Development of synaptic input patterns on dendrites of retinal neurons

Studies of the developing vertebrate retina have recently offered new insights into the molecular and cellular mechanisms that regulate the development and patterning of synapses onto dendrites. The dendrites and axons of retinal neurons are stratified, forming layers of functionally distinct connections. This architecture readily facilitates investigation of the developmental mechanisms that wire neural circuits. Like other central nervous system (CNS) neurons, each retinal neuron type exhibits a stereotypic wiring pattern that is critical for proper circuit function. To form its stereotyped connectivity, a neuron must select specific synaptic partners, make the appropriate number of contacts, and form synapses at proper sites on its dendrites. Both molecular cues and neurotransmission have been found to be responsible for shaping patterns of wiring. This chapter will review the most current knowledge of these developmental mechanisms, with a specific focus on the formation and patterning of synaptic connections onto dendrites in the inner and outer retina.