Neural Signaling: Postsynaptic Potentials

1. Neural Signaling: Postsynaptic Potentials Lesson 8

2. Neural Signaling: Within neuron • Electrical signal • Dendrites & soma • postsynaptic potentials (PSP) • passive current • Axon • action potentials (AP) • propagated / regenerated ~

3. Synapse Postsynaptic Potentials Presynaptic neuron Postsynaptic neuron

4. Postsynaptic Potentials - PSPs • Changes in Em • Chemically-gated ion channels • neurotransmitters • PSP characteristics • Graded • Summation • Fast • Decremental ~

5. Post-synaptic Potentials • Generation of PSP • NT binds to receptor • specific ion channels open • ion moves according to gradients • Neural signal • Na+ influx  excitation ( AP) • K+ efflux  inhibition ( AP) ~

6. EPSPs • Excitatory Postsynaptic Potential • Na+ influx • Depolarization (+) • Em becomes more positive • APs more likely ~

7. Record here + EPSP + 0 mV Em - 70 mV AT REST - Time

8. IPSPs • Inhibitory Postsynaptic Potential • K+ efflux • hyperpolarization (-) • Em becomes more negative • APs less likely • similar to EPSPs • EXCEPT opposite ~

9. - IPSP + Em - 70 mV AT REST - Time

10. Integration: Summation • Temporal summation • repeated stimulation at same synapse(s) • Spatial summation • stimulation from multiple synapses • EPSPs & IPSPs summate • a maximum for both ~

11. + Temporal Summation + • Repeated stimulation • same synapse ~ 0 mV Em - 70 mV AT REST - Time

12. + Temporal Summation + more depolarization 0 mV Em - 70 mV AT REST - Time

13. + + Spatial Summation + • Multiple synapses 0 mV Em - 70 mV AT REST - Time

14. EPSPs & IPSPs summate • Net stimulation • EPSPs + IPSPs = net effects • Integration • net effects = decision • excitation • inhibition •  or  action potentials ~

15. + - + - EPSP IPSP - 70 mV

16. EPSP Excitatory Depolarization Na+ influx AP more likely IPSP Inhibitory Hyperpolarization K+ efflux AP less likely Postsynaptic Potentials • Soma & Dendrites • Chemically-gated channels • Passive current • Graded • Summation