Resting-state Function Research Articles

A resting-state fMRI study in borderline personality disorder combining amplitude of low frequency fluctuation, regional homogeneity and seed based functional connectivity

BackgroundThis resting-state fMRI study investigated thebrain function in patients with borderline personality disorder (BPD) with three data-driven algorithms. MethodsForty BPD patients and thirty-five controls were enrolled and scanned with a 3.0T Philips Ingenia scanner. Rs-fMRI and structural images were preprocessed by DPARSF based on SPM8 on the MATLAB platform. To evaluate BPD related brain function alterations comprehensively, we analyzed the amplitude of low frequency fluctuations (ALFF), regional homogeneity (ReHo), and seed based functional connectivity (seed-based FC), three data-driven algorithms of rs-fMRI. Results were multiply corrected by REST AlphaSim program at the level of p<0.05. Meanwhile, the correlation between imaging and psychological data was also performed in BPD patients. ResultsCompared with control group, BPD group showed decreased ALFF and ReHo both in the right posterior cingulate cortex (PCC) and adjacent precuneus. With these two areas as seeds, disturbed functional connectivity mainly distributed in the frontotemporal and limbic structure in BPD group. There were no significant correlations found between imaging variables and psychological data. LimitationsThe sample size was relatively small, and no significant correlations were found between imaging variables and psychological data, which might limit the clinical application of these results. ConclusionsBased on data-driven analysis, we discovered that the right PCC and precuneus were altered in resting state function in BPD. Combining with our previous Voxel Based Morphometry (VBM) study which has found increased gray matter volume (GMV) in the right PCC and precuneus, we confirmed that these two areas were core brain regions altered both in structure and function in BPD.

Altered eigenvector centrality is related to local resting-state network functional connectivity in patients with longstanding type 1 diabetes mellitus.

Longstanding type 1 diabetes (T1DM) is associated with microangiopathy and poorer cognition. In the brain, T1DM is related to increased functional resting-state network (RSN) connectivity in patients without, which was decreased in patients with clinically evident microangiopathy. Subcortical structure seems affected in both patient groups. How these localized alterations affect the hierarchy of the functional network in T1DM is unknown. Eigenvector centrality mapping (ECM) and degree centrality are graph theoretical methods that allow determining the relative importance (ECM) and connectedness (degree centrality) of regions within the whole-brain network hierarchy. Therefore, ECM and degree centrality of resting-state functional MRI-scans were compared between 51 patients with, 53 patients without proliferative retinopathy, and 49 controls, and associated with RSN connectivity, subcortical gray matter volume, and cognition. In all patients versus controls, ECM and degree centrality were lower in the bilateral thalamus and the dorsal striatum, with lowest values in patients without proliferative retinopathy (PFWE < 0.05). Increased ECM in this group versus patients with proliferative retinopathy was seen in the bilateral lateral occipital cortex, and in the right cuneus and occipital fusiform gyrus versus controls (PFWE < 0.05). In all patients, ECM and degree centrality were related to altered visual, sensorimotor, and auditory and language RSN connectivity (PFWE < 0.05), but not to subcortical gray matter volume or cognition (PFDR > 0.05). The findings suggested reorganization of the hierarchy of the cortical connectivity network in patients without proliferative retinopathy, which is lost with disease progression. Centrality seems sensitive to capture early T1DM-related functional connectivity alterations, but not disease progression. Hum Brain Mapp 38:3623-3636, 2017. © 2017 Wiley Periodicals, Inc.

Electroconvulsive therapy changes the regional resting state function measured by regional homogeneity (ReHo) and amplitude of low frequency fluctuations (ALFF) in elderly major depressive disorder patients: An exploratory study

Electroconvulsive therapy (ECT) is the most effective and rapid treatment for severe major depressive disorder (MDD) in elderly patients. The mechanism of ECT is unclear, and studies on ECT in elderly MDD patients by resting-state functional magnetic resonance imaging are rare. Thirteen elderly MDD patients were scanned before and after ECT using a 3.0T MRI scanner. Regional homogeneity (ReHo) and amplitude of low-frequency fluctuations (ALFF) were processed to compare resting-state function before and after treatment. Depression and anxiety symptoms of all patients abated after ECT. Decreased ReHo values in the bilateral superior frontal gyrus (SFG) were observed after ECT, and the values of right SFG significantly correlated with an altered Hamilton depression rating scale score. Increased ALFF values in the left middle frontal gyrus, right middle frontal gyrus, orbital part, and decreased ALFF values in the left midcingulate area, left precentral gyrus, right SFG/middle frontal gyrus after ECT were also observed. These results support the hypothesis that ECT may affect the regional resting state brain function in geriatric MDD patients.

