Objective In mammalian olfactory pathway, the oscillatory activities of the olfactory bulb (OB), piriform cortex (PCX) and hippocampus (HPC) have been extensively studied to elucidate odor information processing.However, less is known about the oscillations of spontaneous activity and the modulation by behavioral state, especially for the theta (4-t2 Hz) and gamma (35-100 Hz) bands.Methods In the present study, local field potentials (LFP) of spontaneous activity were recorded from the OB, PCX and HPC simultaneously in awake and anesthetized mice.Results Compared with the anesthetized state, awake mice showed increased theta and gamma oscillations in all the three regions, but decreased coherences among them.Furthermore, the spontaneous activities in exploratory walking and motionless mice were investigated.In exploratory state, the power of theta oscillations in the PCX and HPC was decreased, whereas the power of theta in the OB and gamma in all regions were increased significantly.However, the coherences among the three brain regions for both theta and gamma oscillations were significantly increased.It was also found that the coherence between the PCX and the HPC was always the highest regardless of brain state.Conclusion These results suggest that the theta and gamma oscillations in central olfactory pathway could be modulated by behavioral state, and that the higher coherences of both theta and gamma oscillations between PCX and HPC indicate tighter functional coupling between them.