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Neurobiology of Dyspnea: An Overview
Published in Donald A. Mahler, Denis E. O’Donnell, Dyspnea, 2014
Karleyton C. Evans, Robert B. Banzett
Traditional ROI approaches involve testing one or more specific a priori ROIs and analyzing data in only those regions. Regional approaches are particularly vulnerable to Type II error because signal in regions other than those driven by a priori hypotheses will not be detected. ROIs should be defined by a priori hypotheses, which may be derived from stereotactic coordinates from prior studies or by probabilistic atlases75 or by the structural or functional data from the subjects under study.76 Regional analyses have evolved to include capabilities for characterizing regional functional specificity via estimates of condition-related signal magnitude and/or time course (see http://marsbar.sourceforge.net/). An extension of these emerging ROI methods includes psychophysiological interaction (PPI) analyses. In PPI analyses, post hoc linear regression is performed to test for activations in both ROIs identified by a priori hypotheses and ROIs detected in the same data by the main effects analysis. This particular approach is at considerable risk to overinterpretation of findings or reification74 and has been rarely used in dyspnea neuroimaging studies.
Self and other body perception in anorexia nervosa: The role of posterior DMN nodes
Published in The World Journal of Biological Psychiatry, 2018
Esther Via, Ximena Goldberg, Isabel Sánchez, Laura Forcano, Ben J. Harrison, Christopher G. Davey, Jesús Pujol, Ignacio Martínez-Zalacaín, Fernando Fernández-Aranda, Carles Soriano-Mas, Narcís Cardoner, José M. Menchón
As the main analysis of interest, between-group differences during the body-perception task were first evaluated within the DMN (see below for mask definition). Next, psychophysiological interaction analyses were conducted to assess the influence of the task on the functional coupling between the areas identified in our main analysis and other areas within the DMN. Finally, we assessed resting-state connectivity between the areas resulting from our main analysis and the rest of the DMN regions.
Increased Connectivity Between the Nucleus Accumbens and the Default Mode Network in Patients With Schizophrenia During Cigarette Cravings
Published in Journal of Dual Diagnosis, 2019
Stéphane Potvin, Jules R. Dugré, Cherine Fahim, Alexandre Dumais
General psychophysiological interaction analyses were performed using the CONN toolbox. The bilateral nucleus accumbens (ventral striatum and ventromedial frontal cortex) were used as seed regions of interest (ROIs), for three main reasons: (1) substantial preclinical evidence shows that the nucleus accumbens and ventromedial prefrontal cortex play a critical role in drug reward (Wing et al., 2012); (2) several fMRI studies on tobacco cravings have shown that the cigarette cues elicit activations in the ventral striatum and ventromedial prefrontal cortex (Engelmann et al., 2012; McClernon et al., 2008); and (3) cue-elicited activations have been previously observed in the ventral striatum and ventromedial prefrontal cortex in smokers with schizophrenia (Potvin et al., 2015). The ROIs were chosen from the Harvard-Oxford atlas (www.fmrib.ox.ac.uk/fsl/). The psychophysiological interaction method is a multiple regression technique that allows the investigation of functional coupling between regions in relation to the experimental paradigm (Friston et al., 1997). The psychophysiological interaction regressor was calculated as the element-by-element product of the ROI time series and a vector coding for the task effect (craving > neutral). This interaction term was entered as a regressor of interest in a first-level model together with the ROI time series and the vector coding for the task effect. Group comparisons were performed using analyses of variance. Depressive symptoms were entered as covariates. Clusters were reported only when surviving a voxel-level statistical threshold of p < .001 and a cluster-level threshold of p < .05 corrected for the false discovery rate. Beta values of impaired connectivity were extracted and used to perform correlation analyses with measures of cigarette cravings, inside and outside of the scanner. The potential influence of antipsychotics and positive symptoms was also examined.