Task-related functional connectivity dynamics in a block-designed visual experiment

Autism spectrum disorder (ASD) is associated with disruption of local- and long-range functional connectivity (FC). The direction of those changes in FC (increase or decrease), however, is inconsistent across studies. Further, age-dependent changes of distance-specific FC in ASD remain unclear. In this study, we used resting-state functional magnetic resonance imaging data from sixty-four typical controls (TC) and sixty-four patients with ASD, whom we further classified into child (<11 years), adolescent (11–18 years) and adult cohorts (>18 years). Functional connectivity (FC) analysis was conducted at voxel level. We employed a three-way analysis of covariance on FC to conduct statistical analyses. Results revealed that patients with ASD had lower FC than TC in cerebellum, fusiform gyrus, inferior occipital gyrus and posterior inferior temporal gyrus. Significant diagnosis-by-distance interaction was observed in ASD patients with reduced short-range and long-range FC in posterior cingulate cortex and medial prefrontal cortex. Importantly, we found significant diagnosis-by-age-by-distance interaction in orbitofrontal cortex with short-range FC being lower in autistic children, but –to a less extent– higher in autistic adults. Our findings suggest a major role of connection length in development changes of FC in ASD. We hope our study will facilitate deeper understanding of the neural mechanisms underlying ASD.

BackgroundPatients with amnestic mild cognitive impairment (aMCI) and Alzheimer’s disease (AD) show functional and structural connectivity alterations in the default mode network (DMN) while cerebrovascular disease (CeVD) shows functional and structural connectivity changes in the executive control network (ECN). Such disruptions are associated with memory and executive function impairment, respectively. Concurrent AD and CeVD pathology is associated with a higher rate of cognitive decline and differential neurodegenerative patterns. Together, such findings are likely reflective of different underlying pathology in AD with and without CeVD. However, few studies have examined the effect of CeVD on network functional connectivity (task-free functional magnetic resonance imaging (fMRI)) and structural connectivity (diffusion MRI) of the DMN and ECN in aMCI and AD using a hypothesis-driven multiple seed-based approach.MethodsWe examined functional and structural connectivity network changes in 39 aMCI, 50 aMCI+CeVD, 47 AD, 47 AD+CeVD, and 65 healthy controls (HCs) and their associations with cognitive impairment in the executive/attention and memory domains.ResultsWe demonstrate divergent DMN and ECN functional connectivity changes in CeVD and non-CeVD subjects. Compared with controls, intra-DMN hippocampal functional connectivity reductions were observed in both AD and AD+CeVD, while intra-DMN parietal and medial prefrontal-parietal functional connectivity was higher in AD+CeVD and aMCI+CeVD, but lower in AD. Intra-ECN frontal functional connectivity increases and fronto-parietal functional connectivity decreases occurred in CeVD but not non-CeVD subjects. Such functional connectivity alterations were related with cognitive impairment in a dissociative manner: intra-DMN functional connectivity changes were associated with worse cognition primarily in non-CeVD groups, while intra-ECN functional connectivity changes were associated with worse cognition primarily in CeVD groups. Additionally, CeVD and non-CeVD groups showed overlapping and distinct alterations in inter-network DMN-ECN functional connectivity depending on disease severity. In contrast to functional connectivity, CeVD groups had greater network structural connectivity damage compared with non-CeVD groups in both aMCI and AD patients. Network structural connectivity damage was associated with worse cognition.ConclusionsWe demonstrate differential functional and structural network changes between aMCI and AD patients with and without CeVD through diverging and deleterious network-based degeneration underlying domain-specific cognitive impairment.

