1. Neuro Unit 5: How do our choices change our brains?
Unit 5.2: Drugs of abuse alter synaptic transmission

2. Do Now:
Addictive drugs increase synaptic transmission in the reward pathway. Brainstorms ways that drugs could increase synaptic signaling.

3. The Brain’s Reward Circuit
Human Brain
Rat Brain
PFC
NAc
VTA

4. The Brain’s Reward Circuit
Prefrontal Cortex
VTA
NAc

5. Synaptic Transmission
2. Voltage-gated Ca2+ channels open.
Ca2+ flows into cell
3. Ca2+ sensitive proteins fuse synaptic vesicles to membrane, releasing dopamine into synaptic cleft
4. Dopamine binds to postsynaptic receptors.
Ca2+
1. Action Potential in VTA
Dopamine
6. Excess dopamine is pumped back into presynaptic cell.
5. Ion channels open on postsynaptic membrane, allowing ions to flow into cell.

6. How do drugs of abuse alter synaptic transmission???

7. The Reward Pathway
Inhibitory
Neuron
Prefrontal Cortex
VTA
NAc

8. VTA NAc Inhibitory Neuron Prefrontal Cortex Alcohol Heroin & Morphine
Nicotine Marijuana
NAc
Cocaine & Amphetamines
Heroin & Morphine

9. Alcohol Heroin & Morphine
Inhibitory Interneuron
Alcohol Heroin & Morphine
Ca2+
Dopamine

10. Inhibitory Interneuron VTA
Nicotine & Marijuana
Ca2+
Dopamine

11. VTA
NAc
Heroin & Morphine
Ca2+
Dopamine
Cocaine & Amphetamines

12. Site of action in reward pathway
Drug
Site of action in reward pathway
Drug Target (Receptor, Reuptake pump, etc.)
Effect on VTA action potentials
Effect of dopamine release and/or dopamine
Effect on NAc action potentials
Cocaine
VTA
Dopamine reuptake pump
None
Increase dopamine levels
Increase
Amphetamine
Nicotine
Nicotinic receptors
Increase dopamine release & levels
Alcohol
Inhibitory interneuron
GABA receptors
Heroin & Morphine
Inhibitory interneuron & NAc
Opiate receptors
Marijuana
Cannabinoid receptors