The cell was loaded with the voltage-sensitive dye JPW3028, and injected with current pulse into the soma, to produce a doublet of action potentials. (A) Somatic whole-cell recording and corresponding optical signal from soma. Image of neuron is shown below. (B, C and D) Optical signals from apical B, basal C and oblique D dendrites showing change in amplitude and timecourse with backpropagation.