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. Postsynaptic Potentials
Synapse
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. Em Temporal + Summation + - Repeated stimulation same synapse ~ Time
0 mV Em
- 70 mV
AT REST -
Time

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

13. Em Spatial + Summation + + - Multiple synapses Time 0 mV - 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. Postsynaptic Potentials
Soma & Dendrites
Chemically-gated channels
Passive current
Graded
Summation
EPSP
Excitatory
Depolarization
Na+ influx
AP more likely
IPSP
Inhibitory
Hyperpolarization
K+ efflux
AP less likely