title: Real-time electrochemical monitoring of brain tissue oxygen: a surrogate for functional magnetic resonance imaging in rodents.
abstract: Long-term in-vivo electrochemistry (LIVE) enables real-time monitoring and measurement of brain metabolites. In this study we have simultaneously obtained blood oxygenation level dependent (BOLD) fMRI and amperometric tissue O(2) data from rat cerebral cortex, during both increases and decreases in inspired O(2) content. BOLD and tissue O(2) measurements demonstrated close correlation (r=0.7898) during complete (0%) O(2) removal, with marked negative responses occurring ca. 30s after the onset of O(2) removal. Conversely, when the inspired O(2) was increased (50, 70 and 100% O(2) for 1min) similar positive rapid changes (ca. 15s) in both the BOLD and tissue O(2) signals were observed. These findings demonstrate, for the first time, the practical feasibility of obtaining real-time metabolite information during fMRI acquisition, and that tissue O(2) concentration monitored using an O(2) sensor can serve as an index of changes in the magnitude of the BOLD response. As LIVE O(2) sensors can be used in awake animals performing specific behavioural tasks the technique provides a viable animal surrogate of human fMRI experimentation.
authors.affiliation: Department of Chemistry, National University of Ireland, Maynooth, Co. Kildare, Ireland. John.Lowry@nuim.ie
authors.forename: John P
authors.initials: JP
authors.lastname: Lowry
authors.forename: Karen
authors.initials: K
authors.lastname: Griffin
authors.forename: Stephen B
authors.initials: SB
authors.lastname: McHugh
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Lowe
authors.forename: Mark
authors.initials: M
authors.lastname: Tricklebank
authors.forename: Nicola R
authors.initials: NR
authors.lastname: Sibson
mesh_terms: D000818:Animals; D001921:Brain / Q000098:blood supply; D001923:Brain Chemistry; D001931:Brain Mapping / Q000379:methods*; D002560:Cerebrovascular Circulation; D055664:Electrochemical Techniques / Q000379:methods*; D004567:Electrodes, Implanted; D005240:Feasibility Studies; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010100:Oxygen / Q000097:blood / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D010100:Oxygen