Comparison of neuronal and hemodynamic measures of the brain response to visual stimulation: An optical imaging study

The noninvasive mapping of hemodynamic brain activity has led to significan t advances in neuroimaging. This approach is based in part on the assumptio n that hemodynamic changes are proportional to (and therefore constitute a linear measure of) neuronal activity. We report a study investigating the q uantitative relationship between neuronal and hemodynamic measures. This st udy exploited the fact that optical imaging methods can simultaneously prov ide noninvasive measures of neuronal and hemodynamic activity from the same region of the brain. We manipulated Visual stimulation frequency and measu red responses from the medial occipital area of 8 young adults. The results were consistent with a model postulating a linear relationship between the neuronal activity integrated over time and the amplitude of the hemodynami c response. The hemodynamic response colocalized with the neuronal response . These data support the use of quantitative neuroimaging methods to infer the intensity and localization of neuronal activity in occipital areas. Hum . Brain Mapping 13:13-25, 2001. (C) 2001 Wiley-Liss, Inc.