Various studies have identified changes in histone acetylation marks in the brain,either in whole brain in one study using flies or in defined brain regions in mice(Table4).78, , , -82 For example, decreasedH4K16ac was reported in both mice and flies modeling AD, specifically in hippocampalsubregions of APP/PS1-21 mice78 and in the brain of young andold aged Aβ42-induced Drosophila. The gene discussed is PSEN1; the disease is Alzheimer disease.