Fig. 7. γ-aminobutyric acid receptor type A (GABAA) potentiation and input drive reduction combine multiplicatively to reduce excitatory (E) cell firing rate (line ) and the number of polychronous groups activating per second (columns ). Modeling of the direct and indirect effects of GABAApotentiation by propofol produces a collapse in the ability of the network to sustain frequent polychronous group activation, particularly at plasma concentrations consistent with sedation through to general anesthesia. The almost 10-fold reduction in group activity reduces the information-carrying capacity of the network and, should this occur on larger scales, may be consistent with loss of consciousness in some theoretical frameworks.