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Seminar Details

Date 29-6-2007
Time 10:30
Room/Location DISI - Sala conferenze 322 - 3° piano
Title Subjective visual vertical in monkey
Speaker Nabil Daddaoua
Affiliation Hertie Institute for Clinical Brain Research Dept. Cognitive Neurology - Tuebingen - Germany
Link https://www.disi.unige.it/index.php?eventsandseminars/seminars
Abstract When we change our orientation with respect to gravity, we perceive a stable and upright surrounding. The information on the orientation of the gravity vector, mainly provided by the otolith system, is not only used to assess the orientation of our body relative to gravity, but also to judge the orientation of visual objects with respect to the gravity vector. To produce a stable percept of an upright visual world (the subjective visual vertical=SVV), the brain has to use the information on the orientation of the gravity vector in order to reinterpret the orientation of retinal images such as to keep the percept of the visual scene upright. For human subjects, it is well established that this updating of the visual percept is not perfect, leading to a characteristic deviation of the SVV from the gravitational vertical. For small roll-tilt angles (<60°), subjects typically overestimate the tilt (Müller- or E-effect), whereas for larger angles they underestimate it (Aubert- or A-effect). As these effects might be exploited to identify the neural networks underlying the approximately tilt-independent perceptual representation of the orientation of the visual scene, we wanted to know if nonhuman primates, the model system of choice for invasive studies of visual perception, are subject to similar tilt-induced distortions of the SVV.
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