Decreased Voxel-mirrored Homotopic Connectivity Values Research Articles

Impaired interhemispheric synchrony and effective connectivity in right temporal lobe epilepsy.

The brain functional network plays a crucial role in cognitive impairment in temporal lobe epilepsy (TLE). Based on voxel-mirrored homotopic connectivity (VMHC), this study explored how directed functional connectivity changes and is associated with impaired cognition in right TLE (rTLE). Twenty-seven patients with rTLE and twenty-seven healthy controls were included to perform VMHC and Granger causality analysis (GCA). Correlation analysis was performed based on GCA and cognitive function. Bilateral middle frontal gyrus (MFG), middle temporal gyrus, dorsolateral superior frontal gyrus (SFGdor), and supramarginal gyrus (SMG) exhibited decreased VMHC values in the rTLE group. Brain regions with altered VMHC had abnormal directed functional connectivity with multiple brain regions, mainly belonging to the default mode network, sensorimotor network, and visual network. Besides, the Montreal Cognitive Assessment (MoCA) score was positively correlated with the connectivity from the left SFGdor to the right cerebellum crus2 and was negatively correlated with the connectivity from the left SMG to the right supplementary motor area (SMA) before correction. Before correction, both phasic and intrinsic alertness reaction time were positively correlated with the connectivity from the left MFG to the left precentral gyrus (PreCG), connectivity from the left SMG to the right PreCG, and the connectivity from the left SMG to the right SMA. The executive control effect reaction time was positively correlated with the connectivity from the left MFG to the left calcarine fissure surrounding cortex before correction. The disordered functional network tended to be correlated with cognition impairment in rTLE.

Abnormal voxel-mirrored homotopic connectivity in first-episode major depressive disorder using fMRI: a machine learning approach.

To explore the interhemispheric information synergy ability of the brain in major depressive disorder (MDD) patients by applying the voxel-mirrored homotopic connectivity (VMHC) method and further explore the potential clinical diagnostic value of VMHC metric by a machine learning approach. 52 healthy controls and 48 first-episode MDD patients were recruited in the study. We performed neuropsychological tests and resting-state fMRI scanning on all subjects. The VMHC values of the symmetrical interhemispheric voxels in the whole brain were calculated. The VMHC alterations were compared between two groups, and the relationship between VMHC values and clinical variables was analyzed. Then, abnormal brain regions were selected as features to conduct the classification model by using the support vector machine (SVM) approach. Compared to the healthy controls, MDD patients exhibited decreased VMHC values in the bilateral middle frontal gyrus, fusiform gyrus, medial superior frontal gyrus and precentral gyrus. Furthermore, the VMHC value of the bilateral fusiform gyrus was positively correlated with the total Hamilton Depression Scale (HAMD). Moreover, SVM analysis displayed that a combination of all clusters demonstrated the highest area under the curve (AUC) of 0.87 with accuracy, sensitivity, and specificity values of 86.17%, 76.74%, and 94.12%, respectively. MDD patients had reduced functional connectivity in the bilateral middle frontal gyrus, fusiform gyrus, medial superior frontal gyrus and precentral gyrus, which may be related to depressive symptoms. The abnormality in these brain regions could represent potential imaging markers to distinguish MDD patients from healthy controls.

Altered interhemispheric functional connectivity in patients with comitant exotropia before and after surgery: a resting-state fMRI study.

