The neural basis of visual illusions in larvae zebrafish

VERONICA PEREZ SCHSUTER; GERMAN SUMBRE

Marsella

Conferencia; 10th meeting of the French Neuroscience society; 2011

French Neuroscience society

One of the main goals in neurosciences is to understand how cognitive functions, such as sensory perception are encoded by the dynamics of large neuronal networks. The main stream of perception research has mainly focused on sensory stimulation and recordings of the induced neural responses. An alternative approach is the use of sensory illusions, in which sensory perception takes place in absence of physical external stimulus, and therefore help to better isolate the neuronal circuit activities underlying sensory perception. One example of these sensory illusions is the motion after-effect (MAE), in which exposure to coherent motion for a certain period of time, will induce motion perception in the the opposite direction following the end of the stimulus. Here, we propose to study the neuronal mechanisms behind visual perception using the zebrafish larva, which enables us to monitor the activity of large neuronal networks (representing a relevant portion of the whole brain), still with single cell resolution, in an intact, behaving vertebrate. Upon the presentation of a coherent motion visual stimulus, covering a large portion of its field of view, 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 optokinetic response. We have found that following the presentation of a moving stimulus for a duration longer than 250 s, the zebrafish larva performs, in absence of any sensory stimulation, eye movements in the exact opposite direction of the preceding visual stimulation. In correspondence to humans that perceive aMAE 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. We are now performing two-photon Ca2+ imaging in intact behaving larvae to study what are the patterns of neuronal activity that precede the spontaneous-reverse-eye-movements towards the elucidation of the neuronal mechanisms behind sensory perception.