linking senses and behaviour to memory

Question 1

how can david marr’s 3 levels of analysis be applied to decision making

Answer 1

whats the problem?
what abstract methods of processing information could you use to solve the problem?
how can you implement algorithm to solve problem on hardware?

→ integrate noisy sensory input and decide correct action
→ drift-diffusion model of evidence accumulation ⇒ explains frequency distribution of reaction times and speed-accuracy trade-off
→ ramping up neural activity to threshold ⇒ some evidence but neural mechanisms not understood

Question 2

what is decision making

Answer 2

delay between motion and saccade = reaction time

Question 3

gaussian distribution

Answer 3

distribution of reaction times = skewed right

Question 4

rate of evidence accumulation

Answer 4

= height of decision bound / reaction time

Question 5

measuring reaction times in drosophila

Answer 5

• easy task = good/bad odour
• hard task = bad/worse odour

Question 6

speed-accuracy trade off

Answer 6

• quick, non accurate decision/long accurate decision
  short decision time = not enough noisy input to accurately reach correct decision bound
• decreasing decision bound = increases reaction time
• can lower decision bound with environmental stimuli e.g pressure

Question 7

where is evidence accumulated in the brain - physical implementation

Answer 7

monkey experiments
- recordings from lateral intraparietal area = move eyes from right to left
- each neurone has receptive field and respond to different stimuli ie. some neurones move eyes left
- neurones respond faster to stronger stimuli = matches drift diffusion model

Question 8

drift diffusion model

Answer 8

the decision maker accumulates evidence until the process hits either an upper or lower stopping boundary and then stops and chooses the alternative that corresponds to that boundary

stronger sensory input → LIP activity changes faster

Question 9

transcription factors involved in decision making

Answer 9

mutant in FoxP TF, flies take longer to decide = involved in motor patterning and language

• FoxP suppresses expression of K channels = less K leaves cell = prevents cell from being depolarised
  
  • normal spiking
• mutation with decreased FoxP = increased cell depolarisation = cells become leaky
  
  • slower to spike