BMI SEMINAR // Marion Silies - Mechanisms to accurately estimate the salience of visual stimuli


Event details

Date and time 04.12.2019 12:1513:15  
Place and room
Speaker Marion Silies, Johannes-Gutenberg-Universität Mainz, Institute for Development and Neurobiology (iDN), Mainz, Germany
Category Conferences - Seminars

In many contexts, changes in perception are proportional to relative changes in the stimulus, rather than its absolute value, as formulated by Weber’s law. Visual perception for example scales with changes in the visual stimulus, or contrast, irrespective of background illumination. However, visual perception is challenged when adaptation is not fast enough to deal with sudden declines in overall illumination, e.g. when gaze follows a moving object from bright sunlight into a shaded area. Here, we show that the visual system of the fly employs a solution by propagating a corrective luminance-sensitive signal to higher processing stages. We use in vivo 2-photon imaging and behavioral analyses to show that distinct OFF-pathway inputs encode contrast and luminance. Predictions of contrast-sensitive neuronal responses show that contrast information alone cannot explain behavioral responses in sudden dim light. The luminance-sensitive pathway is required for processing visual motion in such conditions, i.e. when pure contrast sensitivity underestimates the salience of a stimulus. Thus, retaining a peripheral feature, luminance, in higher visual processing is required for robust behavioral responses. Given the many similarities in visual processing properties between invertebrates and vertebrates, this likely presents a general processing strategy of all visual systems.


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