Detection of Brain Activation with no Stimulus Using Wavelet Analysis

Most of the methods for investigating brain function observe the localization of brain activity responded by the external stimuli which are executed with simply and repeatedly. On the contrary, when brain function is rest state such as falling asleep, a spontaneous brain signal measured by EEG or the other modalities is used as a trigger of the stimulus. This paper proposes an analysis method for detecting activation areas and activation times from fMRI time series data without giving tasks or stimuli for a subject. The results indicated that the proposed method detected activation areas with similar accuracy to those obtained by SPM99. Also, the proposed method was applied to a subject who did not conduct any tasks. The results showed that the method detected various brain activations, which would be spontaneous brain event, while we give no stimuli or tasks