The neural basis of visual illusions in the larva zebrafish

VERONICA PEREZ SCHUSTER; GERMAN SUMBRE

Paris

Congreso; Young Researchers in life sciences congress; 2011

YRLS

Towards the understanding of the neuronal mechanisms underlying visual perception, we are using two-photon calcium imaging to monitor the neuronal activity of large networks (which represent a relevant portion of the whole brain), still with single cell resolution, in the intact behaving zebrafish larvae. In this context, we are using a motion after-effect (MAE) illusion paradigm, in which exposure to coherent movement for a certain period of time induces motion perception in the the opposite direction following the end of the stimulus. In absence of sensory stimulation, the zebrafish larva moves its eyes in a stereotyped manner, performing rapid saccades in both directions with an interval of ~12 secs.. Upon the presentation of coherent motion visual stimulus, the zebrafish larva will move its eyes in the direction of the moving stimulus in order to to stabilise the moving external world on the retina. This behaviour is known as the optokinetic response. Here, we have found that following the presentation of a moving stimulus for a duration longer than 200 s, the zebrafish larva performs, in absence of any sensory stimulation, eye movements in the exact opposite direction of the preceding visual stimulus. In correspondence to humans who perceive a MAE with a slower velocity and amplitude, the zebrafish larvae show spontaneous eye pursuits of smaller amplitudes and at a lower frequencies than those induced by the visual stimulation.