The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Tor D Wager - One of the best experts on this subject based on the ideXlab platform.
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meta analysis of Functional Neuroimaging data via bayesian spatial point processes
Journal of the American Statistical Association, 2011Co-Authors: Jian Kang, Thomas E. Nichols, Timothy D Johnson, Tor D WagerAbstract:As the discipline of Functional Neuroimaging grows there is an increasing interest in meta analysis of brain imaging studies. A typical Neuroimaging meta analysis collects peak activation coordinates (foci) from several studies and identifies areas of consistent activation. Most imaging meta analysis methods only produce null hypothesis inferences and do not provide an interpretable fitted model. To overcome these limitations, we propose a Bayesian spatial hierarchical model using a marked independent cluster process. We model the foci as offspring of a latent study center process, and the study centers are in turn offspring of a latent population center process. The posterior intensity function of the population center process provides inference on the location of population centers, as well as the interstudy variability of foci about the population centers. We illustrate our model with a meta analysis consisting of 437 studies from 164 publications, show how two subpopulations of studies can be compared...
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Functional Neuroimaging of anxiety a meta analysis of emotional processing in ptsd social anxiety disorder and specific phobia
American Journal of Psychiatry, 2007Co-Authors: Amit Etkin, Tor D WagerAbstract: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 f...
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Functional Neuroimaging of anxiety a meta analysis of emotional processing in ptsd social anxiety disorder and specific phobia
2007Co-Authors: Amit Etkin, Tor D WagerAbstract: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.
Richard N Henson - One of the best experts on this subject based on the ideXlab platform.
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forward inference using Functional Neuroimaging dissociations versus associations
Trends in Cognitive Sciences, 2006Co-Authors: Richard N HensonAbstract:Many people are excited by Functional Neuroimaging as a new tool for cognitive science; many others are sceptical. In this opinion article, I describe a 'forward inference' that one can make from patterns of brain activity to distinguish between cognitive theories. I give an example of forward inferences in research on recognition memory, and outline some statistical criteria for a 'qualitative difference' in brain activity. Forward inferences resemble the dissociation logic long-used in behavioural studies of healthy and brain-damaged people, although I argue that dissociations in Neuroimaging data can go beyond behavioural dissociations. Nonetheless, forward inferences are only as good as the cognitive theories to which they pertain, and are most valuable in conjunction with other types of inference.
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what can Functional Neuroimaging tell the experimental psychologist
Quarterly Journal of Experimental Psychology, 2005Co-Authors: Richard N HensonAbstract:I argue here that Functional Neuroimaging data--which I restrict to the haemodynamic techniques of fMRI and PET--can inform psychological theorizing, provided one assumes a "systematic" function-structure mapping in the brain. In this case, imaging data simply comprise another dependent variable, along with behavioural data, that can be used to test competing theories. In particular, I distinguish two types of inference: function-to-structure deduction and structure-to-function induction. With the former inference, a qualitatively different pattern of activity over the brain under two experimental conditions implies at least one different function associated with changes in the independent variable. With the second type of inference, activity of the same brain region(s) under two conditions implies a common function, possibly not predicted a priori. I illustrate these inferences with imaging studies of recognition memory, short-term memory, and repetition priming. I then consider in greater detail what is meant by a "systematic" function-structure mapping and argue that, particularly for structure-to-function induction, this entails a one-to-one mapping between Functional and structural units, although the structural unit may be a network of interacting regions and care must be taken over the appropriate level of Functional/structural abstraction. Nonetheless, the assumption of a systematic function-structure mapping is a "working hypothesis" that, in common with other scientific fields, cannot be proved on independent grounds and is probably best evaluated by the success of the enterprise as a whole. I also consider statistical issues such as the definition of a qualitative difference and methodological issues such as the relationship between imaging and behavioural data. I finish by reviewing various objections to Neuroimaging, including neophrenology, Functionalism, and equipotentiality, and by observing some criticisms of current practice in the imaging literature.
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the neural basis of episodic memory evidence from Functional Neuroimaging
Philosophical Transactions of the Royal Society B, 2002Co-Authors: Michael D Rugg, Leun J Otten, Richard N HensonAbstract:We review some of our recent research using Functional Neuroimaging to investigate neural activity supporting the encoding and retrieval of episodic memories, that is, memories for unique events. Findings from studies of encoding indicate that, at the cortical level, the regions responsible for the effective encoding of a stimulus event as an episodic memory include some of the regions that are also engaged to process the event 'online'. Thus, it appears that there is no single cortical site or circuit responsible for episodic encoding. The results of retrieval studies indicate that successful recollection of episodic information is associated with activation of lateral parietal cortex, along with more variable patterns of activity in dorsolateral and anterior prefrontal cortex. Whereas parietal regions may play a part in the representation of retrieved information, prefrontal areas appear to support processes that act on the products of retrieval to align behaviour with the demands of the retrieval task.
