Steffen Norbert Krieger1, Robert Trampel1, Markus Streicher1, Robert Turner1
1Neurophysics, Max Plank Institute for Human Cognitive and Brain Sciences, Leipzig, Saxonia, Germany
Due to its good localization to neuronal activity, fMRI studies have begun to utilize changes of cerebral blood volume (CBV). However, if cerebral vessels are considered to be impermeable, the contents of the skull incompressible, and the skull itself inextensible, task-related and hypercapnia-related changes of CBV could produce intolerable changes of intracranial pressure. We propose that much of the change in CBV is facilitated by exchange of water between capillaries and surrounding tissue. To explore this idea we developed a novel hemodynamic boundary-value model and found approximate solutions. A macroscopic experimental model provides biophysical insight.