Correlates of eye blinking as determined by synthetic aperture magnetometry.
OBJECTIVE
To evaluate the spatiotemporal characteristics of ocular and cerebral current sources during voluntary eyeblinking.


METHODS
Whole-head magnetoencephalographic (MEG) recordings were acquired during voluntary blinking in eight healthy adults and analysed using synthetic aperture magnetometry (SAM).


RESULTS
Fronto-temporal MEG sensors showed a large slow wave lasting approximately 400 ms and a small burst of activity with frequencies above 30 Hz at the initiation of the blink. Group maps of blink-related oscillatory activity at frequencies between 1-18 Hz and 32-64 Hz showed increased activity in and around the orbits during the 400 ms following blink onset. Increased oscillatory activity occurred in occipital regions 200 ms after blink onset at frequencies between 18 and 64 Hz.


CONCLUSIONS
Blink-related MEG signals are recorded in the regions of the eyes and in the occipital cortex. The anterior activation is likely a combination of muscle contraction and eyelid currents. Occipital activation likely represents neural processes concerned with re-establishing the visual image after transient ocular occlusion.


CONCLUSIONS
The possibility of eyeblink-related fields should be considered when interpreting frontal and occipital source activities during SAM analyses.
The Rotman Research Institute, Baycrest Centre for Geriatric Care, University of Toronto, Ont., Canada M6A 2E1. tbardouille@rotman-baycrest.on.ca
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D000328:Adult; D001767:Blinking / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D008280:Magnetics / Q000295:instrumentation*; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008875:Middle Aged