BackgroundDysfunctional basal forebrain (BF) connectivity contributes to primary insomnia (PI). This study investigated whether transcutaneous auricular vagus nerve stimulation (taVNS) modulates BF functional connectivity (FC) in patients with PI and whether baseline FC predicts taVNS treatment response.MethodsSeventy patients with PI were randomized to real or sham taVNS for 4 weeks. Clinical assessments—including Pittsburgh Sleep Quality Index (PSQI], Insomnia Severity Index (ISI] and Zung’s Self-Rating Anxiety (SAS], and Depression Scale (SDS)—and resting-state fMRI data were collected at baseline and after treatment. FC of the bilateral BF subregions (Ch_123, Ch_4) was analyzed, and pre-to-post intervention changes in FC and clinical scores were compared between groups. Baseline FC was used to predict treatment response using a support vector regression (SVR) model, validated on an independent dataset.ResultsSixty-seven patients completed the study (33 real taVNS, 34 sham taVNS). Changes in clinical outcomes showed that real taVNS significantly reduce PSQI, ISI, and SAS scores compared to sham. FC analysis revealed reduced connectivity between bilateral BF and areas involved in visual (superior occipital gyrus, SOG; middle occipital gyrus, MOG; fusiform gyrus, FFG), somatosensory (supplementary motor area, SMA) cortex and medial prefrontal cortex (mPFC) after taVNS treatment. Reduced FC between bilateral BF and left MOG correlated positively with ISI improvement (r = 0.490, p = 0.008, Bonferroni correction). The SVR model effectively predicted treatment response based on BF-visual circuit connectivity (r = 0.520, p = 0.0014, 5000 permutation test) and generalized well to an independent dataset (r = 0.443, p = 0.0354, 5000 permutation test).ConclusionsOur findings suggest that taVNS may alleviate symptoms of primary insomnia through modulation of basal forebrain connectivity with visual, sensorimotor, and medial prefrontal cortical regions. Preliminary investigations indicate that baseline functional connectivity in the BF-visual circuit could represent a candidate biomarker for taVNS response, potentially informing personalized treatment strategies.Trial registrationThe study was registered with the China Clinical Trial Registry (Clinical Trial No. ChiCTR1900022535).

Integration of identity and emotion information in faces: fMRI evidence

Brain-computer interface (BCI) technology is being incorporated into new stroke rehabilitation devices, but little is known about brain changes associated with its use. We collected anatomical and functional MRI of nine stroke patients with persistent upper extremity motor impairment before, during, and after therapy using a BCI system. Subjects were asked to perform finger tapping of the impaired hand during fMRI. Action Research Arm Test (ARAT), 9-Hole Peg Test (9-HPT), and Stroke Impact Scale (SIS) domains of Hand Function (HF) and Activities of Daily Living (ADL) were also assessed. Group-level analyses examined changes in whole-brain task-based functional connectivity (FC) to seed regions in the motor network observed during and after BCI therapy. Whole-brain FC analyses seeded in each thalamus showed FC increases from baseline at mid-therapy and post-therapy (p < 0.05). Changes in FC between seeds at both the network and the connection levels were examined for correlations with changes in behavioral measures. Average motor network FC was increased post-therapy, and changes in average network FC correlated (p < 0.05) with changes in performance on ARAT (R2 = 0.21), 9-HPT (R2 = 0.41), SIS HF (R2 = 0.27), and SIS ADL (R2 = 0.40). Multiple individual connections within the motor network were found to correlate in change from baseline with changes in behavioral measures. Many of these connections involved the thalamus, with change in each of four behavioral measures significantly correlating with change from baseline FC of at least one thalamic connection. These preliminary results show changes in FC that occur with the administration of rehabilitative therapy using a BCI system. The correlations noted between changes in FC measures and changes in behavioral outcomes indicate that both adaptive and maladaptive changes in FC may develop with this therapy and also suggest a brain-behavior relationship that may be stimulated by the neuromodulatory component of BCI therapy.