Polymorphism of ERK/PTPRR Genes in Major Depressive Disorder at Resting-State Brain Function

ABSTRACTThe polymorphism of ERK and PTPRR in MDD is rarely reported. The present study investigated the association between the polymorphism of ERK/PTPRR and MDD at resting-state brain function using genomic imaging. It indicated that the amplitude of low-frequency fluctuation (ALFF) and regional homogeneity (ReHo) in functional magnetic resonance imaging (fMRI) changed significantly in various brain regions of MDD patients. The T/G allele of ERK-rs1267842 and G/C allele of PTPRR-rs1513105 showed abnormal ALFF and ReHo changes in cortex including superior frontal gyrus and middle temporal gyrus. The development of MDD may be related with the polymorphism of ERK-rs12678428 and PTPRR-rs1513105.

Altered functional resting-state hypothalamic connectivity and abnormal pituitary morphology in children with Prader-Willi syndrome

BackgroundPrader-Willi syndrome (PWS) is a complex neurodevelopmental disorder, characterized by endocrine problems and hyperphagia, indicating hypothalamic-pituitary dysfunction. However, few studies have explored the underlying neurobiology of the hypothalamus and its functional connectivity with other brain regions. Thus, the aim of this study was to examine the anatomical differences of the hypothalamus, mammillary bodies, and pituitary gland as well as resting state functional connectivity of the hypothalamus in children with PWS.MethodsTwenty-seven children with PWS (13 DEL, 14 mUPD) and 28 typically developing children were included. Manual segmentations by a blinded investigator were performed to determine the volumes of the hypothalamus, mammillary bodies, and pituitary gland. In addition, brain-wide functional connectivity analysis was performed using the obtained masks of the hypothalamus.ResultsChildren with PWS showed altered resting state functional connectivity between hypothalamus and right and left lateral occipital complex, compared to healthy controls. In addition, children with PWS had on average a 50% smaller pituitary volume, an irregular shape of the pituitary, and a longer pituitary stalk. Pituitary volume did not increase in volume during puberty in PWS. No volumetric differences in the hypothalamus and mammillary bodies were found. In all subjects, the posterior pituitary bright spot was observed.ConclusionsWe report altered functional hypothalamic connectivity with lateral occipital complexes in both hemispheres, which are implicated in response to food and reward system, and absence of connectivity might therefore at least partially contribute to the preoccupation with food in PWS.

Frequency-dependent changes in the amplitude of low-frequency fluctuations in patients with Wilson\u2019s disease: a resting-state fMRI study

To investigate the frequency-dependent changes in the amplitude of low-frequency fluctuations (ALFF) in patients with Wilson’s disease (WD). Resting-state function magnetic resonance imaging (R-fMRI) were employed to measure the amplitude of ALFF in 28 patients with WD and 27 matched normal controls. Slow-5 (0.01–0.027 Hz) and slow-4 (0.027–0.073 Hz) frequency bands were analyzed. Apart from the observation of atrophy in the cerebellum, basal ganglia, occipital gyrus, frontal gyrus, precentral gyrus, and paracentral lobule, we also found widespread differences in ALFF of the two bands in the medial frontal gyrus, inferior temporal gyrus, insula, basal ganglia, hippocampus/parahippocampal gyrus, and thalamus bilaterally. Compared to normal controls, WD patients had increased ALFF in the posterior lobe of the cerebellum, inferior temporal gyrus, brain stem, basal ganglia, and decreased ALFF in the anterior lobe of the cerebellum and medial frontal gyrus. Specifically, we observed that the ALFF abnormalities in the cerebellum and middle frontal gyrus were greater in the slow-5 than in the slow-4 band. Correlation analysis showed consistently positive correlations between urinary copper excretion (Cu), serum ceruloplasmin (CP) and ALFFs in the cerebellum. Our study suggests the accumulation of copper profoundly impaired intrinsic brain activity and the impairments seem to be frequency-dependent. These results provide further insights into the understanding of the pathophysiology of WD.

