Neuroscience and decision making (perceptual)

Question 1

making a model system

Answer 1

primate brain as model system
perform simple perceptual tasks based on uncertain sensory info
record key brain areas
suggests perceptual decision making based on evidence accumulation

Question 2

What is perceptual decision making

Answer 2

selecting an action based on uncertain sensory info. Make inference about state of world

Question 3

Random dot motion paradigm

Answer 3

look at random movement of dots. some move coherently. figure out if net movement is left or right and move eyes to indicate. can manipulate uncertainty and viewing time.
tests as evidence comes in overtime and is uncertain

Question 4

behavioural results of random dot paradigm

Answer 4

more accurate with more coherence
decreased reaction time with more coherence
increased accuracy (coherence threshold) with increased viewing time

Question 5

Schematic model

Answer 5

sensory unit (processing visual motion) -> sensorimotor unit (action planning) -> motor unit (action execution)

Question 6

Visual motion processing in area MT

Answer 6

neurons large receptive field. populations of MT neurons Sensitive to direction (left/right preference)
fire when match preference
amount of firing within population estimates motion direction at that time

Question 7

temporal interrogation

Answer 7

measure of total cumulative evidence
at certain point evidence is enough to respond to direction
more accurate the more distinct evidence there is (greater separation in cumulative evidence

Question 8

effect of coherence in cumulative evidence

Answer 8

higher coherence means gain enough cumulative evidence quicker

Question 9

eye movement planning in area LIP

Answer 9

Paradigm animal look at fixation point then target appears. fixation point disappears and move eyes to target
peak of LIP after target appears so involved with action planning

Question 10

LIP and dot movement task

Answer 10

record LIP neuron that contains movement target in response field.
greater activity for good quality evidence (so accumulating evidence)
stop accumulating when sufficent evidence . decision threshold for movement

Question 11

evidence to accumulation threshold

Answer 11

better evidence -> higher accumulation rate -> shorter RT
Accuracy instructions -> raise threshold -> slower more accurate decisions
Speed instructions -> lower threshold -> faster but less accurate decisions
speed-accuracy trade off