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Lecture 8

PSYC 2330 Lecture Notes - Lecture 8: Nucleus Accumbens, Dopaminergic, Limbic System


Department
Psychology
Course Code
PSYC 2330
Professor
Francesco Leri
Lecture
8

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Tuesday, October 2
PSYC 2330
Lecture 8
Midterm next Thursday
Neurobiology of Prediction Error
Dopamine is a neurotransmitter involved in learning, motivation and a variety of
psychobiological functions
Agonists include cocaine, amphetamine, methylphenidate, riddelin
Antagonists include chlorpromazine, haloperidol (anti-psychotic drugs)
Every time there is a problem in prediction (the subject predicts something and it doesn't come
true or the subject is not predicting something and something important happens) the organism
The organism learns when there is a discrepency between the organism's previous knowledge
and what is occuring currently in the situation
In this case we are discussing the unconditional stimuli
The brain has centers that allow us to detect biologically significant stimuli
Cells that produce dopamine are found in the midbrain
Two clusters
Ventral Tegmental Area
Substantia Nigra
Dopamine from this region is sent to the striatum
The nigra-striatal pathway is damaged in Parkinson's disease
The Meso-[cortico]-limbic dopamine pathway
Transfers dopamine to the limbic system and to the frontal cortex
This pathway is influenced in individuals with schitzophrenia
Antipsychotic drugs block the dopamine receptors so they cannot have as much effect
Dopamine is implicated in schitzophrenia
The result of two much dopamine is psychosis
Hearing voices etc...
Drugs that increase dopamine activity in the brain produce a temporary psychosis resembling
positive symptoms of schitzophrenia
Heroin does not reduce dopamine
When dopamine neurons are firing, they are releasing dopamine to their connected areas
Wolfram Schultz
Recorded neurons in the Ventral Tegmental Area of monkeys that are awake
US = Drops of juice
UR = Licks
CS's included a variety of visual stimuli
The idea is to pair a single CS with US to create a CR and then record what happens in the
brain
Dopaminergic Neurons in the VTA encode a Prediction Error
Prior to conditioning, dopaminergic neurons were fired rapidly at the presentation of the US
After conditioning, dopaminergic neurons fire rapidly at the presentation of the CS (in
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