title: EEG gamma-band activity during audiovisual speech comprehension in different noise environments.
abstract: The presence of cross-modal stochastic resonance in different noise environments has been proved in previous behavioral and event-related potential studies, while it was still unclear whether the gamma-band oscillation study was another evidence of cross-modal stochastic resonance. The multisensory gain of gamma-band activity between the audiovisual (AV) and auditory-only conditions in different noise environments was analyzed. Videos of face motion articulating words concordant with different levels of pink noise were used as stimuli. Signal-to-noise ratios (SNRs) of 0, -4, -8, -12 and -16 dB were selected to measure the speech recognition accuracy and EEG activity for 20 healthy subjects. The power and phase of EEG gamma-band oscillations increased in a time window of 50-90 ms. The multisensory gains of evoked and total activity, as well as phase-locking factor, were greatest at the -12 dB SNR, which were consistent with the behavioral result. The multisensory gain of gamma-band activity showed an inverted U-shaped curve as a function of SNR. This finding confirmed the presence of cross-modal stochastic resonance. In addition, there was a significant correlation between evoked activity and phase-locking factor of gamma-band at five different SNRs. Gamma-band oscillation was believed to play a role in the rapid processing and information linkage strengthening of AV modalities in the early stage of cognitive processes.
authors.affiliation: School of Medicine, Tsinghua University, Beijing, 100084 People's Republic of China ; School of Information and Electronics, Beijing Institute of Technology, Beijing, 100081 People's Republic of China.
authors.forename: Yanfei
authors.initials: Y
authors.lastname: Lin
authors.affiliation: School of Computer Science and Technology, Tianjin University, Tianjin, 300072 People's Republic of China.
authors.forename: Baolin
authors.initials: B
authors.lastname: Liu
authors.affiliation: School of Information and Electronics, Beijing Institute of Technology, Beijing, 100081 People's Republic of China.
authors.forename: Zhiwen
authors.initials: Z
authors.lastname: Liu
authors.affiliation: School of Medicine, Tsinghua University, Beijing, 100084 People's Republic of China.
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Gao
keywords: Audiovisual speech; Cross-modal stochastic resonance; Gamma-band activity; Multisensory integration; Noise