To assess the interhemispheric homotopic connectivity alterations in patients with comitant exotropia (CE) before and after surgery, using resting-state functional magnetic resonance imaging (rs-fMRI) with voxel-mirrored homotopic connectivity (VMHC). Thirty-four patients with CE and twenty-four well-matched healthy controls (HCs) were enrolled to undergo a preoperative rs-fMRI scan. The rs-fMRI scan was performed again in twenty-four patients 1 month after surgery. The VMHC method was applied to evaluate the group differences of interhemispheric functional connectivity. The correlations between VMHC values and clinical variables were analyzed in the patient group. Compared with HCs, 34 patients with CE showed significantly increased VMHC values in occipital lobe (cuneus/superior occipital gyrus/middle occipital gyrus/calcarine), cerebellar area 8/cerebellar Crus1 area, and cerebellar Crus1 area. In CE group, VMHC in the cuneus was positively correlated with stereoacuity (r = 0.417, P = 0.014), meanwhile VMHC in the cerebellar Crus1 area was positively correlated with stereoacuity (r = 0.395, P = 0.021). One month after surgery, the 24 CE patients with follow-up showed decreased VMHC values in the cuneus and superior occipital gyrus compared with preoperative collection, meanwhile, non-significant difference compared with HCs. Our study revealed the interhemispheric homotopic connectivity changes of patients with CE in the occipital lobe and cerebellum before and after surgery. The findings may provide a new perspective for the neurological alterations of CE.

Effects of primary angle-closure glaucoma on interhemispheric functional connectivity.

Previous studies on primary angle-closure glaucoma (PACG) primarily focused on local brain regions or global abnormal brain activity; however, the alteration of interhemispheric functional homotopy and its possible cause of brain-wide functional connectivity abnormalities have not been well-studied. Little is known about whether brain functional alteration could be used to differentiate from healthy controls (HCs) and its correlation with neurocognitive impairment. Forty patients with PACG and 40 age- and sex-matched healthy controls were recruited for this study; resting-state functional magnetic resonance imaging (rs-fMRI), and clinical data were collected. We used the voxel-mirrored homotopic connectivity (VMHC) method to explore between-group differences and selected brain regions with statistically significant differences as regions of interest for whole-brain functional connectivity analysis. Partial correlation was used to evaluate the association between abnormal VMHC values in significantly different regions and clinical parameters, with with age and sex as covariates. Finally, the support vector machine (SVM) model was performed in classification prediction of PACG. Compared with healthy controls, patients with PACG exhibited significantly decreased VMHC values in the lingual gyrus, insula, cuneus, and pre- and post-central gyri; no regions exhibited increased VMHC values. Subsequent functional connectivity analysis revealed extensive functional changes in functional networks, particularly the default mode, salience, visual, and sensorimotor networks. The SVM model showed good performance in classification prediction of PACG, with an area under curve (AUC) of 0.85. Altered functional homotopy of the visual cortex, sensorimotor network, and insula may lead to impairment of visual function in PACG, suggesting that patients with PACG may have visual information interaction and integration dysfunction.

The decreased connectivity in middle temporal gyrus can be used as a potential neuroimaging biomarker for left temporal lobe epilepsy.

ObjectiveWe aimed to explore voxel-mirrored homotopic connectivity (VMHC) abnormalities between the two brain hemispheres in left temporal lobe epilepsy (lTLE) patients and to determine whether these alterations could be leveraged to guide lTLE diagnosis.Materials and methodsFifty-eight lTLE patients and sixty healthy controls (HCs) matched in age, sex, and education level were recruited to receive resting state functional magnetic resonance imaging (rs-fMRI) scan. Then VHMC analyses of bilateral brain regions were conducted based on the results of these rs-fMRI scans. The resultant imaging data were further analyzed using support vector machine (SVM) methods.ResultsCompared to HCs, patients with lTLE exhibited decreased VMHC values in the bilateral middle temporal gyrus (MTG) and middle cingulum gyrus (MCG), while no brain regions in these patients exhibited increased VMHC values. SVM analyses revealed the diagnostic accuracy of reduced bilateral MTG VMHC values to be 75.42% (89/118) when differentiating between lTLE patients and HCs, with respective sensitivity and specificity values of 74.14% (43/58) and 76.67% (46/60).ConclusionPatients with lTLE exhibit abnormal VMHC values corresponding to the impairment of functional coordination between homotopic regions of the brain. These altered MTG VMHC values may also offer value as a robust neuroimaging biomarker that can guide lTLE patient diagnosis.

