P1.175 Wednesday, Jan. 4 Mapping developmentally dynamic synaptic inputs on motor neurons in zebrafish YAN, Q.*; DALLMAN, J. E.; University of Miami; University of Miami firstname.lastname@example.org
During development, motor neurons must integrate thousands of excitatory and inhibitory interneuron inputs to produce essential rhythmic motor behaviors, therefore, functional motor behaviors require a balance between excitation and inhibition (E/I balance) of motor neurons. Interestingly, althought the set of rhythmic motor behaviors keeps expanding during development, the E/I balance is always well maintained to produce functional motor behaviors. To better understand how such E/I balance is maintained during development, we conducted this study to obtain a developmental map of synaptic inputs onto zebrafish spinal cord motor neurons. To visualize how pre-motor interneurons synapse onto motor neurons during development, we backfilled ventrally projecting motor neurons in the transgenic fish line in which glutamatergic and glycinergic interneurons are labeled with different fluorescent proteins. Also, we stained wild type fish with antibodies against post-synaptic proteins to specifically label excitatory and inhibitory post-synapses, so as to visualize the localization of stabilized excitatory and inhibitory synapses at different developmental stages. The combination of both the pre-synaptic and post-synaptic components will allow us to further understand the developmental territories of different types of synapses onto motor neurons as well as their impact on E/I balance. Such knowledge will also promote our understanding about the formation of a functional spinal cord motor circuit, as well as provide a baseline for further study about the regulation of motor output in mutants or morphants with disrupted motor behaviors.