Pavlovian (Classical) Conditioning

Example: “Bell” and Food

CS

US

URCR

Later Trials

CS

US

UR

First Few Trials

Time

CS = bellUS = foodUR = salivation

CR = salivation

Central Players

Conditioned Stimulus (CS)

Unconditioned Stimulus (US)

Initially “potent” – Initially elicits a response (inside or outside)

Initially “neutral” – Does not initially trigger same response as does the US

Lights, sounds, tastes, odors, etc.

After pairings with the US, elicits a conditioned response

Food USPositive Emotion (inside and hidden)Salivation (outside and observable)

Early Experiments

• Stefan Wolfsohn:– Dog learns to salivate at the sight of sand

before it is placed in the dog’s mouth

• Anton Snarsky:– Dog learns to salivate at the sight of black

liquid (acid) before it is placed in the dog’s mouth (Pavlov’s interpretation: “higher thinking!”)

1.What are the CS and US?

• A pigeon pecks a light that signals the presentation of food

Autoshaping (Sign Tracking)

When a localized CS and a “pleasurable” US are paired, a CR is sometimes directed at the CS.

PigeonsCR: peck key light CS

Rats

key light CS food US

insert lever CS food USCR: lick lever

Not Reward (Instrumental) Learning

• Long-box autoshaping

• Omission training

Form of the CR in Sign Tracking

From Jenkins & Moore, 1973

US = Water (note the closed beak)

US = Food (note the open beak)

video

Conclusions

• 1. Conditioned behaviour is “evoked” by the CS, it is not “chosen” by the organism

• 2. The situation, species, and procedures used can affect whether animals approach the CS or the US in appetitive conditioning.

2. What are the CS and US?

• An addict goes into severe withdrawal after seeing the dealer’s door

Drug Conditioning Trial 1

Euphoria

Dealer, copping corner, corner syringes, needles, cotton balls, lighters, rubber tying-off cords and stainless-steel spoons

Pre-Drug CSs Drug US

heroin

Trial 2

heroinEuphoria

Pre-Drug CSs

Dealer, copping corner, corner syringes, needles, cotton balls, lighters, rubber tying-off cords and stainless-steel spoons

Pre-Drug CSs Drug US

Trial 10

heroinEuphoria

Dealer, copping corner, corner syringes, needles, cotton balls, lighters, rubber tying-off cords and stainless-steel spoons

Pre-Drug CSs Drug US

Overdose and Death

heroinNew Context

Pain tolerance

Opioid-induced unconditioned

hypoalgesia

Opioid-induced hyperalgesiaOpioid administration

Opioids and Pain Tolerance

Opiate Addiction

Administration

• Hyperthermia

• Decreased Blood Pressure

• Skin Flushed and Warm

• Meiosis

• Drying of Secretions

• Respiratory Depression

• Antitussive

• Relaxation

Withdrawal

• Hypothermia

• Increased Blood Pressure

• Chilliness and Gooseflesh

• Mydriasis

• Lacrimination

• Yawning and Panting

• Sneezing

• Restlessness

Some Controlled Experiments

• Mor-ROOM/Sal-CAGE– Morphine in a distinctive room– Saline in the home cage

• Mor-CAGE/Sal-ROOM– morphine in the home cage– saline in a distinctive room

• Saline– saline in both environments

Test: No morphinein the distinctive room

Conditioning Trials

• Acquisition curve

• Non-linear

• Asymptote

Conditioning Trials

CR

Str

engt

h

asymptote

Conditioning Occurs Over Trials

Extinction

Trials/Time

Str

engt

h of

CR

Acquisition Extinction

CS&US CS alone

Extinction of Tolerance

Group Extinction (M-P-M) 6 E-M 6 E-P

Test E-M?Group No Extinction (M-rest-M)6 E-M Rest in home Cage

Rested animalsshow a CR (moretolerant)

Extingished animals(tolerance is undone)

Discrimination

0

0.2

0.4

0.6

0.8

1

1.2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Trials

Re

sp

on

se

Str

en

gth

CS+

CS-

Discrimination: Absence of pre-drug CSs

Heroin Overdose Death Rates

Conclusions

• 3. Conditioned responses can be “compensatory”, bringing the organism back to homeostasis