Altered fMRI-derived functional connectivity in patients with high-tension glaucoma

BackgroundHigh-tension glaucoma (HTG) is associated with functional changes in the brain, and elevated intraocular pressure (IOP) is one of the major causes.PurposeTo evaluate the effects of high IOP on the brain in patients with HTG by using resting-state functional magnetic resonance imaging (rs-fMRI).Materials and methodsThirty-six patients with HTG and 20 age- and gender-matched healthy controls (HCs) were recruited and underwent IOP examination and rs-fMRI scan. Voxel-wise functional connectivity (FC) values were obtained between the Brodmann Area (BA) 17 (primary visual cortex) and the rest of the brain, two-sample t test was performed between HTG group and HCs. Correlation analysis was performed between FC and clinical information.ResultsCompared with HCs, HTG patients demonstrated decreased FC between BA 17 and the right precuneus gyrus, decreased FC between BA 17 and the right superior frontal gyrus (SFG) (GRF corrected at voxel level P < 0.001 and cluster level P < 0.05, two-tailed). FC between BA 17 and the right SFG showed significantly negative correlation with right eyes’ IOP and mean IOP.ConclusionHTG patients had abnormal FC changes between the visual cortex and multiple functional brain regions related to visual sense, memory consolidation and cognitive processing, which provided image support for the pathophysiology research of HTG, and revealed new targets for the accurate treatment of HTG.     

Voxel‐based morphometry in creative writers: Grey matter increase in a prefronto‐thalamic‐cerebellar network

Continuous practice modulates those features of brain anatomy specifically associated with requirements of the respective training task. This study aimed to highlight brain structural changes going along with long‐term experience in creative writing. To this end, we investigated the grey matter volume of 23 expert writers with voxel‐based morphometry and compared it to 28 matched nonexpert controls. Expert writers had higher grey matter volume in the right superior frontal and middle frontal gyri (BA 9,10) as well as left middle frontal gyrus (BA 9, 10, 46), the bilateral medial dorsal nuclei of the thalamus and left posterior cerebellum. A regression analysis confirmed the association of enhanced grey matter volume in the right superior frontal gyrus (BA 10) with practice index of writing. In region‐of‐interest based regression analyses, we found associations of grey matter volume in the right Broca’s analogue (BA 44) and right primary visual cortex (BA 17) with creativity ratings of the texts written during scanning, but not with a standardised verbal creativity test. Creative writing thus seems to be strongly connected to a prefronto‐thalamic‐cerebellar network that supports the continuous generation, organisation and revision of ideas that is necessary to write literary texts.     

Aberrant static and dynamic functional patterns of frontoparietal control network in antipsychotic‐naïve first‐episode psychosis subjects

Psychotic disorders are disabling clinical syndromes characterized by widespread alterations in cortical information processing. Disruption of frontoparietal network (FPN) connectivity has emerged as a common footprint across the psychosis spectrum. Our goal was to characterize the static and dynamic resting‐state functional connectivity (FC) of the FPN in antipsychotic‐naïve first‐episode psychosis (FEP) subjects. We compared the static FC of the FPN in 40 FEP and 40 healthy control (HC) subjects, matched on age, sex, and socioeconomic status. To study the dynamic FC, we measured quasiperiodic patterns (QPPs) that consist of infraslow spatioemporal patterns embedded in the blood oxygen level‐dependent signal that repeats over time, exhibiting alternation of high and low activity. Relative to HC, we found functional hypoconnectivity between the right middle frontal gyrus and the right middle temporal gyrus, as well as the left inferior temporal gyrus and the left inferior parietal gyrus in FEP (p < .05, false discovery rate corrected). The correlation of the QPP with all functional scans was significantly stronger for FEP compared to HC, suggesting a greater impact of the QPPs to intrinsic brain activity in psychotic population. Regressing the QPP from the functional scans erased all significant group differences in static FC, suggesting that abnormal connectivity in FEP could result from altered QPP. Our study supports that alterations of cortical information processing are not a function of psychotic chronicity or antipsychotic medication exposure and may be regarded as trait specific. In addition, static connectivity abnormality may be partly related to altered brain network temporal dynamics.     

