Brain regions involved in dispositional mindfulness during resting state and their relation with well-being

Mindfulness can be viewed as an important dispositional characteristic that reflects the tendency to be mindful in daily life, which is beneficial for improving individuals’ both hedonic and eudaimonic well-being. However, no study to date has examined the brain regions involved in individual differences in dispositional mindfulness during the resting state and its relation with hedonic and eudaimonic well-being. To investigate this issue, the present study employed resting-state functional magnetic resonance imaging (rs-fMRI) to evaluate the regional homogeneity (ReHo) that measures the local synchronization of spontaneous brain activity in a large sample. We found that dispositional mindfulness was positively associated with the ReHo in the left orbitofrontal cortex (OFC), left parahippocampal gyrus (PHG), and right insula implicated in emotion processing, body awareness, and self-referential processing, and negatively associated with the ReHo in right inferior frontal gyrus (IFG) implicated in response inhibition and attentional control. Furthermore, we found different neural associations with hedonic (i.e., positive and negative affect) and eudaimonic well-being (i.e., the meaningful and purposeful life). Specifically, the ReHo in the IFG predicted eudaimonic well-being whereas the OFC predicted positive affect, both of which were mediated by dispositional mindfulness. Taken together, our study provides the first evidence for linking individual differences in dispositional mindfulness to spontaneous brain activity and demonstrates that dispositional mindfulness engages multiple brain mechanisms that differentially influence hedonic and eudaimonic well-being.     

Regional homogeneity changes in social anxiety disorder: a resting-state fMRI study

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.     

Localized activity alternations in periventricular nodular heterotopia-related epilepsy

Objective

Periventricular nodular heterotopia (PNH) is a common type of heterotopia usually characterized by epilepsy. Previous studies have identified alterations in structural and functional connectivity related to this disorder, but its local functional neural basis has received less attention. The purpose of this study was to combine univariate analysis and a Gaussian process classifier (GPC) to assess local activity and further explore neuropathological mechanisms in PNH-related epilepsy.

Methods

We used a 3.0-T scanner to acquire resting-state data and measure local regional homogeneity (ReHo) alterations in 38 patients with PNH-related epilepsy and 38 healthy controls (HCs). We first assessed ReHo alterations by comparing the PNH group to the HC group using traditional univariate analysis. Next, we applied a GPC to explore whether ReHo could be used to differentiate PNH patients from healthy patients at an individual level.

Results

Compared to HCs, PNH-related epilepsy patients exhibited lower ReHo in the left insula extending to the putamen as well as in the subgenual anterior cingulate cortex (sgACC) extending to the orbitofrontal cortex (OFC) [p < 0.05, family-wise error corrected]. Both of these regions were also correlated with epilepsy duration. Furthermore, the ReHo GPC classification yielded a 76.32% accuracy (sensitivity = 71.05% and specificity = 81.58%) with p < 0.001 after permutation testing.

Interpretation

Using the resting-state approach, we identified localized activity alterations in the left insula extending to the putamen and the sgACC extending to the OFC, providing pathophysiological evidence of PNH. These local connectivity patterns may provide a means to differentiate PNH patients from HCs.     

The optimistic brain: Trait optimism mediates the influence of resting‐state brain activity and connectivity on anxiety in late adolescence

As a hot research topic in the field of psychology and psychiatry, trait optimism reflects the tendency to expect positive outcomes in the future. Consistent evidence has demonstrated the role of trait optimism in reducing anxiety among different populations. However, less is known about the neural bases of trait optimism and the underlying mechanisms for how trait optimism protects against anxiety in the healthy brain. In this investigation, we examined these issues in 231 healthy adolescent students by assessing resting‐state brain activity (i.e., fractional amplitude of low‐frequency fluctuations, fALFF) and connectivity (i.e., resting‐state functional connectivity, RSFC). Whole‐brain correlation analyses revealed that higher levels of trait optimism were linked with decreased fALFF in the right orbitofrontal cortex (OFC) and increased RSFC between the right OFC and left supplementary motor cortex (SMC). Mediation analyses further showed that trait optimism mediated the influence of the right OFC activity and the OFC‐SMC connectivity on anxiety. Our results remained significant even after excluding the impact of head motion, positive and negative affect and depression. Taken together, this study reveals that fALFF and RSFC are functional neural markers of trait optimism and provides a brain‐personality‐symptom pathway for protection against anxiety in which fALFF and RSFC affect anxiety through trait optimism.     

