Cited by 952Functional Brain Connectivity StudiesAdvanced Neuroimaging Techniques and ApplicationsAdvanced MRI Techniques and Applications

Functional connectomics from resting-state fMRI

Open access
Smith, Stephen M., Vidaurre, Diego, Beckmann, Christian F., Glasser, Matthew F., Jenkinson, Mark, Miller, Karla L., Nichols, Thomas E., Robinson, Emma C. +5 more·2013·Trends in Cognitive Sciences

Abstract

Spontaneous fluctuations in activity in different parts of the brain can be used to study functional brain networks. We review the use of resting-state functional MRI for the purpose of mapping the macroscopic functional connectome. After describing MRI acquisition and image processing methods commonly used to generate data in a form amenable to connectomics network analysis, we discuss different approaches for estimating network structure from that data. Finally, we describe new possibilities resulting from the high-quality rfMRI data being generated by the Human Connectome Project, and highlight some upcoming challenges in functional connectomics.

AI snapshot

Written from the paper’s full text.

TL;DR

This review describes how resting-state fMRI (rfMRI) can map the macroscopic functional connectome, covering acquisition, preprocessing, network modelling, and Human Connectome Project (HCP) data. It highlights high-quality HCP rfMRI enabling detailed node-and-edge connectomes and links to behaviour and sex, while noting major challenges in causality, alignment, and dynamic network modelling.

Key findings

  • The HCP is generating rfMRI from over 1000 healthy adults aged 22–35, including twins and non-twin siblings: 1 h of whole-brain 3T rfMRI in two pairs of 15-min runs on separate days, at 2×2×2 mm spatial resolution, 0.7 s temporal resolution, and EPI acceleration factor ×8; over 200 subjects’ datasets were already publicly released, and 3T rfMRI is represented using about 90,000 grayordinates at ~2 mm spacing.
  • In the first 131 HCP subjects, aggregating over 600,000 timepoints, group-ICA at dimensionality 100 yielded 98 network nodes after discarding 2 artefactual components; partial correlation matrices were as strong and consistent across subjects as full correlation matrices, which the authors call unusual and indicative of high data quality and many timepoints.
  • Multimodal surface matching improved cross-subject network similarity: average between-subject network correlations were FreeSurfer=0.613, MSMfolding=0.618, and MSMmultimodal=0.649; sex prediction with leave-one-out linear discriminant analysis reached 87% for MSMmultimodal versus 78% for FreeSurfer and 82% for MSMfolding, and using full correlation instead of partial correlation reduced sex classification accuracy from 87% to 70%.
  • A significant association was found between individual subjects’ network matrices and fluid intelligence, with the 24 strongest edges shown; the node-pair contributing most strongly had only a weak average population connection but varied across subjects in a way that correlated with fluid intelligence. A separate analysis identified 9 edges significantly different in strength between the two sexes.

Methods

  • Design: a review of rfMRI-based functional connectomics, including illustrative analyses using publicly released HCP rfMRI data.
  • Data/sample: HCP cohort of over 1000 healthy adult twins and non-twin siblings aged 22–35; the illustrative analyses used the first 131 subjects’ rfMRI data, aggregating over 600,000 timepoints.
  • Main analysis: preprocessing with FSL, FreeSurfer, and Connectome Workbench; ICA-based artefact removal with FIX (reported >99% classification accuracy on HCP data); group-ICA at dimensionality 100 yielding 98 nodes; full and partial correlation, regularised inverse covariance, multimodal surface matching, permutation testing, linear discriminant analysis, and temporal-ICA.

Limitations

  • Stated in paper: correlation cannot reveal causality or whether connectivity is direct versus indirect; partial correlation estimates direct connections but not directionality; directionality estimation is harder than edge detection, temporal lag is confounded by slow and variable haemodynamics, and observational rfMRI is not a robust tool for inferring causality compared with interventional task-fMRI.
  • Stated in paper: dynamic causal modelling is practical only for networks with fewer than 10 nodes; for 50–500 nodes, partial correlation is a pragmatic compromise but inverse covariance estimation is often unstable and benefits from regularisation; graph-theory measures risk inappropriate node definitions, use of thresholded full correlation matrices, and confounds such as head motion or heart rate.
  • Stated in paper: temporal-ICA forces modes to be fully independent over time, assumes within-mode connection strengths are static, and cannot well identify mutually exclusive modes with negative correlation; sliding-window correlation can be confounded by window length and overlapping networks; no single parcellation technique has emerged as best; and larger heterogeneous datasets such as the Thousand Functional Connectomes have greater scanning-parameter heterogeneity and lower data quality than HCP. Evident from text: the paper is a review with illustrative HCP analyses rather than a single primary empirical study, so its quantitative results are presented as examples of methodological potential and issues.

