Class Notes (838,906)
Canada (511,142)
Psychology (3,977)
PSYC 2330 (214)
Lecture 8

Tuesday, Oct 2/2012 - Lecture 8

4 Pages
Unlock Document

PSYC 2330
Francesco Leri

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 TegmentalArea ◦ 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 TegmentalArea 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 VTAencode 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 prediction of the presentation of the US) ◦ Between the presentation of the CS and the presentation of the US, the rate of firing does not change • During extinction, dopaminergic neurons fire when the CS is presented, but stop firing completely when no US is presented Pidgeons, Pecking and Food • Auto-shaping • You want to produce a conditioned response – say to peck at a light when the light comes on • Set the computer to turn on the light and then present food • Eventually the animal will peck at the light when it is on even though the pecking does not influence whether or not any food is given • Specific branch of auto-shaping Distinction Between Rats • One group of animals become “sign trackers” • The other group of animals will tend to become “goal trackers” • Some animals, knowing the light is important, will go towards the light first when the light is presented ◦ Go to the sign, then the food • Goal trackers, knowing the food is coming, will go towards the food when the light is presented ◦ Skip going to the sign, go directly to the food • Does that mean that the same system is acting differently in different rats? Microdialysis • Allows us to sample the fluid in the brain • Sampled from the nucleus accumbens within the ventral tegmental area ◦ Nucleus accumbens is the meeting place of the limbic and motor systems (Allows motivated movement) • Measures the amount of dopamine in the brain fluid • Done on rats that were selectively bred to be sign trackers or goal trackers Results of Microdialysis • Measures the amount of dopamine release compared from baseline • In the sign trackers ◦ In the initial stage of conditioning, there is a little response to both the CS and the US ◦ The response to the CS gets bigger and bigger as conditioning continues ◦ The response to the US gets smaller and smaller as conditioning continues ◦ Sign trackers attribute more and more value to the CS as compared to the US (Making the connection between the CS and the US) • In the goal trackers ◦ Never de
More Less

Related notes for PSYC 2330

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.