The assembly of functional neural circuits requires the combined action of progressive and
regressive events. Regressive events encompass a variety of inhibitory developmental
processes, including axon and dendrite pruning, which facilitate the removal of exuberant
neuronal connections. Most axon pruning involves the removal of axons that had already
made synaptic connections; thus, axon pruning is tightly associated with synapse
elimination. In many instances, these developmental processes are regulated by the …