Voxel-mirrored Homotopic Connectivity Research Articles

Degree centrality and voxel-mirrored homotopic connectivity in children with nocturnal enuresis: A functional MRI study.

To determine the characteristics of brain development in children with nocturnal enuresis, we investigated the intensity of functional connectivity both among the nodes in the brain network and between the two hemispheres of the brain. Twenty-three children with nocturnal enuresis (NE) and an equal number of normal children were examined using resting-state functional magnetic resonance imaging (fMRI) scans. Data analysis was done via the degree centrality (DC) and voxel-mirrored homotopic connectivity (VMHC) approaches. Moreover, we compared the children's psychological status by utilizing the self-concept scale. In four areas of the brain, the the DC values of the NE group were obviously lower than that of the normal controls. These four areas were the posterior cerebellar lobe, anterior cingulate cortex (ACC), medial frontal gyrus, and superior left temporal gyrus (P < 0.05, after correction). We also found two brain areas where the VMHC values of the NE group were obviously lower than that of the normal controls. The two groups were the cerebellar lobe and the anterior cingulate cortex (ACC) [P < 0.05, after correction]. A psychological comparison between the children with NE and that in the normal group on the self-concept scale was also performed. The scores of the children with NE were lower than normal controls regarding behavior, appearance and property, anxiety, gregariousness, happiness, and satisfaction (P < 0.05). These findings provide evidence of the deficit of urination control in children with NE. Furthermore, through the methods of DC and VMHC, which are based on functional connectivity, it was also possible to explain why children with NE often have the concomitant symptoms of attention, control, and memory problems. The analysis of the self-concept scale suggests that children with NE lack self-confidence.

Monaural-driven Functional Changes within and Beyond the Auditory Cortical Network: Evidence from Long-term Unilateral Hearing Impairment

Long-term unilateral hearing impairment (UHI) results in changes in hearing and psychoacoustic performance that are likely related to cortical reorganization. However, the underlying functional changes in the brain are not yet fully understood. Here, we studied alterations in inter- and intra-hemispheric resting-state functional connectivity (RSFC) in 38 patients with long-term UHI caused by acoustic neuroma. Resting-state fMRI data from 17 patients with left-sided hearing impairment (LHI), 21 patients with right-sided hearing impairment (RHI) and 21 healthy controls (HCs) were collected. We applied voxel-mirrored homotopic connectivity analysis to investigate the interhemispheric interactions. To study alterations in between-network interactions, we used four cytoarchitectonically identified subregions in the auditory cortex as “seeds” for whole-brain RSFC analysis. We found that long-term imbalanced auditory input to the brain resulted in (1) enhanced interhemispheric RSFC between the contralateral and ipsilateral auditory networks and (2) differential patterns of altered RSFCs with other sensory (visual and somatomotor) and higher-order (default mode and ventral attention) networks among the four auditory cortical subregions. These altered RSFCs within and beyond the auditory network were dependent on the side of hearing impairment. The results were reproducible when the analysis was restricted to patients with severe-to-profound UHI and patients with hearing-impairment durations greater than 24 months. Together, we demonstrated that long-term UHI drove cortical functional changes within and beyond the auditory network, providing empirical evidence for the association between brain changes and hearing disorders.

Decreased interhemispheric coordination in the posterior default-mode network and visual regions as trait alterations in first-episode, drug-naive major depressive disorder.

Decreased homotopic connectivity has been implicated in the neurophysiology of major depressive disorder (MDD) with inconsistent findings. A combination of clinical and methodological variabilities may account for the inconsistency, and thus limiting the reproducibility of the findings. The present study aims to examine voxel-mirrored homotopic connectivity (VMHC) alterations in two independent samples of patients with first-episode, drug-naive MDD. The samples included 59 patients and 31 controls from Sample 1 and 29 patients and 24 controls from Sample 2. VMHC was evaluated in both samples with an overlapping technique, which was used to define regions of abnormality common to both samples. Moreover, receiver operating characteristic curve and support vector machine were employed to differentiate the patients from the controls in both samples. Compared with the controls, the patients in both samples exhibited decreased VMHC in overlapped brain clusters, including the posterior cingulate cortex (PCC) and cuneus. Moreover, the VMHC values in the PCC and cuneus and a combination of the VMHC values in these two clusters could robustly discriminate between patients and controls with good sensitivities and specificities in both samples. This study is the first to examine VMHC abnormalities in first-episode, drug-naive patients with MDD in two independent samples by using an overlapped technique. The patients exhibit decreased VMHC in overlapping clusters in the posterior default-mode network and visual regions, which may be trait alterations for MDD. The present study provides a new perspective for understanding the neurophysiologic abnormalities of VMHC in MDD.

