Task4 - Classical Conditioning Flashcards
Unconditioned stimulus (US)
Cue that has biological significance
Evokes response without training
Unconditioned response (UR)
Naturally occurring response to unconditioned stimulus
Conditioned stimulus (CS)
Cue that is paired with unconditioned stimulus and evokes a conditioned response
Conditioned response (CR)
Trained response to a conditioned stimulus in expectancy of unconditioned stimulus that is predicted
Pavlov- before training
- natural stimulus bell evokes no response
2. unconditioned stimulus food naturally evokes unconditioned response salivation
Pavlov - during training
Neutral stimulus bell is repeatedly paired with US food to evoke UR salivation
Pavlov - after training
Bell is conditioned stimulus (CS) and evokes conditioned response (CR) salivation without presenting US food
Appetitive conditioning
Conditioning in which the US is positive (e.g. food)
Aversive conditioning
Conditioning in which the US is negative (e.g. shock/ airpuff)
How can conditioned response be understood?
Conditioned response is an expectancy response to prepare for the expected US
Eyeblink conditioning
US is airpuff
CR and UR is eyeblink
Tolerance
Decrease in reaction to a drug so that larger doses are required to achieve the same effect
Why does tolerance occur?
Homeostasis = tendency of body to gravitate toward a state of equilibrium or balance
What can be an US?
Events that are biologically significant because they are inherently positive or inherently negative
What can be a CS?
Any cue in environment
Extinction
Process of reducing a learned response to a stimulus by stopping to pair that stimulus with reward or punishment
Is extinction like unlearning?
No, it is rather combination of unlearning and learning of new opposing response
-> the learned response is not gone but unexpressed
Compound conditioning
Simultaneous conditioning of two cues, presented at the same time -> the cues are competing against each other, neither is producing as much learning as it would have had if trained alone
Overshadowing
Effect seen in compound conditioning when more salient cue within compound acquires more association strength -> more strongly conditioned
Blocking
Two phase training paradigm:
Prior training to one cue blocks later learning of a second cue when paired together later
-> their first cue has to be a 100% predictable, no prediction error to block the other cue
Erschlafft - Wagner model of conditioning
to understand blocking effect
Key idea: changes in CS-US associations are driven by discrepancy/ error between expectation/ prediction of US and whether US actually occurs or not
Prediction error
Difference between what was predicted and what actually occurred
Error correction learning
Mathematical specification of conditions for learning that holds the degree to which an outcome is surprising modulates the amount of learning that takes place
Positive error (error correction is R-W model)
CS predicts nothing or too little bust US unexpectedly occurs or is unexpectedly strong -> increases association
No error (error correction in R-W model)
CS predicts US and predicted US occurs -> no new learning
Negative error (error correction in R-W model)
CS predicts US, but no US occurs -> decreases association
Associative weight
In Rescorla - Wagner model of conditioning, a value representing the strength of association between CS and US (before learning 0-> change though learning)
Using R-W model to explain blocking
Equation
Prediction error= occurrence of US - Expectation of US (=cue weight= error x prediction error)
Mackintosk‘s theory
Previously conditioned stimulus derives its salience from its past success as a predictor of important events and this happens at the expense of other co-occurring cues that don‘t get access to your limited pool of attention = CS modulation theory
Brain regions in classical conditioning
- Cerebellar cortex: Purkinje cells, Granule cells, parallel fibers
- Cerebellar deep nuclei: Interpositus nucleus, mossy fibers, climbing fibers
- brainstorm: Pontine nuclei, inferior olive
CS pathway
- projection on pontine nuclei (different subregions for each sensory stimulation)
- CS information travels up to deep nuclei of cerebellum along mossy fibers -> branch into two directions
- a. 1 branch to interpositus nucleus
- b. 1 branch to Cerebellar cortex, across parallel fibers -> connects to dendrites of Purkinje cells
US pathway
- US (airpuff) activates inferior olive (connections to thalamus, cerebellum, and spinal cord)
- inferior olive activates interpositus nucleus
- second branch of the pathway: inferior olive projects to Cerebellar cortex by climbing fibers
- climbing fibers have very strong excitatory effect on Purkinje cells
Single output pathway for the CR
Complementing the two converging input pathways
- starts from Purkinje cells
- projects down from Cerebellar cortex into deep nuclei
- form inhibitory synapse with the interpositus nucleus
- putout from the interpositus nucleus travels to the nucleus in the eye
- > generates the eyeblink CR
Classical conditioning in tolerance to addictive drugs
Addicts body adjusts to the drug effect -> larger doses are required (homeostais)
- > works with conditioning
- > environmental cues that accompany drug use condition user to expect to receive the drug
- > body adjusts to environment
