the neural ECM has low levels of fibrillar proteins includ ing laminin, collagens, and fibronectin with the majority of these proteins being localiz ed to substructures of the CNS including basement membranes, the subpial space, blood vessels, and in white matter tracts (Liesi, 1984). Instead, the backbone of the neural EC M is HA, a non-sulfated glycosaminoglycan made up of alternating glucur onic acid and N-acetylglucosam ine disaccharide subunits and devoid of a protein core (Ruoslahti, 1996; Tool e, 2000, 2004