Decreased Resting-State Interhemispheric Functional Connectivity Correlated with Neurocognitive Deficits in Drug-Naive First-Episode Adolescent-Onset Schizophrenia.

BackgroundGiven that adolescence is a critical epoch in the onset of schizophrenia, studying aberrant brain changes in adolescent-onset schizophrenia, particularly in patients with drug-naive first-episode schizophrenia, is important to understand the biological mechanism of this disorder. Previous resting-state functional magnetic resonance imaging studies have shown abnormal functional connectivity in separate hemispheres in patients with adult-onset schizophrenia. Our aim to study adolescent-onset schizophrenia can provide clues for the early aetiology of schizophrenia.MethodA total of 48 drug-naïve, first-episode, adolescent-onset schizophrenia outpatients and 31 healthy controls underwent resting-state functional magnetic resonance imaging scans. Data were subjected to voxel-mirrored homotopic connectivity and support vector machine analyses.ResultsCompared with the healthy controls, the adolescent-onset schizophrenia group showed significantly lower voxel-mirrored homotopic connectivity values in different brain regions, including the fusiform gyrus, superior temporal gyrus/insula, precentral gyrus, and precuneus. Decreased voxel-mirrored homotopic connectivity values in the superior temporal gyrus/insula were significantly correlated with Trail-Making Test: Part A performance (r = −0.437, P = .002). A combination of the voxel-mirrored homotopic connectivity values in the precentral gyrus and precuneus may be used to discriminate patients with adolescent-onset schizophrenia from controls with satisfactory classification results, which showed sensitivity of 100%, specificity of 87.09%, and accuracy of 94.93%.ConclusionOur findings highlight resting-state interhemispheric FC abnormalities within the sensorimotor network of patients with adolescent-onset schizophrenia and confirm the relationship between adolescent-onset schizophrenia and adult-onset schizophrenia. These findings suggest that reduced interhemispheric connectivity within the sensorimotor network has a pivotal role in the pathogenesis of schizophrenia.

Concordance among indices of intrinsic brain function: Insights from inter-individual variation and temporal dynamics

Various resting-state fMRI (R-fMRI) measures have been developed to characterize intrinsic brain activity. While each of these measures has gained a growing presence in the literature, questions remain regarding the common and unique aspects these indices capture. The present work provided a comprehensive examination of inter-individual variation and intra-individual temporal variation for commonly used measures, including fractional amplitude of low frequency fluctuations, regional homogeneity, voxel-mirrored homotopic connectivity, network centrality and global signal correlation. Regardless of whether examining intra-individual or inter-individual variation, we found that these definitionally distinct R-fMRI indices tend to exhibit a relatively high degree of covariation, which doesn’t exist in phase randomized surrogate data. As a measure of intrinsic brain function, concordance for R-fMRI indices was negatively correlated with age across individuals (i.e., concordance among functional indices decreased with age). To understand the functional significance of concordance, we noted that higher concordance was generally associated with higher strengths of R-fMRI indices, regardless of whether looking through the lens of inter-individual (i.e., high vs. low concordance participants) or intra-individual (i.e., high vs. low concordance states identified via temporal dynamic analyses) differences. We also noted a linear increase in functional concordance together with the R-fMRI indices through the scan, which may suggest a decrease in arousal. The current study demonstrated an enriched picture regarding the relationship among the R-fMRI indices, as well as provided new insights in examining dynamic states within and between individuals.

