Functional imaging of spontaneous activity of the brain using green-autofluorescence of flavoprotein

Since the response of the brain to a sensory input is dependent on the state of the brain that fluctuates spontaneously with time, it is very important to know the spontaneous activity of the brain for the stimulus-to-response property evaluation. Recently, green auto-fluorescence (GAF) emitted from mitochondrial flavoprotein has been proved to be correlated with the neuronal activity of the brain. The GAF imaging technique has been used for brain mapping. However, it has not been used for the spontaneous activity of the brain because its signal-to-noise ratio (S/N) is low. To improve S/N, we have optimized the fluorescent measurement system and introduced digital signal processing techniques. In this presentation, we will show that GAF of the brain has a component which is correlated with spontaneous electroencephalographic activity, and discuss utilization for the functional imaging of spontaneous brain activity.