Problem 4 Flashcards
Classical conditioning/
Pavlovian Conditioning
Refers to a form of learning in which one stimulus predicts an upcoming event
ex.: doorbell predicts the delivery of food
Unconditioned stimulus
US
Refers to a stimulus that evokes a response naturally
–> occur unconditionally without prior training
ex.: FOOD –> evokes hunger
Unconditioned response
UR
Refers to a natural response to the natural occurring stimulus (US)
–> occur unconditionally without prior training
ex.: food –> HUNGER
Conditioned stimulus
CS
Refers to a cue that is paired with an US and comes to elicit a conditioned response (CR)
ex.: BELL –> food
Conditioned response
CR
Refers to a trained response to a CS in anticipation of the US
ex.: SALIVATION –> in anticipation of food
Appetitive conditioning
Refers to conditioning in which the US is a POSITIVE event
–> learning to predict something that satisfies a desire or appetite
ex.: food, sex
Aversive conditioning
Refers to conditioning in which the US is a NEGATIVE event
–> learning to avoid or minimize the consequence of an expected aversive event
ex.: shocks etc
Sexual conditioning in male Quails
Experiment
Male quails were conditioned to approach + remain near a light (CS) which was associated with access through a door to a sexually receptive female (US)
Odor Conditioning in flies
Experiment
Flies were first put in a container with an odor were they were shocked, then in a container with another odor where they weren’t shocked
–> they were then placed in a container with both odors to the left and to the right
Eyeblink conditioning
Presenting a tone which ultimately predicts an air puff to the eye.
This elicits an anticipatory defensive response by blinking the eyes before the arrival of the air puff
–> aversive conditioning
In which way is the eye blink being an UR different from being a CR ?
The learned CR takes place BEFORE the onset of the US, therefore protecting the eye from the air puff
–> the UR would take place AFTER the arrival of the US, as one wouldn’t be expecting the US
Conditioned compensatory responses
Refers to an automatic response that the body experiences + that is opposite of the effects of the drug to reach a state of HOMEOSTASIS
- -> elicited by situational cues (CS)
- -> partially mediate
a) tolerance
b) withdrawal distress
c) relapse
Tolerance
Refers to a decrease in reaction to a drug, so that larger doses are required to achieve the same effect
Extinction
Refers to the process of reducing a learned response to a stimulus by ceasing to pair the stimulus with a reward/punishment
–> even though one might not respond to the CS, the learned response isn’t gone, just unexpressed
ex.: stop delivering food when bell is rung
What is evidence for the fact that the original CR isn’t lost during extinction ?
- If a long time passes before new testing, one will react with the old CR when presented with CS
- Previously extinguished CS is learned more rapidly than a novel CS
Compound conditioning
Refers to conditions when 2 cues occur simultaneously in a conditioning experiment, and therefore compete with each other
Overshadowing
Effect that occurs when a more salient cue within a compound acquires more association, and is therefore more strongly conditioned due to
a) salience
b) temporal priority
–> assuming cues are both valuable in info
Blocking effect
Classical conditioning occurs only when a cue is both a useful + nonredundant predictor of the future
ex. : if I have Doris to predict the stock market correctly, I don’t need Hermann to do the same
- -> I will therefore ignore him, no learning
Which characteristics does a stimulus have to have in order to become associated with a US ?
a) reliable
b) useful
c) bonredundant
Rescorla-Wagner model
States that changes in the CS-US associations on a trial are driven by the Prediction error
expects that CS-US association increases proportional to the degree that the US is surprising
–> the larger the error, the greater the learning
FORMULA:
Occurrence of US – Expectation of US based on CS
Prediction Error
Refers to the difference between what was predicted and what actually occurred
Error correction learning
Method in which the errors on each trial lead to small changes in performance that seek to reduce the error on the next trial
Associative weight
Refers to a value representing the strength of association between the cue/CS and the US
–> CSs in a compound experiment will compete for associative weight
=> “How good can I associate/ predict a US by the use of CS ?”
Blocking in the Rescorla-Wagner model
- Repeated pairing of a tine with the air puff
- Presenting the tone + light with the air puff
- -> blink in response due to output of tone
BUT: output of light remains 0.0 as tone already predict air puff perfectly, is therefore sufficient
- Presenting light alone will result in no blink response, due to no learning
Contingency of the potential CS + US
Why is it important ?