Treatment effects of olanzapine on homotopic connectivity in drug-free schizophrenia at rest

Objectives: Deficits in homotopic connectivity have been implicated in schizophrenia. However, alterations in homotopic connectivity associated with antipsychotic treatments in schizophrenia remain unclear due to lack of longitudinal studies.Methods: Seventeen drug-free patients with recurrent schizophrenia and 24 healthy controls underwent resting-state functional magnetic resonance imaging scans. The patients were scanned at three time points (baseline, at 6 weeks of treatment, and at 6 months of treatment). Voxel-mirrored homotopic connectivity (VMHC) was applied to analyse the imaging data to examine alterations in VMHC associated with antipsychotic treatment.Results: The results showed that patients with schizophrenia exhibited decreased VMHC in the default-mode network (such as the precuneus and inferior parietal lobule) and the motor and sensory processing regions (such as the lingual gyrus, fusiform gyrus and cerebellum lobule VI), which could be normalised or denormalised by olanzapine treatment. In addition, negative correlations were found between decreased VMHC and symptom severity in the patients at baseline.Conclusions: The present study shows that olanzapine treatment can normalise or denormalise decreased homotopic connectivity in schizophrenia. The findings also provide a new perspective to understand treatment effects of antipsychotic drugs on homotopic connectivity in schizophrenia that contribute to the disconnection hypothesis of this disease.

Altered interhemispheric functional connectivity in remitted bipolar disorder: A Resting State fMRI Study

Abnormalities in structural and functional brain connectivity have been increasingly reported in patients with bipolar disorder (BD). However, alterations of remitted BD (RBD) in functional connectivity between the cerebral hemispheres are still not well understood. This study was designed to analyze the pattern of the interhemispheric functional connectivity of the whole brain in patients with remitted BD during resting state. Twenty patients with RBD and 38 healthy controls (HC) underwent the resting-state functional magnetic resonance imaging. The functional connectivity between any pair of symmetrical interhemispheric voxels (i.e., functional homotopy) was measured by voxel-mirrored homotopic connectivity (VMHC). The patients with RBD showed lower VMHC than HC in the middle frontal gyrus and precentral gyrus. No regions of increased VMHC were detected in the RBD patients. There were no significant correlations between the VMHC values in these regions and the clinical variables. These findings suggest substantial impairment of interhemispheric coordination in RBD and they may represent trait, rather than state, neurobiological feature of brain function in BD.

Increased interhemispheric resting-state functional connectivity in healthy participants with insomnia symptoms: A randomized clinical consort study.

Background:Abnormalities within the insular cortex of the salience and thalamus of the hyperarousal network have been increasingly reported in healthy participants with insomnia symptoms by recent resting-state functional magnetic resonance imaging (rsfMRI) studies. However, little is known about the changes in functional interaction between the bilateral cerebral hemispheres in healthy participants with insomnia symptoms.Methods:In a randomized trial, 27 healthy participants with insomnia symptoms and 27 age-, gender-, and educational level-matched healthy participants without insomnia symptoms underwent rsfMRI. Voxel-mirrored homotopic connectivity (VMHC) was used to measure functional connectivity between any pair of symmetrical interhemispheric voxels (i.e., functional homotopy).Results:The healthy participants with insomnia symptoms displayed significantly increased VMHC compared to healthy participants without insomnia symptoms in the bilateral thalamus/posterior insula (including anterior insula), fusiform, middle cingulate gyrus, inferior parietal lobe, and postcentral gyrus. No regions of decreased VMHC were detected in healthy participants with insomnia symptoms. There were significantly positive correlations between the VMHC values in the anterior cingulate cortex (ACC) and sleep disturbance scores in all healthy participants.Conclusions:Insomnia is associated with substantial impairment of interhemispheric coordination within the default mode (ACC), salience (insula), hyperarousal (thalamus/posterior insula), and visual (fusiform) networks.

Altered interhemispheric resting-state functional connectivity in young male smokers.

