3. Decision Making

Question 1

External components of subjective value

Answer 1

Commodity (type)
Quantity (number)
Delay (when get reward/temporal discounting)
Risk (prob of getting)
Cost (cost)

Question 2

Normative/Descriptive Theories

Answer 2

Normative - what people should do if we were rational/optimal. Expected value theory (value x probability)
Descriptive - what we actually do as irrational humans. Accounts for differences in gain/loss (want certain gains, gamble losses, risk attitudes). Accounts for temporal discounting (patience/impatience)

Question 3

Cortical regions for subjective value

Answer 3

Anterior Cingulate Cortex
Orbitofrontal Cortex
Ventral Tegmental Area/Substantia Nigra

Question 4

How do neurons store representations of value

Answer 4

fMRI study in monkeys for activity w 3 components of value (reward,cost,risk)
OFC encodes single component of value
ACC encodes multiple components/integrates values

Question 5

What area does temporal discounting

Answer 5

human fMRI study with OFC lesion subjects
task of choosing reward now/delay period
OFC lesion had much worse temporal discoutning curve
OFC shows sensitivity to subjective value, incorporates delay period

Question 6

Neural representation of self-control

Answer 6

human fMRI of subjects on diet
vmPFC encodes taste preferences (aspect of value)
dlPFC corr’d with SELF CONTROL

Question 7

Cortical Networks for decision making

Answer 7

Limbic - OFC and vmPFC encode value
Control - dlPFC for self control, and ACC for integrating decision variables

Question 8

Loci for Dopamine production

Answer 8

Substantia nigra pars compacta
Ventral Tegmental Area

Question 9

Dopamine signal RPE study

Answer 9

monkey electrodes recording from dopaminergic in VTA
Dopamine spikes to reward in unconditioned trials
Spike only to conditioned stimulus once paired
Dopaminergic VTA spikes to RPE, NOT REWARD
Spikes to unexpected rewards (at first, and not when expected, spikes to the light because don’t know when light will shine so when it does… yippee!)

If light but no juice, SUPPRESSED ACTIVITY (negative RPE= suppress, expectation violation)

Question 10

Signaling expectancy to VTA dopaminergic

Answer 10

Optogenetics to inhibit GABAergic neurons in VTA that connect to DA VTA neurons
Rats smell odor with 90% or 10% chance to reward
When inhibit GABA, the DA neurons spike to the reward for 90% signal, but don’t normally!
GABA informing DA of expectancy (when inhibit GABA, DA DOESN’T KNOW EXPECTANCY, so will spike to all rewards because all are unexpected)