International Research Fellowship Program: The Role of Gap-Junction Mediated Synchrony in Sensory Information Processing

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0804305Apergis-SchouteThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four month research fellowship by Dr. John Apergis-Schoute to work with Dr. Simon Schultz at Imperial College in London, UK.Understanding how the brain transforms the physical world into perceptual experience is a central question in modern neuroscience. Through analysis of the functional architecture of primary sensory cortices, research has shown that many fundamental principles of sensory encoding are conserved across sensory modalities. For example, the architecture of most sensory cortices dictates that information regarding the sensory world is distributed across anatomically distinct cortical locations. But how then does the cortex link these fractured sensory representations into a unified percept? An important clue is that synchrony between neuronal pairs is modulated by stimuli which drive them both effectively. Such synchrony has been proposed to be the ?glue? of perceptual integration, either by supporting low-level conjunctive sensory coding or ?temporal binding?. A prevailing mechanistic theory behind both models states that gap junction-coupled interneurons support sensory integration by quickly synchronizing rhythmic activity across cortical domains. However, due to limitations in selectively recording from identified interneurons in vivo, most conclusions regarding gap junction-coupled interneurons? contributions to network function have come from studies where network function was compromised. Using anaesthetized transgenic mice whose neurons expressing the gap junction protein connexin-36 (Cx36) somatically express yellow-fluorescent protein (YFP) the PI and host will monitor visually-driven intra- and juxtacellular signals from Cx36-YFP neurons. Specifically, they will first plan on determining how the identity and position of Cx36 neurons within the cortical network results in their receptive field properties. This will be achieved by comparing the chemical composition and cellular morphology of Cx36 neurons with their visual response properties. Next, they will assess the temporal relation between gap junction-coupled interneurons and V1 network activity monitored using multi-electrode arrays. Information-theoretic analyses will allow us to directly compare the contributions made by different cell types to the overall mutual information regarding stimulus structure. Finally, they aim to modify visually-driven activity patterns in cortical networks by modulating the excitability of Cx36-coupled networks via current injections into individual neurons. These experiments will allow them to unify a large body of anatomical, physiological, and theoretical work aimed at understanding the origin of the stimulus-dependent synchrony, and ultimately, to help them understand how these processes contribute to the way perceptions arise.