With the help of advanced neuroimaging approaches, previous studies revealed structural and functional brain changes in smokers compared with healthy non-smokers. Homotopic resting-state functional connectivity between the corresponding regions in cerebral hemispheres may help us to deduce the changes of functional coordination in the whole brain of young male smokers. Functional homotopy reflects an essential aspect of brain function and communication between the left and right cerebral hemispheres, which is important for the integrity of brain function. However, few studies used voxel mirrored homotopic connectivity (VMHC) method to investigate the changes of homotopic connectivity in young male smokers. Twenty-seven young male smokers and 27 matched healthy male non-smokers were recruited in our study. Compared with healthy male non-smokers, young male smokers showed decreased VMHC values in the insula and putamen, and increased VMHC values in the prefrontal cortex. Correlation analysis demonstrated that there were significant positive correlations between the average VMHC values of the prefrontal cortex and pack-years in young male smokers. In addition, significant negative correlation was found between the average VMHC values in the insula and pack-years. Our results revealed the disrupted homotopic resting-state functional connectivity in young male smokers. The novel findings may extend our understanding of smoking.

Decreased hemispheric connectivity and decreased intra- and inter- hemisphere asymmetry of resting state functional network connectivity in schizophrenia.

Many studies have shown that schizophrenia patients have aberrant functional network connectivity (FNC) among brain regions, suggesting schizophrenia manifests with significantly diminished (in majority of the cases) connectivity. Schizophrenia is also associated with a lack of hemispheric lateralization. Hoptman et al. (2012) reported lower inter-hemispheric connectivity in schizophrenia patients compared to controls using voxel-mirrored homotopic connectivity. In this study, we merge these two points of views together using a group independent component analysis (gICA)-based approach to generate hemisphere-specific timecourses and calculate intra-hemisphere and inter-hemisphere FNC on a resting state fMRI dataset consisting of age- and gender-balanced 151 schizophrenia patients and 163 healthy controls. We analyzed the group differences between patients and healthy controls in each type of FNC measures along with age and gender effects. The results reveal that FNC in schizophrenia patients shows less hemispheric asymmetry compared to that of the healthy controls. We also found a decrease in connectivity in all FNC types such as intra-left (L_FNC), intra-right (R_FNC) and inter-hemisphere (Inter_FNC) in the schizophrenia patients relative to healthy controls, but general patterns of connectivity were preserved in patients. Analyses of age and gender effects yielded results similar to those reported in whole brain FNC studies.

Interhemispheric functional connectivity in anorexia and bulimia nervosa

IntroductionThe functional interplay between brain hemispheres is fundamental for behavioral, cognitive and emotional control. Several pathophysiological aspects of eating disorders (EDs) have been investigated by the use of functional Magnetic Resonance Imaging (fMRI).ObjectivesThe objective of the study was to investigate functional brain asymmetry of resting-state fMRI correlations in symptomatic patients with anorexia nervosa (AN) and bulimia nervosa (BN).AimsWe aimed at revealing whether brain regions implicated in reward, cognitive control, starvation and emotion regulation show altered inter-hemispheric functional connectivity in patients with AN and BN.MethodsUsing resting-state fMRI, voxel-mirrored homotopic connectivity (VMHC) and regional inter-hemispheric spectral coherence (IHSC) analyses in two canonical slow frequency bands (“Slow-5”, “Slow-4”) were studied in 15AN and 13BN patients and 16 healthy controls (HC). Using T1-weighted and diffusion tensor imaging MRI scans, regional VMHC values were correlated with the left-right asymmetry of corresponding homotopic gray matter volumes and with the white matter callosal fractional anisotropy (FA).ResultsCompared to HC, AN patients exhibited reduced VMHC in cerebellum, insula and precuneus, while BN patients showed reduced VMHC in dorso-lateral prefrontal and orbito-frontal cortices. The regional IHSC analysis highlighted that the inter-hemispheric functional connectivity was higher in the ‘Slow-5′Band in all regions except the insula. No group differences in left-right structural asymmetries and in VMHC vs callosal FA correlations were found.ConclusionsThese anomalies indicate that AN and BN, at least in their acute phase, are associated with a loss of inter-hemispheric connectivity in regions implicated in self-referential, cognitive control and reward processing.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Altered interhemispheric functional connectivity in patients with anisometropic and strabismic amblyopia: a resting-state fMRI study.