Functional connectivity (FC) is crucial for the execution of functional activities and the progression of diseases. From a functional perspective, changes in subthalamic nucleus (STN)-based FC and network properties across lifespan and their effectiveness in predicting age require further investigation. The STN-based atlas was constructed using neuroimaging data from 1060 healthy participants. Based on this atlas, the FC and brain network properties were quantified subsequently. Both linear and non-linear changes in FC and network properties with aging, and relationships across brain regions were analyzed with generalized additive model (GAM). Connectome-based predictive modeling (CPM) was used to evaluate the performance of FC in predicting age, while computational lesion analysis was utilized to identify the FC with significant contributions to model performance. The STN-based atlas mainly involved bilateral sensory, motor, and sensory-motor integration cortices, subcortical nuclei, and cerebellar crus I and II. Global network properties were declined with aging (all P ​< ​0.05). Significant non-linear age-related changes were identified in regional network properties of bilateral M1 and right STN (all P ​< ​0.05). There were non-linear negative relationships between bilateral M1, and between right M1 and right STN (all P ​< ​0.05). The FC within motor cortex, and between limbic areas and subcortical nuclei, significantly contributed to the performance of CPM. Therefore, from a functional perspective, dynamic changes in FC and network properties across the lifespan were highlighted, particularly within motor-related circuits. This provides valuable insights into neural mechanisms underlying motor dysfunction during aging and informs circuit-based neuromodulation strategies.

Abnormal dynamic functional connectivity density in patients with generalized anxiety disorder

Variations over time in resting-state correlations in blood oxygenation level-dependent (BOLD) signals from different cortical areas may indicate changes in brain functional connectivity. However, apparent variations over time may also arise from stationary signals when the sample duration is finite. Recently, a vector autoregressive (VAR) null model has been proposed to simulate real functional magnetic resonance imaging (fMRI) data, which provides a robust stationary model for identifying possible temporal dynamic changes in functional connectivity. In this work, we propose a simpler model that uses a filtered stationary dataset. The filtered stationary model generates statistically stationary time series from random data with a single prescribed correlation coefficient that is calculated as the average over the entire time series. In addition, we propose a dynamic model, which is better able to replicate real fMRI connectivity, estimated from monkey brain studies, than the two stationary models. We compare simulated results using these three models with the behavior of primary somatosensory cortex (S1) networks in anesthetized squirrel monkeys at high field (9.4 T), using a sliding window correlation analysis. We found that at short window sizes, both stationary models reproduced the distribution of correlations of real signals well, but at longer window sizes, a dynamic model reproduced the distribution of correlations of real signals better than the stationary models. While stationary models replicate several features of real data, a close representation of the behavior of resting-state data acquired from somatosensory cortex of non-human primates is obtained only when a dynamic correlation is introduced, suggesting dynamic variations in connectivity are real. Hum Brain Mapp 37:3897-3910, 2016. © 2016 Wiley Periodicals, Inc.

BackgroundPrevious autism research has hypothesized that abnormalities of functional connectivity in autism spectrum disorder (ASD) may vary with the spatial distance between two brain regions. Although several resting-state functional magnetic resonance imaging (rsfMRI) studies have extensively examined long-range (or distant) connectivity in the adult ASD brain, short-range (or local) connectivity has been investigated in less depth. Furthermore, the possible relationship between functional connectivity and brain activity level during the resting state remains unclear.MethodsWe acquired rsfMRI data from 50 adults with high-functioning ASD and 50 matched controls to examine the properties of spontaneous brain activity using measures of local and distant connectivity together with a measure of the amplitude of brain activity, known as fractional amplitude of low-frequency fluctuation (fALFF). The two connectivity measures were calculated using a common graph-theoretic framework. We also examined the spatial overlaps between these measures and possible relationships of these disrupted functional measures with autistic traits assessed by the Autism-Spectrum Quotient (AQ).ResultsCompared to the controls, participants with ASD exhibited local over-connectivity in the right superior frontal gyrus and middle frontal gyrus, accompanied by local under-connectivity in the bilateral fusiform gyri (FG) and right middle temporal gyrus (MTG). On the other hand, we did not find any significant alterations in distant connectivity. Participants with ASD also exhibited reduced fALFF in the right middle occipital gyrus, lingual gyrus, and FG. Further conjunction and spatial overlap analyses confirmed that the spatial pattern of reduced fALFF substantially overlapped with that of local under-connectivity, demonstrating the co-occurrence of disrupted connectivity and spontaneous activity level in the right inferior occipital gyrus, posterior MTG (pMTG), and FG. Finally, within the ASD group, disrupted local connectivity in the right pMTG significantly correlated with the “social interaction” subscale score of the AQ.ConclusionsThese findings revealed local functional disruptions in the occipital and temporal regions, especially the right FG and pMTG, in the form of co-occurrence of spontaneous brain activity level and local connectivity, which may underline social and communicative dysfunctions in adult ASD.Electronic supplementary materialThe online version of this article (doi:10.1186/s13229-015-0026-z) contains supplementary material, which is available to authorized users.