Altered voxel-mirrored homotopic connectivity in right temporal lobe epilepsy as measured using resting-state fMRI and support vector machine analyses.

BackgroundPrior reports revealed abnormalities in voxel-mirrored homotopic connectivity (VMHC) when analyzing neuroimaging data from patients with various psychiatric conditions, including temporal lobe epilepsy (TLE). Whether these VHMC changes can be leveraged to aid in the diagnosis of right TLE (rTLE), however, remains to be established. This study was thus developed to examine abnormal VMHC findings associated with rTLE to determine whether these changes can be used to guide rTLE diagnosis.MethodsThe resultant imaging data of resting-state functional MRI (rs-fMRI) analyses of 59 patients with rTLE and 60 normal control individuals were analyzed using VMHC and support vector machine (SVM) approaches.ResultsRelative to normal controls, patients with rTLE were found to exhibit decreased VMHC values in the bilateral superior and the middle temporal pole (STP and MTP), the bilateral middle and inferior temporal gyri (MTG and ITG), and the bilateral orbital portion of the inferior frontal gyrus (OrbIFG). These patients further exhibited increases in VMHC values in the bilateral precentral gyrus (PreCG), the postcentral gyrus (PoCG), and the supplemental motor area (SMA). The ROC curve of MTG VMHC values showed a great diagnostic efficacy in the diagnosis of rTLE with AUCs, sensitivity, specificity, and optimum cutoff values of 0.819, 0.831, 0.717, and 0.465. These findings highlight the value of the right middle temporal gyrus (rMTG) when differentiating between rTLE and control individuals, with a corresponding SVM analysis yielding respective accuracy, sensitivity, and specificity values of 70.59% (84/119), 78.33% (47/60), and 69.49% (41/59).ConclusionIn summary, patients with rTLE exhibit various forms of abnormal functional connectivity, and SVM analyses support the potential value of abnormal VMHC values as a neuroimaging biomarker that can aid in the diagnosis of this condition.

Impaired Interhemispheric Synchrony in Parkinson's Disease with Fatigue.

The characteristics of interhemispheric resting-state functional connectivity (FC) in Parkinson’s disease (PD) with fatigue remain unclear; therefore, we aimed to explore the changes in interhemispheric FC in PD patients with fatigue. Sixteen PD patients with fatigue (PDF), 16 PD patients without fatigue (PDNF) and 15 matched healthy controls (HCs) were enrolled in the retrospective cross-sectional study. We used voxel-mirrored homotopic connectivity (VMHC) to analyze the resting-state functional magnetic resonance imaging (fMRI) data of these subjects. Compared to PDNF, PDF patients had decreased VMHC values in the supramarginal gyri (SMG). Furthermore, the mean VMHC values of the SMG were negatively correlated with the mean fatigue severity scale (FSS/9) scores (r = −0.754, p = 0.001). Compared to HCs, PDF patients had decreased VMHC in the SMG and in the opercular parts of the inferior frontal gyri (IFG operc). The VMHC values in the IFG operc and middle frontal gyri (MFG) were notably decreased in PDNF patients compared with HCs. Our findings suggest that the reduced VMHC values within the bilateral SMG may be the unique imaging features of fatigue in PD, and may illuminate the neural mechanisms of fatigue in PD.

Aberrant Interhemispheric Functional Connectivity in Diabetic Retinopathy Patients.

