تغییرات همگن منطقه ای در اختلال اضطراب اجتماعی: مطالعه مرحله استراحت FMRI
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|39183||2011||7 صفحه PDF||سفارش دهید||5925 کلمه|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Psychiatry Research: Neuroimaging, Volume 194, Issue 1, 31 October 2011, Pages 47–53
Abstract The previous task-based or resting perfusion studies in social anxiety disorder (SAD) patients have highlighted specific differences in brain response. Little is known about the changes in the local synchronization of spontaneous functional magnetic resonance imaging (fMRI) blood oxygen level-dependent (BOLD) signals that occur in SAD during the resting state. We investigated altered neural activity in the resting state using a regional homogeneity (ReHo) analysis on 20 SAD and 20 healthy controls (HC). Compared with HC, SAD patients exhibited decreased coherence (ReHo) in the bilateral angular gyrus and the left medial prefrontal cortex within the default mode network (DMN), suggesting functional impairment of the perception of socially relevant emotional state and self-related mental representations; and also in the right dorsolateral prefrontal cortex and right inferior parietal gyrus within the central-executive network (CEN), reflecting the deficit of cognitive control of social anxiety. Significantly increased coherence (ReHo) was found in the left middle occipital gyrus, which would be consistent with their hypervigilance and hyperprosexia to the social communication even in the resting state. Our results might supply a novel way to look into neuro-pathophysiological mechanisms in SAD patients.
1. Introduction Social anxiety disorder (SAD) is a common and chronic mental disorder (Stein and Stein, 2008), which is thought to involve emotional hyperactivity, cognitive distortions, and ineffective emotion regulation (Goldin et al., 2009b). Results of neurophysiological and neuroimaging studies (Damsa et al., 2009 and Engel et al., 2009) showed that patients with SAD exhibited greater activity than healthy subjects in several brain regions related to emotional processing under social fear and anxiety conditions (Tillfors et al., 2001, Stein et al., 2002, Phan et al., 2006 and Etkin and Wager, 2007). However, these studies were performed under task-based conditions. Further understanding of SAD may be achieved during the resting state (Etkin et al., 2009), which may be absent or masked during an activation paradigm (Warwick et al., 2008). Recently, resting-state functional magnetic resonance imaging (fMRI) techniques have been applied to demonstrate abnormalities in various neuropsychiatric disorders (Anand et al., 2005, Garrity et al., 2007, Greicius et al., 2007, Zhang et al., 2009a, Zhang et al., 2009b, Liao et al., 2010a, Liao et al., 2010b and Zhang et al., 2010). In particular, these abnormalities mostly relate to alterations in the coherent intrinsic neuronal activity of blood oxygen level-dependent (BOLD) fluctuations observed in resting-state fMRI studies. In a previous study, reduced deactivation of the medial prefrontal cortex (MPFC) and increased deactivation of the posterior cingulate cortex (PCC) were observed in anxiety patients during listening to threatening words as compared to a resting condition (Zhao et al., 2007). These two brain regions are known to be critical in the default mode network (DMN) (Buckner et al., 2008 and Broyd et al., 2009). In addition, the results of fMRI and single photon emission computed tomography studies consistently implicate alterations in critical regions in the DMN in SAD patients (Warwick et al., 2008 and Gentili et al., 2009). More recently, a pioneering resting-state study showed increased connectivity of a frontoparietal network (the central-executive network (CEN)) and decreased connectivity of an insula-cingulate network (the salience network) in generalized anxiety disorder (Etkin et al., 2009) using functional connectivity analysis. Moreover, our previous study indicated a diffuse impact on widely distributed resting-state networks and selective changes of intrinsic functional connectivity in SAD patients at rest (Liao et al., 2010a). Regional homogeneity (ReHo), a novel method that differs from functional connectivity, has