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Integrity signals

Registry

Crossref · 10.1016/j.tics.2013.09.016

Cites

92 of 92 references verified0 citation errors · 0 not checkable

Statistics

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Claims the paper makes

0 of 52 cited sources checked · 0 supported · 0 flagged

  • Findingcitation

    Significant improvements in the alignment of task activation regions were found, both quantitatively and qualitatively, when MSMmultimodal is used.

    “Significant improvements in the alignment of task activation regions were found, both quantitatively and qualitatively [Robinson, in submission];”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [Robinson, in submission]

      Not checked in the free run.

  • Findingnone given

    When MSM is only given folding information, the overall degree of alignment is similar to that achieved by FreeSurfer.

    “When MSM is only given folding information to drive the alignment (“MSMfolding”), the overall degree of alignment is similar to that achieved by FreeSurfer.”
    Quote in the paperNot a substantial claim
  • Findingown data

    Figure 5B shows stronger and more sharply defined activation patterns from a group-level analysis of two tasks when MSMmultimodal is utilised compared to MSMfolding, especially in parts of prefrontal cortex.

    “for example, Figure 5B shows stronger and more sharply defined activation patterns from a group-level analysis of two different tasks (“maths vs story” and a social interaction task) when MSMmultimodal is utilised (lower panels) compared to MSMfolding (upper panels), especially in parts of prefrontal cortex (blue arrows).”
    Quote in the paperSubstantial claim
  • Findingown data

    Using full correlation network matrices instead of partial correlation reduced sex classification accuracy from 87% to 70%.

    “When we used the full correlation network matrices instead of partial correlation, the sex classification accuracy was reduced from 87% to 70%.”
    Quote in the paperSubstantial claim
  • Findingcitation

    If MSM is also fed cortical myelin-weighted maps and low-dimensional resting-state network maps, it can utilise richer structural and connectional information and further improve intersubject alignment.

    “However, if MSM is also fed cortical myelin-weighted maps [76], as well as low-dimensional resting-state network maps, it can utilise richer structural and connectional information, and further improve the intersubject alignment (“MSMmultimodal”) [43].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [76] Glasser MF 2011 Comparison of Surface Gradients Derived from Myelin Maps and Functional Connectivity Analysis Int. Conf. on Functional Mapping of the Human Brain

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [43] Glasser MF 2013 The Minimal Preprocessing Pipelines for the Human Connectome Project NeuroImage 80 105 124 23668970 PMC3720813 source

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  • May combine two claims. 45
  • Classified as probably not a substantial claim. 23
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    Findingown data

    The histogram of edge-strength mean group differences is centred at zero, with no gross asymmetry.

    “Indeed, the histogram of edge-strength mean group differences is centred at zero, with no gross asymmetry.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    Average between-subject network similarity correlations were FreeSurfer=0.613, MSMfolding=0.618 and MSMmultimodal=0.649.

    “We found the following average correlation values for the 3 alignment methods: FreeSurfer=0.613, MSMfolding=0.618 and MSMmultimodal=0.649 (Figure 5A).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    The node-pair contributing most strongly to the regression against fluid intelligence has only a weak average connection in the population but varies across subjects in a way that correlates with fluid intelligence.

    “Indeed, the node-pair which contributes most strongly to the regression against fluid intelligence (shown in more detail in B) has only a weak connection on average in the population - but it varies across subjects in a way that correlates with fluid intelligence.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    The three alignment methods gave sex classification accuracies of FreeSurfer=78%, MSMfolding=82% and MSMmultimodal=87%.

    “The 3 alignment methods described above gave classification accuracies of: FreeSurfer=78%, MSMfolding=82% and MSMmultimodal=87%.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    The 24 edges having the strongest weights in the regression against fluid intelligence are shown.

    “The 24 edges (node-pairs) having the strongest weights in the regression are shown;”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    In both cases, strong spatial correspondence to specific task activation maps from HCP task-fMRI datasets was shown, helping interpretation for functional modes identified from resting-state data.