Increased Cognition Connectivity Network in Major Depression Disorder: A fMRI Study

ObjectiveEvidence of the brain network involved in cognitive dysfunction has been inconsistent for major depressive disorder (MDD), especially during early stage of MDD. This study seeks to examine abnormal cognition connectivity network (CCN) in MDD within the whole brain.MethodsSixteen patients with MDD and 16 health controls were scanned during resting-state using 3.0 T functional magnetic resonance imaging (fMRI). All patients were first episode without any history of antidepressant treatment. Both the left and right dorsolateral prefrontal cortex (DLPFC) were used as individual seeds to identify CCN by the seed-target correlation analysis. Two sample t test was used to calculate between-group differences in CCN using fisher z-transformed correlation maps.ResultsThe CCN was constructed by bilateral seed DLPFC in two groups separately. Depressed subjects exhibited significantly increased functional connectivity (FC) by left DLPFC in one cluster, overlapping middle frontal gyrus, BA7, BA43, precuneus, BA6, BA40, superior temporal gyrus, BA22, inferior parietal lobule, precentral gyrus, BA4 and cingulate gyrus in left cerebrum. Health controls did not show any cluster with significantly greater FC compared to depressed subjects in left DLPFC network. There was no significant difference of FC in right DLPFC network between depressed subjects and the health controls.ConclusionThere are differences in CCN during early stage of MDD, as identified by increased FCs among part of frontal gyrus, parietal cortex, cingulate cortex, and BA43, BA22, BA4 with left DLPFC. These brain areas might be involved in the underlying mechanisms of cognitive dysfunction in MDD.     

Early changes of brain connectivity in primary open angle glaucoma

Our aim was to assess in primary open angle glaucoma (POAG), a major cause of irreversible blindness worldwide, whether diffuse brain changes recently shown in advanced stage can be detected since the early stage. We used multimodal magnetic resonance imaging (MRI) in 57 patients with the three POAG stages and in 29 age‐matched normal controls (NC). Voxelwise statistics was performed with nonparametric permutation testing. Compared with NC, disrupted anatomical connectivity (AC) was found in the whole POAG group along the visual pathway and in nonvisual white matter tracts (P < 0.001). Moreover, POAG patients showed decreased functional connectivity (FC) in the visual (P = 0.004) and working memory (P < 0.001) networks whereas an increase occurred in the default mode (P = 0.002) and subcortical (P < 0.001) networks. Altered AC and FC were already present in early POAG (n = 14) in both visual and nonvisual systems (P ≤ 0.01). Only severe POAG (n = 30) showed gray matter atrophy and this mapped on visual cortex (P < 0.001) and hippocampus (P < 0.001). Increasing POAG stage was associated with worsening AC in both visual and nonvisual pathway (P < 0.001), progressive atrophy in the hippocampus and frontal cortex (P < 0.003). Most of the structural and functional alterations within and outside the visual system showed correlation (P < 0.001 to 0.02) with computerized visual field and retinal nerve fiber layer thickness. In conclusion, the complex pathogenesis of POAG includes widespread damage of AC and altered FC within and beyond the visual system since the early disease stage. The association of brain MRI changes with measures of visual severity emphasizes the clinical relevance of our findings. Hum Brain Mapp 37:4581–4596, 2016. © 2016 Wiley Periodicals, Inc.     

Tinnitus distress is linked to enhanced resting‐state functional connectivity from the limbic system to the auditory cortex