基于核磁共振成像技术的甲状腺功能减退伴焦虑患者的脑功能区研究

目的 探讨甲状腺功能减退伴焦虑患者脑功能区核磁共振成像(Magnetic resonance imaging,MRI)表现。方法 选取本院2018年5月-2019年8月收治的甲状腺功能减退伴焦虑患者30例为观察组,并选取同期体检健康者30例为对照组; 收集2组研究对象的一般资料,并对脑功能区进行功能磁共振成像(Functional magnetic resonance imaging,fMRI)扫描,采用局部一致性(Regional homogeneity,ReHo)值找出基础状态下自发异常脑功能活动区,Speaeman分析异常脑功能区与甲状腺激素水平、神经精神症状的相关性。结果 fMRI扫描显示甲状腺功能减退患者右海马旁回、左侧颞下回、左右前扣带回脑功能区的ReHo值明显高于对照组(0.81±0.02 vs. 0.78±0.04、0.73±0.07 vs. 0.69±0.05、0.89±0.12 vs.0.84±0.09、0.87±0.11 vs. 0.83±0.07)(P<0.05),左侧内额上回ReHo值明显低于对照组(0.77±0.13 vs. 0.72±0.11)(P<0.05); 不同焦虑程度的右海马旁回、左侧颞下回、左前扣带回、右前扣带回、左侧内侧额上回5个异常脑功能区ReHo值相近(P>0.05); 左、右前扣带回ReHo值与游离甲状腺素(Free thyroxine,FT4)水平显著相关(r=-0.398,P=0.023; r=-0.424,P=0.031); 左、右前扣带回ReHo值与焦虑等级显著相关(r=0.425,P=0.533; r=0.027,P=0.017)。结论 海马旁回、颞下回、前扣带回、内侧额上回4个脑功能区可能参与甲状腺功能减退患者引发焦虑症状的脑部生理机制,甲状腺功能减退患者焦虑症状的脑神经反常活动与前扣带回自发异常活动密切相关,可为甲状腺功能减退伴焦虑患者的临床诊疗提供新思路。     

青少年广泛性焦虑障碍患者静息态功能磁共振成像研究

目的:运用局部一致性(ReHo)方法研究首发青少年广泛性焦虑障碍患者的局部自发性脑活动. 方法:对19例首发青少年广泛性焦虑障碍患者及14名年龄、性别与其相匹配的正常对照进行静息态脑功能磁共振成像扫描,通过计算每个给定体素与其最邻近的26个体素之间的肯德尔和谐系数(KCC)来获得全脑的局部一致性(ReHo)图,利用双样本t检验分析两组受试者静息态下局部一致性的差异. 结果:与正常对照相比,青少年广泛性焦虑障碍患者局部一致性降低的脑区包括双侧额中回、枕中回,左侧额上回、颞下回、前扣带回及右侧顶下回、枕下回(P ＜0.005,未校正);局部一致性增高的脑区包括:右侧楔前叶、角回及左侧枕上回(P ＜0.005,未校正). 结论:青少年广泛性焦虑障碍患者静息态脑功能局部一致性存在异常.     