    “In both cases we show strong spatial correspondence to specific task activation maps from the HCP task-fMRI datasets, thus helping to provide interpretation for the functional modes identified from the resting-state data.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    Figure 9 shows two example results from feeding 98 nodes' timeseries into temporal-ICA, analysing HCP rfMRI data containing more time points (>600,000, concatenating data from 131 subjects) than spatial points (~90,000 grayordinates).

    “Figure 9 shows 2 example results from feeding 98 nodes’ timeseries into temporal-ICA, where we analysed the high quality HCP rfMRI data containing more time points (>600,000, concatenating data from 131 subjects) than spatial points (~90,000 grayordinates).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Premisecitation

    Different resting-state networks have distinct timecourses, while each network has a relatively consistent timecourse across its set of involved regions.

    “These patterns can be distinguished from each other because, while each has a relatively consistent timecourse across its set of involved regions, the different networks have distinct timecourses [2].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [2] Beckmann CF 2005 Investigations into Resting-State Connectivity using Independent Component Analysis Philosophical Transactions of the Royal Society 360 1001 1013 PMC1854918 16087444 source

      Not checked in the free run.

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    Premisecitation

    Resting-state networks persist even during sleep and under anaesthesia.

    “These “resting-state networks” (RSNs) persist even during sleep and under anaesthesia [3]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [3] Picchioni D 2013 Sleep and the functional connectome Neuroimage 80 387 396 23707592 PMC3733088 source

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    Interpretationreasoning

    Seed-based correlation contains fine spatial detail, but only informs about average correlation with the selected seed(s).

    “Such an approach contains fine spatial detail, but only informs about average correlation with the selected seed(s).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    Effective artefact removal is particularly important for resting-state analyses, which rely fundamentally on correlations between different voxels' timeseries, because these correlations will be corrupted by artefacts that span multiple voxels.

    “Effective artefact removal is particularly important for resting-state analyses, which rely fundamentally on correlations between different voxels’ timeseries, as these will be corrupted by artefacts that span multiple voxels.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Interpretationreasoning

    A high-dimensional parcellation into many nodes allows a richer analysis of the network connections by shifting the emphasis from large-scale maps with fine spatial detail into a network description of nodes and edges.

    “a high-dimensional parcellation into many nodes (potentially hundreds) allows a richer analysis of the network connections – by shifting the emphasis from large-scale maps with fine spatial detail into a network description of “nodes” and “edges”, new information can be obtained.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    The sluggish response of the brain's haemodynamics to neural activity ultimately places a limit on the usefulness of further improvements in temporal resolution.

    “although the sluggish response of the brain’s haemodynamics (to neural activity) will ultimately place a limit on the usefulness of further improvements in temporal resolution.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    Task-fMRI has the advantage of fitting a pre-specified temporal model, which provides greater robustness against artefactual influences.

    “(In contrast, task-fMRI has the advantage of fitting a pre-specified temporal model, which provides greater robustness against artefactual influences.)”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationreasoning

    Accurate alignment of functionally corresponding cortical parcels is an exceedingly challenging problem, largely owing to individual variability of cortical folding patterns and variability of functional parcel locations relative to these folds.

    “accurate alignment of functionally corresponding cortical parcels is an exceedingly challenging problem, largely owing to individual variability of cortical folding patterns along with variability of functional parcel locations relative to these folds”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationreasoning

    To combine or compare connectomes across subjects, it is important to strive for the same parcellation in each subject; comparisons between two network models are inherently flawed if they are derived from non-corresponding sets of nodes.

    “In order to combine or compare connectomes across subjects, it is important to strive for “the same” parcellation in each subject – comparisons between two network models are inherently flawed if they are derived from non-corresponding sets of nodes.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Multiband accelerated EPI enables major improvements in spatial and/or temporal resolution, for example acquiring data with 2mm spatial resolution in less than a second.

    ““multiband accelerated EPI” acquires multiple slices simultaneously [39, 40]. Such approaches enable major improvements in spatial and/or temporal resolution, for example acquiring data with 2mm spatial resolution in less than a second.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [39] Moeller S 2010 Multiband multislice GE-EPI at 7 tesla, with 16-fold acceleration using partial parallel imaging with application to high spatial and temporal whole-brain fMRI Magn Reson Med 63 1144 1153 20432285 PMC2906244 source

      Not checked in the free run.

    • cites [40] Setsompop K 2012 Blipped-controlled aliasing in parallel imaging for simultaneous multislice echo planer imaging with reduced g-factor penalty Magnetic Resonance in Medicine 67 1210 1224 21858868 PMC3323676 source

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    Premisecitation

    Higher temporal resolution of fMRI data can increase the information content of the data, for example in terms of reflecting the richness of neural dynamics.

