Brain oscillations are modulated in the neocortex and the hippocampus by the audiovisual theta timing during movie encoding. A, Source localization of the difference of theta power in response to the audiovisual asynchrony in the movies (synchronous minus asynchronous). The perception of asynchronous movies induced a decrease of theta power as compared with synchronous movies, in cortical regions associated with language network (threshold at significant t values; cluster-corrected at α threshold = 0.05). B, Top, Statistical difference of theta power in the hippocampus in response to the audiovisual asynchrony (x = 31; y = −19; z = −11; threshold at significant t values; cluster-corrected at α threshold = 0.05). Bottom, Logarithmic time–frequency plot of nonrealigned power spectrum difference in the hippocampus. The time–frequency only plots the spectral power difference for visualization purpose and does not report any statistical difference. C, Temporal modulation of theta power in the hippocampus during the encoding of synchronous (blue line, mean ± standard error mean) and asynchronous movies (gray line, mean ± standard error mean). The bottom line (black) depicts the t values between the two cases for each time-point of the movie encoding (−0.3 s to 5 s with respect to the picture onset). The significant time-points are depicted in green (multiple-comparison corrected p values). In B and C, the vertical dashed lines at zero on the x-axis indicate the movie onset. D, Mean difference of hippocampal power in the theta range versus neighboring frequencies in the central time-window of interest. Theta oscillations in the hippocampus were specifically impacted by the audiovisual synchrony at the dominant frequencies (i.e., where lip movements and auditory envelopes were aligned in the movies). The boxplots represent the mean ± standard deviation and the errors bars indicate 5th and 95th percentiles. The dots represent individual means (*p < 0.05).