ICA-based spatiotemporal approach for single-trial analysis of postmovement MEG beta synchronization.
The extraction of event-related oscillatory neuromagnetic activities from single-trial measurement is challenging due to the non-phase-locked nature and variability from trial to trial. The present study presents a method based on independent component analysis (ICA) and the use of a template-based correlation approach to extract Rolandic beta rhythm from magnetoencephalographic (MEG) measurements of right finger lifting. A single trial recording was decomposed into a set of coupled temporal independent components and corresponding spatial maps using ICA and the reactive beta frequency band for each trial identified using a two-spectrum comparison between the postmovement interval and a reference period. Task-related components survived dual criteria of high correlation with both the temporal and the spatial templates with an acceptance rate of about 80%. Phase and amplitude information for noise-free MEG beta activities were preserved not only for optimal calculation of beta rebound (event-related synchronization) but also for profound penetration into subtle dynamics across trials. Given the high signal-to-noise ratio (SNR) of this method, various methods of source estimation were used on reconstructed single-trial data and the source loci coherently anchored in the vicinity of the primary motor area. This method promises the possibility of a window into the intricate brain dynamics of motor control mechanisms and the cortical pathophysiology of movement disorder on a trial-by-trial basis.
Lee
Po-Lei
PL
Laboratory of Integrated Brain Research, Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan.
Wu
Yu-Te
YT
Chen
Li-Fen
LF
Chen
Yong-Sheng
YS
Cheng
Chou-Ming
CM
Yeh
Tzu-Chen
TC
Ho
Low-Tone
LT
Chang
Mau-Song
MS
Hsieh
Jen-Chuen
JC
D000328:Adult; D001288:Attention / Q000502:physiology; D001611:Beta Rhythm; D003344:Cortical Synchronization; D003627:Data Interpretation, Statistical; D004569:Electroencephalography; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D009068:Movement / Q000502:physiology*; D025341:Principal Component Analysis; D015203:Reproducibility of Results