    “and also increase the information content of the data (e.g., in terms of reflecting the richness of the neural dynamics) [41, 42]”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [41] Feinberg DA 2010 Multiplexed Echo Planar Imaging for Sub-second Whole Brain FMRI and Fast Diffusion Imaging PLoS ONE 5 e15710 21187930 PMC3004955 source

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    • cites [42] Smith SM 2012 Temporally-independent functional modes of spontaneous brain activity Proc Natl Acad Sci USA (PNAS) 109 3131 3136 PMC3286957 22323591 source

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  • Classified as probably not a substantial claim.

    Interpretationreasoning

    A detailed nodes+edges network model may reveal which nodes, as sub-parts of large-scale networks, are responsible for the correlations seen between the larger-scale networks.

    “a detailed nodes+edges network model may reveal which nodes (sub-parts of the large-scale networks) are responsible for the correlations seen between the larger-scale networks.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisecitation

    Correlation cannot reveal anything about causality, or even whether connectivity is direct versus indirect.

    “Furthermore, correlation cannot reveal anything about causality, or even whether connectivity is direct vs indirect [49].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [49] Marrelec G 2006 Partial correlation for functional brain interactivity investigation in functional MRI NeuroImage 32 228 237 16777436 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Low-dimensional ICA generates a richer description of multiple networks in the brain, but at the expense of no longer dictating in advance the regions with which the connectivity map(s) are related.

    “This therefore generates a richer description of multiple networks in the brain, but at the expense of no longer dictating in advance the regions with which the connectivity map(s) are related.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    In a 3-node network A→B→C, all three nodes' timeseries will be correlated, so correlation will incorrectly estimate a fully-connected network including an A-C connection.

    “For example, in a 3-node network A→B→C, all three nodes’ timeseries will be correlated, so correlation will incorrectly estimate a fully-connected network (including an A-C connection).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisecitation

    DCM, originally developed for task data, has recently been extended to allow modelling of resting-state data and to search across a wide range of possible network matrix models.

    “while DCM, originally developed for task data, has recently been extended [54] to allow modelling of resting-state data, and to search across a wide range of possible network matrix models”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [54] Friston KJ 2011 Network discovery with DCM NeuroImage 56 1202 1221 21182971 PMC3094760 source

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    Premisecitation

    L1-norm regularisation of the inverse covariance matrix shrinks the estimated values in the partial correlation matrix, so that very small, noisy values are forced to zero, and all other values are better estimated.

    “L1-norm regularisation of the inverse covariance matrix [55] shrinks the estimated values in the partial correlation matrix, so that very small, noisy values are forced to zero, and all other values are better estimated.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [55] Friedman J 2008 Sparse inverse covariance estimation with the Graphical Lasso Biostat 9 432 441 PMC3019769 18079126 source

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  • May combine two claims.

    Interpretationreasoning

    Graph-theoretic techniques are dependent on accurate network modelling at the lower level, and the abstraction of these metrics from the underlying data makes it challenging to evaluate results.

    “Naturally, these techniques are dependent on accurate network modelling at the lower level (carefully constructed network matrices); the abstraction of these metrics from the underlying data makes it challenging to evaluate results”
    Quote in the paperNot a substantial claim
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    Premisenone given

    The HCP is generating a detailed in vivo mapping of functional connectivity in a large cohort of over 1000 subjects, and is making these datasets freely available for use by the neuroimaging community, with over 200 subjects' datasets already acquired and publicly released.

    “The HCP is generating a detailed in vivo mapping of functional connectivity in a large cohort (over 1000 subjects), and is making these datasets freely available for use by the neuroimaging community (over 200 subjects’ datasets are already acquired and publicly released – available via humanconnectome.org).”
    Quote in the paperNot a substantial claim
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    Premisecitation

    Bayes nets model the full set of covariances or conditional dependencies between all nodes' timeseries and show some promise.

    “Bayes nets model the full set of covariances (or conditional dependencies) between all nodes’ timeseries [59] and show some promise.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [59] Ramsey JD 2010 Six problems for causal inference from fMRI NeuroImage 49 1545 1558 19747552 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationnone given

    It is frequently the thresholded full correlation matrix that is input into graph theoretical analyses, rather than an estimate of direct network connections, and interpretations of graph-theory-based measures are often questionable as a result.

