John Lowry1, Karen Griffin2,
Stephen McHugh3, Nicola Sibson4
1Department of Chemistry, National
University of Ireland, Maynooth, Ireland; 2University College
Dublin, Ireland; 3Department of Experimental Psychology,
University of Oxford, Oxford, United Kingdom; 4Gray Institute for
Radiation Oncology and Biology, University of Oxford, Oxford, Oxfordshire,
United Kingdom
Long-term
in-vivo electrochemistry (LIVE) enables real-time measurement of brain
metabolites. Here we have simultaneously obtained BOLD fMRI and amperometric
LIVE tissue oxygen data from rat cerebral cortex, during both increases and
decreases in inspired oxygen. BOLD and tissue oxygen measurements
demonstrated close correlation during both complete oxygen removal (negative
responses) and increases in inspired oxygen (positive responses). Our
findings demonstrate the feasibility of obtaining real-time metabolite
information during fMRI acquisition. The results show that the BOLD signal
provides a close correlate of the tissue oxygen dynamics or, alternatively,
that tissue oxygen concentration can predict the magnitude of the BOLD
response.