Nerve synapse. Composite computer artwork of a junction, or synapse, between two nerve cells (neurons, purple). As the electrical signal reaches the presynaptic end of a neuron it triggers the release of neurotransmitters (dots) across the gap, or synaptic cleft, between the two cells. The neurotransmitters bind to receptors on the postsynaptic membrane, changing the membrane's excitability and triggering an electrical impulse. A brain is at top right. A network of neurons is in the background. Each neuron consists of a central cell body with many dendrites branching from it.