Neuroscience of decision-making: value-based decisions

Question 1

Value-based

Answer 1

Valuing and choosing prospects with uncertain outcomes
- modelled with expected utility theory

Question 2

Perceptual

Answer 2

action selection based on uncertain evidence
- modelled with evidence accumulation threshold

Question 3

Studying neural mechanisms underlying value-based decisions

Answer 3

Neurophysiology - single cell recording
Neuropsychology - patient studies
Neuroimaging- fMRI

Question 4

Neuroeconomics

Answer 4

the study of neural mechanisms underlying the variables and computations assumed in psych economic theories

Question 5

single cell recording - probability in expected value

Answer 5

cued saccade task- Lip neurons recorded. fixation point and 2 other targets appear either side. point changes colour and look at matching target when point disappears. targets cued with different probabilities (.8 and .2) so knowledge about which target cued. so even before cue neural response to target different. differences in activity disappear when cue appears

Question 6

Magnitude of reward

Answer 6

associate different target colours with different rewards. if target in neuro receptive field associated with lower rewards then less activity then ones with higher reward

Question 7

Expected value in the brain

study

Answer 7

recorded LIP neurons
firing rates modulated by probability of movement and magnitude of reward
EV- value x probability
so sensitive to both components of EV

Question 8

Patient studies

Answer 8

most neuroscience correlational
natural manipulation - study patients with neurological damage
Damage to ventromedial pre-frontal cortex associated with decision making in the presence of otherwise normal cognitive function

Question 9

tumour patient

Answer 9

removal led to bilateral lesion to orbitofrontal cortex and serve impairment of decision making

Question 10

Iowa Gambling task outlined

Answer 10

choose a card from one of four decks and try and gain max reward. uncertain outcomes. start with $2000. Decks a and b are high risk choices as give high rewards and punishments and are used to measure learning an decision making impairment. Decks c and d are low risk decks and advantages in the long run

Question 11

Iowa Gambling task results

Answer 11

Typical person initially tries all decks but then moves to predominately c and d
patients- kept going for high risk a and b
Control brain damage- behave like typical person

Question 12

sub-dividing brain areas associated with decision making

Answer 12

vmPFC - assigning values to options in absence of uncertainty or learning
OFC - updating values based on reward feedback

Question 13

fMRI

Answer 13

loss aversion
negative emotional response - amygdala
asymmetric valuation system - vmPFC
gamblers choose form asymmetric matrix where diagonal is loss is 2x gain.
accept if above diagonal.
RT show choices with larger differences between gains and losses easier
gain areas - vmPFC and OFC
loss area- vmPFC and OFC (lower activation)
no activation of amygdala so emotion not important?
network involved - vmPFC and ventral striatum in Basal Ganglia
neural and behavioural loss aversion correlate