Unblocking and schizophrenia Flashcards
(17 cards)
2 ways to unblock according to RW
- Decrease ΣV (remove predictive cues).
- Increase the value of λ (more to learn about).
Dickinson et al. (1976) changing US and RW model
Both an increase and decrease in outcome (US) renewed attention to CS. Learning unblocked by change in reward (violating prediction of RW).
McDannald et al. (2014) unblocking through valueless change
Learning unblocked just by a change in flavour, even though the subjective value of the reward stayed the same.
OFC responds to feature (not just value) changes. Salience neurons responded to previously trained cue, blocked stimulus, US value, and US stimulus feature. Predictive neurons responded only to predictiveness of outcome (no difference between feature vs. size).
Innate releasing stimuli
Some stimuli can have strong impacts on behaviour without learning.
Tinbergen and Perdeck (1950) importance of parent’s bill for chick pecking behaviour
Baby chicks pecked at a pencil with 3 lines. Movement and contrast were important, but realism and colour were not.
Latent inhibition
Reduced rate of learning about a CS after CS has had repeated exposure with no consequences (stimulus change from being unpredictive to being predictive).
Latent inhibition and habituation
They are not the same. In latent inhibition, animals learn about the cue and its association with a context.
Miller et al. (2015) context specificity of extinction vs. latent inhibition
Context specificity of extinction is stronger than context specificity of latent inhibition. Both are context specific.
Mackintosh (1975) learning and salience
Salience is flexible rather than fixed. Salience (α) increases if CS predicts an otherwise unexpected event and decreases if CS predicts no change. Change in α is positive if CS is a better predictor than others (pay attention to what works).
2 types of salience
- Perceptual salience. (How much the cue stands out).
- Associability. (Learnt salience determined by past experience).
More salient cues are better remembered. A cue that reliably predicts an outcome will gain associability (attention).
Pearce-Hall and salience
Predicts the opposite to Mackintosh. Change in attention positive if it is surprising (pay attention to what is unexpected).
What is amphetamine?
Dopamine agonist. Produces symptoms of schizophrenia.
Treatment for schizophrenia
Antagonising (blocking) dopamine D2 receptors.
Serra et al. (2001) latent inhibition and schizophrenia
Schizophrenic patients show reduced blocking and latent inhibition effects (learning about things that should be irrelevant; increased salience).
Jones et al. (1997) schizophrenia and attention
Schizophrenia patients (and relatives) show enhanced learning to normally unattended stimuli.
Brain region for blocking
Medial frontal gyrus. (Higher activation = worse blocking).
Kutlu et al. (2021) role of dopamine
Dopamine tracks perceived saliency (physical salience + experience).
Dopamine only worked for RPE. In shock conditioning, there was learning but no dopamine signal.