    “Another concern is that it is frequently the (thresholded) full correlation matrix that is input into graph theoretical analyses, rather than an estimate of direct network connections; interpretations of graph-theory-based measures (such as communication path length) are often, as a result, somewhat questionable.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given

    Many methods, such as correlation, give no directionality information at all.

    “Many methods, such as correlation, give no directionality information at all.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    The Thousand Functional Connectomes dataset has greater heterogeneity of scanning parameters and lower data quality than the HCP.

    “This growing dataset comes with the caveat of having greater heterogeneity of scanning parameters (and lower data quality) than the HCP”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Premisereasoning

    Partial correlation aims to more accurately estimate the direct connections, though not their directionalities.

    “another simple estimation method, partial correlation, aims to more accurately estimate the “direct” connections (though not their directionalities).”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The MGH-UCLA HCP is using extremely powerful MRI gradients to generate leading-edge 3T diffusion MRI data.

    “The MGH-UCLA HCP is using extremely powerful MRI gradients to generate leading-edge 3T diffusion MRI data.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [16] Setsompop K 2013 Pushing the limits of in vivo diffusion MRI for the Human Connectome Project Neuroimage 80 220 233 23707579 PMC3725309 source

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  • Classified as probably not a substantial claim.

    Interpretationreasoning

    It cannot be assumed that the brain's connections are static.

    “it cannot be assumed that the brain’s connections are static.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The WU-Minn HCP is generating high quality and high resolution 3T rfMRI and diffusion MRI data from over 1000 healthy adults, as well as task-fMRI, genotyping and behavioural data.

    “the WashU-UMinn-Oxford (“WU-Minn”) HCP is generating high quality and high resolution 3T rfMRI and diffusion MRI data from over 1000 healthy adults, as well as task-fMRI, genotyping and behavioural data.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [67] Van Essen DC 2013 The WU-Minn Human Connectome Project: An Overview NeuroImage 80 62 79 23684880 PMC3724347 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    In the 3-node network example, regression of B out of A and C removes the correlation between A and C, and hence the spurious third edge A-C.

    “In this case, regression of B out of A and C removes the correlation between A and C, and hence the spurious third edge (A–C).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    Simpler network modelling methods are in general more robust with respect to fitting the model to the data and faster to compute.

    “The simpler methods are in general more robust (with respect to fitting the model to the data), and faster to compute.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    Simpler network modelling methods do not require the scope of possible network models to be pre-constrained, making them computationally feasible for attempting network discovery.

    “they do not require the scope of possible network models to be pre-constrained, making them computationally feasible for attempting network discovery.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Premisenone given

    HCP subjects are drawn from a population of healthy adult twins and their non-twin siblings in the age range of 22-35 years, thus aiding the study of the influence of heritability and environmental factors on the connectome.

    “Subjects are drawn from a population of healthy adult twins and their non-twin siblings (in the age range of 22–35 years), thus aiding the study of the influence of heritability and environmental factors on the connectome.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisecitation

    Temporal lag between pairs of timeseries is often used to estimate directionality, though it is arguably too confounded by slow and variable haemodynamics to be useful with fMRI data, and is better-suited to electrophysiological modalities.

    “Temporal lag between pairs of timeseries [58] is often used, though it is arguably too confounded by the slow and variable haemodynamics to be useful with fMRI data [56], and is better-suited to electrophysiological modalities.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [56] Smith SM 2011 Network Modelling Methods for FMRI NeuroImage 54 875 891 20817103 source

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  • May combine two claims.

    Interpretationnone given

    Estimation of partial correlation effectively involves inverting the full correlation matrix, a process which is often quite unstable, depending on the quality of the data and the number of original timepoints.

    “The estimation of partial correlation effectively involves inverting the full correlation matrix, a process which is often quite unstable, depending on the quality of the data and the number of original timepoints.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationreasoning

    Causality estimation when the brain is at rest may involve many different functional processes mixed together, and would be estimated as the average relative causality over all possible spontaneous fluctuations.

    “causality estimation when the brain is “at rest” may involve many different functional processes mixed together, and would be estimated as the average “relative causality” over all possible spontaneous fluctuations.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The Thousand Functional Connectomes and related projects are seeking to generate even larger numbers of subjects than the HCP, bringing together data from a wide range of imaging studies and scanners, and covering a wider range of subject groups, including a range of pathologies.