Altered spontaneous activity in young chronic cigarette smokers revealed by regional homogeneity

ABSTRACT: BACKGROUND: Few studies have been previously published about the resting state brain activity in young chronic smokers, although many previous fMRI studies have shown that the task-related activity pattern is altered in chronic smokers. METHODS: In the present study, forty-five healthy smokers (age: 27.9 [PLUS-MINUS SIGN] 5.6 year) and forty-four healthy non-smoking control subjects (age: 26.3 [PLUS-MINUS SIGN] 5.8 year) have been imaged with functional magnetic resonance imaging (fMRI) and analyzed with the regional homogeneity (ReHo) approach. RESULTS: Compared with healthy controls, decreased ReHo was found in smokers in the right inferior frontal cortex and increased ReHo was found in the left superior parietal lobe (P < 0.01, 35 Voxels,Alphasim corrected). CONCLUSIONS: Our data suggested that, during resting state, neural function is less synchronized in the right inferior frontal cortex and more synchronized in the left superior parietal lobe in chronic smokers compared to non-smokers. The decreased synchronization in the right inferior frontal cortex may reflect lacking of control over reward-related behavior, and the increased synchronization may reflect smoking urges.     

Altered regional homogeneity in post-traumatic stress disorder: a restingstate functional magnetic resonance imaging study

Objective Little is known about the brain systems that contribute to vulnerability to post-traumatic stress disorder (PTSD). Comparison of the resting-state patterns of intrinsic functional synchronization, as measured by functional magnetic resonance imaging (fMRI), between groups with and without PTSD following a traumatic event can help identify the neural mechanisms of the disorder and targets for intervention. Methods Fifty-four PTSD patients and 72 matched traumatized subjects who experienced the 2008 Sichuan earthquake were imaged with blood oxygen level-dependent (BOLD) fMRI and analyzed using the measure of regional homogeneity (ReHo) during the resting state. Results PTSD patients presented enhanced ReHo in the left inferior parietal lobule and right superior frontal gyrus, and reduced ReHo in the right middle temporal gyrus and lingual gyrus, relative to traumatized individuals without PTSD. Conclusion Our findings showed that abnormal brain activity exists under resting conditions in PTSD patients who had been exposed to a major earthquake. Alterations in the local functional connectivity of cortical regions are likely to contribute to the neural mechanisms underlying PTSD.     

Regional homogeneity abnormalities in patients with transient ischaemic attack: A resting-state fMRI study

ObjectiveTo investigate regional activity abnormalities in the resting state in patients with transient ischaemic attack (TIA) using a regional homogeneity (ReHo) method combined with functional magnetic resonance imaging (fMRI) and to examine the relationship between regional activity abnormalities and clinical variables.MethodsResting-state fMRI was conducted in 21 patients with right-sided TIA and in 21 healthy volunteers. The ReHo was calculated to assess the strength of the local signal synchrony and was compared between the two groups.ResultsCompared with the controls, the TIA patients exhibited a decreased ReHo in the right dorsolateral prefrontal cortex (dlPFC), the right inferior prefrontal cortex (iPFC), the right ventral anterior cingulate cortex (vACC) and the right dorsal posterior cingulate cortex (dPCC). In addition, the mean ReHo values in the right dlPFC and the right iPFC were significantly correlated with the Montreal Cognitive Assessment (MoCA) in TIA patients.ConclusionsNeural activities in the resting state are changed in TIA patients even without visible ischaemic lesions on conventional MRI. The positive correlation between the ReHo of resting-state fMRI and cognition suggests that ReHo could be a promising tool to observe the neurobiological consequences of TIA.SignificanceThe present study revealed abnormal local synchronisation of spontaneous neural activities in patients with TIA.     

