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Neuroimage. 2014 May 15;92:217-24. doi: 10.1016/j.neuroimage.2014.02.004. Epub 2014 Feb 12.

Intersubject consistency of cortical MEG signals during movie viewing.

Author information

1
Brain Research Unit, O.V. Lounasmaa Laboratory and MEG Core, Aalto NeuroImaging, School of Science, Aalto University, P.O. Box 15100, FI-00076 AALTO, Finland. Electronic address: kaisu.lankinen@aalto.fi.
2
Brain Research Unit, O.V. Lounasmaa Laboratory and MEG Core, Aalto NeuroImaging, School of Science, Aalto University, P.O. Box 15100, FI-00076 AALTO, Finland.

Abstract

According to recent functional magnetic resonance imaging (fMRI) studies, spectators of a movie may share similar spatiotemporal patterns of brain activity. We aimed to extend these findings of intersubject correlation to temporally accurate single-trial magnetoencephalography (MEG). A silent 15-min black-and-white movie was shown to eight subjects twice. We adopted a spatial filtering model and estimated its parameter values by using multi-set canonical correlation analysis (M-CCA) so that the intersubject correlation was maximized. The procedure resulted in multiple (mutually uncorrelated) time-courses with statistically significant intersubject correlations at frequencies below 10 Hz; the maximum correlation was 0.28 ± 0.075 in the ≤1 Hz band. Moreover, the 24-Hz frame rate elicited steady-state responses with statistically significant intersubject correlations up to 0.29 ± 0.12. To assess the brain origin of the across-subjects correlated signals, the time-courses were correlated with minimum-norm source current estimates (MNEs) projected to the cortex. The time series implied across-subjects synchronous activity in the early visual, posterior and inferior parietal, lateral temporo-occipital, and motor cortices, and in the superior temporal sulcus (STS) bilaterally. These findings demonstrate the capability of the proposed methodology to uncover cortical MEG signatures from single-trial signals that are consistent across spectators of a movie.

KEYWORDS:

Magnetoencephalography (MEG); Minimum norm estimate (MNE); Movie; Multi-set canonical correlation analysis (M-CCA); Spatial filtering

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