A pCAG-EGFP plasmid was transfected using our protocol and cells were studied to assess neuronal excitability. (Top) Sample traces from untransfected and transfected CA1 pyramidal neurons in organotypic hippocampal slice cultures. The superimposed traces were elicited by current injections of −100, 0, 200, 500 and 900 pA for 200 ms. (Bottom) Summary graph of the frequency of action potentials in untransfected and transfected neurons. The input–output relationship (number of spikes elicited vs. amount of current injection over a 200 ms duration) was plotted for untransfected and transfected neurons. Neurons were held at resting membrane potentials. Two-way ANOVA with post hoc Tukey: number of cells tested: untrans, 9 cells from 2 mice (9/ 2); trans, (10/ 2). n.s.: not significant.