This image illustrates current flow through all neuronal segments in a full-scale (~30,000,000 segments), biophysically detailed model of a cortical column. Each segment is colored according to the current flowing through that segment. These simulations were used to reveal that the majority of evoked ECoG signals arise from infragranular neuronal spiking. For more information, see the article by Baratham, Dougherty et al. (pages 3733–3748). Cover image: Burlen Loring (Lawrence Berkeley National Lab, Berkeley, CA).