Nonparametric Measures of Association

Gibbons, Jean Dickinson

doi:10.4135/9781412985291

Cited by 108 publications

(73 citation statements)

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“…Patients > comparison subjects and comparison subjects > patients differences were integrated by coding them with values of 1 and −1. Associations between all pairs of regions were assessed using Kendall's tau b (τ) (67,68), a nonparametric measure of association. Positive τ values for a pair of regions indicate that across studies, observing activation in one region increases the likelihood of observing activation in the other (i.e., either hyper-or hypoactivation tends to co-occur).…”

Section: Coactivation Analysismentioning

confidence: 99%

Functional Neuroimaging of Anxiety: A Meta-Analysis of Emotional Processing in PTSD, Social Anxiety Disorder, and Specific Phobia

Etkin¹,

Wager²

2007

AJP

2,769

172

2,306

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Objective-The study of human anxiety disorders has benefited greatly from functional neuroimaging approaches. Individual studies, however, vary greatly in their findings. The authors searched for common and disorder-specific functional neurobiological deficits in several anxiety disorders. The authors also compared these deficits to the neural systems engaged during anticipatory anxiety in healthy subjects.Method-Functional magnetic resonance imaging and positron emission tomography studies of posttraumatic stress disorder (PTSD), social anxiety disorder, specific phobia, and fear conditioning in healthy individuals were compared by quantitative meta-analysis. Included studies compared negative emotional processing to baseline, neutral, or positive emotion conditions.Results-Patients with any of the three disorders consistently showed greater activity than matched comparison subjects in the amygdala and insula, structures linked to negative emotional responses. A similar pattern was observed during fear conditioning in healthy subjects. Hyperactivation in the amygdala and insula were, of interest, more frequently observed in social anxiety disorder and specific phobia than in PTSD. By contrast, only patients with PTSD showed hypoactivation in the dorsal and rostral anterior cingulate cortices and the ventromedial prefrontal cortex-structures linked to the experience and regulation of emotion.Conclusions-This meta-analysis allowed us to synthesize often disparate findings from individual studies and thereby provide neuroimaging evidence for common brain mechanisms in anxiety disorders and normal fear. Effects unique to PTSD furthermore suggested a mechanism for the emotional dysregulation symptoms in PTSD that extend beyond an exaggerated fear response. Therefore, these findings help refine our understanding of anxiety disorders and their interrelationships.Fear and avoidance of trigger cues are common to many anxiety disorders (1) and resemble the arousal and avoidance responses shown by normal subjects to conditioned fear cues (2). Thus, a common element of anxiety disorders may be an abnormally elevated fear response. Based on animal models of fear learning (3, 4), this hypothesis leads to the prediction that amygdalar dysfunction is common to a variety of anxiety disorders. Indeed, amygdalar hyperactivity has been observed during symptom provocation or negative emotional processing in patients with posttraumatic stress disorder (PTSD) (5-8), social anxiety disorder (9-14), specific phobia (15-18), panic disorder (19), and obsessive-compulsive disorder (OCD) (19,20). However, because of the low statistical power of individual studies Address correspondence and reprint requests to Dr. Etkin, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Rd., Stanford, CA 94305; amitetkin@stanford.edu. All authors report no competing interests. NIH Public Access Author ManuscriptAm J Psychiatry. Author manuscript; available in PMC 2012 April 4. NIH-PA Author Manuscr...

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Section: Coactivation Analysismentioning

confidence: 99%

Functional Neuroimaging of Anxiety: A Meta-Analysis of Emotional Processing in PTSD, Social Anxiety Disorder, and Specific Phobia

Etkin¹,

Wager²

2007

AJP

2,769

172

2,306

View full text Add to dashboard Cite

show abstract

“…Associations between each voxel and each component were assessed using Kendall's Tau-b, referred to here as τ (Gibbons, 1993;Gibbons et al, 2003), a nonparametric measure of association that does not require normally distributed data and thus, unlike Pearson's r, is appropriate for indicator data. For each voxel, we computed τ with each component.…”

Section: Functional Group Analysis: Implementationmentioning

confidence: 99%

Functional grouping and cortical–subcortical interactions in emotion: A meta-analysis of neuroimaging studies

et al. 2008

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We performed an updated quantitative meta-analysis of 162 neuroimaging studies of emotion using a novel multi-level kernel-based approach, focusing on locating brain regions consistently activated in emotional tasks and their functional organization into distributed functional groups, independent of semantically defined emotion category labels (e.g., "anger," "fear"). Such brain-based analyses are critical if our ways of labeling emotions are to be evaluated and revised based on consistency with brain data. Consistent activations were limited to specific cortical sub-regions, including multiple functional areas within medial, orbital, and inferior lateral frontal cortices. Consistent with a wealth of animal literature, multiple subcortical activations were identified, including amygdala, ventral striatum, thalamus, hypothalamus, and periaqueductal gray. We used multivariate parcellation and clustering techniques to identify groups of co-activated brain regions across studies. These analyses identified six distributed functional groups, including medial and lateral frontal groups, two posterior cortical groups, and paralimbic and core limbic/brainstem groups. These functional groups provide information on potential organization of brain regions into large-scale networks. Specific follow-up analyses focused on amygdala, periaqueductal gray (PAG), and hypothalamic (Hy) activations, and identified frontal cortical areas co-activated with these core limbic structures. While multiple areas of frontal cortex co-activated with amygdala sub-regions, a specific region of dorsomedial prefrontal cortex (dmPFC, Brodmann's Area 9/32) was the only area co-activated with both PAG and Hy. Subsequent mediation analyses were consistent with a pathway from dmPFC through PAG to Hy. These results suggest that medial frontal areas are more closely associated with core limbic activation than their lateral counterparts, and that dmPFC may play a particularly important role in the cognitive generation of emotional states.

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“…Note that it incorporates unigram probabilities as well as the two distributions q and r. Finally, Kendall's τ , which appears in work on clustering similar adjectives (Hatzivassiloglou and McKeown, 1993;Hatzivassiloglou, 1996), is a nonparametric measure of the association between random variables (Gibbons, 1993). In our context, it looks for correlation between the behavior of q and r on pairs of verbs.…”

Section: Distributional Similarity Functionsmentioning

confidence: 99%

Measures of distributional similarity

Lee

1999

Proceedings of the 37th Annual Meeting of the Association for Computational Linguistics on Computational Linguistics -

373

296

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We study distributional similarity measures for the purpose of improving probability estimation for unseen cooccurrences. Our contributions are three-fold: an empirical comparison of a broad range of measures; a classification of similarity functions based on the information that they incorporate; and the introduction of a novel function that is superior at evaluating potential proxy distributions.

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Nonparametric Measures of Association

Cited by 108 publications

References 0 publications

Functional Neuroimaging of Anxiety: A Meta-Analysis of Emotional Processing in PTSD, Social Anxiety Disorder, and Specific Phobia

Functional Neuroimaging of Anxiety: A Meta-Analysis of Emotional Processing in PTSD, Social Anxiety Disorder, and Specific Phobia

Functional grouping and cortical–subcortical interactions in emotion: A meta-analysis of neuroimaging studies

Measures of distributional similarity

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