title: Head movement compensation in real-time magnetoencephalographic recordings.
abstract: Neurofeedback- and brain-computer interface (BCI)-based interventions can be implemented using real-time analysis of magnetoencephalographic (MEG) recordings. Head movement during MEG recordings, however, can lead to inaccurate estimates of brain activity, reducing the efficacy of the intervention. Most real-time applications in MEG have utilized analyses that do not correct for head movement. Effective means of correcting for head movement are needed to optimize the use of MEG in such applications. Here we provide preliminary validation of a novel analysis technique, real-time source estimation (rtSE), that measures head movement and generates corrected current source time course estimates in real-time. rtSE was applied while recording a calibrated phantom to determine phantom position localization accuracy and source amplitude estimation accuracy under stationary and moving conditions. Results were compared to off-line analysis methods to assess validity of the rtSE technique. The rtSE method allowed for accurate estimation of current source activity at the source-level in real-time, and accounted for movement of the source due to changes in phantom position. The rtSE technique requires modifications and specialized analysis of the following MEG work flow steps.•Data acquisition•Head position estimation•Source localization•Real-time source estimation This work explains the technical details and validates each of these steps.
authors.affiliation: Biomedical Translational Imaging Centre (BIOTIC), IWK Health Sciences Centre, Halifax, Nova Scotia, Canada.
authors.forename: Graham
authors.initials: G
authors.lastname: Little
authors.affiliation: Laboratory for Brain Recovery and Function, School of Physiotherapy, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Shaun
authors.initials: S
authors.lastname: Boe
authors.affiliation: Biomedical Translational Imaging Centre (BIOTIC), IWK Health Sciences Centre, Halifax, Nova Scotia, Canada ; Department of Diagnostic Imaging, IWK Health Sciences Centre, Halifax, Nova Scotia, Canada ; Laboratory for Brain Recovery and Function, School of Physiotherapy, Dalhousie University, Halifax, Nova Scotia, Canada ; Department of Computer Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Timothy
authors.initials: T
authors.lastname: Bardouille
keywords: Brain computer interface (BCI); Magnetoencephalography (MEG); Neurofeedback; Real-time analysis