Mouse Brain (IMAGE) Howard Hughes Medical Institute Caption This image shows Galanin-positive MPOA neurons projecting to a motor command region of the brain (the periaqueductal gray, PAG). These neurons were labeled by injecting a fluorophore-expressing retrograde virus into the PAG. Credit Dulac Lab/Howard Hughes Medical Institute/Harvard Usage Restrictions Use with credit. 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.