Postsynaptic effect of neurotransmission

Action potential isn't produced by postsynaptic terminal right away
1. Result can be graded potentials that increase or decrease likelihood of an action potential being produced
NT receptors can open ion channels to produce an excitatory presynaptic potential (EPSP)
1. Via Na+ influx (depolarisation)
Integrating EPSP & IPSP
1. EPSP & IPSPs travel along dendrite to membrane
  1. Action potentials aren't produced here
    1. No voltage-gated Na+ & K+ channels
2. Graded potentials must reach axon hillock
  1. So EPSP can produce action potential
NT receptors can open ion channels
1. Produce Excitatory Postsynaptic Potential (EPSP) via Na+ influx (depolarisation)
2. Inhibitory Postsynaptic Potential (IPSP) produced via Cl- influx or K+ efflux (hyperpolarisation)
Summation
1. Neuron can have >50,000 connections to others
  1. Can receive enormous No. of EPSP & IPSP in space & time, which must be integrated
2. Temporal
  1. Graded potentials that occur at approx same time on membrane
    1. Summed & produce large EPSP or IPSP
3. Spatial
  1. Graded potentials that occur at approx same place on membrane
    1. Summed
  2. Action potential produced when enough EPSPs sum to reach activation threshold
IPSP
1. Inhibits generation of action potentials
  1. Because inhibition stabilises responses, control timing of signals, prevent too much electrical firing

Zusammenfassung der Ressource

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