Nanoparticles (IMAGE) RIKEN Caption Non-invasive activation of neurons in the VTA, a reward center of the mouse brain. The blue-light sensitive ChR2 channel (green) was expressed on both sides of the VTA, however UCNPs (blue) were only injected on the right. NIR light was applied to both sides, however it only activated the expression of the activity-induced cFos gene (red) on the side with the nanoparticles. Credit RIKEN Usage Restrictions credit RIKEN License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.