The phantom sound of tinnitus is believed to be triggered by aberrant neural activity in the central auditory pathway, but since this debilitating condition is often associated with emotional distress and anxiety, these comorbidities likely arise from maladaptive functional connections to limbic structures such as the amygdala and hippocampus. To test this hypothesis, resting‐state functional magnetic resonance imaging (fMRI) was used to identify aberrant effective connectivity of the amygdala and hippocampus in tinnitus patients and to determine the relationship with tinnitus characteristics. Chronic tinnitus patients (n = 26) and age‐, sex‐, and education‐matched healthy controls (n = 23) were included. Both groups were comparable for hearing level. Granger causality analysis utilizing the amygdala and hippocampus as seed regions were used to investigate the directional connectivity and the relationship with tinnitus duration or distress. Relative to healthy controls, tinnitus patients demonstrated abnormal directional connectivity of the amygdala and hippocampus, including primary and association auditory cortex, and other non‐auditory areas. Importantly, scores on the Tinnitus Handicap Questionnaires were positively correlated with increased connectivity from the left amygdala to left superior temporal gyrus (r = 0.570, P = 0.005), and from the right amygdala to right superior temporal gyrus (r = 0.487, P = 0.018). Moreover, enhanced effective connectivity from the right hippocampus to left transverse temporal gyrus was correlated with tinnitus duration (r = 0.452, P = 0.030). The results showed that tinnitus distress strongly correlates with enhanced effective connectivity that is directed from the amygdala to the auditory cortex. The longer the phantom sensation, the more likely acute tinnitus becomes permanently encoded by memory traces in the hippocampus. Hum Brain Mapp 38:2384–2397, 2017. © 2017 Wiley Periodicals, Inc.     

Hemifield visual motion stimulation: an example of interhemispheric crosstalk

Coherent motion stimulation of the right or left visual hemifield was performed in nine healthy volunteers in order to investigate interhemispheric visuo-visual interaction by means of functional magnetic resonance imaging. The vertical edge of the motion pattern field was located 8 degrees distant from the fixation point to avoid stimulating the vertical meridian, which is represented retinotopically in both hemispheres. Bilateral activation was significant in the middle occipital gyrus (motion-sensitive middle temporal/middle superior temporal areas; BA 19/37). A negative signal change was found in the primary visual cortex including the lingual and fusiform gyri (BA 18/17) and the occipital white matter containing the optic radiation contralateral to the stimulated hemisphere. These data are most compatible with an interhemispheric transfer of visual motion information, most likely through the corpus callosum. Transcallosal transfer of visual motion information, evident as increases (BA 19/37) and decreases (BA 18/17) of the fMRI signals, may be functionally significant for the processing of motion perception.     

A multicentre study of motor functional connectivity changes in patients with multiple sclerosis

In this multicentre study involving eight European centres, we characterized the spatial pattern of functional connectivity (FC) in the sensorimotor network from 61 right-handed patients with multiple sclerosis (MS) and 74 age-matched healthy subjects assessed with the use of functional magnetic resonance imaging (fMRI) and a simple motor task of their right dominant hand. FC was investigated by using: (i) voxel-wise correlations between the left sensorimotor cortex (SMC) and any other area in the brain; and (ii) bivariate correlations between time series extracted from several regions of interest (ROIs) belonging to the sensorimotor network. Both healthy controls and MS patients had significant FC between the left SMC and several areas of the sensorimotor network, including the bilateral postcentral and precentral gyri, supplementary motor area, middle frontal gyri, insulae, secondary somatosensory cortices, thalami, and right cerebellum. Voxel-wise assessment of FC revealed increased connectivity between the left SMC and the right precentral gyrus, right middle frontal gyrus (MFG) and bilateral postcentral gyri in MS patients as compared with controls. ROI analysis also showed a widespread pattern of altered connectivity, characterized by increased FC between the right MFG, the left insula and the right inferior frontal gyrus in comparison with many regions of the sensorimotor network. These results provide further evidence for increased bihemispheric contributions to motor control in patients with MS relative to healthy controls. They further suggest that multicentre fMRI studies of FC changes are possible, and provide a potential imaging biomarker for use in experimental therapeutic studies directed at enhancing adaptive plasticity in the disease.     