Background: Accumulating lines of evidence demonstrated that diabetic retinopathy (DR) patients trigger abnormalities in brain’s functional connectivity (FC), whereas the alterations of interhemispheric coordination pattern occurring in DR are not well understood. Our study was to investigate alterations of interhemispheric coordination in DR patients.Methods: Thirty-four DR individuals (19 males and 15 females: mean age: 52.97 ± 8.35 years) and 37 healthy controls (HCs) (16 males and 21 females; mean age: 53.78 ± 7.24 years) were enrolled in the study. The voxel-mirrored homotopic connectivity (VMHC) method was conducted to investigate the different interhemispheric FC between two groups. Then, the seed-based FC method was applied to assess the different FCs with region of interest (ROI) in the brain regions of decreased VMHC between two groups.Results: Compared with HC groups, DR groups showed decreased VMHC values in the bilateral middle temporal gyrus (MTG), lingual/calcarine/middle occipital gyrus (LING/CAL/MOG), superior temporal gyrus (STG), angular (ANG), postcentral gyrus (PosCG), inferior parietal lobule (IPL), and precentral gyrus (PreCG). Meanwhile, altered FC includes the regions of auditory network, visual network, default mode network, salience network, and sensorimotor network. Moreover, a significant positive correlation was observed between the visual acuity-oculus dexter (OD) and zVMHC values in the bilateral LING/CAL/MOG (r = 0.551, p = 0.001), STG (r = 0.426, p = 0.012), PosCG (r = 0.494, p = 0.003), and IPL (r = 0.459, p = 0.006) in DR patients.Conclusion: Our results highlighted that DR patients were associated with substantial impairment of interhemispheric coordination in auditory network, visual network, default mode network, and sensorimotor network. The VMHC might be a promising therapeutic target in the intervention of brain functional dysfunction in DR patients.

Alternations of interhemispheric functional connectivity in children with strabismus and amblyopia: a resting-state fMRI study

Previous neuroimaging studies demonstrated that patients with strabismus or amblyopia can show significant functional and anatomical changes in the brain, but alterations of interhemispheric functional connectivity (FC) have not been well studied in this population. The current study analyzed whole-brain changes of interhemispheric FC in children with strabismus and amblyopia (CSA) using voxel-mirrored homotopic connectivity (VMHC).A total of 24 CSA (16 males and 8 females) and 24 normal controls (NCs) consisting of 16 and 8 age-, sex, and education-matched males and females, respectively, underwent functional magnetic resonance imaging (fMRI) scans in the resting state. According to Gaussian random field theory, changes in the resting state FC (rsFC) between hemispheres were evaluated using the VMHC method. The relationships between mean VMHC values in multiple brain regions and behavioral performance were evaluated by Pearson correlation analysis. In contrast to NCs, the CSA group showed significantly decreased VMHC values in the bilateral cerebellum, bilateral frontal superior orbital (frontal sup orb), bilateral temporal inferior(temporal inf),and bilateral frontal superior(frontal sup). CSA have abnormal interhemispheric FC in many brain regions, which may reflect dysfunction of eye movements and visual fusion. These findings might provide insight into the underlying pathogenetic mechanisms of CSA.

Abnormal interhemispheric resting state functional connectivity in Parkinson\u2019s disease patients with impulse control disorders

Impulse control disorders (ICD) in Parkinson’s disease (PD) might be attributed to misestimate of rewards or the failure to curb inappropriate choices. The mechanisms underlying ICD were reported to involve the lateralization of monoamine network. Our objective was to probe the significant role of lateralization in the pathogenesis of ICD. Twenty-one PD patients with ICD (PD-ICD), thirty-three without ICD (PD-no ICD), and thirty-seven healthy controls (HCs) were recruited and performed T1-weighted, diffusion tensor imaging (DTI) scans and resting state functional magnetic resonance imaging (rs-fMRI). By applying the Voxel-mirrored Homotopic Connectivity (VMHC) and Freesurfer, we evaluated participants’ synchronicity of functional connectivity and structural changes between hemispheres. Also, tract-based spatial statistics (TBSS) was applied to compare fiber tracts differences. Relative to PD-no ICD group, PD-ICD group demonstrated reduced VMHC values in middle frontal gyrus (MFG). Compared to HCs, PD-ICD group mainly showed decreased VMHC values in MFG, middle and superior orbital frontal gyrus (OFG), inferior frontal gyrus (IFG) and caudate, which were related to reward processing and inhibitory control. The severity of impulsivity was negatively correlated with the mean VMHC values of MFG in PD-ICD group. Receiver operating characteristic (ROC) curves analyses uncovered that the mean VMHC values of MFG might be a potential marker identifying PD-ICD patients. However, we found no corresponding asymmetrical alteration in cortical thickness and no significant differences in fractional anisotropy (FA) and mean diffusivity (MD). Our results provided further evidence for asymmetry of functional connectivity in mesolimbic reward and response inhibition network in ICD.

