Denoising Single Trial Event Related Magnetoencephalographic Recordings

  • Authors:
  • Elina Karp;Lauri Parkkonen;Ricardo Vigário

  • Affiliations:
  • Adaptive Informatics Research Centre, Helsinki University of Technology, Finland FI-02015 TKK;Brain Research Unit, Low Temperature Laboratory, Helsinki University of Technology, Finland FI-02015 TKK;Adaptive Informatics Research Centre, Helsinki University of Technology, Finland FI-02015 TKK

  • Venue:
  • ICA '09 Proceedings of the 8th International Conference on Independent Component Analysis and Signal Separation
  • Year:
  • 2009

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Abstract

Functional brain mapping is often performed by analysing neuronal responses evoked by external stimulation. Assuming constant brain responses to repeated identical stimuli, averaging across trials is usually applied to improve the typically poor signal-to-noise ratio. However, since wave shape and latency vary from trial to trial, information is lost when averaging. In this work, trial-to-trial jitter in visually evoked magnetoencephalograms (MEG) was estimated and compensated for, improving the characterisation of neuronal responses. A denoising source separation (DSS) algorithm including a template based denoising strategy was applied. Independent component analysis (ICA) was used to compute a seed necessary for the template construction. The results are physiologically plausible and indicate a clear improvement compared to the classical averaging method.