神経活動の増加に伴う負の BOLD 信号

未 fMRI

Negative BOLD with Large Increases in Neuronal Activity.

Schridde U, Khubchandani M, Motelow JE, Sanganahalli BG, Hyder F, Blumenfeld H

Cereb Cortex. 2007 Dec 5;


Blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is widely used in neuroscience to study brain activity. However, BOLD fMRI does not measure neuronal activity directly but depends on cerebral blood flow (CBF), cerebral blood volume (CBV), and cerebral metabolic rate of oxygen (CMRO(2)) consumption. Using fMRI, CBV, CBF, neuronal recordings, and CMRO(2) modeling, we investigated how the signals are related during seizures in rats. We found that increases in hemodynamic, neuronal, and metabolic activity were associated with positive BOLD signals in the cortex, but with negative BOLD signals in hippocampus. Our data show that negative BOLD signals do not necessarily imply decreased neuronal activity or CBF, but can result from increased neuronal activity, depending on the interplay between hemodynamics and metabolism. Caution should be used in interpreting fMRI signals because the relationship between neuronal activity and BOLD signals may depend on brain region and state and can be different during normal and pathological conditions.

ラットの脳血流量 (CBF)、脳血液量(CBV)、脳酸素消費量 (CMRO2)、神経活動 と fMRI の BOLD 信号を比較。


血行動態・神経活動・代謝の増加

  • 皮質：正の BOLD
  • 海馬：負の BOLD



負の BOLD は必ずしも神経活動の低下を意味しない。
神経活動と代謝の相互作用に依存し、部位や状態、病態によって変化するので注意。