Neural Signaling: Postsynaptic Potentials Lesson 9

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

Postsynaptic Potentials Presynaptic neuron Postsynaptic neuron Synapse

Postsynaptic Potentials - PSPs n Changes in E m n Chemically-gated ion channels l neurotransmitters n PSP characteristics l Graded l Summation l Fast l Decremental ~

Post-synaptic Potentials n Generation of PSP l NT binds to receptor l specific ion channels open l ion moves according to gradients n Neural signal l Na + influx excitation ( AP) l K + efflux inhibition ( AP) ~

n Excitatory Postsynaptic Potential n Na+ influx n Depolarization (+) l E m becomes more positive l APs more likely ~ EPSPs

0 mV - 70 mVAT REST EmEm Time EPSP + - Record here +

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

- 70 mVAT REST EmEm Time IPSP + - -

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

Temporal Summation n Repeated stimulation n same synapse ~ + AT REST Time mV - 70 mV EmEm

Temporal Summation more depolarization + AT REST Time mV - 70 mV EmEm

Spatial Summation + n Multiple synapses + AT REST Time mV - 70 mV EmEm

EPSPs & IPSPs summate n Net stimulation l EPSPs + IPSPs = net effects n Integration l net effects = decision l excitation l inhibition n or action potentials ~

- 70 mV EPSP IPSP +

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