Altered brain functional connectivity has been reported in patients with amblyopia by recent neuroimaging studies. However, relatively little is known about the alterations in interhemispheric functional connectivity in amblyopia. The present study aimed to investigate the functional connectivity patterns between homotopic regions across hemispheres in patients with anisometropic and strabismic amblyopia under resting state. Nineteen monocular anisometropic amblyopia (AA), 18 strabismic amblyopia (SA), and 20 normal-sight controls (NC) were enrolled in this study. After a comprehensive ophthalmologic examination, resting-state fMRI scanning was performed in all participants. The pattern of the interhemispheric functional connectivity was measured with the voxel-mirrored homotopic connectivity (VMHC) approach. VMHC values differences within and between three groups were compared, and correlations between VMHC values and each the clinical variable were also analyzed. Altered VMHC was observed in AA and SA patients in lingual gyrus and fusiform gyrus compared with NC subjects. The altered VMHC of lingual gyrus showed a pattern of AA > SA > NC, while the altered VMHC of fusiform gyrus showed a pattern of AA > NC > SA. Moreover, the VMHC values of lingual gyrus were positively correlated with the stereoacuity both in AA and SA patients, and the VMHC values of fusiform gyrus were positively correlated with the amount of anisometropia just in AA patients. These findings suggest that interhemispheric functional coordination between several homotopic visual-related brain regions is impaired both in AA and SA patients under resting state and revealed the similarities and differences in interhemispheric functional connectivity between the anisometropic and strabismic amblyopia.

Family-based case-control study of homotopic connectivity in first-episode, drug-naive schizophrenia at rest

Family-based case-control design is rarely used but powerful to reduce the confounding effects of environmental factors on schizophrenia. Twenty-eight first-episode, drug-naive patients with schizophrenia, 28 family-based controls (FBC), and 40 healthy controls (HC) underwent resting-state functional MRI. Voxel-mirrored homotopic connectivity (VMHC), receiver operating characteristic curve (ROC), and support vector machine (SVM) were used to process the data. Compared with the FBC, the patients showed lower VMHC in the precuneus, fusiform gyrus/cerebellum lobule VI, and lingual gyrus/cerebellum lobule VI. The patients exhibited lower VMHC in the precuneus relative to the HC. ROC analysis exhibited that the VMHC values in these brain regions might not be ideal biomarkers to distinguish the patients from the FBC/HC. However, SVM analysis indicated that a combination of VMHC values in the precuneus and lingual gyrus/cerebellum lobule VI might be used as a potential biomarker to distinguish the patients from the FBC with a sensitivity of 96.43%, a specificity of 89.29%, and an accuracy of 92.86%. Results suggested that patients with schizophrenia have decreased homotopic connectivity in the motor and low level sensory processing regions. Neuroimaging studies can adopt family-based case-control design as a viable option to reduce the confounding effects of environmental factors on schizophrenia.

Interhemispheric functional connectivity in anorexia and bulimia nervosa.

The functional interplay between hemispheres is fundamental for behavioral, cognitive, and emotional control. Anorexia nervosa (AN) and bulimia nervosa (BN) have been largely studied with brain magnetic resonance imaging (MRI) in relation to the functional mechanisms of high-level processing, but not in terms of possible inter-hemispheric functional connectivity anomalies. Using resting-state functional MRI (fMRI), voxel-mirrored homotopic connectivity (VMHC) and regional inter-hemispheric spectral coherence (IHSC) were studied in 15 AN and 13 BN patients and 16 healthy controls (HC). Using T1-weighted and diffusion tensor imaging MRI scans, regional VMHC values were correlated with the left-right asymmetry of corresponding homotopic gray matter volumes and with the white matter callosal fractional anisotropy (FA). Compared to HC, AN patients exhibited reduced VMHC in cerebellum, insula, and precuneus, while BN patients showed reduced VMHC in dorso-lateral prefrontal and orbito-frontal cortices. The regional IHSC analysis highlighted that the inter-hemispheric functional connectivity was higher in the 'Slow-5' band in all regions except the insula. No group differences in left-right structural asymmetries and in VMHC vs. callosal FA correlations were significant in the comparisons between cohorts. These anomalies, not explained by structural changes, indicate that AN and BN, at least in their acute phase, are associated with a loss of inter-hemispheric connectivity in regions implicated in self-referential, cognitive control and reward processing. These findings may thus gather novel functional markers to explore aberrant features of these eating disorders.

