A Multi-Scale Approach to Cortical Representation of Visual Scenery

Orateur : Björn KAMPA (Junior Group Leader, Vision Lab, Brain Research Institute, University of Zurich)

How is our visual environment represented and processed in the brain ? In my lab, we seek answers to this fundamental question with a multi-scale approach combining two-photon imaging with electrophysiological recordings. Neurons in the visual cortex have a receptive field like a keyhole through which they look at the scenery in front of the eyes. Visual input from the area surrounding the receptive field fails to induce neuronal firing but can modulate the neuronal responses to receptive field stimulation. Recent studies have shown that natural movie stimulation beyond the receptive field leads to reduced but more precise neuronal responses. We have established this paradigm in mouse visual cortex where we investigate the interaction of incoming sensory evidence with internal feedback from surrounding and higher visual areas. We find precise and sparse responses to presentations of different visual scenes. Our results suggest a population code, where the visual environment is dynamically represented in the activation of distinct functional sub-networks. Furthermore, we find higher visual areas to be well tuned to the characteristics of natural scenes indicating the role of their feedback in visual perception. Integrated studies at multiple scales from neuronal dendrites to populations of neurons together with their input from higher visual areas will assemble the puzzle of local computation in visual cortex revealing the picture of how we perceive and interpret visual scenes.

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