Altered fractional amplitude of low frequency fluctuation associated with cognitive dysfunction in first-episode drug-na\xefve major depressive disorder patients

BackgroundPrevious studies have demonstrated that abnormities of both resting-state brain activity and cognitive dysfunction are frequently observed in patients with major depressive disorder (MDD). However, the underlying relationship between these two aspects is less investigated. In this context, the aim of the present study was to investigate the association between cognitive dysfunction and altered resting-state brain function in first-episode drug-naïve MDD patients.MethodsTwenty-five drug-naïve MDD patients and twenty-six age-, sex-, and education-matched normal controls were recruited in this study. Cognitive function was evaluated by using a series of validated test procedures. The resting-state functional magnetic resonance imaging data were obtained on a Philips 3.0 Tesla scanner and analysed using the fractional amplitude of low frequency fluctuation (fALFF) method. Correlations of fALFF values with cognitive dysfunction were further analysed.ResultsCompared with healthy controls, MDD patients showed significantly fewer completed categories in the Wisconsin Card Sorting Test (WCST) and decreased scores in the first and second subtests of the Continuous Performance Test (CPT). However, the two groups did not differ in their performance on the Stroop Colour Word Test and Trail-making Test. MDD patients exhibited significantly decreased fALFF values in the left superior frontal gyrus (SFG), left middle frontal gyrus, and left inferior frontal gyrus, as well as increased fALFF values in the left inferior temporal gyrus (ITG), bilateral parahippocampal gyrus, and the right caudate. Finally, the correlation analyses revealed that fALFF values in the left SFG and left ITG were associated with the number of WSCT completed categories and scores on the second subtest of the CPT in MDD, respectively.ConclusionsThe present findings suggest that there is little evidence of an association between regional abnormalities in resting-state brain function and cognitive deficits in MDD.

The Effects of Equine-assisted Activities and Therapy on Resting-state Brain Function in Attention-deficit/Hyperactivity Disorder: A Pilot Study.

ObjectiveEquine-assisted activities and therapy (EAA/T) have been used as adjunct treatment options for physical and psychosocial rehabilitation. However, the therapeutic effects on resting-state brain function have not yet been studied. The aim of this study is to investigate the effects of EAA/T on participants with attention-deficit/hyperactivity disorder (ADHD) by comparing resting-state functional magnetic resonance imaging (rs-fMRI) signals and their clinical correlates.MethodsTen participants with ADHD participated in a 12-week EAA/T program without any medication. Two rs-fMRIs were acquired for all participants before and after EAA/T. For estimating therapeutic effect, the regional homogeneity (ReHo) method was applied to capture the changes in the regional synchronization of functional signals.ResultsAfter the EAA/T program, clear symptom improvement was found even without medication. Surface-based pairwise comparisons revealed that ReHo in the right precuneus and right pars orbitalis clusters had significantly diminished after the program. Reduced ReHo in the right precuneus cluster was positively correlated with changes in the scores on DuPaul’s ADHD Rating Scale-Korean version.ConclusionOur results indicate that EAA/T is associated with short-range functional connectivity in the regions related to the default mode network and the behavioral inhibition system, which are associated with symptom improvement.

Changes in functional connectivity of the brain associated with a history of sport concussion: A preliminary investigation

ABSTRACTObjective: There is evidence of long-term clinical consequences associated with a history of sport concussion. However, there remains limited information about the underlying changes in brain function. The goal of this study was to identify brain regions where abnormal resting-state function is associated with chronic concussion, for athletes without persistent symptoms.Methods: Functional Magnetic Resonance Imaging (fMRI) was performed on a group of athletes with prior concussion (n = 22) and a group without documented injury (n = 21). Multivariate predictive modelling was used to localize reliable changes in brain connectivity that are associated with a history of concussion and with clinical factors, including number of prior concussions and recovery time from last injury.Results: No significant differences were found between athletes with and without a history of concussion, but functional connectivity was significantly associated with clinical history. The number of prior concussions was associated with most extensive connectivity changes, particularly for elements of the visual attention network and cerebellum.Conclusion: The findings of this preliminary study indicate that functional brain abnormalities associated with chronic concussion may be significantly dependent on clinical history. In addition, elements of the visual and cerebellar systems may be most sensitive to the long-term effects of sport concussion.

