Neurovascular Coupling Relationship between Spontaneous EEG and CBF Responses Is Sensitive to Anesthesia Depth

Introduction It has been demonstrated in our previous study [1] that spontaneous cerebral blood flow (CBF) and electroencephalography (EEG) simultaneously recorded from rat primary somatosensory cortex are tightly coupled under burst-suppression anesthesia induced by isoflurane. On the other hand, other studies [2-3] have reported that the rat brain can exhibit distinct hemodynamic responses to external stimulation under different anesthesia levels, which may indicate a significant effect of anesthesia depth on neurovascular coupling relationship. One relevant and interesting question is whether the neurovascular coupling between spontaneous CBF and EEG in a resting brain also is sensitive to anesthesia depth. To answer this question, we analyzed the hemodynamic response function (HRF) linking spontaneous CBF and EEG signals measured under two isoflurane anesthesia conditions (1.8% vs. 2.0%). The results indicate that a small isoflurane dose change (0.2%) has a substantial effect on HRF.