Effects of local feedback on dispersion of electrical waves in the cerebral cortex

This paper generalizes an existing continuum model of the large-scale elect rical activity of the brain by incorporating local feedback. The model is f irst reformulated by parametrizing neuronal function in more detail and we then show that only four broad classes of local feedback are consistent wit h general physiological constraints. The corresponding linear dispersion re lations ale found to contain additional modes as a result of feedback. It i s shown that each feedback class can produce lightly damped or undamped osc illatory modes at frequencies similar to those seen in electroencephalograp hy, although not all combinations of type and speed of feedback result in o scillatory behavior. Three kinds of lightly damped resonances are found, ea ch with distinctive frequency characteristics. The effect of feedback on ot her roots is also described. [S1063-651X(99)05901-2].