Continuum neural dynamics of brain-stem function and dysfunction

A model is presented of the brain-stem as two layers of purely excitatory and purely inhibitory cells, with instantaneous interactions within layers and variable time delay between layers. As inhibitory delay increases, input is increasingly amplified first and confined spatially. At larger delays, spatial summation is achieved by propagation of amplified activity into other regions. Temporal frequency of the amplified activity decreases with increasing delay, but its spatial frequency remains relatively constant. As delay increases through a critical region, a new regime is reached in which highly amplified activity occurs simultaneously over large areas. This regime exhibits many properties of seizure activity.