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Total neuroenergetics support localized brain activity: Implications for the interpretation of fMRI
被引:159
作者:
Hyder, F
Rothman, DL
Shulman, RG
机构:
[1] Yale Univ, Sch Med, Dept Diagnost Radiol, Magnet Resonance Res Ctr, New Haven, CT 06510 USA
[2] Yale Univ, Sch Med, Dept Biomed Engn, New Haven, CT 06510 USA
[3] Yale Univ, Sch Med, Dept Mol Biophys & Biochem, New Haven, CT 06510 USA
[4] Yale Univ, Sch Med, Sect Bioimaging Sci, New Haven, CT 06510 USA
来源:
关键词:
D O I:
10.1073/pnas.132272299
中图分类号:
O [数理科学和化学];
P [天文学、地球科学];
Q [生物科学];
N [自然科学总论];
学科分类号:
07 ;
0710 ;
09 ;
摘要:
In alpha-chloralose-anesthetized rats, changes in the blood oxygenation level-dependent (BOLD) functional MRI (fMRI) signal (DeltaS/S), and the relative spiking frequency of a neuronal ensemble (Deltanu/nu) were measured in the somatosensory cortex during forepaw stimulation from two different baselines. Changes in cerebral oxygen consumption (DeltaCMR(O2)/CMRO2) were derived from the BOLD signal (at 7T) by independent determinations in cerebral blood flow (DeltaCBF/CBF) and volume (DeltaCBV/CBV). The spiking frequency was measured by extracellular recordings in layer 4. Changes in all three parameters (CMRO2, nu, and S) were greater from the lower baseline (i.e., deeper anesthesia). For both baselines, DeltaCMR(O2)/CMRO2 and Deltanu/nu were approximately one order of magnitude larger than DeltaS/S. The final values of CMRO2 and nu reached during stimulation were approximately the same from both baselines. If only increments were required to support functions then their magnitudes should be independent of the baseline. In contrast, if particular magnitudes of activity were required, then sizes of increments should inversely correlate with the baseline (being larger from a lower baseline). The results show that particular magnitudes of activity support neural function. The disregard of baseline activity in fMRI experiments by differencing removes a large and necessary component of the total activity. Implications of these results for understanding brain function and fMRI experiments are discussed.
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页码:10771 / 10776
页数:6
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