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Granger causal time-dependent source connectivity in the somatosensory network.

Gao L, Sommerlade L, Coffman B, Zhang T, Stephen JM, Li D, Wang J, Grebogi C, Schelter B - Sci Rep (2015)

Bottom Line: However, the underlying neural patterns are confounded by time-dependent dynamics, non-stationarity and observational noise contamination.Source analysis confirmed that somatosensory evoked MEG was mainly generated from the contralateral primary somatosensory cortex (SI) and bilateral secondary somatosensory cortices (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.

View Article: PubMed Central - PubMed

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.

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.

No MeSH data available.


Representative source locations and the corresponding grand average source time courses of somatosensory MEG responses from all participants are presented.
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f2: Representative source locations and the corresponding grand average source time courses of somatosensory MEG responses from all participants are presented.

Mentions: Figure 2 shows the locations and grand average time series of the representative sources (SI-l, SII-r and SII-l) of the subjects. The results indicate that 1 the sources explaining the peak at 71 ms are mainly located in contralateral SI (SI-l) and contralateral SII (SII-l), 2 the sources explaining the peak at 201 ms are mainly located in ipsilateral SII (SII-r). Post hoc comparisons by Fisher’s least significant difference (LSD) test revealed that 1 the peak latencies of SI-l are significantly shorter than the peak latencies of SII-r (P < 0.001), 2 the peak latencies of SII-l are significantly shorter than the peak latencies of SII-r (P < 0.001).


Granger causal time-dependent source connectivity in the somatosensory network.

Gao L, Sommerlade L, Coffman B, Zhang T, Stephen JM, Li D, Wang J, Grebogi C, Schelter B - Sci Rep (2015)

Representative source locations and the corresponding grand average source time courses of somatosensory MEG responses from all participants are presented.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4441010&req=5

f2: Representative source locations and the corresponding grand average source time courses of somatosensory MEG responses from all participants are presented.
Mentions: Figure 2 shows the locations and grand average time series of the representative sources (SI-l, SII-r and SII-l) of the subjects. The results indicate that 1 the sources explaining the peak at 71 ms are mainly located in contralateral SI (SI-l) and contralateral SII (SII-l), 2 the sources explaining the peak at 201 ms are mainly located in ipsilateral SII (SII-r). Post hoc comparisons by Fisher’s least significant difference (LSD) test revealed that 1 the peak latencies of SI-l are significantly shorter than the peak latencies of SII-r (P < 0.001), 2 the peak latencies of SII-l are significantly shorter than the peak latencies of SII-r (P < 0.001).

Bottom Line: However, the underlying neural patterns are confounded by time-dependent dynamics, non-stationarity and observational noise contamination.Source analysis confirmed that somatosensory evoked MEG was mainly generated from the contralateral primary somatosensory cortex (SI) and bilateral secondary somatosensory cortices (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.

View Article: PubMed Central - PubMed

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.

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.

No MeSH data available.