Nerve cell synapse formation. Computer artwork of the formation of a synapse, the junction between a nerve cell and another cell. The nerve cell (blue) has been found by the axon (orange) of another nerve cell (main body not seen). The axon is an extension that a nerve cell uses to transmit electrical impulses to other cells. The target cell will form its own extension (a dendrite, five already seen here) to receive the signals and to strengthen the synapse formed. The formation and strengthening of new brain synapses is a key part of childhood development. The axon's terminal bouton (bulge) contains neurotransmitter chemicals that carry signals across the synaptic junction.