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Classical Conditioning

Learning & Memory

Arlo Clark-Foos

What is classical conditioning?

• Learning to associate previously neutral

stimuli with the subsequent events.

• Howard Eichenbaum’s Thanksgiving

Pavlov’s

psychic secretion

Are you conditioned?

• Some examples of every day

conditioning…

– Holiday Traditions

– Food Associations

– Fears

– Superstitions

– Habits

– Skills?

Ivan Pavlov

• How are digestive fluids controlled?

– Historical view

– Pavlov’s view

– Pavlov’s Original Experiment

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Pavlov’s Experiments

• Psychic Secretion

– Specialized procedure for introducing food

• Claude Bernard’s psychic secretion in horses

– Pavlov’s psychic secretion was unreliable but…

Pavlov Museum, Ryazan, Russia

Stimuli and Responses

This is appetitive

conditioning. What is an

example of aversive

conditioning?

Conditioned Emotional Response

Estes & Skinner

(Dudai, Jan, Byers, Quinn, &

Benzer, 1976)(Domjan, Lyons, North, &

Bruell, 1986)

Appetitive

Slapping and Blinking in the Name of Research

Clark HullErnest Hilgard

Electromyography (EMG) Photo Sensors

Very well

studied

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Rabbit Eyeblink Conditioning

reactive

predictive

It gets more complicated…

• Similarity among species

• Tolerance, compensatory responses, and homeostasis

• Stimulus Timing and Presentation

– Contemporaneous Presentation

• Not spaced too far apart in time

– Is there an ideal spacing?

– Order and Consistency

• Reliable relationship/expectation

Conditioning Procedures

Forw

ard

Conditio

nin

g

Interstimulus

Interval

Intertrial

Interval

Learning Not to Respond

Conditioned Inhibition: Decrease in CR in

response to CS.

– Need Baseline

CS+1(Tone) US

CS-2(Light)

CS1 ?

CS2 ?

Baseline

CS1 + CS2

CRs diminish

over time as CS-

inhibits CS+

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Transfer of Learning

• Generalization

• Discrimination

CS(Tone,1200mHz) US

CS800mHz CR

CS1200mHz Max CR

CS1600mHz CR

CS(Tone,300mHz)

CS(Tone,500mHz) US

CS(Tone,800mHz)

CS300mHz

CS500mHz CR

CS800mHz

Context as CS

• Penick & Solomon (1991)

– Eyeblink conditioning in rats

– Hippocampal Lesions

Transfer Appropriate Processing

& Encoding Specificity

What is being conditioned?

• How is it learned and what is the nature of the

association?

S-S or S-R Association?

• Stimulus Substitution Theory (Pavlov)

– Definition (S-R Association)

– US, CS, and Response centers in the brain

– Problem: a CR is not a UR

• CR eyeblink is often more gradual and less complete

US

Response

CS S-R Association

S-S Association

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Rescorla (1973)

US Devaluation

Less CR after US devaluation.

S-S Association

Conditioned

Suppression

(Light/CS +

Loud Noise/US)

Lever RewardHabituate Noise

Lever + Light?

US

Response

CS S-R

Association

S-S

Association

After Conditioning

• After learning, what happens when you

present the CS alone?

Extinction

What happens in extinction?

• What do we (researchers) see?

– No CR = Forgetting?

– Excitatory and Inhibitory Associations (Pavlov)

• CC

• Extinction

Human eyeblink conditioning and the reduction in responses during extinction.

Extinction = Forgetting?

• Spontaneous Recovery

– Pavlov: Inhibitory connections are weak, fade

– Alt. Theory: Attention/Interest in CS (habituation?)

Human eyeblink conditioning and the reduction in responses during extinction.

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Extinction = Forgetting?

• Disinhibition

– Surprising, typically arousing, new stimulus

– Return of CR (akin to sensitization)

• Rapid Reacquisition

– Retraining vs. Original Conditioning

– Something is retained

Extinction is NOT Forgetting

Compound Conditioning

• Context, Multiple Cues

– Extinction: “respond” and “don’t respond”

• Overshadowing

– Salience

Error Correction

• Problems with Aristotle’s contiguity

• Informational value of cues

• Kamin’s (1969)

Compound

conditioning

Rescorla-Wagner (1972)

• Learning on Trains

– Contiguity is not enough

• Competition for associative strength

• Prediction Error

– Positive vs. Negative prediction errors

– Error-correction learning

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R-W in Humans

• Error Correction in Human Category Learning

– Bower & Trabasso, 1964

• Informational value of dot

Modelling Conditioning

• Associative Weights

– Connectionist Models (e.g., McClelland & Rumelhart)

Pay Attention!

• Exposure to CS alone retards later learning

– Attention to stimuli

– Latent inhibition

• Lubow & Moore (1959)

– Sheep and Goats

• Where is the surprise?

– US Modulation Theory

• Prediction error (Rescorla & Wagner, 1972)

– CS Modulation Theory

• Attention to stimuli (Mackintosh, 1975)

Properties of C Conditioning

• It takes time

– 4-5 mo., no eyeblink conditioning in

first block but exposure necessary for

later learning.

• Other Factors

– Intensity of CS-US

– Timing, ISI

Ivkovich et al., 1999

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Intensity of CS-US

• Faster and More effective

US Intensity

Decreased

US Intensity

Maintained

Timing, ISI

• Timing is critical!

– Ideal ISI for rapid learning

– Humans = AnimalsPavlov observed no CRs

with Backward

Conditioning: CS does not

predict US.

Animals must be learning

association AND temporal

contiguity

Taste Aversion (Garcia Effect)

• Temporal Contiguity

– Food poisoning after a date…

• Belongingness: CS-US pairings.

– Tone + Food Shock or Poison

– (Garcia & Koelling, 1966)

• Neurological basis: gustatory cortex

• Coyotes (Gustavson et al., 1974)

Neural Basis in Mammals

• Cerebellum

– Purkinje cells

• Inhibitory connection to

interpositus nucleus

– Interpositus nucleus

• CR output pathway

• Error correction

• Brain Stem

– Pontine nuclei (CS)

• Specialized sensory processing

– Inferior Olive (US)

• Activates interpositus nucleus and

Purkinje cells

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Neural Bases of CC

A simpler

diagram of

Rabbit

eyeblink

conditioning

Cerebellum

• Electrical activity

• Stimulating the inferior olive

– Even specific tones, lights, etc.

– Substitute for actual US

• CC impaired after damage

Purkinje cells

CS Modulation

• Latent inhibition not explained by RW

• Mackintosh (1975)

– Salience of Sensory cues

– Hippocampus

• Animals without do NOT

show latent inhibition

Back to Aplysia

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CC in Aplysia

1. Aplysia and Eric Kandel

Neural Bases of CC

In the long run,

it’s all just LTP

Proteins

• Two routes to long lasting memory

– Activate CREB-1

• Synaptic growth

– Deactivate CREB-2

• Rapid learning

Addiction and Tolerance

• Homeostasis and compensatory responses

– Environmental cues as CS

• Reducing reliance on drugs?

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