The relationship between age-related changes in brain structural connectivity (SC) and functional connectivity (FC) with cognition is not well understood. Furthermore, it is not clear whether cognition is represented via a similar spatial pattern of FC and SC or instead is mapped by distinct sets of distributed connectivity patterns. To this end, we used a longitudinal, within-subject, multimodal approach aiming to combine brain data from diffusion-weighted MRI (DW-MRI), and functional MRI (fMRI) with behavioral evaluation, to better understand how changes in FC and SC correlate with changes in cognition in a sample of older adults. FC and SC measures were derived from the multimodal scans acquired at two time points. Change in FC and SC was correlated with 13 behavioral measures of cognitive function using Partial Least Squares Correlation (PLSC). Two of the measures indicate an age-related change in cognition and the rest indicate baseline cognitive performance. FC and SC—cognition correlations were expressed across several cognitive measures, and numerous structural and functional cortical connections, mainly cingulo-opercular, dorsolateral prefrontal, somatosensory and motor, and temporo-parieto-occipital, contributed both positively and negatively to the brain-behavior relationship. Whole-brain FC and SC captured distinct and independent connections related to the cognitive measures. Overall, we examined age-related function-structure associations of the brain in a comprehensive and integrated manner, using a multimodal approach. We pointed out the behavioral relevance of age-related changes in FC and SC. Taken together, our results highlight that the heterogeneity in distributed FC and SC connectivity patterns provide unique information about the variable nature of healthy cognitive aging.

Study objectivesPrimary insomnia (PI) triggers a decline in cognitive function, and the thalamus plays an integral role in this process; however, the mechanisms are unclear. The purpose of this study was to investigate the altered functional connectivity (FC) of the thalamus in PI patients with mild cognitive impairment (MCI) and to explore the potential neural mechanisms of thalamic involvement in these patients.MethodsThis case–control study was conducted in older adults from various communities in Fuzhou, China with a PI diagnosis. These participants underwent neuropsychological assessment and were matched in a 1:2 ratio to the healthy control (HC) group and the PI group according to sex, age, and education level. Resting‐state functional magnetic resonance imaging was used to explore changes in thalamic FC in PI patients. To further compare changes in thalamic and whole‐brain FC, we further divided the PI group into cognitively normal patients and patients with MCI according to the diagnostic criteria for MCI. The relationship between abnormal FC and cognitive function was investigated.ResultsThe 28 HCs and 58 participants with PI showed significant differences in Montreal Cognitive Assessment (MoCA) scores (p = .044). In comparison to the HC group, the PI group showed enhanced FC of the occipital thalamus with the left inferior occipital gyrus, right lingual gyrus, left middle temporal gyrus, left superior marginal gyrus, left dorsolateral superior frontal gyrus, and right anterior central gyrus. The MoCA total score and the executive function, attention, and abstraction scores of PI patients with MCI (PI–MCI) were worse than those of PI patients without MCI. In comparison to the simple PI group, FC was enhanced in the PI–MCI group between the left occipital thalamus and the middle occipital gyrus, and between the right occipital thalamus and the right superior frontal gyrus, left middle frontal gyrus, right superior occipital gyrus, and orbital inferior frontal gyrus. There was a significant negative correlation between the MoCA total score and the enhanced FC between the right occipital thalamus and right superior occipital gyrus (r = −.419, p = .042).ConclusionThe early onset of cognitive impairment in patients with PI is associated with altered FC between the thalamus and the cortex. Enhanced FC between the thalamus and the visual cortex, that is, the superior occipital gyrus, which is involved in attentional processing, may play a role in the early onset of cognitive impairment in insomnia patients. Moreover, due to the fact that PI patients “overdraw” the compensatory capacity of these brain regions earlier, the PI–MCI may fall into the abyss of “decompensation” faster and face more severe cognitive impairments.