Acupuncture at the Taixi （KI3） acupoint activates cerebral neurons in elderly patients with mild cognitive impairment

Our previous ifndings have demonstrated that acupuncture at the Taixi （KI3） acupoint in healthy youths can activate neurons in cognitive-related cerebral cortex. Here, we investigated whether acupuncture at this acupoint in elderly patients with mild cognitive impairment can also activate neurons in these regions. Resting state and task-related functional magnetic resonance imaging showed that the pinprick senstation of acupuncture at the Taixi acupoint differed signiifcantly between elderly patients with mild cognitive impairment and healthy elderly controls. Results showed that 20 brain regions were activated in both groups of participants, including the bi-lateral anterior cingulate gyrus （Brodmann areas [BA] 32, 24）, left medial frontal cortex （BA 9, 10, 11）, left cuneus （BA 19）, left middle frontal gyrus （BA 11）, left lingual gyrus （BA 18）, right medial frontal gyrus （BA 11）, bilateral inferior frontal gyrus （BA 47）, left superior frontal gyrus （BA11）, right cuneus （BA 19, 18）, right superior temporal gyrus （BA 38）, left subcallosal gyrus （BA 47）, bilateral precuneus （BA 19）, right medial frontal gyrus （BA 10）, right superior frontal （BA 11）, left cingulate gyrus （BA 32）, left precentral gyrus （BA 6）, and right fusiform gyrus （BA 19）. These results suggest that acupuncture at the Taixi acupoint in elderly patients with mild cogni-tive impairment can also activate some brain regions.     

偏头痛与静息态脑功能连接研究

目的本文研究采用静息态功能磁共振成像(rfMRI)技术描述偏头痛患者静息态脑功能连接改变,为探索偏头痛的发病机制提供影像学资料。方法收集16例偏头痛患者与16例健康对照,采集rfMRI成像,计算低频振幅,找出感兴趣区做功能连接进行统计分析。结果偏头痛患者左侧岛叶、左侧额下回低频振幅显著低于对照组,右侧视觉皮质低频振幅显著高于对照组;以左侧额下回、右侧枕中回为感兴趣区,发现左侧额下回与脑干之间的功能连接增强,与双侧枕叶之间的功能连接减弱;右侧枕中回与双侧楔前叶延伸至扣带回中部区域之间的功能连接增强,与双侧中央前回、双侧缘上回、双侧颞上回及双侧额下回之间的功能连接减弱。结论偏头痛患者无头痛发作时神经元活动强度改变,大脑功能连接异常,这导致大脑整合信息过程改变,并与偏头痛发病相关。     

Extratemporal functional connectivity impairments at rest are related to memory performance in mesial temporal epilepsy

Mesial temporal lobe epilepsy (MTLE) is the most frequent form of focal epilepsy. At rest, there is evidence that brain abnormalities in MTLE are not limited to the epileptogenic region, but extend throughout the whole brain. It is also well established that MTLE patients suffer from episodic memory deficits. Thus, we investigated the relation between the functional connectivity seen at rest in fMRI and episodic memory impairments in MTLE. We focused on resting state BOLD activity and evaluated whether functional connectivity (FC) differences emerge from MTL seeds in left and right MTLE groups, compared with healthy controls. Results revealed significant FC reductions in both patient groups, localized in angular gyri, thalami, posterior cingulum and medial frontal cortex. We found that the FC between the left non‐pathologic MTL and the medial frontal cortex was positively correlated with the delayed recall score of a non‐verbal memory test in right MTLE patients, suggesting potential adaptive changes to preserve this memory function. In contrast, we observed a negative correlation between a verbal memory test and the FC between the left pathologic MTL and posterior cingulum in left MTLE patients, suggesting potential functional maladaptative changes in the pathologic hemisphere. Overall, the present study provides some indication that left MTLE may be more impairing than right MTLE patients to normative functional connectivity. Our data also indicates that the pattern of extra‐temporal FC may vary as a function of episodic memory material and each hemisphere's capacity for cognitive reorganization. Hum Brain Mapp 34:2202–2216, 2013. © 2012 Wiley Periodicals, Inc.     

