome -> emotions & learning signal -> impact future decisions
14
Q
Dual Process Theories
A
- competing systems in our decision-making
- System 1: intuition
- Fast, automatic, effortless, emotional (will get there first)
- Parallel, associative, slow to learn/adapt
- Heuristics, gut feeling, somatic markers
- “hot”
- System 2: reasoning
- Slow, controlled, effortful, neutral (valence)
- Serial, rule-based, flexible
- Cost/benefit (algorithmic) analysis
- “cool”
15
Q
Influence of social factors (the risky shift)
A
- Subjects play a game either alone or in a group of 3 peers (trying to get car across the screen -> will you play it safe or take a risk for more points)
- Adults aren’t influenced by social context, but adolescents are –> make riskier decisions in peer group condition
- High response in ventral striatum during risky decisions in peer condition
