Decoding visual content and perception from neuronal population activity in visual cortex: VSDI, fMRI and computational modeling

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How visual stimuli are encoded by neuronal population responses and how they can be decoded by subsequent stages of the visual system are fundamental questions that are to date still open. Our consortium proposes a highly novel, interdisciplinary approach, in which we combine our unique expertise and synergistic scientific skills in multi-scale brain activity measurements with our expertise in brain modeling, neural computation and computer vision. We suggest studying how neuronal population responses encode visual information and how this information is "read out" by subsequent brain areas in order to mediate visual perception and behavior. First, we plan to decode ("read out") stimuli from population responses in the visual cortex of anaesthetized animals, behaving monkeys and humans using brain activity measurements at multiple resolutions: voltage-sensitive dye (VSD) and fMRI signals. VSD imaging measures neural population responses at high spatial and temporal resolution simultaneously whereas fMRI provides extended coverage of the brain but with decreased spatial and temporal resolution. Based on these signals we aim to develop and compare decoding rules that are used to reconstruct in detail visual stimuli ranging from basic stimulus features to natural images and movies. The comparison will provide information on stimulus encoding across measurement modalities and species. In addition, we will combine state-of-the-art computer vision techniques with multi-scale modeling of brain signals to facilitate decoding performance. Next, we will study how neural representation and decoding rules change along the visual pathway and whether the brain uses different decoding rules for higher visual functions. Achieving our goals will allow better understanding and modeling of brain signals and may facilitate the development of medical