Functional connectivity constrains the category‐related organization of human ventral occipitotemporal cortex

One of the most robust and oft‐replicated findings in cognitive neuroscience is that several spatially distinct, functionally dissociable ventral occipitotemporal cortex (VOTC) regions respond preferentially to different categories of concrete entities. However, the determinants of this category‐related organization remain to be fully determined. One recent proposal is that privileged connectivity of these VOTC regions with other regions that store and/or process category‐relevant properties may be a major contributing factor. To test this hypothesis, we used a multicategory functional magnetic resonance imaging (MRI) localizer to individually define category‐related brain regions of interest (ROIs) in a large group of subjects (n = 33). We then used these ROIs in resting‐state functional connectivity MRI analyses to explore spontaneous functional connectivity among these regions. We demonstrate that during rest, distinct category‐preferential VOTC regions show differentially stronger functional connectivity with other regions that have congruent category‐preference, as defined by the functional localizer. Importantly, a “tool”‐preferential region in the left medial fusiform gyrus showed differentially stronger functional connectivity with other left lateralized cortical regions associated with perceiving and knowing about common tools—posterior middle temporal gyrus (involved in perception of nonbiological motion), lateral parietal cortex (critical for reaching, grasping, manipulating), and ventral premotor cortex (involved in storing/executing motor programs)—relative to other category‐related regions in VOTC of both the right and left hemisphere. Our findings support the claim that privileged connectivity with other cortical regions that store and/or process category‐relevant properties constrains the category‐related organization of VOTC. Hum Brain Mapp 36:2187–2206, 2015. © Published 2015. This article is a U.S. Government work and is in the public domain in the USA.     

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.     

Disruption of visual and motor connectivity in spinocerebellar ataxia type 7

Spinocerebellar ataxia type 7 (SCA7) is an autosomal‐dominant neurodegenerative disorder characterized by progressive ataxia and retinal dystrophy. It is caused by a CAG trinucleotide expansion in the ataxin7 gene. Anatomical studies have shown severe cerebellar degeneration and region‐specific neocortical atrophy in SCA7 patients. However, the impact of the neurodegeneration on the functional integration of the remaining tissue is still unknown. The aim of this study was to examine functional connectivity abnormalities in areas with significant gray matter atrophy in SCA7 patients and their relationship with number of CAG repeats. Using a combination of voxel‐based morphometry and resting‐state fMRI, we studied 26 genetically confirmed SCA7 patients and aged‐matched healthy controls. In SCA7 patients we found reduced functional interaction between the cerebellum and the middle and superior frontal gyri, disrupted functional connectivity between the visual and motor cortices, and increased functional coordination between atrophied areas of the cerebellum and a range of visual cortical areas compared with healthy controls. The degree of mutation expansion showed a negative effect on both the functional interaction between the right anterior cerebellum and the left superior frontal gyrus and the connectivity between the right anterior cerebellum and left parahippocampal gyrus. We found abnormal functional connectivity patterns, including both hypo‐ and hyperconnectivity, compared with controls. These abnormal patterns show reasonable association with the severity of gene mutation. Our findings suggest that aberrant changes are prevalent in both motor and visual systems, adding significantly to our understanding of the pathophysiology of SCA7. © 2013 International Parkinson and Movement Disorder Society     

Structural and functional magnetic resonance imaging correlates of motor network dysfunction in primary progressive multiple sclerosis

We combined functional magnetic resonance imaging (fMRI) and diffusion tensor tractography to investigate the functional and structural substrates of motor network dysfunction in patients with primary progressive multiple sclerosis (PPMS). In 15 right‐handed PPMS patients and 15 age‐matched healthy controls, we acquired diffusion tensor magnetic resonance imaging and fMRI during the performance of a simple motor task. Tractography was used to calculate diffusion tensor‐derived measures of the corpus callosum, the corticospinal tract, the optic radiation, the fronto‐occipital fasciculus, and the inferior longitudinal fasciculus. Analyses of fMRI activations and functional connectivity were performed using statistical parametric mapping (cluster threshold of P = 0.001, and extent cluster threshold of 10 voxels for comparison of activations; P < 0.05, family‐wise error corrected for functional connectivity). As compared with controls, PPMS patients had more significant activations of the left postcentral gyrus, left secondary sensorimotor area, left parahippocampal gyrus, left cerebellum, right primary sensorimotor cortex (SMC), right basal ganglia, right insula, right cingulum, and cuneus bilaterally. As compared with PPMS patients, controls had increased functional connectivity between the left primary SMC and the ipsilateral inferior frontal gyrus. Conversely, PPMS patients showed increased functional connectivity between the left primary SMC and the right cuneus. Moderate correlations were found between functional activations and damage to the tracts studied (r‐values between 0.82 and 0.84; P < 0.001). These results suggest that, as compared with healthy controls, PPMS patients show increased activations and abnormal functional connectivity measures in several areas of the sensorimotor network. Such changes are correlated with the structural damage to the white matter fiber bundles connecting these regions.     

