title: Granger causal time-dependent source connectivity in the somatosensory network.
abstract: Exploration of transient Granger causal interactions in neural sources of electrophysiological activities provides deeper insights into brain information processing mechanisms. However, the underlying neural patterns are confounded by time-dependent dynamics, non-stationarity and observational noise contamination. Here we investigate transient Granger causal interactions using source time-series of somatosensory evoked magnetoencephalographic (MEG) elicited by air puff stimulation of right index finger and recorded using 306-channel MEG from 21 healthy subjects. A new time-varying connectivity approach, combining renormalised partial directed coherence with state space modelling, is employed to estimate fast changing information flow among the sources. Source analysis confirmed that somatosensory evoked MEG was mainly generated from the contralateral primary somatosensory cortex (SI) and bilateral secondary somatosensory cortices (SII). Transient Granger causality shows a serial processing of somatosensory information, 1) from contralateral SI to contralateral SII, 2) from contralateral SI to ipsilateral SII, 3) from contralateral SII to contralateral SI, and 4) from contralateral SII to ipsilateral SII. These results are consistent with established anatomical connectivity between somatosensory regions and previous source modeling results, thereby providing empirical validation of the time-varying connectivity analysis. We argue that the suggested approach provides novel information regarding transient cortical dynamic connectivity, which previous approaches could not assess.
authors.affiliation: 1] Institute of Biomedical Engineering, Key Laboratory of Biomedical Information Engineering of Education Ministry, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, P. R. China [2] State Key Laboratory of Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, P. R. China.
authors.forename: Lin
authors.initials: L
authors.lastname: Gao
authors.affiliation: Institute for Complex Systems and Mathematical Biology, King's College, University of Aberdeen, Aberdeen AB24 3UE, UK.
authors.forename: Linda
authors.initials: L
authors.lastname: Sommerlade
authors.affiliation: The Mind Research Network and Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM 87131, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Coffman
authors.affiliation: Department of Neurology, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Tongsheng
authors.initials: T
authors.lastname: Zhang
authors.affiliation: The Mind Research Network and Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM 87131, USA.
authors.forename: Julia M
authors.initials: JM
authors.lastname: Stephen
authors.affiliation: State Key Laboratory of Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, P. R. China.
authors.forename: Dichen
authors.initials: D
authors.lastname: Li
authors.affiliation: 1] Institute of Biomedical Engineering, Key Laboratory of Biomedical Information Engineering of Education Ministry, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, P. R. China [2] State Key Laboratory of Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, P. R. China.
authors.forename: Jue
authors.initials: J
authors.lastname: Wang
authors.affiliation: Institute for Complex Systems and Mathematical Biology, King's College, University of Aberdeen, Aberdeen AB24 3UE, UK.
authors.forename: Celso
authors.initials: C
authors.lastname: Grebogi
authors.affiliation: Institute for Complex Systems and Mathematical Biology, King's College, University of Aberdeen, Aberdeen AB24 3UE, UK.
authors.forename: Bjoern
authors.initials: B
authors.lastname: Schelter
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D001931:Brain Mapping; D002648:Child; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D009434:Neural Pathways / Q000502:physiology*; D011859:Radiography; D013003:Somatosensory Cortex / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D055815:Young Adult