Sub-threshold electric fields polarize cortical neuronal soma linearly. A, Example morphological reconstruction of a L5 pyramidal neuron (black), and L5 fast-spiking interneuron (red) B, Incrementing electric field steps of 5.8 mV/mm (bottom) linearly polarize cell soma (top). Reconstructions shown are from L5 regular spiking pyramidal neuron of A (top). C, Summary of the polarization per electric field for the neurons shown in A. The slope of the fitted line determines the sub-threshold field polarization sensitivity for each neuron. LV pyramidal neuron (black) = .27 mV*(mV/mm)−1, LV fast-spiking interneuron (red) = −.02 mV*(mV/mm)−1.