L06-Neurotransmitters - Neurotransmitters and Receptors...

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2/6/07 Neurotransmitters and Receptors Postsynaptic Potentials o EPSP Excitatory Increases probability that neuron will fire an action potential Sodium ion Axon hillock (spike initiating zone; voltage-gated sodium channels found here) reaches threshold; action potential is triggered in postsynaptic axon o IPSP Inhibitory Decreases probability that neuron will fire an action potential Efflux of Potassium ions or influx of Chloride ions Counteract EPSPs; action potential is not triggered Two kinds of integration o Temporal summation A single input fires rapidly, raising the postsynaptic potential above threshold o Spatial summation Many inputs fire simultaneously (or nearly so) Neurotransmitter Inactivation o Two mechanisms: ways to inactivate the neurotransmitter Reuptake: neurotransmitter binds to postsynaptic cell; taken back up into presynaptic; recycled and reused; presynaptic neuron or glia cells clear the space; active transport used bring back up into the presynaptic cell Enzymatic Degradation: chemical in cleft that breaks down neurotransmitter; effect of neurotransmitter wears off; enzymes made by
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This note was uploaded on 04/09/2008 for the course PSYC 220 taught by Professor Brunges during the Spring '07 term at UVA.

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L06-Neurotransmitters - Neurotransmitters and Receptors...

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