Luis Herrero

14 septembre 2012

Departamento de Fisiología, Facultad de Biología, Sevilla, Spain

Neural control of the orienting response in the goldfish

invité par Laurent Goffart

The appearance of a stimulus in the visual field generates an orienting response, which involves a coordinated movement of the eyes, the head and/or the body toward the location where the stimulus appeared. Visual orienting movements are intended to project the image of a stimulus on the retinal area of greatest visual acuity (fovea, area centralis). The neural structures involved in the generation of saccadic eye movements have been widely studied in cats and monkeys during the last three decades. These species are frontal-eyed, and the appearance of salient sensory stimuli (visual, auditive, or somatosensory) evokes conjugate saccadic movements of both eyes to bring the image of the stimulus onto the fovea. The control of these movements depends, in part, on the mesencephalic structures, although other regions are also involved.

The neural control of orienting movements in non-mammalian species is almost unexplored. Our group is studying this system in goldfish. In contrast to cats and monkeys, these animals are lateral-eyed, and their retinas have a poorly developed fovea. Species with these characteristics extend widely across vertebrates. For this reason, it is important to expand our knowledge to answer the following question : are the neural substrates and physiological mechanisms underlying saccadic eye movements similar or different across vertebrates ? This comparative approach provides insights about the ancestral neural organization supporting these movements, as well as about its modifications throughout vertebrate phylogeny. It also provides a better understanding of the coding principles subtending the orienting response. During my talk, I will review some of our recent findings on the control of the orienting eye movements in goldfish, and compare them with those reported in mammals.

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