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

LUCIA SALATINO; A BELEN ELGOYHEN; PAOLA V. PLAZAS

Congreso; XXXIII Reunión Anual. de la. Sociedad Argentina de Investigación en Neurociencias; 2018

Spontaneous electrical activity (SEA) expressed during early stages of development is required for the correct assembly and function of the nervous system. Previous work showed the important role that this activity plays in the establishment of mammalian sensory systems. In the developing auditory system, SEA originates in the cochlea and is key for neuronal survival, maturation of auditory neurons, and refinement of tonotopic maps.In order to decipher the role of SEA in the development of sensory circuits, we used the Zebrafish (Danio rerio) lateral line system (LL). The LL is the hydrodynamic sensory system that allows fishes and aquatic amphibians to detect water motion. It consists of clusters of mechanosensory hair cells, called neuromasts, which are innervated by afferent and efferent neurons and surrounded by non-sensory supporting cells. LL hair cells share structural, functional and molecular similarities with the hair cells in the vertebrate inner ear, making them a popular model for studying hair cell biology. It has been reported that zebrafish LL afferent neurons exhibit SEA between 5 and 7 days post-fertilization. However its role in the assembly of LL sensory circuits is still unknown. To answer this question, we silenced electrical activity by stochastic expression of inward rectifier K+ channels in single LL afferent neurons and analysed the resulting phenotype under a confocal microscope. Suppression of SEA in single LL afferent neurons led to anomalous growth of axon arbors in the developing hindbrain and errors in neuromasts innervation. Our results provide an in vivo demonstration of the role of SEA in the correct assembly of the LL system