Tyrosine (IMAGE) Neural Regeneration Research Caption Tyrosine hydroxylase-positive noradrenergic neurons (arrow) in the locus coeruleus of aged mice carrying mutant amyloid-β precursor protein and presenilin-1 genes were decreased. Credit <i>Neural Regeneration Research</i> Usage Restrictions None 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.