Salk Han science image (IMAGE) Salk Institute Caption In this image of a mouse brain cross-section, a cluster of neurons that play a critical role in regulating breathing during an opioid overdose is highlighted in bright green. Credit Salk Institute Usage Restrictions with credit and related coverage. License Original 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.