Phase Synchrony Measurement of ERP Based on Complex Wavelet During Visual-Audio Multisensory Integration

In this paper, we employ the measurement of phase synchrony to investigate the activities of multisensory integration during cognitive process. This approach is illustrated by exploiting a complex Morlet wavelet to quantify the frequency-specific synchronization (i.e., transient phase-locking value, PLV) between two neuroelectric signals at a predefined frequency range. The motivation for its development is to be able to investigate the role of neural synchronies as a putative mechanism for neural integration during cognitive tasks. Unlike the more traditional method of spectral coherence, PLV separates the phase and amplitude components and can be directly interpreted in the framework of neural integration. We apply PLV to investigate electrode recordings from subjects performing a visual and auditory discrimination task. We find different synchronies in brain regions between unisensory and multisensory stimuli conditions. We argue that phase synchrony effects do reflect cognitive processing. Obtaining results indicate a possible relevance of this method based on Morlet wavelet in the context of cognitive science as well as in other fields.