Local synchronization and amplitude of the fluctuation of spontaneous brain activity in attention-deficit/hyperactivity disorder: a resting-state fMRI study

Regional homogeneity（ReHo）and the amplitude of low-frequency fluctuation（ALFF）are two approaches to depicting different regional characteristics of resting-state functional magnetic resonance imaging（RS-fMRI）data.Whether they can complementarily reveal brain regional functional abnormalities in attention-deficit/hyperactivity disorder（ADHD）remains unknown.In this study,we applied ReHo and ALFF to 23 medication-na ve boys diagnosed with ADHD and 25 age-matched healthy male controls using whole-brain voxel-wise analysis.Correlation analyses were conducted in the ADHD group to investigate the relationship between the regional spontaneous brain activity measured by the two approaches and the clinical symptoms of ADHD.We found that the ReHo method showed widely-distributed differences between the two groups in the fronto-cingulo-occipitocerebellar circuitry,while the ALFF method showed a difference only in the right occipital area.When a larger smoothing kernel and a more lenient threshold were used for ALFF,more overlapped regions were found between ALFF and ReHo,and ALFF even found some new regions with group differences.The ADHD symptom scores were correlated with the ReHo values in the right cerebellum,dorsal anterior cingulate cortex and left lingual gyrus in the ADHD group,while no correlation was detected between ALFF and ADHD symptoms.In conclusion,ReHo may be more sensitive to regional abnormalities,at least in boys with ADHD,than ALFF.And ALFF may be complementary to ReHo in measuring local spontaneous activity.Combination of the two may yield a more comprehensive pathophy-siological framework for ADHD.     

Involvement of the lateral orbitofrontal cortex in drug context-induced reinstatement of cocaine-seeking behavior in rats

Orbitofrontal cortex (OFC) damage produces impaired decision‐making, impulsivity and perseveration and potentially contributes to compulsive drug seeking in cocaine users. To further explore this phenomenon, we assessed the role of the lateral OFC (lOFC) in drug context‐induced cocaine‐seeking behavior in the reinstatement model of drug relapse. Rats were trained to lever press for intravenous cocaine infusions in a distinct environmental context (cocaine‐paired context) followed by extinction training in a different context (extinction‐paired context). Reinstatement of cocaine seeking (non‐reinforced lever presses) was assessed in the cocaine context in the absence of response‐contingent stimuli. In Experiment 1, we evaluated whether acute inhibition of lOFC output alters context‐induced cocaine‐seeking behavior by infusing the GABA_{B + A} agonists (baclofen + muscimol) or vehicle into the lOFC immediately before exposure to the cocaine‐paired context. In Experiments 2 and 3, we assessed how prolonged loss of lOFC output affects drug context‐induced cocaine seeking by administering bilateral N‐methyl‐d ‐aspartic acid or sham lesions of the lOFC either before or after self‐administration and extinction training. Remarkably, IOFC functional inactivation attenuated, post‐training lesions failed to alter and pre‐training lesions potentiated drug context‐induced cocaine seeking without altering responding in the extinction context. These results suggest that neural activity in the lOFC promotes context‐induced cocaine‐seeking behavior. However, prolonged loss of lOFC output enhances the motivational salience of cocaine‐paired contextual stimuli probably by eliciting compensatory neuroadaptations, with the effects of post‐training lOFC lesions reflecting an intermediate state of compensatory neuroplasticity. Overall, these findings support the idea that OFC dysfunction may promote cue reactivity and enhance relapse propensity in cocaine users.     

以妄想为主的男性精神分裂症患者脑局部一致性的功能磁共振研究

目的：探讨男性偏执型精神分裂症患者在静息状态下是否存在脑功能活动异常及其区域。方法：采用病例一对照研究方法,对20例以妄想为主的男性精神分裂症患者（患者组）和20名性别、年龄、受教育程度相匹配的正常对照者（正常对照组）进行功能磁共振成像（fMRI）扫描,分析静息状态下各脑区的局部一致性（regionalhomogeneity,ReHo）的差异。结果：设P〈0．05、体素范围（k值）≥85,与正常对照组比较,患者组双侧额上回、双侧颞中回、左额中回、左中央前回、左小脑脚和右扣带回局部一致性（ReHo值）减低,右颞上回和左颞下回ReHo值增高,而左梭状回ReHo值既有增高也有减低。结论：以妄想为主的男性精神分裂症患者在静息状态下可能存在广泛分布的脑区功能异常。     

