ROLE OF ELECTRICAL ACTIVITY IN THE ASSEMBLY OF SENSORY CIRCUITS DURING THE DEVELOPMENT OF THE NERVOUS SYSTEM

LUCIA SALATINO; ANA BELÉN ELGOYHEN; PAOLA PLAZAS

Congreso; IHear Congress; 2019

Spontaneous electrical activity (SEA) in early stages of the development is required for the correct assembly and function of the central nervous system (CNS). Previous works showed the importance of this activity in mammalian?s sensory systems. In the developing mammalian?s auditory system, the early activity in the cochlea is determinant for neuronal survival, refinement and maintenance of synapses in the brain at an adult stage. However, we still don?t know how this mechanism works during the development of the CNS. For our research, we chose Zebrafish (Danio rerio) larvae?s lateral line (LL) as a model of somatotopic sensory system research as it has ease of handling as well as external development and molecular advantages. The LL is the hydrodynamic sensory system that allows fishes and aquatic amphibians to detect water motion with a molecular mechanism, physiology and functional features similar to the hair cells in the mammalian?s cochlea. It consists of clusters of mechanosensitive hair cells called neuromasts, which are innervated by afferent and efferent neurons and surrounded by non-sensory support cells. It?s reported the presence of SEA in Zebrafish larvae?s neuromasts between 5 and 7 days post-fertilization but its function is still unknown. To answer this question, we injected embryos at stage of one cell with a double cassette plasmid to mark single neurons with the human inward rectifier K+ channel KIR2.1 and the red fluorescent marker DsRed driven by the enhancer SILL for specific afferent neurons destination, and then we observed the phenotype under a confocal microscope. Exogenous expression of KIR2.1 has been shown to be a useful tool for electrically silencing individual neurons. Our results show that the silencing of single afferent neurons has morphological impacts not only in the CNS, but also at a periphery level. We observed an anomalous trajectory of the axons and neuromasts? innervation. Finally, we concluded that the SEA in the development would play a crucial role in the correct assembly of the LL system