Functional connectivity in the resting brain as biological correlate of the Affective Neuroscience Personality Scales

According to Jaak Panksepp's Affective Neuroscience Theory and the derived self-report measure, the Affective Neuroscience Personality Scales (ANPS), differences in the responsiveness of primary emotional systems form the basis of human personality. In order to investigate neuronal correlates of personality, the underlying neuronal circuits of the primary emotional systems were analyzed in the present fMRI-study by associating the ANPS to functional connectivity in the resting brain. N=120 healthy participants were invited for the present study. The results were reinvestigated in an independent, smaller sample of N=52 participants. A seed-based whole brain approach was conducted with seed-regions bilaterally in the basolateral and superficial amygdalae. The selection of seed-regions was based on meta-analytic data on affective processing and the Juelich histological atlas. Multiple regression analyses on the functional connectivity maps revealed associations with the SADNESS-scale in both samples. Functional resting-state connectivity between the left basolateral amygdala and a cluster in the postcentral gyrus, and between the right basolateral amygdala and clusters in the superior parietal lobe and subgyral in the parietal lobe was associated with SADNESS. No other ANPS-scale revealed replicable results. The present findings give first insights into the neuronal basis of the SADNESS-scale of the ANPS and support the idea of underlying neuronal circuits. In combination with previous research on genetic associations of the ANPS functional resting-state connectivity is discussed as a possible endophenotype of personality.

Fractional amplitude of low-frequency fluctuations in childhood and adolescence-onset schizophrenia: a resting state fMRI study

Objective: To explore the whole brain activity features of childhood and adolescence-onset schizophrenia using resting state fMRI. Methods: A total of 63 childhood and adolescence-onset schizophrenia patients (patients group), admitted to the second affiliated hospital of Xinxiang Medical University from October 2013 to October 2015 and fulfilled our inclusion criteria, and 39 healthy controls with age, sex and education matched (control group) were enrolled, then a resting-state fMRI scan was conducted for each participant. Fractional amplitude of low-frequency fluctuations (fALFF) approach was used to explore the differences of resting-state brain function between patients and controls. Results: Compared with the healthy control group, patients group showed significantly decreased fALFF in left superior temporal gyrus and parietal lobe (MNI coordinate: x=-42, -57; y=-3, -21; z=-12, 9; voxels: 22, 32; t=-4.792 3, -5.269 7; Alphasim corrected, corrected P<0.05); patients group showed significantly increased fALFF in left frontal lobe and medial frontal gyrus, right superior frontal gyrus, Postcentral Gyrus, caudate, (MNI coordinate: x=-42, -21, 12, 27, 15; y=54, 39, 48, -18, 15; z=0, 21, 33, 30, 9; voxels: 12, 21, 17, 28, 18; t=4.784 8, 4.90 7, 4.861 5, 5.444 1, 4.270 4; Alphasim corrected, corrected P<0.05). When included age as a covariant, the analysis found that the brain region with significant fALFF change was the left thalamus with decreased fALFF (MNI coordinate: x=-6, y=-12, z=24; voxels: 9; t=-4.268 4; Alphasim corrected, corrected P<0.05) in patients group, while for other brain regions, there was no obvious change in the fALFF, compared with healthy group. Conclusion: Compared with control group, the results indicate that there are intrinsic brain activity abnormalities of some brain regions in childhood and adolescence-onset schizophrenia.

