[FieldTrip] cross-frequency coupling between MEG planar channel twins?

[Frédéric Roux]

Dear all,

in my MEG-data (Elekta Vectorview System) I am observing that the amplitude of higher frequencies over one planar gradient channel is coupled to the
phase of lower frequencies on its corresponding twin-channel . I am attaching a figure to illustrate this. The upper row shows a low-frequency oscillation for one planar-channel and the bottom row shows the amplitude of a higher-frequency oscillation on its corresponding twin channel. Note that this separation is fairly consistent across other channels as well.

My question relates to what could explain such a coupling of low and high freq activity over channel-pairs with different gradient orientations (ie vertical vs. horizontal)? 

Could this be an indicator of two separate sources which are being picked up by the different spatial sensitivity of the planar gradients and where the phase of one source modulates the amplitude of the other source?

Any comments or suggestions on this would be highly appreciated.

Fred







--
Frédéric Roux
Postdoctoral Scientist, Marie-Curie fellow
BCBL. Basque Center on Cognition, Brain & Language.

f.roux at bcbl.eu
Tel: +34 943 309 300 Ext 211
Fax: +34 943 309 052

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