    “The Thousand Functional Connectomes (and related) projects [74, 75], led by Mike Milham, are seeking to generate even larger numbers of subjects than the HCP, bringing together data from a wide range of imaging studies and scanners, and covering a wider range of subject groups, including a range of pathologies.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [74] Biswal BB 2010 Towards discovery science of human brain function Proc Natl Acad Sci USA (PNAS) 107 4734 4739 PMC2842060 20176931 source

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    • cites [75] Yan CG 2013 Standardizing the intrinsic brain: Towards robust measurement of inter-individual variation in 1000 functional connectomes Neuroimage 80 246 262 23631983 PMC4074397 source

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  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisereasoning

    FreeSurfer provides one way to improve intersubject alignment of features on the cortical surface using folding features.

    “Once each subject’s cortical surface has been estimated from the structural data using FreeSurfer, FreeSurfer also provides one way to improve intersubject alignment of features on the surface.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    Partial correlation matrices being as strong and consistent across subjects as full correlation is unusual and indicates high quality of the data and a large number of timepoints in each subject's rfMRI dataset.

    “For the partial correlation matrices to be as strong and consistent across subjects as the full correlation is unusual and is indicative of the high quality of the data and large number of timepoints in each subject’s rfMRI dataset.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationown data

    Multimodal MSM improves the alignment of function across subjects, as it improves the accuracy with which derived network matrices can predict sex, and this supports that sex prediction is primarily driven by network connection strength and not systematic functional misalignments.

    “This suggests that multimodal MSM improves the alignment of function across subjects (as it improves the accuracy with which the derived network matrices can predict sex), and also supports the hypothesis that this sex prediction is indeed primarily being driven by network connection strength and not (for example) by systematic functional misalignments across (groups of) subjects.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    This kind of analysis has previously been used to predict subjects' psychiatric condition and cognitive state.

    “This kind of analysis has previously been used (albeit from full correlation network matrices) to predict subjects’ psychiatric condition [77] and cognitive state [78];”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [77] Craddock RC 2009 Disease state prediction from resting state functional connectivity Magnetic Resonance in Medicine 62 1619 1628 19859933 PMC3749911 source

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    • cites [78] Shirer WR 2012 Decoding subject-driven cognitive states with whole-brain connectivity patterns Cereb Cortex 22 158 165 21616982 PMC3236795 source

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationnone given

    An important issue is to distinguish between changes in correlation due to nodes being part of multiple overlapping functional networks versus internal connections within any given network being non-constant.

    “One important issue is to distinguish between changes in correlation due to some nodes being part of multiple overlapping functional networks, vs. the internal connections within any given network being non-constant.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Multimodal Surface Matching (MSM) is an alternative surface warping approach developed by the authors.

    “We have recently developed an alternative surface warping approach, Multimodal Surface Matching (MSM) [70].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [70] Robinson E 2013 Multimodal Surface Matching: Fast and Generalisable Cortical Registration using Discrete Optimisation Springer Berlin Heidelberg 24683992

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  • May combine two claims.

    Interpretationreasoning

    A problem can arise when applying a window length that does not encompass at least several cycles of resting fluctuations, because the rfMRI signal is dominated by low frequencies (~0.015Hz), and a sliding window containing a fraction of a cycle is expected to show correlations appearing to fluctuate wildly over time even if the underlying network structure is stationary.

    “In addition, a problem can arise when applying a window length that does not encompass (at least) several cycles of the resting fluctuations, as the rfMRI signal is dominated by low frequencies (~0.015Hz), and a sliding window containing a fraction of a cycle is expected to show correlations appearing to fluctuate wildly over time, even if the underlying network structure is stationary.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The rfMRI signal is dominated by low frequencies (~0.015Hz).
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation

    FIX achieves classification accuracy on HCP data of over 99%.

    “FIX achieves classification accuracy on HCP data of over 99%.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Salimi-Khorshidi, unpublished manuscript

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    No single parcellation technique has emerged as the best approach, and investigations are ongoing.

    “At this point, no single parcellation technique has emerged as the best approach, and investigations are ongoing.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    Better alignments should yield more accurate network matrices, because functional parcels defined at the group level should be more accurately aligned to the true subject-specific versions of those same parcels.

    “Therefore, better alignments should yield more accurate network matrices, because the functional parcels defined at the group level should be more accurately aligned to the true subject-specific versions of those same parcels.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The functional parcels defined at the group level correspond to true subject-specific versions of those same parcels.
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Nonstationarities in correlation have been studied utilising either wavelet decompositions or sliding-window correlation.

