Abstract
Several laboratories have consistently reported small concentration changes in lactate, glutamate, aspartate, and glucose in the human cortex during prolonged stimuli. However, whether such changes correlate with blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) signals have not been determined. The present study aimed at characterizing the relationship between metabolite concentrations and BOLD-fMRI signals during a block-designed paradigm of visual stimulation. Functional magnetic resonance spectroscopy (fMRS) and fMRI data were acquired from 12 volunteers. A short echo-time semi-LASER localization sequence optimized for 7 Tesla was used to achieve full signal-intensity MRS data. The group analysis confirmed that during stimulation lactate and glutamate increased by 0.26±0.06 μmol/g (∼30%) and 0.28±0.03 μmol/g (∼3%), respectively, while aspartate and glucose decreased by 0.20±0.04 μmol/g (∼5%) and 0.19±0.03 μmol/g (∼16%), respectively. The single-subject analysis revealed that BOLD-fMRI signals were positively correlated with glutamate and lactate concentration changes. The results show a linear relationship between metabolic and BOLD responses in the presence of strong excitatory sensory inputs, and support the notion that increased functional energy demands are sustained by oxidative metabolism. In addition, BOLD signals were inversely correlated with baseline γ-aminobutyric acid concentration. Finally, we discussed the critical importance of taking into account linewidth effects on metabolite quantification in fMRS paradigms.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 601-610 |
| Number of pages | 10 |
| Journal | Journal of Cerebral Blood Flow and Metabolism |
| Volume | 35 |
| DOIs | |
| State | Published - Mar 31 2015 |
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Keywords
- Functional Spectroscopy
- GABA quantification
- Neurochemistry
- Visual Stimulation
Cite this
Neurochemical and BOLD responses during neuronal activation measured in the human visual cortex at 7 Tesla. / Bednarik, Petr; Tkac, Ivan; Giove, Federico; Dinuzzo, Mauro; Deelchand, Dinesh K; Emir, Uzay E.; Eberly, Lynn E; Mangia, Silvia.
In: Journal of Cerebral Blood Flow and Metabolism, Vol. 35, 31.03.2015, p. 601-610.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Neurochemical and BOLD responses during neuronal activation measured in the human visual cortex at 7 Tesla
AU - Bednarik, Petr
AU - Tkac, Ivan
AU - Giove, Federico
AU - Dinuzzo, Mauro
AU - Deelchand, Dinesh K
AU - Emir, Uzay E.
AU - Eberly, Lynn E
AU - Mangia, Silvia
PY - 2015/3/31
Y1 - 2015/3/31
N2 - Several laboratories have consistently reported small concentration changes in lactate, glutamate, aspartate, and glucose in the human cortex during prolonged stimuli. However, whether such changes correlate with blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) signals have not been determined. The present study aimed at characterizing the relationship between metabolite concentrations and BOLD-fMRI signals during a block-designed paradigm of visual stimulation. Functional magnetic resonance spectroscopy (fMRS) and fMRI data were acquired from 12 volunteers. A short echo-time semi-LASER localization sequence optimized for 7 Tesla was used to achieve full signal-intensity MRS data. The group analysis confirmed that during stimulation lactate and glutamate increased by 0.26±0.06 μmol/g (∼30%) and 0.28±0.03 μmol/g (∼3%), respectively, while aspartate and glucose decreased by 0.20±0.04 μmol/g (∼5%) and 0.19±0.03 μmol/g (∼16%), respectively. The single-subject analysis revealed that BOLD-fMRI signals were positively correlated with glutamate and lactate concentration changes. The results show a linear relationship between metabolic and BOLD responses in the presence of strong excitatory sensory inputs, and support the notion that increased functional energy demands are sustained by oxidative metabolism. In addition, BOLD signals were inversely correlated with baseline γ-aminobutyric acid concentration. Finally, we discussed the critical importance of taking into account linewidth effects on metabolite quantification in fMRS paradigms.
AB - Several laboratories have consistently reported small concentration changes in lactate, glutamate, aspartate, and glucose in the human cortex during prolonged stimuli. However, whether such changes correlate with blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) signals have not been determined. The present study aimed at characterizing the relationship between metabolite concentrations and BOLD-fMRI signals during a block-designed paradigm of visual stimulation. Functional magnetic resonance spectroscopy (fMRS) and fMRI data were acquired from 12 volunteers. A short echo-time semi-LASER localization sequence optimized for 7 Tesla was used to achieve full signal-intensity MRS data. The group analysis confirmed that during stimulation lactate and glutamate increased by 0.26±0.06 μmol/g (∼30%) and 0.28±0.03 μmol/g (∼3%), respectively, while aspartate and glucose decreased by 0.20±0.04 μmol/g (∼5%) and 0.19±0.03 μmol/g (∼16%), respectively. The single-subject analysis revealed that BOLD-fMRI signals were positively correlated with glutamate and lactate concentration changes. The results show a linear relationship between metabolic and BOLD responses in the presence of strong excitatory sensory inputs, and support the notion that increased functional energy demands are sustained by oxidative metabolism. In addition, BOLD signals were inversely correlated with baseline γ-aminobutyric acid concentration. Finally, we discussed the critical importance of taking into account linewidth effects on metabolite quantification in fMRS paradigms.
KW - Functional Spectroscopy
KW - GABA quantification
KW - Neurochemistry
KW - Visual Stimulation
UR - http://www.scopus.com/inward/record.url?scp=84926513383&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84926513383&partnerID=8YFLogxK
U2 - 10.1038/jcbfm.2014.233
DO - 10.1038/jcbfm.2014.233
M3 - Article
C2 - 25564236
AN - SCOPUS:84926513383
VL - 35
SP - 601
EP - 610
JO - Journal of Cerebral Blood Flow and Metabolism
JF - Journal of Cerebral Blood Flow and Metabolism
SN - 0271-678X
ER -