The aim of this study was to find the best method for achieving widespread cortical expression of a calcium sensor, enabling brain cell activity to be imaged in live mice. The best method was injecting into the transverse sinus, a blood vessel in the brain, during early postnatal development. <div><br></div><div>This poster was uploaded for the SGS Research Showcase 2021.</div>Choose your favourite poster to win the People's Choice Award at the 2021 SGS Research Showcase: https://auckland.au1.qualtrics.com/jfe/form/SV_9Fw8Omf43pstYUu