Formation and rearrangement of synapses in a growing insect.

Sensory neurons in the cricket cuticle project with their axons in a spatially ordered manner into the central nervous system. There they possess synapses with particular interneurons, according to their receptor type, age and the location on the body surface. A sensory neuron is programmed at the time of differentiation by an unknown position specific factor to search with its axonal growth cone for the correct target area, and to form synapses with appropriate central neurons. New receptors intercalate additional synapses into the existing network. Older synapses become rearranged, probably under the influence of changing properties of the pre- and postsynaptic membranes.