To investigate the spatio-temporal properties of green auto-fluorescence (GAF) of the neocortex, we concurrently recorded spontaneous electroencephalographic signals (EEG) and GAF from the cerebral cortex of mice under urethane anesthesia. As the previous studies reported, the EEG delta wave was most frequently observed during urethane anesthesia. Power spectral density analysis showed that the activity in the delta frequency band was significant in the GAF as well. Cross-correlation analysis and magnitude-squared coherence analysis revealed that the EEG and GAF were significantly correlated in the delta frequency band. In addition, the GAF delta activity was spatially correlated in a wide area of the cortical hemisphere. These data suggest that the GAF delta activity would represent the EEG delta activity of the neocortex of mice. On the basis of these results, we visualized the spatio-temporal activity of the GAF delta component. We observed complex spatio-temporal dynamics such as a transient and localized activity, propagating waves, and disappearance of the waves after a collision. Since these characteristics are similar to those of the excitable media, it is suggested that the generation mechanism of the neocortical delta activity is similar to the excitable media. In addition, these results indicate the availability of the GAF for evaluating the spontaneous delta activity of the neocortex.