ESI TALKS: Marion Silies

At this bi-weekly event, we invite speakers from Neuroscience and related fields to share their current research in an informal and casual environment. The ESITALKS last around 45 minutes, followed by discussions.

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Visual processing strategies in dynamically changing environments

It is a major challenge for the brain to keep stable neural representations of stimulus features while facing a wide range of sensory inputs in natural scenes. Visual systems for example, stably compute contrast and motion cues while actively navigating through the environment. Self-motion of the animal, for example, leads to rapid changes in background illumination and global motion occurring across the animal’s eye. How does the visual system deal with such changes caused by animal behavior? Here, I will discuss what we can learn from animals, fruit flies in particular, to stably process visual information under constantly changing conditions. First, I will talk about changes in luminance that occur slowly throughout the day, but also happen at millisecond time scales when our eyes saccade across a natural scene, or when the visual input changes rapidly due to self-motion. Recently, we identified a mechanism that allows flies to handle such changes in illumination. This post-photoreceptor luminance gain control adjusts contrast signals when background luminance rapidly changes quickly, but also at slow timescales. We have elucidated the circuit mechanisms that achieve luminance-invariant visual behaviors and are currently investigating the biophysical mechanisms that combine different types of signals to achieve stable contrast computation. Stable contrast signals are then used to compute higher-order visual features, one of which is the direction of motion. In the second part of my talk, I will show how motion computation is tuned to the behavior of the animal already in local direction-selective cells, which encode patterns of optic flow at the population level. Together, our work argues that visual processing strategies have evolved to handle the demands imposed by the animal’s behavior.

To register for the upcoming session of ESITALKS please send an email to one of the hosts: nisa.cuevas(at), farzad.ziaie(at) or marius.schneider(at)

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