Spatio-temporal analysis of spontaneous low frequency oscillations to single whisker stimulation in rat cerebral cortex

Spontaneous low frequency oscillations (LFOs) have been found in cerebral hemodynamics and metabolisms with different techniques and species. In this study, optical imaging system was employed to detect hemodynamic changes in the anesthetized rat cerebral cortex. Under 546-nm or 630-nm illumination, the phase and amplitude distributions of spontaneous LFOs were investigated before and after single whisker stimulation. Spontaneous LFOs can be modulated by the stimulation, and we found obvious synchronization of phase distributions at around 0.1-hz in two hemispheres. After stimulation, the amplitude of spontaneous LFOs in the region of arteries was increased under 546-nm illumination, while the amplitude of spontaneous LFOs in the region of veins was increased under 630-nm illumination. The precise mechanisms and roles of spontaneous LFOs remain unclear. We speculated the extensive synchronization of LFO phases may be associated with the brain function of global alertness and vigilance.