A voxel-based morphometry study of frontal gray matter correlates of impulsivity

Impulsivity is a personality trait exhibited by healthy individuals, but excessive impulsivity is associated with some mental disorders. Lesion and functional neuroimaging studies indicate that the ventromedial prefrontal region (VMPFC), including the orbitofrontal cortex (OFC), anterior cingulate cortex (ACC) and medial prefrontal cortex, and the amygdala may modulate impulsivity and aggression. However, no morphometric study has examined the association between VMPFC and impulsivity. We hypothesized that healthy subjects with high impulsivity would have smaller volumes in these brain regions compared with those with low impulsivity. Sixty-two healthy subjects were studied (age 35.4 +/- 12.1 years) using a 1.5-T MRI system. The Barratt impulsiveness scale (BIS) was used to assess impulsivity. Images were processed using an optimized voxel-based morphometry (VBM) protocol. We calculated the correlations between BIS scale scores and the gray matter (GM) and white matter (WM) volumes of VMPFC and amygdala. GM volumes of the left and right OFC were inversely correlated with the BIS total score (P = 0.04 and 0.02, respectively). Left ACC GM volumes had a tendency to be inversely correlated with the BIS total score (P = 0.05). Right OFC GM volumes were inversely correlated with BIS nonplanning impulsivity, and left OFC GM volumes were inversely correlated with motor impulsivity. There were no significant WM volume correlations with impulsivity. The results of this morphometry study indicate that small OFC volume relate to high impulsivity and extend the prior finding that the VMPFC is involved in the circuit modulating impulsivity.     

Dysfunctional beliefs and attitudes about sleep are associated with regional homogeneity of left inferior occipital gyrus in primary insomnia patients: A preliminary resting state functional magnetic resonance imaging study

BackgroundThe neural mechanisms of sleep beliefs and attitudes in primary insomnia (PI) patients at resting state remain unclear. The aim of this study was to investigate the features of regional homogeneity (ReHo) in PI using resting-state functional magnetic resonance imaging (rsfMRI).MethodsThirty-two PI patients and 34 normal controls (NC) underwent rsfMRI using a 3 T scanner at Tongde Hospital of Zhejiang Province. Participants were assessed with the Dysfunctional Beliefs and Attitudes about Sleep scale (DBAS-16) and Pittsburgh Sleep Quality Index (PSQI). Statistical analyses were performed to determine the regions in which ReHo differed between the two groups. Correlation analyses were performed between the ReHo index of each of these regions and DBAS-16 in PI patients.ResultsPI patients showed increased ReHo values in the right superior frontal gyrus, and decreased ReHo values in the left cerebellar gyrus, left inferior occipital gyrus (IOG) and left amygdala compared with those of NC. ReHo values in the left IOG were negatively correlated with total DBAS-16 scores, and scores for “consequences of insomnia” and“worry/helplessness about sleep”in PI patients.ConclusionsThese results suggest that ReHo alterations in the left IOG may play an important role in the dysfunctional beliefs and attitudes about sleep in PI.     

Effects of methylphenidate on resting-state brain activity in normal adults: an fMRI study

Methylphenidate (MPH) is one of the most commonly used stimulants for the treatment of attention deficit hyperactivity disorder (ADHD). Although several studies have evaluated the effects of MPH on human brain activation during specific cognitive tasks using functional magnetic resonance imaging (fMRI), few studies have focused on spontaneous brain activity. In the current study, we investigated the effect of MPH on the intra-regional synchronization of spontaneous brain activity during the resting state in 18 normal adult males. A handedness questionnaire and the Wechsler Adult Intelligence Scale were applied before medication, and a resting-state fMRI scan was obtained 1 h after medication (20 mg MPH or placebo, order counterbalanced between participants). We demonstrated that: (1) there were no significant differences in the performance of behavioral tasks between the MPH and placebo groups; (2) the left middle and superior temporal gyri had stronger MPH-related regional homogeneity (ReHo); and (3) the left lingual gyrus had weaker MPH-related ReHo. Our findings showed that the ReHo in some brain areas changes with MPH compared to placebo in normal adults, even though there are no behavioral differences. This method can be applied to patients with mental illness who may be treated with MPH, and be used to compare the difference between patients taking MPH and normal participants, to help reveal the mechanism of how MPH works.     

