title: Beamformer-based spatiotemporal imaging of linearly-related source components using electromagnetic neural signals.
abstract: Functional connectivity calculated using multiple channels of electromagnetic brain signals is often over- or underestimated due to volume conduction or field spread. Considering connectivity measures, coherence is suitable for the detection of rhythmic synchronization, whereas temporal correlation is appropriate for transient synchronization. This paper presents a beamformer-based imaging method, called spatiotemporal imaging of linearly-related source component (SILSC), which is capable of estimating connectivity at the cortical level by extracting the source component with the maximum temporal correlation between the activity of each targeted region and a reference signal. The spatiotemporal correlation dynamics can be obtained by applying SILSC at every brain region and with various time latencies. The results of six simulation studies demonstrated that SILSC is sensitive to detect the source activity correlated to the specified reference signal and is accurate and robust to noise in terms of source localization. In a facial expression imitation experiment, the correlation dynamics estimated by SILSC revealed the regions with mirror properties and the regions involved in motor control network when performing the imitation and execution tasks, respectively, with the left inferior frontal gyrus specified as the reference region.
authors: Department of Computer Science, National Chiao Tung University, Hsinchu, Taiwan; Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Canada. Electronic address: hlchan@cs.nctu.edu.tw.
authors: Hui-Ling
authors: HL
authors: Chan
authors: Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan; Integrated Brain Research Unit, Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan. Electronic address: lfchen@ym.edu.tw.
authors: Li-Fen
authors: LF
authors: Chen
authors: Department of Computer Science, National Chiao Tung University, Hsinchu, Taiwan. Electronic address: quits.c@gmail.com.
authors: I-Tzu
authors: IT
authors: Chen
authors: Department of Computer Science, National Chiao Tung University, Hsinchu, Taiwan; Institute of Biomedical Engineering, National Chiao Tung University, Hsinchu, Taiwan. Electronic address: yschen@cs.nctu.edu.tw.
authors: Yong-Sheng
authors: YS
authors: Chen
mesh_terms: D000465:Algorithms; D001921:Brain / Q000502:physiology*; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D055590:Electromagnetic Phenomena; D005149:Facial Expression; D000066499:Facial Recognition / Q000502:physiology; D006801:Humans; D007100:Imitative Behavior; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D012815:Signal Processing, Computer-Assisted
keywords: Beamformer; Functional connectivity; Magnetoencephalography; Temporal correlation