title: Reply to Willie.
authors.affiliation: Neurologia Clinica, Università Campus Bio-Medico, Rome, Italy;
authors.forename: Paola
authors.initials: P
authors.lastname: Maggio
authors.forename: Angela S M
authors.initials: AS
authors.lastname: Salinet
authors.forename: Ronney B
authors.initials: RB
authors.lastname: Panerai
authors.forename: Thompson G
authors.initials: TG
authors.lastname: Robinson
mesh_terms: D002540:Cerebral Cortex / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology*; D008297:Male; D020768:Middle Cerebral Artery / Q000502:physiology*