Effects of increasing Mg2+ on neuronal-network electrophysiological activity: (a) spike rate, (b) burst rate, (c) burst duration, and (d) spike frequency in burst ([Mg2+]: 0.01-3 mmol/L, values are expressed as mean ± SEM based on normalized activity, reference = 100%, n = 6, Dunnett's multiple comparison post hoc test, *p < 0.5, ***p < 0.001).