A resting-state functional magnetic resonance imaging study on the first-degree relatives of persons with schizophrenia

In this study, resting state fMRI images and BOLD signals were recorded from 13 first-degree relatives of schizophrenic patients and 13 healthy controls. The data were analyzed with the ReHo approach after realignment, registration, and normalization in statistical parametric mapping 2 (SPM2). A two-sample t-test was used to analyze the ReHo differences between first-degree relatives and healthy controls in a voxel by voxel manner. A combined threshold of p < 0.005 and number of voxels >5 was designated as statistically significant. To evaluate cognitive deficits in first-degree relatives, attention/vigilance and verbal/visual memory were measured. Significant impairments in attention were observed in first-degree relatives compared to healthy controls. Significant abnormalities in ReHo were observed in resting brain in first-degree relatives. Decreased ReHo was found to be distributed over the bilateral middle frontal, middle temporal, cingulate gyrus and cerebellar tonsil; the left inferior frontal gyrus, inferior parietal lobule and dorsolateral prefrontal cortex; the right superior frontal gyrus and dorsolateral prefrontal cortex. Increased ReHo was found to be distributed in the right precuneus and superior temporal gyrus. These changes in ReHo suggest abnormality in the resting state brain function of first-degree relatives of schizophrenic patients and may be early signs for the development of schizophrenia.     

基于局域一致性分析的BOLD-fMRI探讨无灶性癫痫的发作机制

目的利用基于局域一致性（regional homogeneity,ReHo）分析方法的血氧水平依赖功能磁共振成像技术,探讨无灶性癫痫的发作机制。方法运用功能性磁共振成像技术,采集无灶性癫痫患者17例和健康对照组16例的静息态数据,然后运用局域一致性分析方法对数据进行分析,观察无灶性癫痫患者脑局域一致性与正常对照组的变化。结果无灶性癫痫组和健康对照组相比ReHo值增强的脑区主要分布在双侧海马;ReHo值降低的脑区主要分布在右顶叶、右中央前回、右额叶、右侧小脑半球及左楔前叶、左前额。结论无灶性癫痫患者静息状态下脑功能活动较对照组有所改变,ReHo值升高的脑区反映了该脑区参与了癫痫的高活动,而降低的脑区可能反应了由于长期癫痫发作导致这些区域的神经元受损。     

Abnormal functional integration of thalamic low frequency oscillation in the BOLD signal after acute heroin treatment

Heroin addiction is a severe relapsing brain disorder associated with impaired cognitive control, including deficits in attention allocation. The thalamus has a high density of opiate receptors and is critically involved in orchestrating cortical activity during cognitive control. However, there have been no studies on how acute heroin treatment modulates thalamic activity. In a cross‐over, double‐blind, vehicle‐controlled study, 29 heroin‐maintained outpatients were studied after heroin and placebo administration, while 20 healthy controls were included for the placebo condition only. Resting‐state functional magnetic resonance imaging was used to analyze functional integration of the thalamus by three different resting state analysis techniques. Thalamocortical functional connectivity (FC) was analyzed by seed‐based correlation, while intrinsic thalamic oscillation was assessed by analysis of regional homogeneity (ReHo) and the fractional amplitude of low frequency fluctuations (fALFF). Relative to the placebo treatment and healthy controls, acute heroin administration reduced thalamocortical FC to cortical regions, including the frontal cortex, while the reductions in FC to the mediofrontal cortex, orbitofrontal cortex, and frontal pole were positively correlated with the plasma level of morphine, the main psychoactive metabolite of heroin. Furthermore, heroin treatment was associated with increased thalamic ReHo and fALFF values, whereas fALFF following heroin exposure correlated negatively with scores of attentional control. The heroin‐associated increase in fALFF was mainly dominated by slow‐4 (0.027–0.073 Hz) oscillations. Our findings show that there are acute effects of heroin within the thalamocortical system and may shed new light on the role of the thalamus in cognitive control in heroin addiction. Future research is needed to determine the underlying physiological mechanisms and their role in heroin addiction. Hum Brain Mapp 36:5287–5300, 2015. © 2015 Wiley Periodicals, Inc.     