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frontal lobes and human memory insights from Functional Neuroimaging
Brain, 2001Co-Authors: Paul C Fletcher, Richard N HensonAbstract:The new Functional Neuroimaging techniques, PET and Functional MRI (fMRI), offer sufficient experimental flexibility and spatial resolution to explore the Functional neuroanatomical bases of different memory stages and processes. They have had a particular impact on our understanding of the role of the frontal cortex in memory processing. We review the insights that have been gained, and attempt a synthesis of the findings from Functional imaging studies of working memory, encoding in episodic memory and retrieval from episodic memory. Though these different aspects of memory have usually been studied in isolation, we suggest that there is sufficient convergence with respect to frontal activations to make such a synthesis worthwhile. We concentrate in particular on three regions of the lateral frontal cortex-ventro-lateral, dorsolateral and anterior-that are consistently activated in these studies, and attribute these activations to the updating/maintenance of information, the selection/manipulation/monitoring of that information, and the selection of processes/subgoals, respectively. We also acknowledge a number of empirical inconsistencies associated with this synthesis, and suggest possible reasons for these. More generally, we predict that the resolution of questions concerning the Functional neuroanatomical subdivisions of the frontal cortex will ultimately depend on a fuller cognitive psychological fractionation of memory control processes, an enterprise that will be guided and tested by experimentation. We expect that the Neuroimaging techniques will provide an important part of this enterprise.
Kalina Christoff - One of the best experts on this subject based on the ideXlab platform.
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Functional neuroanatomy of meditation a review and meta analysis of 78 Functional Neuroimaging investigations
arXiv: Neurons and Cognition, 2016Co-Authors: Kieran C R Fox, Matthew L Dixon, Savannah Nijeboer, Manesh Girn, James L Floman, Michael Lifshitz, Melissa Ellamil, Peter Sedlmeier, Kalina ChristoffAbstract:Meditation is a family of mental practices that encompasses a wide array of techniques employing distinctive mental strategies. We systematically reviewed 78 Functional Neuroimaging (fMRI and PET) studies of meditation, and used activation likelihood estimation to meta-analyze 257 peak foci from 31 experiments involving 527 participants. We found reliably dissociable patterns of brain activation and deactivation for four common styles of meditation (focused attention, mantra recitation, open monitoring, and compassion/loving-kindness), and suggestive differences for three others (visualization, sense-withdrawal, and non-dual awareness practices). Overall, dissociable activation patterns are congruent with the psychological and behavioral aims of each practice. Some brain areas are recruited consistently across multiple techniques - including insula, pre/supplementary motor cortices, dorsal anterior cingulate cortex, and frontopolar cortex - but convergence is the exception rather than the rule. A preliminary effect-size meta-analysis found medium effects for both activations (d = .59) and deactivations (d = -.74), suggesting potential practical significance. Our meta-analysis supports the neurophysiological dissociability of meditation practices, but also raises many methodological concerns and suggests avenues for future research.
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the wandering brain meta analysis of Functional Neuroimaging studies of mind wandering and related spontaneous thought processes
NeuroImage, 2015Co-Authors: Kieran C R Fox, Melissa Ellamil, Nathan R Spreng, Jessica R Andrewshanna, Kalina ChristoffAbstract:The neural basis and cognitive functions of various spontaneous thought processes, particularly mind-wandering, are increasingly being investigated. Although strong links have been drawn between the occurrence of spontaneous thought processes and activation in brain regions comprising the default mode network (DMN), spontaneous thought also appears to recruit other, non-DMN regions just as consistently. Here we present the first quantitative meta-analysis of Neuroimaging studies of spontaneous thought and mind-wandering in order to address the question of their neural correlates. Examining 24 Functional Neuroimaging studies of spontaneous thought processes, we conducted a meta-analysis using activation likelihood estimation (ALE). A number of key DMN areas showed consistent recruitment across studies, including medial prefrontal cortex, posterior cingulate cortex, medial temporal lobe, and bilateral inferior parietal lobule. Numerous non-DMN regions, however, were also consistently recruited, including rostrolateral prefrontal cortex, dorsal anterior cingulate cortex, insula, temporopolar cortex, secondary somatosensory cortex, and lingual gyrus. These meta-analytic results indicate that DMN activation alone is insufficient to adequately capture the neural basis of spontaneous thought; frontoparietal control network areas, and other non-DMN regions, appear to be equally central. We conclude that further progress in the cognitive and clinical neuroscience of spontaneous thought will therefore require a re-balancing of our view of the contributions of various regions and networks throughout the brain, and beyond the DMN.