Study on regional homogeneity and low frequency amplitude of brain resting state functional magnetic resonance imaging in patients with depression

Objective To explore the abnormally functional brain regions of female patients with depression by resting state functional magnetic resonance imaging(fMRI), and analyze the correlation with the severity of depressive symptoms. Methods 32 female patients diagnosed with depressive disorder and 40 matched healthy controls completed resting state fMRI scans. The whole brain’s regional homogeneity (ReHo) and amplitude of low-frequency fluctuation(ALFF) were calculated, and the correlation analysis between ReHo and ALFF of brain regions with significant difference and the severity of depressive symptoms was conducted. Results Compared with control group, the left precuneus/left cuneus(MNI: -18, -81, 45), bilateral precentral gyrus(MNI: -58, -5, 35 and 57, -6, 33), left inferior parietal lobule(MNI: -42, -36, 45) and right inferior temporal gyrus(MNI: 60, -45, -18)(P<0.05, corrected by AlphaSim)in the case group showed significantly decreased ReHo, with statistical significance. Compared with control group, the left cuneus(MNI: -3, -87, 30), right inferior temporal gyrus(MNI: 60, -48, -18) and left precentral gyrus(MNI: -63, -3, 26)(P<0.05, corrected by AlphasSim)in the case group showed significantly decreased ALFF. The ReHo in the right inferior temporal gyrus was negative correlated with the HAMD-17 total score and retardation factor(r=-0.484, P=0.017; r=-0.408, P=0.048), the ALFF in the right inferior temporal gyrus was positively correlated with weight factor(r=0.574, P=0.003), and negative correlated with the number of depressive episodes(r=-0.416, P=0.043). Conclusion Female with depression in resting state have several abnormally functional brain regions and the extent of damage is correlated with the severity of depressive symptoms.Combination of the two parameters may yield a more comprehensive pathophy-siological mechanism for depressive disorder. Key words: Depressive disorder; Gender; Resting-state function magnetic resonance imaging; Regional homogeneity; Low frequency amplitude

Feeling, learning from and being aware of inner states: interoceptive dimensions in neurodegeneration and stroke.

Interoception is a complex process encompassing multiple dimensions, such as accuracy, learning and awareness. Here, we examined whether each of those dimensions relies on specialized neural regions distributed throughout the vast interoceptive network. To this end, we obtained relevant measures of cardiac interoception in healthy subjects and patients offering contrastive lesion models of neurodegeneration and focal brain damage: behavioural variant fronto-temporal dementia (bvFTD), Alzheimer's disease (AD) and fronto-insular stroke. Neural correlates of the three dimensions were examined through structural and functional resting-state imaging, and online measurements of the heart-evoked potential (HEP). The three patient groups presented deficits in interoceptive accuracy, associated with insular damage, connectivity alterations and abnormal HEP modulations. Interoceptive learning was differentially impaired in AD patients, evidencing a key role of memory networks in this skill. Interoceptive awareness results showed that bvFTD and AD patients overestimated their performance; this pattern was related to abnormalities in anterior regions and associated networks sub-serving metacognitive processes, and probably linked to well-established insight deficits in dementia. Our findings indicate how damage to specific hubs in a broad fronto-temporo-insular network differentially compromises interoceptive dimensions, and how such disturbances affect widespread connections beyond those critical hubs. This is the first study in which a multiple lesion model reveals fine-grained alterations of body sensing, offering new theoretical insights into neuroanatomical foundations of interoceptive dimensions.This article is part of the themed issue 'Interoception beyond homeostasis: affect, cognition and mental health'.

Altered resting-state regional homogeneity after 13 weeks of paliperidone injection treatment in schizophrenia patients

This study aimed to explore the effects of the long-acting antipsychotic drug palmitate paliperidone in resting-state brain activity of schizophrenia patients. Seventeen schizophrenia outpatients were included and received palmitate paliperidone injection (PAL) treatment for 13 weeks. These patients were compared to seventeen matched healthy controls. All subjects underwent two scan sessions of resting-state magnetic resonance imaging (baseline and the 13th week) and regional homogeneity (ReHo) at resting-state where compared. After 13 weeks of treatment, PAL increased ReHo of the prefrontal cortex, anterior cingulate gyrus and orbital frontal gyrus, while PAL decreased ReHo of the thalamus, parahippocampal gyrus and superior temporal gyrus. Furthermore, improvement of psychiatric symptoms correlated with changing amplitude of ReHo: positively correlated with postcentral gyrus and negatively correlated with the occipital cortex. Baseline ReHo values of the middle occipital gyrus were positively correlated with the rate of reduction of psychiatric symptoms and improvement of social function. These results suggested that PAL might achieve its clinical effect in schizophrenia by influencing the resting-state function of the occipital cortex, lateral prefrontal cortex and temporal lobe. Baseline function of the inferior occipital gyrus might potentially predict the short-term effect of PAL in schizophrenia.

