of histone PTMs is that they can influence each other in a synergistic or antagonistic manner, leading to a complex “histone code” (110). Of these histone PTMs, histone acetylation is the most widely investigated in terms of epigenetic mechanisms underlying region-specific changes in brain gene networks required for long-term memory processes. Many rodent studies have detailed how different learning paradigms trigger distinct histone acetylation patterns in the brain, which are accompanied by region-, task-, and age-specific changes in memory-associated genes [for reviews, see Ref. (111–115)]. For instance, increased acetylation of histones, H3 and H4, occurred in the dorsal HPC or the dorsal striatum, depending on whether mice were subjected to a spatial or cued training in the water maze task, respectively (116, 117).
