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Postsynaptic Potentials. Lesson 10. Postsynaptic Potentials. Signaling in Dendrites & Soma V m changes dendrites & soma Excitatory: + Inhibitory: - ~. Postsynaptic Potentials - PSPs. Chemically-gated ion channels Graded Summation Duration 10 – 100 milliseconds
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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 ~
Record here + EPSP + • Depolarization more likely to AP ~ Vm -55 mV - 65 mv AT REST - Time
+ Temporal Summation + • 2 pulses • same synapse ~ Vm -55 mV - 65 mv AT REST - Time
+ Temporal Summation + Repeated stimulation Vm -55 mV - 65 mv AT REST - Time
+ + Spatial Summation + • Multiple synapses Vm -55 mV - 65 mv AT REST - Time
IPSPs • Inhibitory Postsynaptic Potential • similar to EPSPs • EXCEPT opposite • hyperpolarization (-) • Vm becomes more negative • K+ efflux ~
- IPSP + • 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
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