Brain Drain

Scientists want to know how the glymphatic system sluices out waste from the central nervous system, acting like a drain for harmful waste. Yet watching the flow of cerebrospinal fluid around the brain is challenging. A new technique called 3D-PAULM combines an advanced form of photoacoustic imaging with ultrasound localisation microscopy to produce super resolution images of cerebrospinal fluid flow patterns. In these mouse brains (pictured from different angles on different rows) 3D-PAULM reveals high fluid flow in brighter regions, with warmer colours showing fluid close to the surface and cooler colours deeper in the tissue. While all three mice are anaesthetised, the flow is much lower in old mice (right) compared to young (left). A more intense form of anaesthesia disrupts cerebrospinal fluid flow, even in young mice (middle), suggesting 3D-PAULM could detect changes in the efficiency of the glymphatic system brought by the environment, ageing or disease.

Written by John Ankers

John Ankers

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A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Image from work by Nanchao Wang and Xinyuan Yu, and colleagues
• Duke University, Durham, NC, USA
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY-NC 4.0)
• Published in Science Advances, June 2026