A resting-state fMRI study of obese females between pre- and postprandial states before and after bariatric surgery.

Past studies utilizing resting-state functional MRI (rsfMRI), have shown that obese humans exhibit altered activity in brain areas related to reward compared to normal-weight controls. However, to what extent bariatric surgery-induced weight loss alters resting-state brain activity in obese humans is less well-studied. Thus, we measured the fractional amplitude of low-frequency fluctuations from eyes-closed, rsfMRI in obese females (n=11, mean age=42years, mean BMI=41kg/m2 ) in both a pre- and postprandial state at two time points: four weeks before, and four weeks after bariatric surgery. Several brain areas showed altered resting-state activity following bariatric surgery, including the putamen, insula, cingulate, thalamus and frontal regions. Activity augmented by surgery was also dependent on prandial state. For example, in the fasted state, activity in the middle frontal and pre- and postcentral gyri was found to be decreased after surgery. In the sated state, activity within the insula was increased before, but not after surgery. Collectively, our results suggest that resting-state neural functions are rapidly affected following bariatric surgery and the associated weight loss and change in diet.

Thalamo-cortical network activity between migraine attacks: Insights from MRI-based microstructural and functional resting-state network correlation analysis.

BackgroundResting state magnetic resonance imaging allows studying functionally interconnected brain networks. Here we were aimed to verify functional connectivity between brain networks at rest and its relationship with thalamic microstructure in migraine without aura (MO) patients between attacks.MethodsEighteen patients with untreated MO underwent 3 T MRI scans and were compared to a group of 19 healthy volunteers (HV). We used MRI to collect resting state data among two selected resting state networks, identified using group independent component (IC) analysis. Fractional anisotropy (FA) and mean diffusivity (MD) values of bilateral thalami were retrieved from a previous diffusion tensor imaging study on the same subjects and correlated with resting state ICs Z-scores.ResultsIn comparison to HV, in MO we found significant reduced functional connectivity between the default mode network and the visuo-spatial system. Both HV and migraine patients selected ICs Z-scores correlated negatively with FA values of the thalamus bilaterally.ConclusionsThe present results are the first evidence supporting the hypothesis that an abnormal resting within networks connectivity associated with significant differences in baseline thalamic microstructure could contribute to interictal migraine pathophysiology.

Effectiveness of cognitive-coping therapy and alteration of resting-state brain function in obsessive-compulsive disorder

BackgroundCognitive-coping therapy (CCT), integrating cognitive theory with stress-coping theory, is an efficacious therapy for obsessive-compulsive disorder (OCD). However, the potential brain mediation for the effectiveness remains unclear. We sought to investigate differences of resting-state brain function between OCD and healthy controls and if such differences would be changed by a four-week CCT. Patients and methodsThirty-one OCD patients were recruited and randomized into CCT (n=15) and pharmacotherapy plus CCT (pCCT, n=16) groups, together with 25 age-, gender- and education-matched healthy controls. The Yale-Brown Obsessive Compulsive Scale (Y-BOCS) was scored to evaluate the severity in symptoms. Resting-state functional magnetic resonance imaging was scanned pre- and post-treatment. ResultsFor patients, Y-BOCS scores were reduced during four-week treatment for CCT and pCCT (P<0.001), but no group difference was observed. No differences in amplitude of low-frequency fluctuation (ALFF) values were found between CCT and pCCT either pre- or post-treatment. Compared to controls, ALFF in OCD patients was higher in the left hippocampus, parahippocampus, and temporal lobes, but lower in the right orbitofrontal cortex, rectus, bilateral calcarine, cuneus, lingual, occipital, left parietal, postcentral, precentral, and parietal (corrected P<0.05). The ALFF in those regions was not significantly correlated to the severity of OCD symptoms. After a 4-week treatment, the ALFF differences between OCD patients and controls disappeared. LimitationsThe pharmacotherapy group was not included since OCD patients generally do not respond to pharmacotherapy in four weeks. ConclusionsOur data indicated that resting-state brain function was different between OCD and controls; such differences disappeared after OCD symptoms were relieved.

Thalamo-cortical network activity during spontaneous migraine attacks.