been developed to analyze the local synchronization of spontaneous fMRI BOLD signals (Zang et al., 2004). The ReHo method assumes that the hemodynamic characteristics of every voxel are similar within a functional cluster and that there is dynamic synchronization of voxels within a given cluster (Zang et al., 2004). ReHo may be absent or masked during an activation paradigm and therefore is useful for resting-state fMRI data analysis. In addition, ReHo provides an approach for using fMRI to investigate local connectivity (Zang et al., 2004) and reflects the temporal synchrony of the regional fMRI BOLD signal. It may be potentially helpful to understand human brain activity in the resting state and may be useful for revealing the complexity of human brain function (Liu et al., 2008). In contrast, abnormal ReHo is most likely related to changes in the temporal aspects of spontaneous neural activity in the regional brain (Wu et al., 2009 and Shukla et al., 2010). It may be speculated that an abnormal ReHo may be a clue to disrupted local functionality (He et al., 2007) and may provide insight into the pathophysiology of psychiatric disorder (Liu et al., 2010). This method has been used to investigate the functional modulations and characterize the pathophysiological changes in the resting state in patients with attention-deficit/hyperactivity disorder (Zhu et al., 2008), Alzheimer's disease (He et al., 2007 and Liu et al., 2008), depression (Liu et al., 2010 and Wu et al., 2010), Parkinson's disease (Wu et al., 2009) and autism spectrum disorders (Paakki et al., 2010 and Shukla et al., 2010). Little is known about the changes in the local synchronization of spontaneous fMRI BOLD signals that occur in SAD during the resting state. We hypothesized that ReHo of resting-state brain activity would be different between patients with SAD and healthy controls, particularly in brain regions that have been implicated in previous task-based fMRI studies. In the present study, we document for the first time the ReHo values for patients with SAD compared to those of HCs. In addition, correlation analyses of the ReHo value for each voxel within one-sample t-test results were carried out in the SAD group to explore whether changes are related to clinical severity as measured by the total Liebowitz Social Anxiety Scale (LSAS).
نتیجه گیری انگلیسی
3. Results 3.1. Psychological data and group characteristics The details of psychological scores are shown in Table 1 of our previous study (Liao et al., 2010a). No significant differences were found between SAD patients and HCs in terms of gender, age, educational level and post-scanning STAI-S. Compared with HCs, SAD patients showed significantly higher scores on the LSAS (including total score, fear factor and avoidance factor) assessment social anxiety symptom scales, and higher scores on the HAMD and HAMA, and higher levels of anxiety as assessed by the STAI-T and pre-scanning STAI-S. Table 1. Regions of increased/decreased ReHo in SAD patients. Anatomical region MNI (x,y,z) a BA Voxels t b ReHo increased regions L MOG − 33,−78,15 18/19 35 3.61 R PUT 24,15,3 – 14 2.83 ReHo decreased regions R DLPFC 24,30,45 8 63 − 4.76 L AG − 39,−63,39 39/40 39 − 4.23 R AG 42,−63,48 40 38 − 3.87 R ACC 9,39,21 32 26 − 3.75 L MPFC − 21,45,42 9 76 − 3.59 R IPG 42,−45,51 40 36 − 3.34 R FG 21,−57,−12 19 14 − 3.06 Abbreviations: ReHo, regional homogeneity; SAD, social anxiety disorder; HC, healthy controls; MNI, Montreal Neurological Institute; BA, Brodmann's area; L, left; MOG, middle occipital gyrus; R, right; PUT, putamen; DLPFC, dorsolateral prefrontal cortex; AG, angular gyrus; ACC, anterior cingulate gyrus; MPFC, medial prefrontal cortex; IPG, inferior parietal gyrus; FG, fusiform gyrus. a Coordinates of primary peak locations in the MNI space. b Represents the statistical value of peak voxel showing ReHo differences comparing SAD patients and HC. Positive t value indicates increased ReHo, and negative t value indicates decreased ReHo. Table options 3.2. Within-group and between-group ReHo analyses ReHo results for HC and the SAD patient group are shown in Fig. 1 (one-sample t-test; P < 0.05, FDR corrected). Visual inspection indicated that the posterior cingulate cortex (PCC)/precuneus, medial prefrontal cortex (MPFC) and bilateral angular gyrus (AG) had significantly higher ReHo than other brain regions. The ReHo pattern was very similar to the DMN ( Raichle et al., 2001). In addition, we also find that other brain regions, including the bilateral supplementary motor area (SMA), dorsolateral prefrontal cortex (DLPFC), insula, inferior parietal gyrus (IPG), medial temporal gyrus (MTG), middle occipital gyrus (MOG), putamen (PUT), anterior cingulate gyrus (ACC), cuneus (CUN) and fusiform gyrus (FG), have higher ReHo values. Here these within-group maps are merely for visualizing ReHo. Results of ReHo shown as a Kendall's coefficient of concordance (KCC) map for HC ... Fig. 1. Results of ReHo shown as a Kendall's coefficient of concordance (KCC) map for HC (top plane) and SAD patients (bottom plane). Threshold was P < 0.05 with FDR corrected. Numbers in the upper left of each image refer to the z-plane coordinates of the Montreal Neurological Institute (MNI) space. Letters L and R correspond to the left and right sides of the brain, respectively. Figure options The results obtained from the two-sample t-test clearly showed significant differences in ReHo between the two groups (P < 0.05, AlphaSim corrected; Fig. 2, Table 1). Compared with HC, the SAD patient group showed significantly decreased ReHo in the left MPFC, the right DLPFC, IPG, ACC and FG and the bilateral AG; and significantly increased ReHo in the left MOG and the right PUT. ReHo map of statistically significant differences by two-sample t-test between ... Fig. 2. ReHo map of statistically significant differences by two-sample t-test between SAD patients and HC (P < 0.05 [AlphaSim corrected], a combined threshold of P < 0.01, and a minimum cluster size of 13 voxels). Hot and cold colors indicate ReHo increases and decreases, respectively, in the SAD patient group. Numbers in the upper left of each image refer to the z-plane coordinates of the MNI space. Letters L and R correspond to the left and right sides of the brain, respectively. Further details of these regions are presented in Table 1. Figure options 3.3. Correlations between ReHo and total LSAS in SAD patients Correlation analysis of ReHo against the total LSAS score showed significantly negative correlations for the left putamen and MPFC and the bilateral DLPFC, and significantly positive correlations for the left MOG and CUN and the bilateral IPG in the SAD patients (P < 0.05, AlphaSim corrected; Fig. 3, Table 2). Results of correlation analysis between the total LSAS score and ReHo in the SAD ... Fig. 3. Results of correlation analysis between the total LSAS score and ReHo in the SAD patient group (P < 0.05 [AlphaSim corrected], a combined threshold of P < 0.01, and a minimum cluster size of 12 voxels). Hot and cold colors indicate positive and negative correlations, respectively, between ReHo and total LSAS score. Numbers in the upper left of each image refer to the z- (top), y- (middle), and x- (bottom) plane coordinates of the MNI space. Letters L and R correspond to the left and right sides of the brain, respectively. Further details of these regions are presented in Table 2. Figure options Table 2. Correlation between ReHo and clinical severity in SAD patients. Anatomical region MNI (x,y,z) a BA Voxels t b Positive correlation between total LSAS and ReHo in SAD L IPG − 36,−45,39 40 26 4.93 R IPG 36,−51,42 40 27 3.89 L MOG − 12,−93,0 17 19 3.18 L CUN − 9,−75,30 7 29 3.44 Negative correlation between total LSAS and ReHo in SAD L MPFC − 12,45,3 11 23 − 3.51 L PUT − 21,12,−3 – 56 − 4.59 L DLPFC − 30,45,30 9/10 35 − 4.72 R DLPFC 42,30,42 8/9 21 − 4.12 Abbreviations: ReHo, regional homogeneity; SAD, social anxiety disorder; HC, healthy controls; MNI, Montreal Neurologic Institute; BA, Brodmann's area; L, left; IPG, inferior parietal gyrus; R, right; MOG, middle occipital gyrus; CUN, cuneus; DLPFC, dorsolateral prefrontal cortex; PUT, putamen; MPFC, medial prefrontal cortex. a Coordinates of primary peak locations in the MNI space. b Represents the statistical value of peak voxel showing correlation between total LSAS score and ReHo in SAD patients. Positive and negative t values indicate positive and negative correlations, respectively.