Decreased Resting-State Interhemispheric Functional Connectivity in Medication-Free Obsessive-Compulsive Disorder.

ObjectiveDecreased homotopic connectivity of brain networks such as the cortico-striato-thalamo-cortical (CSTC) circuits may contribute to the pathophysiology of obsessive-compulsive disorder (OCD). However, little is known about interhemispheric functional connectivity (FC) at rest in OCD. In this study, the voxel-mirrored homotopic connectivity (VMHC) method was applied to explore interhemispheric coordination at rest in OCD.MethodsForty medication-free patients with OCD and 38 sex-, age-, and education level-matched healthy controls (HCs) underwent a resting-state functional magnetic resonance imaging. The VMHC and support vector machine (SVM) methods were used to analyze the data.ResultsPatients with OCD had remarkably decreased VMHC values in the orbitofrontal cortex, thalamus, middle occipital gyrus, and precentral and postcentral gyri compared with HCs. A combination of the VMHC values in the thalamus and postcentral gyrus could optimally distinguish patients with OCD from HCs.ConclusionsOur findings highlight the contribution of decreased interhemispheric FC within and outside the CSTC circuits in OCD and provide evidence to the pathophysiology of OCD.

Alterations of Functional Connectivity in Stroke Patients With Basal Ganglia Damage and Cognitive Impairment.

Background: Stroke with basal ganglia damage (SBG) is a neurological disorder characterized by cognitive impairment. The neurobiological mechanism of cognitive impairment in stroke patients with basal ganglia damage (SBG patients) remains unclear. This study aimed to explore the underlying neurobiological mechanism of cognitive impairment in SBG patients using resting-state functional magnetic resonance imaging (rs-fMRI).Methods: The differences in functional connectivity (FC) between 14 SBG patients (average age: 61.00 ± 7.45 years) and 21 healthy controls (HC) (average age: 60.67 ± 6.95 years) were examined using voxel-mirrored homotopic connectivity (VMHC) and degree centrality (DC). Moreover, we compared the cognitive functions of SBG patients with HC using the Chinese Revised Wechsler Adult Intelligence Scale (WAIS-RC) and Wechsler Memory Scale (WMS).Results: Full-scale intelligence quotient (FIQ) (t = 2.810, p < 0.010) and memory quotient (MQ) (t = 2.920, p < 0.010) scores of SBG patients were significantly lower than those of HC. Compared with HC, significantly decreased VMHC values in the bilateral angular gyrus, supramarginal gyrus, inferior frontal gyrus, middle temporal gyrus, hippocampus, precuneus, precentral gyrus, and middle occipital gyrus and decreased DC values in the right supramarginal gyrus, bilateral angular gyrus, and right postcentral gyrus were observed in SBG patients. Moreover, the VMHC values in the angular gyrus, inferior frontal gyrus, supramarginal gyrus, and middle temporal gyrus and the DC values in the right supramarginal gyrus were significantly correlated with cognitive functions in all participants.Conclusion: Our findings may provide a neural basis for cognitive impairments in SBG patients. Furthermore, local abnormalities of functional networks and interhemispheric interaction deficits may provide new ideas and insights for understanding and treating SBG patients' cognitive impairments.

Structural remodeling secondary to functional remodeling in advanced-stage peripheral facial neuritis.

