MVT imaging setup and enclosure pattern for laser-cut acrylic sheets to produce chamber walls angling slightly outward (to allow full view of the inside corners from above). Void spots along the cage walls and corners can diffuse radially beneath the enclosures.
Micturition Video Thermography (MVT)
Our understanding of the neural circuits controlling micturition and continence is constrained by a paucity of techniques for measuring voiding in awake, behaving mice. To facilitate progress in this area, we developed a new, non-invasive assay, micturition video thermography (MVT), using a down-facing thermal camera above mice on a filter paper floor. Initially voided urine (35-36 °C) has warm thermal contrast relative to the cage floor (~20-22 °C), and then cools as it spreads radially through filter paper flooring. The final “void spot” has thermal contrast that is 1-2 °C cooler than the dry filter paper surrounding it. By measuring the area of cool contrast comprising this "thermal void spot," we can derive the initially voided volume. Thermal videos also reveal mouse behaviors including a home-corner preference apart from void spots, and a stereotyped, seconds-long pause while voiding. MVT is a robust, non-invasive method for measuring the timing, volume, and location of voiding. It improves on an existing technique, the void spot assay, by adding timing information, and unlike the cystometrogram preparation, MVT does not require surgical catheterization. Combining MVT with current neuroscience techniques will improve our understanding of the neural circuits that control continence, which is important for addressing the growing number of patients with urinary incontinence as the population ages.
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