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dreaming as mind wandering evidence from Functional Neuroimaging and first person content reports
Frontiers in Human Neuroscience, 2013Co-Authors: Kieran C R Fox, Savannah Nijeboer, Elizaveta Solomonova, William G Domhoff, Kalina ChristoffAbstract:Isolated reports have long suggested a similarity in content and thought processes across mind wandering (MW) during waking, and dream mentation during sleep. This overlap has encouraged speculation that both ‘daydreaming’ and dreaming may engage similar brain mechanisms. To explore this possibility, we systematically examined published first-person experiential reports of MW and dreaming and found many similarities: in both states, content is largely audiovisual and emotional, follows loose narratives tinged with fantasy, is strongly related to current concerns, draws on long-term memory, and simulates social interactions. Both states are also characterized by a relative lack of meta-awareness. To relate first-person reports to neural evidence, we compared meta-analytic data from numerous Functional Neuroimaging (PET, fMRI) studies of the default mode network (DMN, with high chances of MW) and rapid eye movement (REM) sleep (with high chances of dreaming). Our findings show large overlaps in activation patterns of cortical regions: similar to MW/DMN activity, dreaming and REM sleep activate regions implicated in self-referential thought and memory, including medial prefrontal cortex (PFC), medial temporal lobe structures, and posterior cingulate. Conversely, in REM sleep numerous PFC executive regions are deactivated, even beyond levels seen during waking MW. We argue that dreaming can be understood as an ‘intensified’ version of waking MW: though the two share many similarities, dreams tend to be longer, more visual and immersive, and to more strongly recruit numerous key hubs of the DMN. Further, whereas MW recruits fewer PFC regions than goal-directed thought, dreaming appears to be characterized by an even deeper quiescence of PFC regions involved in cognitive control and metacognition, with a corresponding lack of insight and meta-awareness. We suggest, then, that dreaming amplifies the same features that distinguish MW from goal-directed waking thought.
Amit Etkin - One of the best experts on this subject based on the ideXlab platform.
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Functional Neuroimaging of anxiety a meta analysis of emotional processing in ptsd social anxiety disorder and specific phobia
American Journal of Psychiatry, 2007Co-Authors: Amit Etkin, Tor D WagerAbstract: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 f...
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Functional Neuroimaging of anxiety a meta analysis of emotional processing in ptsd social anxiety disorder and specific phobia
2007Co-Authors: Amit Etkin, Tor D WagerAbstract: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.
Lisa M Shin - One of the best experts on this subject based on the ideXlab platform.
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neurocircuitry models of posttraumatic stress disorder and beyond a meta analysis of Functional Neuroimaging studies
Neuroscience & Biobehavioral Reviews, 2012Co-Authors: Ronak Patel, Lisa M Shin, Nathan R Spreng, Todd A GirardAbstract:Over the past two decades a relatively large number of studies have investigated the Functional neuroanatomy of posttraumatic stress disorder (PTSD). However, findings are often inconsistent, thus challenging traditional neurocircuitry models of PTSD. As evidence mounts that cognition and behavior is an emergent property of interacting brain networks, the question arises whether PTSD can be understood by examining dysfunction in large-scale, spatially distributed neural networks. We used the activation likelihood estimation quantitative meta-analytic technique to synthesize findings across Functional Neuroimaging studies of PTSD that either used a non-trauma (N=20) or trauma-exposed (N=19) comparison control group. In line with neurocircuitry models, our findings support hyperactive amygdala and hypoactive medial prefrontal regions, but suggest hyperactive hippocampi. Characterization of additional regions under a triple network model showed Functional alterations that largely overlapped with the salience network, central executive network, and default network. However, heterogeneity was observed within and across the neurocircuitry and triple network models, and between results based on comparisons to non-trauma and trauma-exposed control groups. Nonetheless, these results warrant further exploration of the neurocircuitry and large-scale network models in PTSD using connectivity analyses.
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Functional Neuroimaging studies of post traumatic stress disorder
Expert Review of Neurotherapeutics, 2011Co-Authors: Katherine C Hughes, Lisa M ShinAbstract:Post-traumatic stress disorder (PTSD) is a significant problem that can affect individuals who have been exposed to a traumatic event or events, such as combat, violent crime or childhood abuse. Over the past several years, Neuroimaging studies of PTSD have focused on elucidating the brain circuits that mediate this disorder. In this article, we will briefly introduce some of the methods used in Functional Neuroimaging studies of PTSD. We will then review Functional Neuroimaging studies that have reported significant findings in the amygdala, medial prefrontal cortex, hippocampus and insula. Finally, we will suggest future directions for research.
