I am trying to determine a hypothesus that increased inner brain pressures favour molecule binding from Van der Waals interactions. The Distribution of Testosterone in the inner brain bears this out. I calculated the ratio of neurons from outer cortex to limbic system as 1.64 and the ratio of fluid from outer arachnoid spaces to inner ventricles as 3.43. (less CSF fluid than neurons in inner brain)

It would seem likely that inner brain fluid pressures would be higher than outer brain. Certainly this is true within the ventricles and arteries themselves. Is there any known relationship between higher internal brain pressures reducing also the ratio of extracellular fluids from outer to inner brain ? Or just any data on brain interstitial fluid ratios ?

Thanks. The research is being used to determine the difference between inner and outer brain neurochemical environments, if a greater pressure can explain conceptually both the "pruning" nature of the thalamus and the higer incidence in the limbic system of non polar hydrophobic molecules such as testosterone (which form van der waals interactions)

the difference between inner and outer brain neurochemical environments is due to electrochemical gradients and selective gene expression. I would be very surprised if ventricular pressure had anything to do with this since the ventricles occupy little volume in the brain and are not distributed throughout the neuropil.

Thanks for replying..this has been a real puzzle for me...