The human hypothalamus produces endogenous membrane sodium potassium ATPase inhibitor digoxin. The isoprenoid pathway synthesises digoxin. The other products of the isoprenoid pathway are -- dolichol, ubiquinone and cholesterol. Hemispheric chemical dominance can be related to the isoprenoid pathway and digoxin synthesis. In right hemispheric chemical dominance there is an unregulated isoprenoid pathway and elevated digoxin synthesis. In left hemispheric chemical dominance there is a downregulated isoprenoid pathway and decreased digoxin synthesis. This book examines digoxin via its modulation of membrane sodium potassium ATPase can regulate neurotransmitter transport, immunity and all aspects of cellular organelle function -- mitochondrial, golgi body, lysosomal and nuclear. It can also modulate cellular aging and cell differentiation. Hemispheric chemical dominance can thus modulate various psychological and pathological states. An endogenous digoxin mediated model for conscious and extrasensory quantal perception is postulated. As well in this book an endogenous digoxin mediated model for quantal perception and brain evolution is also highlighted.