    “For example, nonstationarities in correlation have been studied utilising either wavelet decompositions or sliding-window correlation [88].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [88] Hutchison RM 2013 Dynamic functional connectivity: Promise, issues, and interpretations Neuroimage 80 360 378 23707587 PMC3807588

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    An increase in cross-subject network similarity is not conclusive proof of a better alignment method; it might indicate over-strong application of prior information.

    “However, although this is encouraging, an increase in cross-subject network similarity is not conclusive proof of a better alignment method; for example, it might indicate over-strong application of prior information (e.g., in the extreme, setting all subjects to a constant network), which would reduce sensitivity when attempting to relate the network matrices to other measures.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationnone given

    A limitation is that multiple distinct functional networks might overlap each other in space and also vary over time in how they interact with each other.

    “A limitation, however, is that multiple distinct functional networks might overlap each other in space and also vary over time in how they interact with each other.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationnone given

    rfMRI does not provide the more direct view of neuronal activity and information flow that can be obtained from electrophysiological techniques, or inform us regarding the biochemistry of brain connectivity.

    “It does not provide the more direct view of neuronal activity and information flow that can be obtained from electrophysiological techniques, or inform us regarding the biochemistry of brain connectivity.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisecitation

    [42] showed several temporal functional modes with plausible functional interpretability and large spatial overlap; default-mode network patterns can be decomposed into several modes of distinct but overlapping spatial layout.

    “[42] showed several such modes, with plausible functional interpretability and large amounts of spatial overlap; for example, the patterns of average correlation and anti-correlation associated with the default-mode network can be decomposed into several modes of distinct but overlapping spatial layout (and hence presumably distinct function).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [42] Smith SM 2012 Temporally-independent functional modes of spontaneous brain activity Proc Natl Acad Sci USA (PNAS) 109 3131 3136 PMC3286957 22323591 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Evidence indicates that rfMRI signal includes complex spatiotemporal patterns of spontaneous activity that propagate across the brain and are therefore not well modelled by spatially fixed network modelling approaches.

    “A related challenge is raised by evidence that rfMRI signal includes complex spatiotemporal patterns of spontaneous activity that propagate across the brain [92], and are therefore not at all well modelled by spatially fixed network modelling approaches.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [92] Majeed W 2010 Spatiotemporal dynamics of low frequency BOLD fluctuations in rats and humans Neuroimage 54 1140 1150 20728554 PMC2997178

      Not checked in the free run.

  • May combine two claims.

    Interpretationnone given

    rfMRI provides the ability to create a richly detailed mapping of the functional connectome, at the millimetre scale, covering the whole brain, with in vivo, non-invasive imaging across thousands of subjects.

    “However, rfMRI does provide us with something valuable and unique – the ability to create a richly detailed mapping of the functional connectome, at the millimetre scale, covering the whole brain, with in vivo, non-invasive imaging across thousands of subjects.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationnone given

    rfMRI does not tell us directly about the microscopic neuronal-level structural connectome, or even about the macroscopic-level structural connectome such as is inferred from diffusion MRI.

    “It does not tell us directly about the microscopic, neuronal-level, structural connectome, or even about the macroscopic-level structural connectome such as is inferred from diffusion MRI.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    Another limitation with temporal-ICA is the assumption that connections within a given mode are not changing in strength over time; this is an oversimplistic view of brain networks.

    “Another limitation with temporal-ICA is the assumption that the connections within a given mode are not changing in strength over time; this is surely an oversimplistic view of brain networks.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    Two distinct functional modes might be mutually exclusive if they share one node that strongly participates in only one function at any given time; this would imply a negative correlation between the modes' timeseries, and this situation will not be well identified through temporal-ICA.

    “For example, two distinct functional modes might in reality be mutually exclusive, if they share one node that strongly participates in only one function at any given time; this would imply a negative correlation between the modes’ timeseries, and this situation will not be well identified through the application of temporal-ICA.”
    Quote in the paperSubstantial claim
62 of 62
  • The paper relies on this without support.

    The biological significance of the rich and continuously-present set of spontaneous, correlated activities in the resting brain remains poorly understood.

    “The biological significance of such a rich and continuously-present set of spontaneous, correlated activities in the “resting” brain remains poorly understood.”
  • The authors state this as an assumption.

    The brain is continuously engaged in undirected cognitive activities, including conscious thought processes and sub-conscious activity such as learning/unlearning, and also responds to uncontrolled external stimuli.

