1. Dopamine (DA) neuron Cell body (Soma) terminals axons Dendrites

2. Dopamine (DA) neuron Cell body (Soma) terminals axons Most information comes in here Dendrites

3. Dopamine (DA) neuron Cell body (Soma) terminals axons Chemical signals Generate EPSPs Or IPSPs

4. Dopamine (DA) neuron Cell body (point of origin) terminals axons If excitation caused By EPSPs is great Enough to cross the threshold, An Action Potenial is generated.

5. Dopamine (DA) neuron Cell body (point of origin) terminals axons Action Potentials travel along the axon

6. AXON Towards soma Towards terminals

7. AXON Towards soma Towards terminals Na+ Excitation above the threshold Opens Voltage-gated Na+ channels

8. AXON Towards soma Towards terminals Na+ Na+ ions rush into cell, causing Action Potential (ascending limb) Na+

9. AXON Towards soma Towards terminals Na+ Action Potential is propagated down The Axon Na+ K+ K+ moves out To restore resting Potential (i.e., Descending limb) K+

10. AXON Towards soma Towards terminals Na+ Action Potential is propagated down The Axon Na+ K+

11. AXON Towards soma Towards terminals Na+ Action Potential is propagated down The Axon Na+ K+

12. AXON Towards soma Towards terminals Na+ Action Potential is propagated down The Axon Na+ K+

13. AXON Towards soma Towards terminals Na+ Action Potential is propagated down The Axon Na+ K+

14. AXON Towards soma Towards terminals Na+ Action Potential is propagated down The Axon Na+ K+

15. AXON Towards soma Towards terminals Na+ Action Potential is propagated down The Axon Na+ K+

16. AXON Towards soma Towards terminals Na+ Action Potential is propagated down The Axon Na+ K+

17. AXON Towards soma Towards terminals Na+ Action Potential is propagated down The Axon Na+ K+

18. AXON Towards soma Towards terminals Na+ Action Potential is propagated down The Axon Na+ K+

19. AXON Towards soma Towards terminals Na+ Action Potential is propagated down The Axon Na+ K+

20. Dopamine (DA) neuron Cell body (point of origin) terminals axons Action Potentials travel along the axon

21. Dopamine (DA) neuron Cell body (point of origin) terminals axons

22. Dopamine (DA) neuron Cell body (point of origin) terminals axons

23. Dopamine (DA) neuron Cell body (point of origin) terminals axons

24. Dopamine (DA) neuron Cell body (point of origin) terminals axons

25. Dopamine (DA) neuron Cell body (point of origin) causing neurotransmitter release from the terminals axons..............................

26. Dopamine (DA) neuron Cell body (point of origin) causing neurotransmitter release from the terminals axons..............................

27. Stages of Synaptic Transmission SYNTHESIS- neurotransmitter is produced by enzymes STORAGE- stored in vesicles RELEASE- released into the synapse POSTSYNAPTIC ACTION- acts on postsynaptic receptors INACTIVATION- broken down by enzymes or taken up into cells

28. DA terminal Postsynaptic cell Synaptic cleft 1.Transmitter is synthesized from a precursor molecule by enzymes in the presynaptic cell SYNAPSE: Point of functional connection

29. DA terminal Postsynaptic cell Synaptic cleft 2. Transmitter is stored in presynaptic vesicles SYNAPSE: Point of functional connection

30. DA terminal Postsynaptic cell Synaptic cleft Electrical impulse “action potential”

31. DA terminal Postsynaptic cell Synaptic cleft

32. DA terminal Postsynaptic cell Synaptic cleft Ca++ 3. Release. Action Potential opens voltage- Gated Ca++ channels

33. DA terminal Postsynaptic cell Synaptic cleft Ca++ 3. Release. There is an influx of Ca++ into the terminal

34. DA terminal Postsynaptic cell Synaptic cleft..... 3. Ca++ influx promotes several processes that lead the vesicles to go from a pre-release state into a fusion with release sites on the membrane. Transmitter is released.

35. DA terminal Postsynaptic cell Synaptic cleft...... Transmitter diffuses across synaptic cleft...

36. DA terminal Postsynaptic cell Synaptic cleft...... Transmitter diffuses across synaptic cleft....

37. DA terminal Postsynaptic cell Synaptic cleft...... 4. Postsynaptic Action. a) Transmitter binds to postsynaptic receptors DA Receptor proteins...

38. DA terminal Postsynaptic cell Synaptic cleft Physiological and biochemical effects (EPSPs or IPSPs) 4. Postsynaptic Action. b) Transmitter binding induces intrinsic biological activity (i.e. signal transduction effects) in postsynaptic cell....

39. DA terminal Postsynaptic cell Synaptic cleft 5. Inactivation. a)Transmitter is transported back into presynaptic terminal by protein transporter (i.e., uptake or “reuptake”)....

40. DA terminal Postsynaptic cell Synaptic cleft 5. Inactivation. b) Transmitter is broken down (i.e. “metabolized”) by enzymes...

41. STUDIES OF THE BEHAVIORAL EFFECTS OF DRUGS DRUGS MODIFY THE PROCESS OF CHEMICAL TRANSMISSION IN THE NERVOUS SYSTEM -Alter neurotransmitter synthesis -Block storage of transmitter -Stimulate or reduce release -Stimulate or block receptors -Block the enzymatic breakdown or uptake of transmitter