Physostigmine enhances blood flow-metabolism ratio in neocortex.

Inhibition of central nervous system cholinesterase with a single pulse of physostigmine induces a pronounced increase of blood flow in the neocortex, cingulate gyrus, claustrum, and amygdala. This phenomenon is not accompanied by an increase in energy metabolism and may help explain the effect of this drug on memory in normal humans and patients with Alzheimer's disease, as well as other conditions. In contrast, a parallel increase of blood flow and metabolism was observed in the superior colliculus, a component of the visual pathways. Prolonged administration of physostigmine lead to persistent vasodilatation in the neocortex, a lessening of this effect in cingulate gyrus, claustrum and amygdala, and an increase in primary olfactory cortex and hippocampus when compared with single pulse administration. Effects of physostigmine on glucose utilization remained essentially the same as with pulse administration.