Title: Regulation of Synapse Development by Miniature Neurotransmission in vivo
Description: Miniature neurotransmission is the trans-synaptic process where single synaptic vesicles spontaneously released from presynaptic neurons induce miniature postsynaptic potentials. Since their discovery over 60 years ago, miniature events have been found at every chemical synapse studied. However, the in vivo necessity for these small-amplitude events has remained enigmatic. In this thesis, I show that miniature neurotransmission is required for the normal structural maturation of Drosophila glutamatergic synapses in a developmental role that is not shared by evoked neurotransmission. Conversely, I find that increasing miniature events is sufficient to induce synaptic terminal growth. I show that miniature neurotransmission acts locally at terminals to regulate synapse maturation via a Trio guanine nucleotide exchange factor (GEF) and Rac1 GTPase molecular signaling pathway. My thesis study establishes that miniature neurotransmission, a universal but often-overlooked feature of synapses, has unique and essential functions in vivo.