BOLD Brain Measurement
Today in Science, scientists from the University of California at Berkley found that functional magnetic resonance (fMRI) imaging provides a powerful, non-invasive window on brain function. Using a technique called “blood oxygen-level depletion” or (BOLD) fMRI researchers are able to tracks changes in neural activity by measuring the decrease in deoxyhemoglobin, corresponding to gradually increased blood flow to active regions. In the past the limited spatial resolution of this technique has prevented analysis of activity within the neural columns that provide the functional architecture of much of the cerebral cortex. Using BOLD, greater fMRI resolution can be obtained by measuring a highly localized, transient increase in deoxyhemoglobin corresponding to rapid oxygen uptake by active cells. Jeffrey K. Thompson and colleagues show that this signal does tightly correlate with neuronal firing activity, enabling sub-column analysis of brain function.
The authors conclude that “these results indicate that fMRI detection of rapid, highly localized increases in deoxyhemoglobin can accurately track neural activity on a scale finer than current standard methods. This technique has the potential to resolve functional cortical columns that are thought to be fundamental for a wide variety of brain processes,"
(Science 299:1070-1072, February 14, 2003).
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