Reduction of Interhemispheric Functional Brain Connectivity in Early Blindness: A Resting-State fMRI Study.

Objective The purpose of this study was to investigate the resting-state interhemispheric functional connectivity in early blindness by using voxel-mirrored homotopic connectivity (VMHC). Materials and Methods Sixteen early blind patients (EB group) and sixteen age- and gender-matched sighted control volunteers (SC group) were recruited in this study. We used VMHC to identify brain areas with significant differences in functional connectivity between different groups and used voxel-based morphometry (VBM) to calculate the individual gray matter volume (GMV). Results VMHC analysis showed a significantly lower connectivity in primary visual cortex, visual association cortex, and somatosensory association cortex in EB group compared to sighted controls. Additionally, VBM analysis revealed that GMV was reduced in the left lateral calcarine cortices in EB group compared to sighted controls, while it was increased in the left lateral middle occipital gyri. Statistical analysis showed the duration of blindness negatively correlated with VMHC in the bilateral middle frontal gyri, middle temporal gyri, and inferior temporal gyri. Conclusions Our findings help elucidate the pathophysiological mechanisms of EB. The interhemispheric functional connectivity was impaired in EB patients. Additionally, the middle frontal gyri, middle temporal gyri, and inferior temporal gyri may be potential target regions for rehabilitation.

Increased inter-hemispheric resting-state functional connectivity in acute lacunar stroke patients with aphasia.

Aphasia is a devastating neurological condition affecting a person's ability to communicate and reintegrate into the society. It may occur in 20% or more of patients after stroke. The recovery of language function is accompanied by brain reorganization, and identifying the inter-hemispheric interaction post-stroke will conduce to more targeted treatments. Previous studies suggested that robust homotopic resting-state functional connectivity is a key characteristic of the brain's intrinsic functional architecture, and communication between the left and right cerebral hemispheres is important for language processing. In this study, voxel-mirrored homotopic connectivity (VMHC) was used to examine the inter-hemispheric resting-state functional connectivity (RSFC) differences between 37 patients with acute lacunar stroke in the left hemisphere and 28 healthy controls. Besides, correlation analyses were carried out to investigate the relationship between VMHC values of brain regions showing abnormal inter-hemispheric RSFC and clinical variables [i.e., aphasia quotient (AQ) scores, National Institutes of Health Stroke Scale (NIHSS) and Mini-Mental State Examination of patients]. Compared with healthy controls, patients showed significantly increased VMHC in the pars orbitalis of the inferior frontal gyrus, anterior part of the superior temporal gyrus (STG) and lingual gyrus. No brain region showed decreased VMHC in the patient group than in the healthy control group. The AQ scores were negatively correlated with VMHC values in the STG. NIHSS scores were positively correlated with VMHC values in the lingual gyrus. We hope these results could shed new insights into the pathology of aphasia in patients with acute lacunar stroke.

Disturbed Interhemispheric Functional Connectivity Rather than Structural Connectivity in Irritable Bowel Syndrome.

Neuroimaging studies have demonstrated that irritable bowel syndrome (IBS)—a relapsing functional bowel disorder—presents with disrupted brain connections. However, little is known about the alterations of interhemispheric functional connectivity and underlying structural connectivity in IBS. This study combined resting-state functional magnetic resonance imaging (rs-fMRI) and diffusion tensor imaging (DTI) to investigate changes in interhemispheric coordination in IBS patients. Resting-state functional and structural magnetic resonance images were acquired from 65 IBS patients and 67 healthy controls (HCs; matched for age, sex and educational level). Interhemispheric voxel-mirrored homotopic connectivity (VMHC) was calculated and compared between groups. Homotopic regions showing abnormal VMHC in patients were targeted as regions of interest (ROIs) for analysis of DTI tractography. The fractional anisotropy (FA), fiber number and fiber length were compared between groups. Statistical analysis was also performed by including anxiety and depression as covariates to evaluate their effect. A Pearson correlation analysis between abnormal interhemispheric connectivity and clinical indices of IBS patients was performed. Compared to HCs, IBS patients had higher interhemispheric functional connectivity between bilateral thalami, cuneus, posterior cingulate cortices (PCC), lingual gyri and inferior occipital/cerebellum lobes, as well as lower interhemispheric functional connectivity between bilateral ventral anterior cingulate cortices (vACC) and inferior parietal lobules (IPL). The inclusion of anxiety and depression as covariates abolished VMHC difference in vACC. Microstructural features of white matter tracts connecting functionally abnormal regions did not reveal any differences between the groups. VMHC values in vACC negatively correlated with the quality of life (QOL) scores of patients. In conclusion, this study provides preliminary evidence of the disrupted functional coordination rather than anatomic coordination between interhemispheric regions within the cortex-thalamus circuit in IBS patients, which could partly account for the enhanced visceral information processing and impaired endogenous pain or emotion inhibition associated with IBS.