Structural remodeling is a classic manifestation of disease decompensation. Facial synkinesis is the most troubling sequela of peripheral facial neuritis, and its structural remodeling, especially in white matter (WM), is still poorly understood. Therefore, understanding WM microstructure is important for predicting WM pathology and for early intervention in facial synkinesis patients. A total of 20 facial synkinesis patients (18 men and 2 women; mean age, 33.35 ± 6.97years old) and 19 healthy controls (17 men and 2 women; mean age, 33.21 ± 6.75years old) were enrolled in this study. rs-fMRI data, diffusion tensor imaging (DTI) data, and Beck's Depression Inventory (BDI) data were collected, and tract-based spatial statistics (TBSS) and voxel-mirrored homotopic connectivity (VMHC) values were used to analyze changes in WM microstructure and interhemispheric coordination. Compared with the healthy controls, facial synkinesis patients exhibited significantly lower regional fractional anisotropy (FA) in the genu of the corpus callosum and the body of the corpus callosum, significantly higher regional FA in the retrolenticular part of the internal capsule, and significantly decreased VMHC values bilaterally in the orbital inferior frontal gyri, the fusiform gyri, the superior temporal gyri, the superior frontal gyri, and the supplementary motor areas. Furthermore, a lower regional FA in the genu of the corpus callosum was correlated with higher BDI scores in facial synkinesis patients. Structural remodeling, especially changes in white matter microstructure, may be the central mechanism for severe sequelae of peripheral facial neuritis.

Aberrant resting-state interhemispheric functional connectivity in patients with postpartum depression

The aim of this study is to investigate the alterations of interhemispheric functional connectivity in patients with postpartum depression (PPD) during resting state, and their potential correlations with clinical severity. Twenty- eight patients with PPD and twenty-five matched healthy postpartum (HP) women within 4 weeks after delivery were recruited and performed resting-state functional magnetic resonance imaging(fMRI) scans. Voxel-mirrored homotopic connectivity (VMHC), which is useful for exploring interhemispheric functional connectivity, and has been widely utilized to identify abnormal functional connectivity between the symmetrical brain regions in many diseases, was calculated in the present study, and intergroup VMHC differences in the voxel manner were analyzed. Correlations between VMHC values and clinical variables were also analyzed. Compared with HP, patients with PPD exhibited significantly decreased VMHC values in bilateral dorsomedial prefrontal cortex (dmPFC), dorsal anterior cingulate cortex (dACC) and orbitofrontal cortex (OFC). Furthermore, VMHC values within the dmPFC negatively correlated with the Edinburgh postpartum depression scale (EPDS) score. These findings suggested that functional coordination between several homotopic brain regions were impaired in patients with PPD. This study provided evidences of aberrant interhemispheric connectivity within brain regions involved in the maternal care network in PPD, and may contribute to the further understanding of the neural mechanism underlying PPD.

Impaired interhemispheric synchrony in late blindness.

Background Several neuroimaging studies demonstrated that visual deprivation led to significant cross-modal plasticity in the brain’s functional and anatomical architecture. Purpose To investigate the pattern of the interhemispheric functional connectivity in individuals with late blindness using the voxel-mirrored homotopic connectivity (VMHC) and seed-based functional connectivity (FC) methods. Material and Methods Forty-four individuals with late blindness (22 men, 22 women; mean age = 39.88 ± 12.84 years) and 55 sighted control individuals (35 men, 20 women; mean age = 43.13 ± 13.98 years)—closely matched for age, sex, and education—underwent resting-state magnetic resonance imaging scans. The VMHC and seed-based FC methods were applied to assess interhemispheric coordination in a voxel-wise manner. Results Compared with the sighted control groups, the late blindness groups showed decreased VMHC values in the bilateral cuneus/calcarine/lingual gyrus (CUN/CAL/LING) (BA 17/18/19) (voxel level: P &lt; 0.001, Gaussian random field [GRF] correction, cluster level: P &lt; 0.005). Meanwhile, for seed-based FC analysis, compared with the sighted control group, the late blindness group showed a decreased FC between the right lower VMHC regions and the bilateral CUN/LING/CAL/precuneus (PreCUN)/left middle occipital gyrus (MOG) (BA 18/19/30/31) and left precentral gyrus (PreCG) and postcentral gyrus (PostCG) (BA 2/3/4/6). The late blindness group showed a decreased FC between the left lower VMHC regions and the bilateral CUN/LING/CAL/PreCUN (BA 18/19/31) and left PreCG and PostCG (BA 2/3/4/6) relative to the sighted control group (voxel level: P &lt; 0.001, GRF correction, cluster level: P &lt; 0.005). Moreover, a negative correlation was observed between the duration of blindness and VMHC values in the bilateral CUN/CAL/LING (r = −0.393, P = 0.008) in individuals with late blindness. Conclusion Our results indicated that late blindness induced substantial impairment of interhemispheric coordination in the visual cortex. This might reflect impaired visual fusion, visual recognition function, and top-down modulations in individuals with late blindness.

