Modeling the decoupling of the hemodynamic and metabolic responses to neural stimulus in the primary visual cortex

Stimulus-evoked neural activity increases both local oxygen metabolism and blood flow in active regions of the brain. However, multiple imaging modalities including functional magnetic resonance imaging and positron emission tomography have demonstrated that the degree of coupling between metabolism and blood flow is highly non-linear. Specifically oxygen metabolism appears to peak and decline at significantly lower levels of stimulus than does blood flow. This model attempts to explain this phenomenon as a consequence of balanced excitation and inhibition in a network of neurons in the primary visual cortex.