Aberrant interhemispheric homotopic functional and structural connectivity in amyotrophic lateral sclerosis

ObjectiveAmyotrophic lateral sclerosis (ALS) is an idiopathic and fatal neurodegenerative disease of the human motor system. While microstructural alterations in corpus callosum (CC) have been identified as a consistent feature...

Reduction of Interhemispheric Functional Connectivity in Sensorimotor and Visual Information Processing Pathways in Schizophrenia.

Background:Previous studies have demonstrated interhemispheric functional connectivity alterations in schizophrenia. However, the relationship between these alterations and the disease state of schizophrenia is largely unknown. Therefore, we aimed to investigate this relationship using voxel-mirrored homotopic connectivity (VMHC) method.Methods:This study enrolled 36 schizophrenia patients with complete remission, 58 schizophrenia patients with incomplete remission and 55 healthy controls. The VMHC was calculated based on resting-state functional magnetic resonance imaging data. Differences in VMHC among three groups were compared using one-way analysis of variance. A brain region with a significant difference in VMHC was defined as a region of interest (ROI), and the mean VMHC value in the ROI was extracted for the post hoc analysis, i.e., pair-wise comparisons across the three groups.Results:VMHC in the visual region (inferior occipital and fusiform gyri) and the sensorimotor region (paracentral lobule) showed significant differences among the three groups (P < 0.05, a false discovery rate method corrected). Pair-wise comparisons in the post hoc analysis showed that VMHC of the visual and sensorimotor regions in schizophrenia patients with complete remission and incomplete remission was lower than that in healthy controls (P < 0.05, Bonferroni corrected); however, there was no significant difference between the two patient subgroups.Conclusions:Interhemispheric functional connectivity in the sensorimotor and visual processing pathways was reduced in patients with schizophrenia, but this reduction was unrelated to the disease state; thus, this reduction may serve as a trait marker of schizophrenia.

Altered homotopic connectivity in postherpetic neuralgia: a resting state fMRI study.

ObjectiveThe aim of this study was to explore interhemispheric intrinsic connectivity in patients with postherpetic neuralgia (PHN).MethodsWe obtained resting-state functional magnetic resonance imaging data from 18 right-handed PHN patients (11 males, 7 females; mean age, 59.67±8.41 years) and 18 well-matched healthy controls (11 males, 7 females; mean age, 38.50±7.51 years). Interhemispheric connectivity was examined using voxel-mirrored homotopic connectivity (VMHC), and seed-based functional connectivity analysis was performed.ResultsCompared with the healthy controls, the patients with PHN showed abnormally decreased homotopic connectivity in the dorsolateral prefrontal cortex and the precuneus and posterior cingulate cortex (PCUN/PCC). The decreased VMHC in the PCUN/PCC was positively correlated with the visual analog scale of PHN in the PHN patient group (ρ=0.651; P=0.006). Receiver operating characteristic (ROC) analysis revealed that the areas under the curves for the two brain regions were 0.898 for the prefrontal cortex and 0.923 for the PCUN/PCC, which indicated that the VMHC could be used to discriminate PHN patients from healthy controls. A subsequent seed-based functional connectivity analysis revealed widely disrupted intrinsic connectivity between the regions that showed local homotopic connectivity deficits and the areas subserving the default-mode network.ConclusionOur results indicated reduced interhemispheric functional connectivity in patients with PHN, which seems to be an important new avenue to investigate to better understand the nature of disconnection of the functional architecture in patients with PHN.