Linking Senses+Behaviour to Memory Flashcards

1
Q

What is the Drift Diffusion Model?

A
  • Framework used to describe the decision making process regarding neuroscience in noisy/ambiguous environments
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2
Q

What are the components of the drift diffusion model?

A
  1. Drift rate: Rate at which evidence accumulates in favour of one decision over another
  2. Threshold: How much evidence is needed to make a decision?
  3. Noise : Random fluctuations in accumulation of evidence
  4. reaction time: The gap in time from when the evidence starts accumulating to when the decision is made
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3
Q

What is the other title for ‘Normal distribution’?

A

Gaussian distribution

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4
Q

How does reaction time plot on a graph?

A

1/reaction time gives a normal distribution which implies the varying factor is rate of evidence accumulation

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5
Q

What experiments can be used to test reaction time in drosophila and what were the results?

A
  • Odours in two chambers one is attractive one is repellent - quick reaction time
  • When the odours are more complex and more ambiguous then the decision making takes longer
  • Rightward skew in reaction time
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6
Q

Explain reaction time experiments in mice

A
  • Mouse pokes its nose in the odour port – when it hears a buzz, it has to stop sniffing and choose a water port based on which odour it smelled.
  • Reward only for going to the correct water port.
  • If mouse’s odour sampling time is cut short by the buzzer it makes less accurate decisions
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7
Q

How can the mouse reaction time experiments be explained by the drift diffusion model?

A
  • Accumulating lots of evidence when the buzzer allows a long time , you make the right decision
  • If you don’t allow enough time to reach the full decision threshold you are likely to make a mistake (not gathering enough evidence)
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8
Q

When is the threshold for evidence accumulation set lower?

A

Under certain conditions where there is a priority on speed not accuracy e.g. in danger

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9
Q

What is the physical implication of drift diffusion?

A

Ramping up neural activity

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10
Q

Explain the physical implications of the drift diffusion model including motor command neurons in monkeys brain

A
  • Motor command neurons exhibit increased activity when monkey is ab to move its eyes to the right (opposite for the left)
  • Before the monkey makes a decision about which direction to move its eyes, neuron activity gradually increases (evidence accumulation)
  • The rate of this ‘ramping’ depends on the strength of evidence accumulation (higher/lower drift rate)
  • Neuron reaches peak activity around 70ms before decision, suggests consistent timing despite stimulus strength
  • Once threshold is reached, decision is made implying evidence for the neuron ‘causing’ the decision
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11
Q

How are Kenyon cells related to decision making?

A
  • Kenyon cells store olfactory memories
  • Fly mutant, FoxP takes abnormally long to decide between two odours
  • Due to Kenyon cells being ‘leaky due to excess K+ channel expression
  • This slows down their rate of evidence accumulation
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