Excitatory and inhibitory chemical synapses

The arrival of an action potential at an axon terminal allows the influx of calcium through voltage-dependent calcium channels (VDCC), which triggers synaptic vesicle (SV) fusion with the plasma membrane releasing neurotransmitter into the synaptic cleft. The main excitatory neurotransmitter is glutamate, which binds to and activates the glutamate ligand-gated ion channel receptors such as NMDA and AMPA receptors that are permeable to sodium and calcium. The main inhibitory neurotransmitter is GABA, which binds to and activates GABAA receptors that are permeable to chloride ions. In a mature central inhibitory synapse the influx of chloride ions causes hyperpolarisation making it less likely that an action potential will fire in a postsynaptic neuron.

This figure was part of my PhD thesis, completed in 2010.