Task 4 - classical conditioning Flashcards
Unconditioned stimulus
-biologically significant stimulus that elicits a natural reflective response
Unconditioned response
Natural reflex elicited by US
Conditioned Stimulus
-cue that was previously neutral but that through training becomes associated with US
Conditioned response
-learned response to CS that has been paired with US
Aversive /appetitive conditioning
- US is unpleasant or negative event
- US is a positive event
Conditioned compensatory response
- results in tolerance
- decrease in reaction to a drug (or something else) , so that larger doses are required to have a similar effect
- occurs primarily in body system that has mechanism for homeostasis (tendency to gravitate towards state of equilibrium)
Extinction
-reducing a learned response to a stimulus , by stopping to pair that stimulus with a reward/punishment
- > association that became ‘inhibited’ following extinction will not be lost in its entirety
- > in fact, learned response is not gone, just unexpressed
- extinction is not forgetting!
- extinction = overwriting/replacing
Compound conditioning
- Simultaneously conditioning of two cues , usually presented at same time
- two cues compete against each other
- neither produces as much learning as it would have ( if trained alone)
- compound cues share predictive value
- > learning is faster with compound cues
- learning rate is faster -> steep learning curve
Overshadowing
-effect seen in compound conditioning when a more salient cue within a compound acquires more association strength than less salient cue
Acquisition
- the CR gets stronger gradually
- if CS proves to be predictive of US then CR follows CS, also without US n
Tolerance
-compensatory response in preparation to US , in an attempt to maintain a balanced state (homeostasis)
Evidence:
-heart rate drops when awaiting an adrenaline injection, diminishing the heart rising effect of adrenaline
Blocking
-a stimulus can only become an CS if it brings ne predictive value
Evidence:
- light and sound are followed by a shock
- > both stare the predictive power
- if only light is followed by the shock and sound is added later
- > sound will not add value to prediction
No Error = No learning
Rescola - Wagner Model general idea
- if you are surprised, you are learning
- US occurs unexpectedly + positive error ( E) -> increase in association of CS and US
-US does not occur as expected = negative E -> decrease in association of CS and US
Prediction Error
-determines how much learning (change in association) occurs
Error - correction - rule
- with trials of learning the prediction error gets reduced
- learning occurs incrementally
Formula prediction error
Actual US - Expected US
Formula Expected - US
(Learning rate * predition error) + previous Exp US
Problem - latent inhibition
- rescorla Wagner model can’t explain latent inhibition
- > prior exposure to a CS retards later learning of the CS-US association during acquisition training
-> model makes false prediction that pre-exposed group should be no different from control group
US -Modulation theory
- Solar-Wagner model
- > how unexpected is US given preceding CS
CS - Modulation theory
- Mackintosh
- which CS is attended determines which becomes associated with US
Cerebellar Cortex
- granule cells
- parallel fibers
- Purkinje cells -> location of learning
- climbing fibers
Cerebellar deep nuclei
- mossy fibers
- interpositus -> output
- climbing fibers
Brainstem
- Pontine nuclei
- inferior olive
-> Inputs
Steps conditioning
Purkinje cell inhibits interpositus (as normal)
- > CS (tone, light)
- > reduced Purkinje cell activation
- > releases interpositus form inhibition
- > interpositus triggers eye muscle before standard reflex pathway is triggered by US sensory input
- > after conditioning the CS pathway is faster
Cellular perspective in Purkinje cell
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Rescorla Wagner model - 3 assumptions
1) a cue (CS) has a weight (predictive value) that predicts the US
2) in compound cues, the weiht is spread over cues
3) learning corresponds to an increase in cue weight (accumulated over trials) and a corresponding reduction in prediction error
Additional learning after removal of one of two compound cues
-predictive value of the remaining cue should be 50 % and new learning should occur until you reach full level of learning again
Cerebellar function in motor performance (and motor learning)
-compares motor plans with feedback on the execution of movements based on sensory feedback
Canonical modulators circuit cerebellum
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Cerebellar pathology
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Optogenetics
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Optogenetics - use
- alleviating epilepsy by optogenetic stimulation of Purkinje cells
- deep brain stimulation ( Parkinson’s, depression)
- treatment of heart arithmia’s
- modification of traumatic memory, treatment of addictions etc.
