A neuron, neurone, or nerve cell, is a cell that is excitable, firing electric signals called action potentials. Neurons form neural networks in the nervous system, mainly in the central nervous system. Neurons receive and conduct impulses. They communicate with other cells via synapses, which are specialized connections that commonly use minute amounts of chemical neurotransmitters to pass the electric signal from the presynaptic neuron to the target cell through the synaptic gap.