Refers to the degree of correlation between CS + US
–> if US occurs just a s often without the tone as it does in the presence of the tone, little - no conditioning will occur
Experimental chamber
Refers to the context/ background stimuli that are relatively constant on all trials
ex.: sound, smell, feelings
Latent inhibition
Refers to a reduction on learning about a stimulus (CS) to which there has been prior exposure without any consequence
- -> impaired learning following cue pre exposure
- -> contradicts Rescorla-Wagner model
ex.: Bell without food being delivered
US modulation theory
States that the manner in which the US is processed determines what stimuli become associated with the US
ex.: Rescorla-Wagner model
CS modulation theory
States that the way ATTENTION to different CSs is modulated (increased/decreased) determines which of them become associated
–> paying attention to one stimulus diminishes our ability to attend to others
Cerebellum
Involved in coordinating motor activities + learning new motor skills
–> small lesions can permanently prevent the acquisition of new classically conditioned responses
Cerebellar cortex
Top-main region of the cerebellum that contains 3 layers
a) Molecular layer
b) Purkinje layer
c) Granule layer
- -> connects to deep nuclei + vestibular nuclei
- -> contains Purkinje cells
Purkinje cell
Large, drop shaped, densely branched neurons that synapse on + inhibits
a) deep nuclei
b) vestibular neurons
- -> located in cerebellar cortex
- -> only cell that has axons leaving the cerebellar cortex
Interpositus nucleus
One of the cerebellar deep nuclei
–> inhibits the inferior olivary nucleus
CS input pathway
- Pontine nuclei
- -> have subregions for each kind of sensor stimulation - Mossy fibers, synapse on granule cells which branch in 2 directions
a) interpositus nucleus
b) cerebellar cortex to connect to purkinje cells
- Purkinje cells form an inhibitory synapse with interpositus nucleus
US input pathway
Air puff travels to
- Inferior olive, which branch in 2 directions
a) Interpositus nucleus
b) cerebellar cortex by means of climbing fibers to connect with purkinje cells
- Purkinje cells form an inhibitory synapse with interpositus nucleus
What confirms that the cerebellum is responsible for CRs ?
The lack of interpositus activity in the US alone trials
–> no CR = no interpositus activity
Why do Purkinje cells decrease their firing in response to a CS ?
Because they have an inhibitory effect on the interpositus nucleus
Homeostasis
Refers to the tendency of the body to gravitate toward a state of equilibrium/balance
Situational Cue/stimuli
Act as CS associated with the drug (US)
–> related to withdrawal distress
ex.: place, people, etc.
Why are a lot of long time drug addicts found dead due to overdose in settings like a hotel room ?
When in a novel setting, the body will not expect a drug influx, and therefore won’t use the compensatory mechanisms necessary to survive a drug doses this high
–> one is usually projected from overdose by the conditioned tolerance learned during the administration of lower doses in the same setting
How can Classical conditioning aid to reduce medication ?
By first pairing the drug with a certain cue like odor or taste, then gradually only giving the cue
–> the presentation of the cue will still elicit the compensatory mechanisms to work
Withdrawal distress
Compensatory mechanisms make themselves felt, when encountering a CS even with the absence of the drug
–> related to the occurrence of situational stimuli previously associated with drug administration
How can the likelihood of relapse be reduced ?
Repeated presentation of the CSs without the drug or with less than the usual amount of the drug
= EXTINCTION
–> this way drug-associated stimuli (CS) are prevented form eliciting craving/withdrawal
How is the cerebellum connected to the brain stem ?
By 3 peduncles
- Superior peduncle
- -> connects it to midbrain - Middle peduncle
- -> largest, connects to pons - Inferior peduncle
- -> medulla
Cerebellar deep nuclei
Represent all of the output from the cerebellum
- -> contain the interposed nuclei
- -> located dorsal to cerebellar cortex
Whch 2 types of axons enter the cerebellum ?
- Mossy fibers
- Climbing fibers
–> both have collateral branches that synapse on + excite the deep nuclei
BUT: have different effects + terminations on the cerebellar cortex
Mossy fibers
- Arises from all cerebellar inputs except ION
- Releases glutamate (excitatory)
- Each synapses on a group of granule cells + excites them
- Granule cells in turn excite Purkinje cells
Climbing fibers
- Arise from the Inferior olivary nucleus
- Releases Aspartate (excitatory)
- Synapse directly on the Purkinje cells + excite them
Granule cells
Run toward molecular layer where they divide into a “T”
–> receive all of their input from mossy fibers
Parallel fibers
Refer to the axonal extensions of granule cells, with each fiber making single synapses on hundreds of thousands of Purkinje cells
Why is it critical for the correct amount of inhibition to arrive at the deep nuclei (Interpositus nucleus) ?
So that an appropriate output is produced, by inhibiting unwanted activity in the deep nuclei
ex.: when creating a sculpture, the unwanted parts of stone are removed to create a pattern
Expectancy change (EC)
How reliably can the CS predict the US
FORMULA:
Prediction Error x Learning Rate
Expectation of US
Formula ?
FORMULA:
Pre EC + New EC
(Cue1 + Cue2) –> when compound conditioning
Mackintosh Model
People have limited capacity for info processing, therefore attention to one stimulus reduces the ability to pay attention to another
–> eventually the stimuli are ignored because they don’t reliably predict that anything bad/good is about to happen
=> explains latent inhibition
What are the main regions of the Cerebellum ?
- Cerebellar cortex
- Deep nuclei
- -> Nucleus Intepositus - Brain stem
- -> contains Pontine + Inferior Olivary Nucleus
Why is there increased inhibition of the Inferior Olivary nucleus by the Interpositus nucleus ?
Because with learning, we don’t need the US anymore to evoke a response
Primary + secondary memory trace
Primary
–> immediate connection to Interpositus nucleus
Secondary
–> connection to cerebellar cortex
