Event-related dynamics of glutamate and BOLD effects measured using functional magnetic resonance spectroscopy (fMRS) at 3T in a repetition suppression paradigm
Research output: Contribution to journal › Article › peer-review
Electronic versions
DOI
Proton MR spectroscopy (1H-MRS) complements other brain research methods by providing
measures of neurometabolites noninvasively in a localized brain area. Improvements in MR scanner
technologies, and data acquisition and analysis methods should allow functional 1H-MRS (fMRS) to
measure neurometabolite concentration changes during task-induced brain activation. The aim of the
current study was to further develop event-related fMRS at 3T to investigate glutamate dynamics in
response to repetition suppression. A secondary aim was to investigate the relationship between
blood-oxygen-level-dependent (BOLD) responses and glutamate dynamics in the same paradigm at the
same time. A novel approach of interleaved water-suppressed (metabolite) and unsuppressed (water)
fMRS was used to simultaneously detect the event-related dynamics of glutamate and BOLD signal to
repetition suppression in the lateral occipital cortex of thirteen (N = 13) volunteers. On average, 1HMRS-
visible glutamate increased after novel visual stimuli presentations by 12% and decreased by 11-
13% on repeated compared to novel presentations. The BOLD signal, as measured by water peak
amplitude changes, showed significant difference between Task and Rest trials, and, on a GLM based
analysis of the time series, demonstrated a significant difference between the novel and repeated trials,
however appeared to be decoupled from the glutamate response as no correlation was found between
the two. These results are the first demonstration that reductions in neuronal activity typical of
repetition suppression effects are reflected by reduced glutamatergic and BOLD measures, that
glutamate and BOLD responses may not be coupled as previously thought, and that these changes and
relationships can be measured simultaneously using event-related fMRS at 3T.
Original language | English |
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Pages (from-to) | 292-300 |
Journal | Neuroimage |
Volume | 118 |
DOIs | |
Publication status | Published - 10 Jun 2015 |
Prof. activities and awards (2)
International Society for Magnetic resonance in Medicine
Activity: Participating in or organising an event › Participation in Academic conference
Towards a Theory for Functional Magnetic Resonance Spectroscopy
Activity: Talk or presentation › Invited talk