Glutamatergic and GABAergic specification requires at least four sequential
stages: cell fate determination, migration, axon guidance and target recognition, and
synapse formation. The synapse formation stage includes synaptic differentiation, synaptic
maturation, and synaptic modification (refinement, plasticity, etc.). A variety of
mechanisms coordinate in each stage, with distinct sets of molecules in the establishment
of glutamatergic and GABAergic synapses.