A method for generating reproducible evidence in fMRI studies

Liou, Michelle; Su, Hong-Ren; Lee, Juin-Der; Aston, John A. D.; Tsai, Arthur C.; Cheng, Philip E.

doi:10.1016/j.neuroimage.2005.08.015

Cited by 20 publications

(17 citation statements)

References 31 publications

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“…[18][19][20] We found that the neural response evoked by acupuncture did not turn on and off rapidly but lasted longer, violating the basic assumption of standard GLM analysis. Consequently, because of the sustained effect of acupuncture, contradictory and uncertain results may be obtained when using standard GLM analysis for 'on-off ' design acupuncture studies.…”

Section: Discussionmentioning

confidence: 99%

Additional Evidence for the Sustained Effect of Acupuncture at the Vision-Related Acupuncture Point, Gb37

et al. 2013

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Objective To investigate the dynamics underlying the sustained effect of acupuncture as a possible explanation of earlier findings that acupuncture stimulation at the vision-related acupuncture point, GB37, cannot specifically change the functional MRI (fMRI) signals of the visual cortex compared with stimulation at an adjacent non-meridian point. Methods The 'on-off' experimental design was separated into four series conditions: 1 min of baseline scanning at the beginning, then two stimulation epochs separated by a 50 s 'rest' period, and then a 1 min 'rest' epoch. The standard General Linear Model (GLM) approach and multi-conditions analysis were used. Results Results from the multi-conditions analysis were different from those from the standard GLM analysis. We found that the neural signal of the limbic-paralimbic-neocortical system after acupuncture stimulus lasted longer than the putative period. Furthermore, the fMRI signal changes in the occipital cortex showed different temporal patterns between GB37 and the non-meridian point. Conclusions Owing to the sustained effect of acupuncture, standard GLM analysis may be unsuitable for 'on-off' design acupuncture studies and lead to uncertain and contradictory results. The findings from this study suggest that acupuncture at GB37 can induce complex brain activity in the vision cortex. The state-related neural signal may reflect one of the significant characteristics underlying acupuncture.

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Section: Discussionmentioning

confidence: 99%

Additional Evidence for the Sustained Effect of Acupuncture at the Vision-Related Acupuncture Point, Gb37

et al. 2013

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“…We use the reliability indexes elaborated in [Genovese et al, 1997, Liou et al, 2003, Liou et al, 2005. Assume that a statistical procedure (e.g.…”

Section: Reliability Measure At the Voxel Levelmentioning

confidence: 99%

Analysis of a large fMRI cohort: Statistical and methodological issues for group analyses

et al. 2007

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Validating the association between brain activity, as measured in functional MRI, with a combination or a contrast of tasks is usually performed by replicating an experiment in a small group of subjects, and by assessing the presence of a statistically significant average effect across subjects (random effects analyses). While many efforts have been made to control the rate of false detections, statistical characteristics of the data have rarely been studied, and the reliability of the results (supra-thresholds areas that are considered as activated regions) has rarely been assessed. In this work, we take advantage of the large cohort of subjects who underwent the Localizer experiment to study the statistical nature of group data, propose some measures of the reliability of group studies, and address simple methodological questions as : is there, from the point of view of reliability, an optimal statistical threshold for activity maps ? How many subjects should be included in group studies ? What method should be preferred for inference ? Our results suggest that i) optimal thresholds can indeed be found, and are rather lower than usual corrected for multiple comparison thresholds ii) 20 subjects or more should be included in functional neuroimaging studies in order to have sufficient reliability, iii) non-parametric significance assessment should be preferred to parametric methods iv) cluster-level thresholding is more reliable than voxel-based thresholding v) mixed effects tests are much more reliable than random effects tests. Moreover, our study shows that inter-subject variability plays a prominent role in the relatively low sensitivity and reliability of group studies.

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“…These estimates can be interpreted as the empirical sensitivity and specificity of the method, which provides us with a way to establish the receiver-operatingcharacteristics (ROC) curve. Several studies have recommended the ROC approach for validating and comparing statistical methods, e.g., Friston et al (1996b), Genovese et al (1997), Skudlarski et al (1999), Maitra et al (2002), Liou et al (2003), Fadili and Bullmore (2004), and Liou et al (2006).…”

Section: Reproducibility Studymentioning

confidence: 99%

WSPM: Wavelet-based statistical parametric mapping

et al. 2007

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Recently, we have introduced an integrated framework that combines wavelet-based processing with statistical testing in the spatial domain. In this paper, we propose two important enhancements of the framework. First, we revisit the underlying paradigm; i.e., that the effect of the wavelet processing can be considered as an adaptive denoising step to "improve" the parameter map, followed by a statistical detection procedure that takes into account the non-linear processing of the data. With an appropriate modification of the framework, we show that it is possible to reduce the spatial bias of the method with respect to the best linear estimate, providing conservative results that are closer to the original data. Second, we propose an extension of our earlier technique that compensates for the lack of shift-invariance of the wavelet transform. We demonstrate experimentally that both enhancements have a positive effect on performance. In particular, we present a reproducibility study for multisession data that compares WSPM against SPM with different amounts of smoothing. The full approach is available as a toolbox, named WSPM, for the SPM2 software; it takes advantage of multiple options and features of SPM such as the general linear model. © 2007 Elsevier Inc. All rights reserved.Keywords: Wavelets; Wavelet thresholding; Statistical testing; Bias reduction; Shift-invariant transform; Reproducibility study IntroductionStatistical parametric mapping (SPM) Frackowiak et al., 1997) is probably the most popular parametric hypothesis-driven method for the analysis of fMRI data. To control the multiple testing problem, SPM considers the data as a lattice representation of a continuous Gaussian Random Field (GRF). To conform with this hypothesis, the data are pre-smoothed with a Gaussian filter with fixed size (Worsley et al., 1996;Poline et al., 1997). The user has the option to adjust the smoothing strength for optimal detection (compromise between SNR enhancement and spatial definition).The discrete wavelet transform (DWT) has also been applied to the analysis of fMRI data for parametric hypothesis testing. Three important properties justify the use of wavelets in this application. First, they typically encode activation patterns with a small set of wavelet coefficients; this is referred to as the DWT's sparsifying property. Second, an orthogonal DWT leaves the noise evenly distributed in the wavelet domain; it therefore increases the SNR. Third, the DWT acts (approximately) as a decorrelator. Therefore, a conservative Bonferroni correction for multiple hypothesis testing is closer to optimal in the wavelet domain than in the spatial domain. Basically, the standard wavelet approach to parametric hypothesis testing consists in statistical testing the wavelet domain representation of the parameter map (Ruttimann et al., 1998;Turkheimer et al., 2000). The remaining difficulty is how to fully exploit the reconstruction of the parameter map after thresholding in the wavelet domain. Several approaches have been proposed, s...

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A method for generating reproducible evidence in fMRI studies

Cited by 20 publications

References 31 publications

Additional Evidence for the Sustained Effect of Acupuncture at the Vision-Related Acupuncture Point, Gb37

Additional Evidence for the Sustained Effect of Acupuncture at the Vision-Related Acupuncture Point, Gb37

Analysis of a large fMRI cohort: Statistical and methodological issues for group analyses

WSPM: Wavelet-based statistical parametric mapping

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