Neurotransmitter release is a process that occurs at the synapse, the junction between two neurons. When an electrical signal, or action potential, travels down the axon of a neuron, it triggers the opening of calcium channels. This influx of calcium ions causes vesicles filled with neurotransmitters to fuse with the neuron's membrane and release their contents into the synaptic cleft. Once released, neurotransmitters bind to specific receptors on the surface of the adjacent neuron, leading to various effects, such as the initiation of a new action potential. This communication between neurons is essential for processes like muscle contraction, mood regulation, and overall brain function.