Between them lies the synaptic cleft. This is actually very narrow. Nevertheless, it prevents the electrical impulses from being easily transmitted.

When a presynaptic cell is electrically excited, synaptic vesicles fuse with the presynaptic membrane causing messenger substances within the vesicles to be released into the synaptic cleft.

Neurotransmitter molecules cross the synaptic cleft and bind to receptors known as ligand-gated ion channels (LGICs) and G-protein–coupled receptors (GPCRs) on the postsynaptic neuron.

(3) This causes synaptic vesicles to fuse with the terminal membrane, releasing neurotransmitter into the gap between neurons, known as the synaptic cleft.