TY  - JOUR
AU  - Garcés, P.
AU  - López-Sanz, D.
AU  - Maestú, F.
AU  - Pereda, E.
T1  - Choice of magnetometers and gradiometers after signal space separation
LA  - eng
PY  - 2017
T2  - Sensors (Switzerland)
SN  - 1424-8220
VL  - 17
IS  - 12
PB  - MDPI AG
PP  - Basel
AB  - Background: Modern Elekta Neuromag MEG devices include 102 sensor triplets containing one magnetometer and two planar gradiometers. The first processing step is often a signal space separation (SSS), which provides a powerful noise reduction. A question commonly raised by researchers and reviewers relates to which data should be employed in analyses: (1) magnetometers only, (2) gradiometers only, (3) magnetometers and gradiometers together. The MEG community is currently divided with regard to the proper answer. Methods: First, we provide theoretical evidence that both gradiometers and magnetometers result from the backprojection of the same SSS components. Then, we compare resting state and task-related sensor and source estimations from magnetometers and gradiometers in real MEG recordings before and after SSS. Results: SSS introduced a strong increase in the similarity between source time series derived from magnetometers and gradiometers (r2 = 0.3-0.8 before SSS and r2 > 0.80 after SSS). After SSS, resting state power spectrum and functional connectivity, as well as visual evoked responses, derived from both magnetometers and gradiometers were highly similar (Intraclass Correlation Coefficient > 0.8, r2 > 0.8). Conclusions: After SSS, magnetometer and gradiometer data are estimated from a single set of SSS components (usually ≤ 80). Equivalent results can be obtained with both sensor types in typical MEG experiments.
DO  - 10.3390/s17122926
UR  - https://portalciencia.ull.es/documentos/5df8a7dc2999525886b70094
DP  - Dialnet - Portal de la Investigación
ER  -