Combined fMRI-MRS acquires simultaneous glutamate and BOLD-fMRI signals in the human brain

Neuroimage. 2017 Jul 15;155:113-119. doi: 10.1016/j.neuroimage.2017.04.030. Epub 2017 Apr 19.


Combined fMRI-MRS is a novel method to non-invasively investigate functional activation in the human brain using simultaneous acquisition of hemodynamic and neurochemical measures. The aim of the current study was to quantify neural activity using combined fMRI-MRS at 7T. BOLD-fMRI and semi-LASER localization MRS data were acquired from the visual cortex of 13 participants during short blocks (64s) of flickering checkerboards. We demonstrate a correlation between glutamate and BOLD-fMRI time courses (R=0.381, p=0.031). In addition, we show increases in BOLD-fMRI (1.43±0.17%) and glutamate concentrations (0.15±0.05 I.U., ~2%) during visual stimulation. In contrast, we observed no change in glutamate concentrations in resting state MRS data during sham stimulation periods. Spectral line width changes generated by the BOLD-response were corrected using line broadening. In summary, our results establish the feasibility of concurrent measurements of BOLD-fMRI and neurochemicals using a novel combined fMRI-MRS sequence. Our findings strengthen the link between glutamate and functional activity in the human brain by demonstrating a significant correlation of BOLD-fMRI and glutamate over time, and by showing ~2% glutamate increases during 64s of visual stimulation. Our tool may become useful for studies characterizing functional dynamics between neurochemicals and hemodynamics in health and disease.

Keywords: BOLD fMRI; Functional Spectroscopy; Glutamate; Neurochemistry; Visual cortex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Brain / diagnostic imaging*
  • Brain / physiology
  • Brain Mapping / methods*
  • Female
  • Glutamic Acid / analysis*
  • Hemodynamics / physiology
  • Humans
  • Magnetic Resonance Imaging / methods*
  • Magnetic Resonance Spectroscopy / methods*
  • Male


  • Glutamic Acid