Chronic postsurgical pain (CPSP) occurs in up to 50% of individuals after surgeries and 32% after hysterectomy, leading to major adverse effects on quality of life and socioeconomic burden. Little is known about whether and how large-scale neural networks being affected in CPSP, particularly with regard to the functional connectivity (FC) of insula which is known to be the hub of the intrinsic neural network playing a critical role in pain processing. Here, we sought to examine the dynamics of insular FC in the context of noxious stimuli in CPSP patients. To this aim, resting state fMRI data were acquired, before and after acute heat pain stimulation, from 11 individuals with chronic post-hysterectomy pain (CPHP) and 22 age-matched healthy controls (HCs) who had a hysterectomy but without chronic post-surgical pain. We examined whole-brain FC were mapped by seeding at the sensorimotor and chemosensory subfields of the insula and found significant group × stimulation interaction effects. Specifically, the HC group had increased FC between the left sensorimotor insula and right angular and middle occipital gyrus (MOG) and increased FC between the left chemosensory insula and bilateral angular and MOG following pain stimulation. In contrast, such pain stimulation related FC changes were absent in the CPHP group. Furthermore, higher insular FC at baseline and smaller increased insular FC after pain stimulation correlated with clinical pain scores in CPHP patients. Our findings suggest that CPSP is associated with altered dynamics of large-scale functional networks anchored in the insula.

Changes in regional cerebral blood flow and functional connectivity in the cholinergic pathway associated with cognitive performance in subjects with mild Alzheimer's disease after 12-week donepezil treatment

Our objective was to explore the disparities in the intrinsic functional connectivity (FC) patterns of primary visual cortex (V1) between patients with thyroid-associated ophthalmopathy (TAO) and healthy controls (HCs) utilizing resting-state functional MRI. Twenty-one patients with TAO (14 males and 7 females; mean age: 54.17 ± 4.83 years) and 21 well-matched HCs (14 males and 7 females; mean age: 55.17 ± 5.37 years) underwent functional MRI scans in the resting-state. We assessed modifications in the intrinsic FC patterns of the V1 in TAO patients using the FC method. Subsequently, the identified alterations in FC regions in the analysis were selected as classification features to distinguish TAO patients from HCs through the support vector machine (SVM) method. The results indicated that, in comparison to HCs, patients with TAO exhibited notably reduced FC values between the left V1 and the bilateral calcarine (CAL), lingual gyrus (LING) and superior occipital gyrus, as well as between the right V1 and the bilateral CAL/LING and the right cerebellum. Furthermore, the SVM classification model based on FC maps demonstrated effective performance in distinguishing TAO patients from HCs, achieving an accuracy of 61.9% using the FC of the left V1 and 64.29% using the FC of the right V1. Our study revealed that patients with TAO manifested disruptions in FC between the V1 and higher visual regions during rest. This might indicate that TAO patients could present with impaired top-down modulations, visual imagery and vision-motor function. These insights could be valuable in understanding the underlying neurobiological mechanisms of vision impairment in individuals with TAO.

Changes in functional connectivity related to direct training and generalization effects of a word finding treatment in chronic aphasia