Spontaneous electrical activity regulates axonal arbor growth in developing zebrafish laleral line afferent neurons.

LUCIA SALATINO; ANA BELÉN ELGOYHEN; PAOLA V. PLAZAS

Congreso; XXXIV Reunión Anual. de la. Sociedad Argentina de Investigación en Neurociencias; 2019

Neuronal circuits responsible for processing sensory information are established early in development through a combination of genetic programs and activity-dependent processes. A remarkable feature of this process is that it relies on stimulus-independent or ?spontaneous? electrical activity (SEA) generated within sensory organs. In order to decipher the mechanisms by which SEA affects the assembly of developing sensory circuits, we used the Zebrafish (Danio rerio) lateral line system (LL). The LL allows fishes and amphibians to detect water motion and pressure changes and consists of clusters of mechanosensory hair cells and non-sensory supporting cells. LL hair cells are innervated by afferent and efferent neurons, and share structural, functional and molecular similarities with hair cells in the vertebrate inner ear. Zebrafish LL afferent neurons exhibit SEA between 5 and 7 days post-fertilization (dpf), however its role in the assembly of LL circuit is still unknown. To answer this question, we silenced SEA in single LL afferent neurons by stochastic over-expression of inward rectifier K+ channels. At 5 dpf, suppression of SEA in single LL afferent neurons led to a decrease in both axonal arbor length and innervation area in the hindbrain. Our results provide an in vivo demonstration that SEA regulates axonal arbor growth and territory in the hindbrain, in developing LL afferent neurons.