15 August 2012
Vol 4, Issue 147

About The Cover

Cover image expansion

ONLINE COVER Clearing Your Head. Shown is the paravascular pathway—described in this week's issue by Iliff et al.—along which cerebrospinal fluid (CSF) enters the brain and facilitates the clearing of proteins and other solutes from the brain interstitial space. The authors show that the water channel aquaporin-4 in the endfoot processes of astroglial cells, which surround brain vessels, facilitates water flux through the brain tissue and supports bulk fluid flow between the paravascular influx and efflux routes. A fluorescent tracer (green) that was injected into the CSF in the subarachnoid space surrounding the brain can be seen entering the brain along the penetrating arteries. This gliovascular clearance path may be the main one responsible for removal of amyloid β from the brain. See also the accompanying Focus by Begley. [CREDIT: IMAGE FROM J. ILIFF, T. TAKANO, AND M. NEDERGAARD]