CA1 L-LTP is absent in αCaMKII autophosphorylation-deficient mice. fEPSP slope compared to baseline. Means ± s.e.m. are shown. Four trains of high frequency stimulation induced in hippocampal area CA1 an L-LTP in WT mice (n = 6, open symbols) and an early potentiation that declined to baseline within one hour in αCaMKIIT286A mutants (Mutants, n = 6, filled symbols). Traces show representative recordings of fEPSP before and three hours after the trains in mutants (left: c,d) and in WT (right: a,b).