Mechanism of vasodilation in the cerebral cortex induced by stimulation of the cortical masticatory area

Abstract

Mastication not only assists eating and digesting, but also effects the brain eliciting awakening and attention. It is known that the cerebral cortical regional blood flow (rCBF) increases during human mastication, but the mechanism behind this has remained unknown. We found that repetitive electrical stimulation of the cortical masticatory area of anesthetized rats induces a marked increase in rCBF that is independent of blood pressure changes, and is preceded by an increase in neuronal activity in the nucleus basalis of Meynert (NBM). The inhibition of the NBM activity attenuates the rCBF increase, suggesting that NBM activation is involved in the rCBF increase during mastication. In addition, since the increase in rCBF due to stimulation of the masticatory area is unaffected by suppressing masticatory muscle activity, we hypothesize that motor imagery of mastication potentially activates the NBM neurons and increases rCBF similar to actual masticatory jaw movement.