Ca2+/calmodulin-dependent protein kinase II (CaMKII) is involved in Ca2+signaling throughout the body. CaMKII is enriched in the hippocampus and required for learning and memory formation. Four highly conserved genes encode CaMKII in vertebrates: A, B, G, and D. All CaMKII variants are constituted of a kinase domain, regulatory segment, variable linker, and hub domain. These domains comprise an individual subunit which oligomerize together via the hub domain to form multimeric holoenzymes. These four genes are most variable in the linker domain due to extensive alternative splicing. The variable linker significantly impacts the activation of CaMKIIA. Herein, I attempt to develop an in vitro assay which resembles physiological activation of CaMKII via Ca2+ oscillations. I provide preliminary data which indicate that alternative splicing of the variable linker in CaMKIIA modulates the Ca2+ frequency dependent autonomy of these variants. Additionally, neuronal CaMKII variants of CaMKIIA and CaMKIIB decode Ca2+ oscillations into different levels of autonomous activity. Lastly, I assess the impacts of three de novo mutations (Q274P, R275H, and F294S) on Ca2+/CaM sensitivity in CaMKIID by providing data that these 3 mutants increase the sensitivity of CaMKIId to Ca2+/CaM and that Q274P and F294S mutants display Ca2+/CaM independent activity.