Altered intra- and interregional synchronization in the absence of the corpus callosum: a resting-state fMRI study

Agenesis of the corpus callosum (AgCC) can result in subtle to severe cognitive deficits. Individuals with impaired cognition often show abnormalities on resting-state functional magnetic resonance imaging (rs-fMRI). This study used rs-fMRI to investigate changes in regional homogeneity (ReHo) and functional connectivity (FC) among individuals with AgCC. AgCC individuals (n = 10) and age-, sex-, and education-matched healthy control subjects (n = 19) were included in this study. The ReHo values were calculated to represent spontaneous brain activity. The regions which showed altered ReHo were selected as seeds to compare FC with the whole brain between the AgCC group and the healthy control group. Compared with healthy control subjects, the AgCC individuals had increased ReHo in the left anterior cingulate gyrus, left rolandic operculum, and right precuneus and decreased ReHo in the right calcarine, right cingual gyrus and right cuneus gyrus. The right calcarine and the right lingual gyrus in the AgCC exhibited decreased FC with bilateral cuneus, superior occipital gyrus, Rolandic operculum, superior temporal gyrus, posterior central gyrus, and midcingulate gyrus.The right cuneus gyrus in the AgCC individuals exhibited decreased FC with the bilateral calcarine gyrus, left cuneus, and left superior occipital gyrus. Our study revealed several subareas within the visual cortex exhibited remarkable abnormalities of spontaneous brain activity and decreased FC with the higher-order cognitive cortex.The abnormalities of ReHo and FC in AgCC individuals may provide new insights into the neurological pathophysiology.     

Diffuse brain damage in normal tension glaucoma

Brain changes within and beyond the visual system have been demonstrated in primary open angle glaucoma (POAG), the most common type of glaucoma. These changes have been often interpreted as a neurodegenerative process due, at least partially, to the raised intraocular pressure (IOP). In this context, normal tension glaucoma (NTG), a form of POAG with IOP <21 mm Hg despite the typical glaucomatous findings, represents the most suitable model of glaucoma to test the validity of this hypothesis. We acquired multimodal brain MRI in NTG patients (n = 17) and compared them with demographically matched groups of POAG patients with raised IOP (n = 17) and normal controls (NC, n = 29). Voxelwise statistics was performed with nonparametric permutation testing. Both NTG and POAG patients showed, compared to NC, significantly more gray matter atrophy in both the visual system and in nonvisual brain regions and altered diffusion tensor imaging‐derived anatomical connectivity (AC; lower fractional anisotropy and/or higher diffusivities). Compared with NTG, POAG had both more atrophic visual cortex and higher axial diffusivity in nonvisual regions. Functional connectivity (FC) with respect to NC was altered in NTG at short‐range level [visual network (VN), ventral attention network] and in POAG at long‐range level (between secondary VN and limbic network). FC of POAG was higher than NTG in both VN and executive network. This study provides further evidence that diffuse structural and functional abnormalities across glaucoma brain may be, at least partially, independent of raised IOP and the consequent retinal degeneration. This further defines glaucoma as a condition with neurodegeneration spreading. Hum Brain Mapp 39:532–541, 2018. © 2017 Wiley Periodicals, Inc.     

