ICA-based analysis of movement-related modulation on beta activity of single-trial MEG measurement using spatial and temporal templates

Chi Hsun Wu, Po Lei Lee, Yu Te Wu, Jen Chuen Hsieh

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

An independent component analysis (ICA) based method is proposed to quantify the single-trial response of beta-band activities of sensorimotor rhythm in finger lifting tasks. The magnetic fields of four right-handed subjects (2 males and 2 females) and one idiopathic Parkinson's disease patient were recorded by whole-head magnetoencephalography (Neuromag-306). ICA was applied to separate each rhythmic epoch into temporally independent components by means of an un-mixing matrix. Each column of the inverse of the un-mixing matrix represents a spatial map describing the relative projection weights of the corresponding temporal components at each of the MEG sensors. According to the temporal and spatial characteristics of neuromagnetic rhythmic activities, task-related signals can be selected by comparing the spatial map of each independent component with a pre-defined spatial template. Those selected ICs are then subject to data reconstruction so that task-unrelated external and internal noise can be eliminated. Single-trial-detected beta event-related desynchronizations (ERD) were 12.86±4.4, 7.64±2.25, 16.4±7.1, and 4.5±2.2 fT/cm, respectively, and the amplitudes of single-trial-detected beta rebounds were 19.4±9.1, 24.3±11.4, 21.11±12.2, and 11.1±4.4 fT/cm. The single-trial method demonstrated higher performance in extracting beta ERD and event-related synchronization (ERS), compared to the 100-trial averaged results using conventional amplitude modulation (AM) method (6.03 fT/cm for beta ERD and 11.57 fT/ cm for beta ERS, four subject averaged). The proposed ICA-based single-trial method is a useful way to provide insightful view for examining neuromagnetic rhythmic dynamics. We used our developed ICA-based single-trial brain rhythm analysis method to discover the mechanisms of beta ERD and ERS in Parkinson's patients. It is helpful to investigate the reasoning of ERS vanishment due to suppression of post-movement beta rebound in each single trial, rather than the cause of temporal jittering and/or loss of synchronization, in Parkinson's disease.

Original languageEnglish
Pages (from-to)155-159
Number of pages5
JournalJournal of Medical and Biological Engineering
Volume28
Issue number3
StatePublished - Sep 2008

Keywords

  • Event-related desynchronization (ERD)
  • Event-related synchronization (ERS)
  • Independent component analysis (ICA)
  • Magnetoencephalography (MEG)
  • Parkinson's disease (PD)

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