Altered temporal variance and neural synchronization of spontaneous brain activity in anesthesia

Recent studies at the cellular and regional levels have pointed out the multifaceted importance of neural synchronization and temporal variance of neural activity. For example, neural synchronization and temporal variance has been shown by us to be altered in patients in the vegetative state (VS). This finding nonetheless leaves open the question of whether these abnormalities are specific to VS or rather more generally related to the absence of consciousness. The aim of our study was to investigate the changes of inter‐ and intra‐regional neural synchronization and temporal variance of resting state activity in anesthetic‐induced unconsciousness state. Applying an intra‐subject design, we compared resting state activity in functional magnetic resonance imaging (fMRI) between awake versus anesthetized states in the same subjects. Replicating previous studies, we observed reduced functional connectivity within the default mode network (DMN) and thalamocortical network in the anesthetized state. Importantly, intra‐regional synchronization as measured by regional homogeneity (ReHo) and temporal variance as measured by standard deviation (SD) of the BOLD signal were significantly reduced in especially the cortical midline regions, while increased in the lateral cortical areas in the anesthetized state. We further found significant frequency‐dependent effects of SD in the thalamus, which showed abnormally high SD in Slow‐5 (0.01–0.027 Hz) in the anesthetized state. Our results show for the first time of altered temporal variance of resting state activity in anesthesia. Combined with our findings in the vegetative state, these findings suggest a close relationship between temporal variance, neural synchronization and consciousness. Hum Brain Mapp 35:5368–5378, 2014. © 2014 Wiley Periodicals, Inc.     

Sex‐related differences in resting‐state brain activity and connectivity in the orbital frontal cortex and insula in patients with functional constipation

Functional magnetic resonance imaging (fMRI) has been used to investigate sex‐related differences in brain abnormalities in patients with irritable bowel syndrome (IBS). Like IBS, women with functional constipation (FC) are 2.1 times as many as men. No study has been performed yet to examine sex‐related differences in brain activity and connectivity in patients with FC. Here, we employed resting‐state fMRI with amplitude of low‐frequency fluctuation (ALFF) to investigate brain functional differences in 51 patients with FC (34 females) and 52 healthy controls (34 females). Results showed abdominal pain and abdominal distension correlated with trait (TAI) and state (SAI) anxiety ratings in the female FC group, and abdominal distension correlated with sensation of incomplete evacuation in the male FC group. Two‐way ANOVA revealed sex effects on ALFF in precentral gyrus, thalamus, insula (INS), and orbital frontal cortex (OFC, P_FWE < 0.05). Post hoc test showed that the female FC group had lower ALFF than males in these brain regions (P < 0.01), and ALFF in INS and OFC was correlated with abdominal pain and difficulty of defecation, respectively. Seed voxel correlation analysis showed that the female FC group had weaker connectivity than males between INS and lateral OFC (lOFC). INS‐lOFC connectivity was negatively correlated with the anxiety score in the female FC group and was negatively correlated with abdominal distension in the male FC group. These findings provide the first insight into sex‐related differences in patients with FC and highlight that INS and OFC play an important role in modulating the intrinsic functional connectivity of the resting brain network showing that this role is influenced by sex.