Power of spontaneous BOLD signal and neural activity fluctuations is baseline-dependent

INTRODUCTION Evoked responses in functional studies show baseline dependence [1], i.e. in higher metabolic baseline state the functional response is smaller but delocalized, whereas lower metabolic baseline shows higher amplitude localized responses. Other human studies [2] showed that spontaneous fluctuations in BOLD signal seem to be important in local variability or trial-to-trial reproducibility of the functional response. In this study we examined high and low energy baselines of light (Domitor) and deep (α-chloralose) anesthesia, respectively, to compare whether high or low energy baselines are related to fluctuations in neural activity and baseline BOLD signals.