Non-neuronal DC offsets in occipital α oscillations

The origin of magnetic DC offsets in occipital α oscillations was investigated for the case of oscillations induced by closing of the eyes. Magnetoencephalographic recordings from DC to 500 Hz in an eight layer magnetically shielded room allowed to resolve the superposition of α generators and eye dipole using independent component analysis. The resulting signals suggest that the DC offsets are of non-neuronal origin, i.e. due to the eye dipole.