The model presented by Nunez is based on interaction between cortical volume units. The output g of one volume at position arrives at its target at position with a delay determined by conduction velocity (). Every volume unit is characterized by its synaptic activity, both for excitatory () and inhibitory synapses (). In the mammalian brain, the excitatory cortical synaptic activity is assumed to make the principal contributions to the electroencephalogram (EEG).