Stimulation of the nucleus basalis of Meynert increases diameter of the parenchymal blood vessels in the rat cerebral cortex.

To verify the hypothesis that stimulation of the nucleus basalis of Meynert (NBM) induces vasodilation in the cerebral cortical parenchyma, we investigated whether the diameter of parenchymal blood vessels of rat parietal cortex is increased during stimulation of NBM using histological techniques. The parietal cortex was fixed by immersion fixation in situ during focal electrical stimulation of the NBM, which increased cortical blood flow. Cortical tissues were sectioned horizontally to the cortical surface, and the parenchymal blood vessels were morphometrically analyzed using electron microscopy. Mean inner diameter of the parenchymal blood vessels in NBM stimulated rats (5.51+/-0.33 microm) was significantly larger than that in non-stimulated control rats (4.93+/-0.23 microm). The result suggests that functional vasodilation in the cortical parenchyma during NBM stimulation correlates with histologically observed vasodilation in the cortical parenchyma.