1. A method for optimizing the configuration of multisite transcranial current stimulation, comprising: providing an electric field characteristic target map on the brain's cortex, said target map including multiple cortical targets, where said multiple cortical targets are localized and/or continuously varying and spatially extended; providing a weight map on the cortical surface prioritizing the important of areas in said target map for the purposes of optimization; and calculating, based on said target and weight maps, optimal currents and optimal locations for a plurality of electrodes intended for providing transcranial current stimulation to globally stimulate at once said multiple cortical targets with excitatory, inhibitory or neutral stimulation.