title: Are glutamate and lactate increases ubiquitous to physiological activation? A (1)H functional MR spectroscopy study during motor activation in human brain at 7Tesla.
abstract: Recent studies at high field (7Tesla) have reported small metabolite changes, in particular lactate and glutamate (below 0.3μmol/g) during visual stimulation. These studies have been limited to the visual cortex because of its high energy metabolism and good magnetic resonance spectroscopy (MRS) sensitivity using surface coil. The aim of this study was to extend functional MRS (fMRS) to investigate for the first time the metabolite changes during motor activation at 7T. Small but sustained increases in lactate (0.17μmol/g±0.05μmol/g, p<0.001) and glutamate (0.17μmol/g±0.09μmol/g, p<0.005) were detected during motor activation followed by a return to the baseline after the end of activation. The present study demonstrates that increases in lactate and glutamate during motor stimulation are small, but similar to those observed during visual stimulation. From the observed glutamate and lactate increase, we inferred that these metabolite changes may be a general manifestation of the increased neuronal activity. In addition, we propose that the measured metabolite concentration increases imply an increase in ΔCMRO2 that is transiently below that of ΔCMRGlc during the first 1 to 2min of the stimulation.
authors.affiliation: Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Federale de Lausanne, Station 6, 1015 Lausanne, Switzerland. Electronic address: benoit.schaller@cardiov.ox.ac.uk.
authors.forename: Benoît
authors.initials: B
authors.lastname: Schaller
authors.affiliation: Department of Radiology, University Hospitals of Lausanne Rue du Bugnon 21, 1011 Lausanne, Switzerland. Electronic address: lijing.xin@epfl.ch.
authors.forename: Lijing
authors.initials: L
authors.lastname: Xin
authors.affiliation: Centre d'Imagerie BioMédicale, University of Geneva, Geneva 14, Geneva, Switzerland. Electronic address: kieran.obrien@epfl.ch.
authors.forename: Kieran
authors.initials: K
authors.lastname: O'Brien
authors.affiliation: Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Federale de Lausanne, Station 6, 1015 Lausanne, Switzerland; Department of Radiology, University Hospitals of Lausanne Rue du Bugnon 21, 1011 Lausanne, Switzerland. Electronic address: a.magill@fz-juelich.de.
authors.forename: Arthur W
authors.initials: AW
authors.lastname: Magill
authors.affiliation: Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Federale de Lausanne, Station 6, 1015 Lausanne, Switzerland; Department of Radiology, University Hospitals of Lausanne Rue du Bugnon 21, 1011 Lausanne, Switzerland; Department of Radiology, University Hospitals of Geneva, Rue Gabrielle-Perret-Gentil 4, 1211 Geneva 14, Switzerland. Electronic address: rolf.gruetter@epfl.ch.
authors.forename: Rolf
authors.initials: R
authors.lastname: Gruetter
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000378:metabolism*; D001931:Brain Mapping; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism*; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D055815:Young Adult
chemical_list: D019344:Lactic Acid; D018698:Glutamic Acid
keywords: (1)H MR spectroscopy; Cerebral metabolic rate; Glutamate; Lactate; Motor stimulation; Neurotransmitter; Oxidative metabolism