Linear and nonlinear multidimensional functional connectivity methods reveal similar networks for semantic processing in EEG/MEG data
IntroductionInvestigating task- and stimulus-dependent connectivity is key to understanding how the interactions between brain regions underpin complex cognitive processes. Yet, the connections identified depend on the assumptions of the connectivity method. To date, methods designed for time-resolv...
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Frontiers Media S.A.
2025-07-01
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| Series: | Frontiers in Human Neuroscience |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fnhum.2025.1533034/full |
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| author | Setareh Rahimi Rebecca L. Jackson Rebecca L. Jackson Olaf Hauk |
| author_facet | Setareh Rahimi Rebecca L. Jackson Rebecca L. Jackson Olaf Hauk |
| author_sort | Setareh Rahimi |
| collection | DOAJ |
| description | IntroductionInvestigating task- and stimulus-dependent connectivity is key to understanding how the interactions between brain regions underpin complex cognitive processes. Yet, the connections identified depend on the assumptions of the connectivity method. To date, methods designed for time-resolved electroencephalography/magnetoencephalography (EEG/MEG) data typically reduce signals in regions to one time course per region. This may fail to identify critical relationships between activation patterns across regions. Time-Lagged Multidimensional Pattern Connectivity (TL-MDPC) is a promising new EEG/MEG functional connectivity method improving previous approaches by assessing multidimensional relationships between patterns of brain activity. However, TL-MDPC remains linear and may therefore miss nonlinear interactions among brain areas.MethodsThus, we introduce Nonlinear TL-MDPC (nTL-MDPC), a novel bivariate functional connectivity method for event-related EEG/MEG applications, and compare its performance to the original linear TL-MDPC. nTL-MDPC describes how well patterns in ROI X at a time point tx can predict patterns of ROI Y at a time point ty using artificial neural networks.ResultsApplying this method and its linear counterpart to simulated data demonstrates that both can identify nonlinear dependencies, with nTL-MDPC achieving up to ~0.75 explained variance under optimal conditions (e.g., high SNR), compared to ~0.65 with TL-MDPC. However, with a sufficient number of trials- e.g., a trials-to-vertex ratio ≥10:1 - nTL-MDPC achieves up to 15% higher explained variance than the linear method. Nevertheless, application to a real EEG/MEG dataset demonstrated only subtle increases in nonlinear connectivity strength at longer time lags with no significant differences between the two approaches.DiscussionOverall, this suggests that linear multidimensional methods may be a reasonable practical choice to approximate brain connectivity, given the additional computational demands of nonlinear methods. |
| format | Article |
| id | doaj-art-4d32fcabae8f4ad489d0ad5c6b5d15de |
| institution | DOAJ |
| issn | 1662-5161 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Human Neuroscience |
| spelling | doaj-art-4d32fcabae8f4ad489d0ad5c6b5d15de2025-08-20T02:46:20ZengFrontiers Media S.A.Frontiers in Human Neuroscience1662-51612025-07-011910.3389/fnhum.2025.15330341533034Linear and nonlinear multidimensional functional connectivity methods reveal similar networks for semantic processing in EEG/MEG dataSetareh Rahimi0Rebecca L. Jackson1Rebecca L. Jackson2Olaf Hauk3MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, United KingdomMRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, United KingdomDepartment of Psychology and York Biomedical Research Institute, University of York, York, United KingdomMRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, United KingdomIntroductionInvestigating task- and stimulus-dependent connectivity is key to understanding how the interactions between brain regions underpin complex cognitive processes. Yet, the connections identified depend on the assumptions of the connectivity method. To date, methods designed for time-resolved electroencephalography/magnetoencephalography (EEG/MEG) data typically reduce signals in regions to one time course per region. This may fail to identify critical relationships between activation patterns across regions. Time-Lagged Multidimensional Pattern Connectivity (TL-MDPC) is a promising new EEG/MEG functional connectivity method improving previous approaches by assessing multidimensional relationships between patterns of brain activity. However, TL-MDPC remains linear and may therefore miss nonlinear interactions among brain areas.MethodsThus, we introduce Nonlinear TL-MDPC (nTL-MDPC), a novel bivariate functional connectivity method for event-related EEG/MEG applications, and compare its performance to the original linear TL-MDPC. nTL-MDPC describes how well patterns in ROI X at a time point tx can predict patterns of ROI Y at a time point ty using artificial neural networks.ResultsApplying this method and its linear counterpart to simulated data demonstrates that both can identify nonlinear dependencies, with nTL-MDPC achieving up to ~0.75 explained variance under optimal conditions (e.g., high SNR), compared to ~0.65 with TL-MDPC. However, with a sufficient number of trials- e.g., a trials-to-vertex ratio ≥10:1 - nTL-MDPC achieves up to 15% higher explained variance than the linear method. Nevertheless, application to a real EEG/MEG dataset demonstrated only subtle increases in nonlinear connectivity strength at longer time lags with no significant differences between the two approaches.DiscussionOverall, this suggests that linear multidimensional methods may be a reasonable practical choice to approximate brain connectivity, given the additional computational demands of nonlinear methods.https://www.frontiersin.org/articles/10.3389/fnhum.2025.1533034/fullnonlinearevent-related connectivityfunctional connectivitysemantic representationsemantic controlmultidimensional |
| spellingShingle | Setareh Rahimi Rebecca L. Jackson Rebecca L. Jackson Olaf Hauk Linear and nonlinear multidimensional functional connectivity methods reveal similar networks for semantic processing in EEG/MEG data Frontiers in Human Neuroscience nonlinear event-related connectivity functional connectivity semantic representation semantic control multidimensional |
| title | Linear and nonlinear multidimensional functional connectivity methods reveal similar networks for semantic processing in EEG/MEG data |
| title_full | Linear and nonlinear multidimensional functional connectivity methods reveal similar networks for semantic processing in EEG/MEG data |
| title_fullStr | Linear and nonlinear multidimensional functional connectivity methods reveal similar networks for semantic processing in EEG/MEG data |
| title_full_unstemmed | Linear and nonlinear multidimensional functional connectivity methods reveal similar networks for semantic processing in EEG/MEG data |
| title_short | Linear and nonlinear multidimensional functional connectivity methods reveal similar networks for semantic processing in EEG/MEG data |
| title_sort | linear and nonlinear multidimensional functional connectivity methods reveal similar networks for semantic processing in eeg meg data |
| topic | nonlinear event-related connectivity functional connectivity semantic representation semantic control multidimensional |
| url | https://www.frontiersin.org/articles/10.3389/fnhum.2025.1533034/full |
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