ICA-based spatiotemporal approach for single-trial analysis of postmovement MEG beta synchronization

Po Lei Lee, Yu Te Wu, Li Fen Chen, Yong Sheng Chen, Chou Ming Cheng, Tzu Chen Yeh, Low Tone Ho, Mau Song Chang, Jen Chuen Hsieh

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


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.

Original languageEnglish
Pages (from-to)2010-2030
Number of pages21
Issue number4
StatePublished - Dec 2003


  • Event-related synchronization
  • Independent component analysis (ICA)
  • Magnetoencephalography
  • Motor cortex
  • Rolandic rhythm
  • Single-trial


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