THE ELECTROENCEPHALOGRAM AND CORTICAL NEURAL NETWORKS

The character of the EEG, its cellular sources, and its relationship to cognitive events am outlined. Then four theories of the EEG are discussed-the Amsterdam group's model of alpha activity, the Nunez model of global resonance, Freeman's model of oscillation in the Cortical minicolumn, and the New Zealand group's stochastic model of EEG at millimetric scale. Experiments supporting these theories are outlined, including spatial and temporal characteristics of the alpha rhythm, velocities of EEG wave propagation, and phase relations of cell action potentials with EEG near 40 Hz. These theories are mutually consistent, differing only with regard to the scale of phenomenon accounted for. They imply that real cortical dynamic properties bear analogy to those of Hopfield-networks, Boltzmann machines, and Amit probabilistic attractor networks. The cortex may be described as a system with a single instantaneous basin of attraction, the locus of the basin being subject to adiabatic control by brain-stem afferents to the cortex.