Postsynaptic Potentials Lesson 10

Postsynaptic Potentials Signaling in Dendrites & Soma Vm changes dendrites & soma Excitatory: + Inhibitory: - ~

Postsynaptic Potentials - PSPs Chemically-gated ion channels Graded Summation Duration 10 – 100 milliseconds Velocity Fast  approximately speed of light Decremental Weaken over time & space ~

EPSPs Excitatory Postsynaptic Potential Depolarization (+) Vm becomes more positive Na+ influx ~

Vm EPSP + + - Record here Depolarization more likely to  AP ~ Time -55 mV - 65 mv AT REST - Time

Vm Temporal + Summation + - 2 pulses same synapse ~ Time -55 mV AT REST - Time

Vm Temporal + Summation + - Time Repeated stimulation -55 mV - 65 mv AT REST - Time

Vm Spatial + Summation + + - Time Multiple synapses -55 mV - 65 mv AT REST - Time

IPSPs Inhibitory Postsynaptic Potential similar to EPSPs EXCEPT opposite hyperpolarization (-) Vm becomes more negative K+ efflux ~

Vm IPSP - + - Time Hyperpolarization less likely to fire also summate (max) Vm -55 mV - 65 mv AT REST - Time

EPSPs & IPSPs summate CANCEL EACH OTHER Net stimulation EPSPs + IPSPs = net effects *Integration ~

+ EPSP IPSP - - 65 mv

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