Optogenetic Localization and Genetic Perturbation of Saccade-Generating Neurons in Zebrafish

• DOI: 10.1523/jneurosci.5193-09.2010
• Publication Date: 2010-05-19T17:18:21Z
• Authors: Peter J. Schoonheim; Aristides B. Arre...; Filippo Del Bene; Herwig Baier
• Keywords: Photostimulation; Superior colliculus; Optokinetic reflex; Stimulus (psychology); Danio

The optokinetic response (OKR) to a visual stimulus moving at constant velocity consists of series two alternating components, slow phase, during which the eyes follow stimulus, and quick resets begin new cycle. phases OKR resemble saccades observed free viewing. It is unclear what extent premotor circuitry underlying these types jerky, conjugate eye movements conserved among vertebrates. Zebrafish ( Danio rerio ) larvae, broadly expressing halorhodopsin (NpHR) or channelrhodopsin-2 (ChR2) in most neurons, were used map location neurons involved this behavior. By blocking activity localized groups NpHR-expressing with an optic fiber positioned above head fish by systematically varying site photostimulation, we discovered that small hindbrain area rhombomere 5 was necessary for occur. Unilateral block affected behavior direction-specific manner. Inhibition right side suppressed rightward both eyes, while leaving leftward unaffected, vice versa. Photostimulation ChR2-transgenic sufficient trigger precisely locked light pulses. These extra could be induced viewing OKR, distinct their kinetics from elicited stimulating abducens motor neurons. double indemnity didy mutants identified chemical mutagenesis screen based on defect sustaining OKR. Positional cloning, molecular analysis, electrophysiology revealed mutation disrupts voltage-gated sodium channel Scn1lab (Nav1.lb). ChR2 photostimulation putative saccade generator able fully reconstitute mutant. Our studies demonstrate optogenetic approach useful targeted loss-of-function gain-of-function manipulations neural zebrafish saccade-generating circuit species shares many its properties mammals.