    “Presumably, the brain is continuously engaged in undirected cognitive activities (both conscious thought processes and sub-conscious activity such as learning/unlearning), and also responds to uncontrolled external stimuli.”
  • The paper relies on this without support.

    The functional parcels defined at the group level correspond to true subject-specific versions of those same parcels.

    “because the functional parcels defined at the group level should be more accurately aligned to the true subject-specific versions of those same parcels.”
  • The paper relies on this without support.

    The subject-wise variations of all edges are not fully independent of each other.

    “because we do not expect the subject-wise variations of all edges to be fully independent of each other.”
  • The paper relies on this without support.

    The rfMRI signal is dominated by low frequencies (~0.015Hz).

    “as the rfMRI signal is dominated by low frequencies (~0.015Hz)”
  • The paper relies on this without support.

    There is a true macroscopic functional connectome that partial correlation matrices estimate better than full correlation.

    “partial correlation matrices provide a better estimate of the “true” macroscopic functional connectome than full correlation.”
6 of 6

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Functional connectivity as measured using fMRI is a powerful but indirect measure of network organization that can provide high spatial resolution but should not be considered a surrogate for direct anatomical connectivity.

    “Functional connectivity as measured using fMRI is a powerful but indirect measure of network organization that can provide high spatial resolution but should not be considered a surrogate for direct anatomical connectivity29, 30.”

    From Canonical genetic signatures of the adult human brain (2015) · cites this paper as [30]

  • Each of four 15-min resting state runs for each subject was cleaned (denoised) using 24-parameter motion regression followed by ICA+FIX denoising.

    “Each of four 15-min resting state runs for each subject in the group was cleaned (denoised) using 24-parameter motion regression followed by ICA+FIX denoising30, 48.”

    From Canonical genetic signatures of the adult human brain (2015) · cites this paper as [30]

Cites

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1 of the 93 references couldn’t be matched to a known paper.

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Authors
Smith, S. M., Vidaurre, D., Beckmann, C. F., Glasser, M. F., Jenkinson, M., Miller, K. L., Nichols, T. E., Robinson, E. C., Salimi-Khorshidi, G., Woolrich, M. W., Barch, D. M., Uğurbil, K., & Van Essen, D. C.
Affiliations
  • University of Oxford (GB)
  • Radboud University Nijmegen (NL)
  • Washington University in St. Louis (US)
  • University of Warwick (GB)
Corresponding author
Smith, Stephen M.
Venue
Trends in Cognitive Sciences
Publisher
Elsevier BV
Published
2013-12
Volume
17
Issue
12
Pages
666-682
ISSN
1364-6613 (ISSN-L)
OpenAlex
W2124698428
Cited by
952
References
93
Citations by year
2026: 55 · 2025: 77 · 2024: 84 · 2023: 76 · 2022: 83 · 2021: 82 · 2020: 88 · 2019: 77 · 2018: 81 · 2017: 72 · 2016: 71 · 2015: 63 · 2014: 38 · 2013: 3
FWCI
4.96
Type
journal article
Language
en
Open access
Locations
  • Trends in Cognitive Sciences (publishedVersion)
  • PubMed (publishedVersion)
  • University of Twente Research Information (publishedVersion)
  • PubMed Central (acceptedVersion)
  • Adelaide Research & Scholarship (AR&S) (University of Adelaide) (submittedVersion)
  • Radboud Repository (Radboud University) (submittedVersion)
  • University of Twente Research Information (submittedVersion)
Funders
  • Wellcome Trust (1U54MH091657, 098369/Z/12/Z, 098369, 100309/A/12/Z, 100309)
  • National Institutes of Health (5u54mh091657-05, 1u54mh091657-01, 1U54‐MH‐091657, RR08079)
  • National Institute of Mental Health (1U54-MH091657-01, U54-MH091657, F30MH097312)
  • National Institute of Neurological Disorders and Stroke (P30NS076408, P30NS057091)
  • National Institute of Biomedical Imaging and Bioengineering (P41EB015894, P41-RR08079/EB015894)
  • National Center for Research Resources (P41RR008079)
Topics
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Functional Brain Connectivity Studies
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Advanced Neuroimaging Techniques and Applications
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Advanced MRI Techniques and Applications
Keywords
functional connectomics, resting-state fMRI, spontaneous brain activity, functional brain networks, network structure estimation, Human Connectome Project, MRI image processing, connectome mapping
MeSH terms
Animals, Brain, Humans, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Nerve Net, Neural Pathways, Oxygen, Rest

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-09.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-09.

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