1. Neural Communication Signaling within a neuron

2. Postsynaptic Potentials n E m changes dendrites & soma n Excitatory: + n Inhibitory: - ~

3. Postsynaptic Potentials - PSPs n Chemically-gated ion channels n Graded Summation n Fast n Decremental ~

4. n Excitatory Postsynaptic Potential n Depolarization (+) E m becomes more positive n Na+ influx ~ EPSPs

5. -65mv - 70mvAT REST EmEm Time EPSP + - n *Depolarization more likely to fire ~ Record here +

6. -65mv - 70mvAT REST EmEm Time *Temporal Summation + - n Repeated stimulation n same synapse ~ +

7. -65mv - 70mvAT REST EmEm Time + - *Temporal Summation more depolarization +

8. -65mv - 70mvAT REST EmEm Time + - *Temporal Summation more depolarization +

9. -65mv - 70mvAT REST EmEm Time + - *Spatial Summation + n Multiple synapses +

10. n Inhibitory Postsynaptic Potential n similar to EPSPs EXCEPT opposite n hyperpolarization (-) l E m becomes more negative n K+ efflux ~ IPSPs

11. - 70mvAT REST EmEm Time IPSP + - n *Hyperpolarization less likely to fire also summate (max) -

12. EPSPs & IPSPs summate n CANCEL EACH OTHER n Net stimulation l *EPSPs + IPSPs = net effects ~

13. - 70mv + - - EPSP IPSP +

14. ExcitatoryInhibitory DepolarizationHyperpolarization Na+ influxK+ efflux or Cl- influx more likely to fireless likely ~ EPSP IPSP

15. -70mV EPSP IPSP threshold toward threshold away from threshold

16. Action Potentials n Large and rapid change in membrane potential n electrically-gated channels n EPSPs l threshold potential n Occurs in axon triggered at axon hillock ~

17. AP Characteristics n Voltage-gated channels n All or none n Slow n Non-decremental n Self Propagated l regenerated ~

18. -70 -60 0 +40 -80 Time Depolarization Na+ influx C & E gradients drive Na+ into cell

19. Na+ K+ pos neg axon outside DEPOLARIZATION

20. Na+ K+ Na+ axon outside DEPOLARIZATION neg pos

21. -70 -60 0 +40 -80 Time Depolarization Na+ influx = 110 mV Amplitude - 70 mV to +40 mV

22. -70 -60 0 +40 -80 Time Repolarization K+ efflux

23. Na+ K+ Na+ axon outside REPOLARIZATION neg pos

24. Na+ axon outside K+ REPOLARIZATION pos neg

25. -70 -60 0 +40 -80 Time After- hyperpolarization

26. Na+ axon outside K+ AFTER-HYPERPOLARIZATION K+ pos neg

27. Refractory Period n after AP won’t fire again relative & absolute n Relative during after hyperpolarization requires greater depolarization ~

28. Absolute refractory period n Na+ channels deactivate will not trigger AP must reset n Ball & Chain Model ~

29. Na+ channel deactivation

30. Saltatory Conduction n Myelinated neurons l oligodendroglia & Schwann cells n Transmit long distances l APs relatively slow, regenerates l EPSPs - fast, decremental n Saltatory: combines both types of current l speed without loss of signal ~

31. Saltatory Conduction n Nodes of Ranvier l action potentials n Myelinated l like electricity through wire l decremental but triggers AP at next node l Safety factor - trigger AP across 5 nodes ~

32. Saltatory Conduction

33. Presynaptic Modulation n Modifying PSP by influencing presynaptic neuron n Presynaptic inhibition  amount of NT released n Presynaptic inhibition  amount of NT released n Effect on activity of postsynaptic neuron l depends on nature of synapse ~

34. Excitatory Synapse n A active n B more likely to fire n Add a 3d neuron ~ A B + Presynaptic Inhibition

35. Excitatory Synapse n axoaxonic synapse n C is inhibitory ~ A B + Presynaptic Inhibition C -

36. Excitatory Synapse A B + Presynaptic Inhibition C - n C active n less NT from A when active n B less likely to fire ~

37. A B Presynaptic Inhibition C - n C active n more NT from A when active n B more likely to fire ~ Inhibitory Synapse -

38. Excitatory Synapse A B + Presynaptic Facilitation C + n C active (excitatory) n more NT from A when active n B more likely to fire ~

39. A B Presynaptic Facilitation C - n C active n more NT from A when active n B even less likely to fire ~ Inhibitory Synapse - C +