Differential alterations of resting‐state functional connectivity in generalized anxiety disorder and panic disorder

Generalized anxiety disorder (GAD) and panic disorder (PD) are most common anxiety disorders with high lifetime prevalence while the pathophysiology and disease‐specific alterations still remain largely unclear. Few studies have taken a whole‐brain perspective in the functional connectivity (FC) analysis of these two disorders in resting state. It limits the ability to identify regionally and psychopathologically specific network abnormalities with their subsequent use as diagnostic marker and novel treatment strategy. The whole brain FC using a novel FC metric was compared, that is, scaled correlation, which they demonstrated to be a reliable FC statistics, but have higher statistical power in two‐sample t‐test of whole brain FC analysis. About 21 GAD and 18 PD patients were compared with 22 matched control subjects during resting‐state, respectively. It was found that GAD patients demonstrated increased FC between hippocampus/parahippocampus and fusiform gyrus among the most significantly changed FC, while PD was mainly associated with greater FC between somatosensory cortex and thalamus. Besides such regional specificity, it was observed that psychopathological specificity in that the disrupted FC pattern in PD and GAD correlated with their respective symptom severity. The findings suggested that the increased FC between hippocampus/parahippocampus and fusiform gyrus in GAD were mainly associated with a fear generalization related neural circuit, while the greater FC between somatosensory cortex and thalamus in PD were more likely linked to interoceptive processing. Due to the observed regional and psychopathological specificity, their findings bear important clinical implications for the potential treatment strategy. Hum Brain Mapp 37:1459‐1473, 2016. © 2016 Wiley Periodicals, Inc.     

Activation of right fronto-temporal cortex characterizes the 'living' category in semantic processing.

It is a vital ability for humans to distinguish between living and non-living objects. Whether the semantic features of these two classes of objects are represented in distinct brain areas, is unknown. In our study, words belonging to the categories 'living' and 'non-living' were presented visually to twelve right-handed volunteers, while brain activation was measured with event-related fMRI. Subjects had to judge whether the item belonged to one of these categories. Common areas of activation (P<0.05, corrected) during processing of both categories include the inferior occipital gyri bilaterally (BA 17/18), left inferior frontal gyrus (BA 44/45) and left inferior parietal lobe (BA 40). During processing of 'living' minus 'non-living' items, signal changes (P<0.05, corrected) were present in the the right inferior frontal (BA 47), middle temporal (BA 21) and fusiform gyrus (BA 19). Our results are in line with findings from patients with a deficit in semantic processing of living things, who specifically suffer from right hemispheric lesions.     

Neural correlates of formal thought disorder: An activation likelihood estimation meta‐analysis

Formal thought disorder (FTD) refers to a psychopathological dimension characterized by disorganized and incoherent speech. Whether symptoms of FTD arise from aberrant processing in language‐related regions or more general cognitive networks, however, remains debated. Here, we addressed this question by a quantitative meta‐analysis of published functional neuroimaging studies on FTD. The revised Activation Likelihood Estimation (ALE) algorithm was used to test for convergent aberrant activation changes in 18 studies (30 experiments) investigating FTD, of which 17 studies comprised schizophrenia patients and one study healthy subjects administered to S‐ketamine. Additionally, we analyzed task‐dependent and task‐independent (resting‐state) functional connectivity (FC) of brain regions showing convergence in activation changes. Subsequent functional characterization was performed for the initial clusters and the delineated connectivity networks by reference to the BrainMap database. Consistent activation changes were found in the left superior temporal gyrus (STG) and two regions within the left posterior middle temporal gyrus (p‐MTG), ventrally (vp‐MTG) and dorsally (dp‐MTG). Functional characterization revealed a prominent functional association of ensuing clusters from our ALE meta‐analysis with language and speech processing, as well as auditory perception in STG and with social cognition in dp‐MTG. FC analysis identified task‐dependent and task‐independent networks for all three seed regions, which were mainly related to language and speech processing, but showed additional involvement in higher order cognitive functions. Our findings suggest that FTD is mainly characterized by abnormal activation in brain regions of the left hemisphere that are associated with language and speech processing, but also extend to higher order cognitive functions. Hum Brain Mapp 38:4946–4965, 2017. © 2017 Wiley Periodicals, Inc.