Anitcipatory nausia and vomiting Flashcards
What is anticipatory nausea and vomiting (ANV)?
Anticipatory nausea and vomiting (ANV) is a learned or conditioned response. It appears to be the result of previous experiences with a stimulus which led to nausea and vomiting, in which the brain pairs some parts of the treatment such as the sights, sounds, and smells of the stimulus with vomiting. Anticipatory nausea and/or vomiting can happen before or during treatment is given.
Classical conditioning type of learning
How frequent ANV is in chemotherapy patients?
Roscoe et al (2011)
~20% after any 1 chemo cycle
~25-30% after their 4th cycle of chemo
Probably increases with the number of cycles
Unconditioned stimulus (US)
The stimulus that is related to the unconditioned response.
e.g. ‘food’
Will be paired with something which later becomes (CS).
Naturally casues a response e.g. salivation.
Conditioned stimulus (CS)
Stimulus related to conditioned response. It is the thing paired with unconditoned stimulus. This will be a neutral thing which doesn’t evoce a resposne on its own –> initially neutral, acquires meaning and relevance through pairing with US.
Conditioned response (CR)
The response evoced by the conditioned stimulus. It is usually the same type of response as unconditional resposne but it is a result of seeing something which on it’s own doesn’t normalny casue this resposne (e.g. bell doesn’t usually casue salivation).
After pairing of CS + US this resposne is casued by CS.
Unconditioned response (UR)
A natural response to unconditoned stimulus (e.g. salivation).
Error driven learning
Error prediction is central to the Rescorla-Wagner model. The bigger the error (what we expect to occur vs what really happens) the larger the surprise and the greater the learning.
Rescorla-Wagner equation
ΔV = αβ(λ – ΣV)
Asymptotic learning
Salience
How attention grabbing outcome or stimulus is.
The learning is faster when the stimuli is more salient.
Contingency
The strength of pairing of the CS with the US. The extent to which knowledge of one event increases certainty about another event.
e.g. if US always follows CS the learning will be faster (high contingency) vs when US follows only 50% of time or if there is a substential delay in the US occuring.
Temporal contiguity
How closely the US follows the CS
Overshadowing
Occurs when conditioning takes place with one stimulus that is more salient than other stimuli. Salient stimulus overshadows other stimuli.
Possible becasue US is able to support a fixed associatevie strength. So when only 1 thing (CS) is paired with US the associative strength is 1. But when 3 CSs are paired with US the a.s. is 0.33
Can be an effective way to prevent ANV.
Classical conditoning
Occurs when we learn to predict the occurance of an event (after 2 stimuli are paired= most important part )
First demonstrated in experiment by Pavlov (end of 19th century) in dogs.
What is Retrospective Revaluation?
Used by Rescorla (1974) in experiment showing classical conditioning.
It is the manipulation of US AFTER conditioning took place and observing the reactions to CS.
Rescorla (1974) in experiment showing classical conditioning.
- Rats take a weak shock (weak US).
- They stop lever pressing for food.
- CS is paired with US so conditioning= learning can occur.
- CS results in CR = the conditioning is observed to have taken place.
- US shock is stronger but CS is absent.
- CS is presented to rats again so see what will happen.
- CS produses stronger CR (more freezing) than obseved initially in point 4.
==> US was revaluated
==> CR is mediated by the CS-US learned association
+ CR can be influenced by experiences outside of the original learning trials.
