1. A method for estimating brain activity of a human subject from electrical voltage potentials from scalp site measurements of electroencephalograms (EEG) that is executed by an electronic processor comprising electronic modules, the method comprising: receiving measurement signals for actual scalp site voltage potentials which originate from an EEG collection system worn by the subject; specifying, by an electronic module, a plurality of cortical neural sources of electrical potentials in the cerebral cortex of the brain of the subject; using a model of the human brain which treats the cortical neural sources as nodes connected together in a cortical source network topologically distributed in the cerebral cortex, estimating, by an electronic module, cortical source activations from actual scalp site voltage potentials measured by electrodes of the EEG collection system worn by the subject for each of the cortical neural sources in the network for the subject; determining, by an electronic module, source network modulation electrical control signals for the subject from the cortical source activations which are assumed to correspond to neural control modulators in the human brain; and computing, by an electronic module, a network activity classification from determined modulation electrical control signals as an estimation of brain activity of the subject, wherein, estimating the cortical source activations comprises computing a node-excitation driving function for each of the cortical source nodes of the network, where each node is assumed to constitute an activation function formed from weighted inputs, a node-excitation driving function, and an emitter function formed from weighted outputs, and where inputs to each node comprise signal power spectrums from nodes of the network and the weights are measures of the directed causality of the spectral power transfer between nodes.