In a paper published online in advance in Nature this week, a team led by investigators at the Massachusetts Institute of Technology shows that "cognitive capacities in the neurodegenerating brain are constrained by an epigenetic blockade of gene transcription that is potentially reversible." The MIT-led team says that histone deacetylase 2 mediates this blockade, adding that it "associates with and reduces the histone acetylation of genes important for learning and memory, which