Abnormalities of interhemispheric functional connectivity in individuals with acute eye pain: a resting-state fMRI study.

To study the changes of the resting state functional connectivity (rsFC) between acute eye pain (EP) subjects and healthy controls (HCs) in the two hemispheres by using voxel-mirrored homotopic connectivity (VMHC) method. Totally 20 patients with EP and 20 HCs were enrolled, sex, age, and education were matched, and all subjects were examined by functional magnetic resonance imaging (fMRI) scans at resting-state. The changes of rsFC between the hemispheres were evaluated by the VMHC method according to Gaussian random field (GRF) theory. In order to identify the VMHC, as biomarkers for distinguishing EP and from HC, the receiver operating characteristic curves (ROC) had been analyzed. The relationships were evaluated with Pearson correlation analysis between the mean VMHC signal values and clinical features in these patients. By comparing with health subjects, the significant decreased VMHC values was observed in lingual/calcarine (Brodmann area, BA 30), precentral/postcentral gyrus (PreCG/PosCG; BA 4) and medial frontal gyrus (MFG; BA 8) (false discovery rate corrected <0.01) in the acute EP individuals. The accuracy of area under curve was excellent indicated by the ROC curve analysis of each brain regions. Our study demonstrates preliminary evidence of disrupted interhemispheric rsFC in acute EP in sensorimotor and limbic system and somatosensory cortex, which might give some useful information for understanding the neurological mechanisms in acute EP individuals.

Aberrant interhemispheric functional connectivity in first-episode, drug-naïve major depressive disorder.

Many studies have indicated that depression is associated with impairment of the topological organization of the brain functional network, which may lead to disruption of mood and cognition in depressive patients. The abnormality of homotopic connectivity provides a basis for the clinical manifestations of depression, such as emotional and cognitive disorders. Several studies have investigated the abnormal imbalance of homotopic regions between the hemispheres in depressive patients. However, the reported findings are inconsistent. Additionally, the published studies have focused on only the grey matter when investigating functional connectivity abnormalities of the bilateral cerebral hemispheres in major depressive disorder (MDD). The aim of this study is to investigate functional connectivity abnormalities of the bilateral cerebral hemispheres in patients with first-episode, drug-naïve MDD using a voxel-mirrored homotopic connectivity (VMHC) method. Based on DSM-IV diagnostic criteria, 23 first-episode, drug-naïve MDD patients were recruited, together with 20 gender- and age-matched healthy normal controls. A Philips Achieva 3.0T MRI scanner was used to acquire brain functional images at resting state as well as high-resolution structural images. The functional images were preprocessed by using Data Processing Assistant for Resting-State Functional MR Imaging toolkit and SPM8.VMHC between the bilateral hemispheres was computed and compared between the MDD and control groups. The correlation between the VMHC values of the abnormal homotopy function areas and the Hamilton Depression Rating Scale (HAMD) was evaluated in the MDD patients. Compared with the control group, the MDD patients showed significantly decreased VMHC values in the bilateral brain regions including the insular, putamen, and frontal white matter. The MDD patients did not exhibit increased VMHC values in any brain regions compared with the normal controls. In addition, a negative correlation was observed between the VMHC value in the frontal lobe white-matter and the HAMD in the MDD patients. Abnormalities in brain homotopic functional connectivity observed in this study may indicate abnormal neural circuits related to aberrant cognition and emotional processing in MDD. Although the physiological significance underlaying abnormal VMHC in white matter in the frontal lobe needs further research, our study new angle to investigate the role of white-matter abnormalities in MDD as well as other psychiatric disorders.

