マウスの尻尾を用いたバランス機能の解明

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Introduction: Studies in mice have suggested that the tail is important for balance. However this hypothesis has never been addressed with high resolution motion capture, and the neuronal system that implement this motor program is currently unknown. In the project described here, I study the functional role of the vestibular system, which plays an important role in balancing motor responses, for the motor control of the tail.In the last fiscal year, I addressed the two main questions:(1) whether and how mice use their tail to maintain balance in the ridge task(2) whether tail motoneurons in the spinal cord receive projections from the vestibular nuclei.Ridge experiment (1): We revealed that mice employ two strategies with their tails to adapt to the smaller widths: the tail swing amplitude is bigger, and the tail is positioned closer to the roll plane of the mouse. We speculate that this last strategy allows the mouse to increase the effective length of the tail in the roll plane.Labeling of vestibular projections onto tail MNs (2): The goal of this part of the project is to assess whether tail motoneurons in the spinal cord receive projections from the vestibular nuclei. Within this framework the first achieved objective was the identification of the tail motoneurons (MN) pool in the spinal cord. In order to identify the approximate number of neurons that the MN pool consists of, I injected intramuscularly cholera toxin subunit (CTb).