How are signals transmitted across a chemical synapse?
- Depolarization of the presynaptic neuron by an arriving action potential
- Activation of voltage-dependent calcium (Ca 2+ ) channels, focal entry of intracellular Ca 2+
- Synchronized, quantal vesicular release of neurotransmitter from the presynaptic terminal
- Diffusion of neurotransmitter across the synaptic cleft
- Binding of neurotransmitter to specific receptors on the postsynaptic membrane
- Receptor-mediated ion channel mediation of inhibitory (GABA) or excitatory (glutamate) postsynaptic potentials
- Postsynaptic action potential initiation if the postsynaptic potentials sum to reach activation threshold