Decreased interhemispheric homotopic connectivity in Parkinson's disease patients with freezing of gait: A resting state fMRI study

IntroductionFreezing of gait is a common complaint in patients with Parkinson's disease (PD). However, the neural bases of freezing of gait in PD remain uncertain. Existing studies on PD patients with freezing of gait (PD-FOG+) have reported damage of the corpus callosum, the largest commissural bundle of the brain. Thus, in this study we explored homotopic connectivity to investigate FOG-related interehemispheric alterations MethodsA total of 21 PD-FOG + patients, 33 PD patients without freezing of gait (PD-FOG-), and 24 matched healthy controls were recruited. All PD patients were evaluated via the FOG questionnaire (FOGQ) and all subjects had a resting state functional magnetic resonance imaging (rs-fMRI) scan. The pattern of the homotopic connectivity was measured with the voxel-mirrored homotopic connectivity (VMHC) approach. ResultThe PD-FOG + patients showed decreased VMHC values in the inferior parietal lobe (IPL) compared to both PD-FOG-patients and healthy controls. In PD-FOG + patients, the mean VMHC values in the IPL were negatively correlated with the FOGQ scores. Receiver operating characteristic curves analyses revealed that the VMHC in the IPL had discriminatory function distinguishing PD-FOG + patients from PD-FOG-patients or healthy controls. ConclusionDecreased VMHC values of PD-FOG + patients relative to PD-FOG- and healthy controls in IPL maybe a unique feature for PD-FOG+ and it may have the ability to separate PD-FOG + patients from PD-FOG- and healthy controls.

Comparative study of interhemispheric functional connectivity in left eye monocular blindness versus right eye monocular blindness: a resting-state functional MRI study.

ObjectiveIn the present study, we investigated the brain interhemispheric functional connectivity changes in left eye MB versus right eye MB patients by voxel-mirrored homotopic connectivity (VMHC) methods.MethodsA total of 31 patients with MB (15 with left eye MB and 16 with right eye MB), and 31 healthy controls (HCs) closely matched for age were recruited. All subjects underwent functional magnetic resonance imaging (fMRI) examinations. The VMHC method was used to evaluate directly functional interactions between the hemispheres. A one-way ANOVA was performed to determine the regions in which the VMHC differs between the three groups. Patients with MB were distinguished from HCs by a receiver operating characteristic (ROC) curve. The relationships between the mean VMHC signal values in many brain regions and clinical features in MB patients were calculated by pearson correlation analysis.ResultsCompared with HCs, MB patients had significantly decreased VMHC values in the cuneus/calcarine/lingual gyrus. Furthermore, left eye MB showed decreased VMHC values in the cuneus/calcarine/lingual gyrus and showed increased VMHC values in the insula and middle frontal gyrus compared with HC. In addition, right eye MB showed decreased VMHC values in the cuneus/calcarine/lingual gyrus, primary motor cortex (M1)/primary somatosensory cortex (S1) and superior parietal lobule.ConclusionMB subjects showed abnormal brain interhemispheric functional connectivity in visual pathways. Furthermore, different patterns of brain interhemispheric functional connectivity occurred in the left eye and right eye MB. These VMHC values provide much useful information to explain the neural mechanism changes in MB.

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.