We used MRI to search for changes in thalamo-cortical networks and thalamic microstructure during spontaneous migraine attacks by studying at the same time structure with diffusion tensor imaging and resting state function in interconnected brain networks with independent component analysis. Thirteen patients with untreated migraine without aura (MI) underwent 3T MRI scans during an attack and were compared to a group of 19 healthy controls (HC). We collected resting state data in 2 selected networks identified using group independent component (IC) analysis. Fractional anisotropy (FA) values of bilateral thalami were calculated in the same participants and correlated with resting state IC z scores. Functional connectivity between the executive and the dorso-ventral attention networks was reduced in MI compared to HC. In HC, but not in MI, the higher the IC24 z score, encompassing interconnected areas of the dorso-ventral attention system, the lower the bilateral thalamic FA values. In patients, the higher the executive control network z scores, the lower the number of monthly migraine days. These results provide evidence for abnormal connectivity between the thalamus and attentional cerebral networks at rest during migraine attacks. This abnormality could subtend the known ictal impairment of cognitive performance and suggests that the latter might worsen with increasing attack frequency.

Progressively Disrupted Intrinsic Functional Connectivity of Basolateral Amygdala in Very Early Alzheimer's Disease.

Very early Alzheimer’s disease (AD) – i.e., AD at stages of mild cognitive impairment (MCI) and mild dementia – is characterized by progressive structural and neuropathologic changes, such as atrophy or tangle deposition in medial temporal lobes, including hippocampus and entorhinal cortex and also adjacent amygdala. While progressively disrupted intrinsic connectivity of hippocampus with other brain areas has been demonstrated by many studies, amygdala connectivity was rarely investigated in AD, notwithstanding its known relevance for emotion processing and mood disturbances, which are both important in early AD. Intrinsic functional connectivity (iFC) patterns of hippocampus and amygdala overlap in healthy persons. Thus, we hypothesized that increased alteration of iFC patterns along AD is not limited to the hippocampus but also concerns the amygdala, independent from atrophy. To address this hypothesis, we applied structural and functional resting-state MRI in healthy controls (CON, n = 33) and patients with AD in the stages of MCI (AD-MCI, n = 38) and mild dementia (AD-D, n = 36). Outcome measures were voxel-based morphometry (VBM) values and region-of-interest-based iFC maps of basolateral amygdala, which has extended cortical connectivity. Amygdala VBM values were progressively reduced in patients (CON > AD-MCI and AD-D). Amygdala iFC was progressively reduced along impairment severity (CON > AD-MCI > AD-D), particularly for hippocampus, temporal lobes, and fronto-parietal areas. Notably, decreased iFC was independent of amygdala atrophy. Results demonstrate progressively impaired amygdala intrinsic connectivity in temporal and fronto-parietal lobes independent from increasing amygdala atrophy in very early AD. Data suggest that early AD disrupts intrinsic connectivity of medial temporal lobe key regions, including that of amygdala.

Fluctuations in Global Brain Activity Are Associated With Changes in Whole-Brain Connectivity of Functional Networks

The aim of this study was to explore the relationship between global brain activity, changes in whole-brain connectivity, and changes in brain states across subjects using resting-state functional magnetic resonance imaging. We extended current methods that use a sparse set of coactivation patterns to extract critical time points in global brain activity. Critical activity time points were defined as points where the global signal is greater than one standard deviation above or below the average global signal. Four categories of critical points were defined along dimensions of global signal intensity and trajectory. Voxel-based methods were used to interrogate differences in connectivity between these critical points. Several differences in connectivity were found in functional resting-state networks (RSNs) as a function of global activity. RSNs associated with cognitive functions in frontal, parietal, and subcortical regions exhibited greater whole-brain connectivity during lower global activity states. Meanwhile, RSNs associated with sensory functions exhibited greater whole-brain connectivity during the higher global activity states. Moreover, we present evidence that these results depend in part upon the standard deviation threshold used to define the critical points, suggesting critical points at different thresholds represent unique brain states. Overall, the findings support the hypothesis that the brain oscillates through different states over the course of a resting-state study reflecting differences in RSN connectivity associated with global brain activity. Increased understanding of brain dynamics may help to elucidate individual differences in behavior and dysfunction.