PSYC 318- Lecture#3

2nd Paper

Methods:

Q: How can we find out when dopamine neurones fire
Q: How can we make neurones glow when they fire action potentials?

GCaMP= 'genetically encoded' calcium indicator

Method GCaMP

Q: How do we determine precisely when genetically-identified dopamine neurones fire?

Overview of Technique

Dopamine Neurone activity is detected during juice reward consumption

Dopamine neurones are active during social interactions

Dopamine neurones are also active in interactions w. novel objects

Dopamine neurone is diff. between social & novel object interactions ( but dopamine neurones in midbrain are active in both )

Does stimulation of dopamine neurones promote social interactions?

Optogenetics

How Optogenetics Works #1

How Optogenetics Works #2

Does optical exciting dopamine neurones promote social interactions?

Optical stimulation of dopamine neurones promotes social interactions & optical inhibition of dopamine neurones dec. social interactions

Dopamine neurones project to many diff. place. Which pathway is driving this effect?

Immediate Early Genes ( IEGs ) a.k.a. Activity-Dependent Genes)

VTA stimulation -> downstream cFos quantification

Dopamine neurone stimulation causes cFOS expression in 2 places

Which dopamine neurone projection promotes social interactions NAc or PFC?

Shining light into NAc will activate all axons there that have ChR2 #1

Shining light into NAc will activate all axons there that have ChR2 #2

Summary of social interaction manipulations

Optical stimulation of dopamine axons in PFC causes a conditioned place preference aversion

Optical stimulation of dopamine neurones in PFC promotes an "anxiety-like" effect

stimulation of dopamine neurones projecting to PFC

stimulation of dopamine neurones projecting to NAc

Do NAc projecting neurones selectively fire during social interactions?

If dopamine release in NAc promotes social behaviour, what receptors there are important

Dopamine neurones release dopamine, glutamate, & GABA- how do you know D1 receptor is sufficient?

Dopamine D1 receptor activation in NAc is sufficient to inc. social interactions

Is an increase in firing of dopamine D1 receptor-containing NAc projection neurones sufficient to promote social interactions?