[Seminar] Genetic and functional dissection of neural circuits formation in the zebrafish visual system by Del Bene Filippo

[Seminar]

Title: Genetic and functional dissection of neural circuits formation in the zebrafish visual system

Speaker: Professor. Del Bene Filippo

Institution: Institut Curie, Unité de Génétique et Biologie du Développement, 26, rue d'Ulm, 75248 PARIS France

Abstract:

 The optic tectum is the main retino-recipient brain structure in zebrafish and as such receives direct input exclusively from the contralateral retina. Based on observations of the behaviour of zebrafish larvae during capturing of prey like e.g. paramecia, it is likely that visual signals coming from both eyes of the animal have to be integrated e.g. for efficient hunting (Bianco et al. 2011, Bianco et al. 2015) but the neural substrate for such a mechanism is as of yet unknown.

We recently identified a zebrafish line that specifically expresses the trans-activator Gal4 in a novel, previously undescribed neuron population in the visual system of the zebrafish. Using transient UAS:GFP-expression for single-cell labeling in this zebrafish line, we find these neurons to be distributed in two bilateral-symmetric nuclei adjacent to the ventral tectum. Furthermore, they send their axons and form arbors in both tectal halves and were thus termed intertectal neurons (ITNs). ITNs are therefore good candidates for the potential transfer and/or the integration of visual signals coming from both eyes.

First, we described the anatomy and temporal development of the ITN neurons and their connections, i.e. their axon trajectories, potential up- and downstream neurons, the development and distribution of the ITN synapses and also their neurotransmitter type.

Second, using 2-photon Calcium-imaging, we established that ITNs respond to a range of visual stimuli including looming stimuli and direction selective bars. Furthermore, after unilateral eye-ablation at 2dpf, we observed Calcium transients in the tectal hemisphere not receiving any retinal input at 5-6dpf that were time-locked to the presented visual stimuli and co-localized with the trajectories of the arbors originating from the contralateral ITNs.

Finally, we analyzed the role of the ITNs during behavior. To this end we unilaterally ablated genetically stained ITNs using 2photon imaging and subsequently examined free-swimming behavior parameters using a high-speed camera in ablated vs. ctrl fish.

In summary, we anatomically describe novel, previously unknown, inter-hemispheric neural connections in the zebrafish visual system, establish their role in inter-tectal visual signal transfer and their functional role during behavior.

PERSONAL INFORMATION
Del Bene, Filippo
Researcher unique identifier(s): https://orcid.org/0000-0001-8551-2846
Nationality: Italy

EDUCATION

2012    HDR (Habilitation to supervise research) Paris 6 University, France
2004     PhD Developmental Biology Program, Heidelberg University/EMBL, Germany
    Supervisor: Prof. Joachim Wittbrodt
2000     Master (Laurea in Biotechnology)
    Department of Biochemistry, University of Bologna, Italy

CURRENT POSITION(S)

2019 –    Group Leader
        Institut de la Vision, Department of Developmental Paris / France
2014 –      Research Director (DR2), INSERM, France    
                        
SCIENTIFIC ACHIVEMENT TRACK RECORD

Publications: Since 2004, 44 scientific publications.
Total Citations =  33347; h-index = 22;
Source = Scopus (Retrieved 25/08/2018)