Most recent paper

Interhemispheric resting-state functional connectivity abnormalities in type 2 diabetes patients

Fri, 08/06/2021 - 18:00

Ann Palliat Med. 2021 Jul;10(7):8123-8133. doi: 10.21037/apm-21-1655.

ABSTRACT

BACKGROUND: There has been a considerable focus on the changes of functional connections between brain regions in patients with type 2 diabetes mellitus (T2DM) by previous resting-state functional magnetic resonance imaging (rs-fMRI) studies. However, little is known about the function of brain information integration between the two hemispheres of the brain. This study explores differences in interhemispheric coordination between T2DM patients and normal control (NC) subjects using the voxel-mirrored homotopic connectivity (VMHC) method. We also assess whether differences in VMHC were relevant to cognitive dysfunction in T2DM patients.

METHODS: Sixty-nine T2DM patients and 69 NC subjects were enrolled (matched for age, sex and education level). All participants underwent cognitive assessments. VMHC between brain regions was obtained by rs-fMRI analysis. Partial correlation analysis (after controlling for age, sex and education level) was used to explore the correlation between VMHC value and neuropsychological tests.

RESULTS: Compared with NC subjects, T2DM patients exhibited significantly lower VMHC in the medial orbitofrontal gyrus cortex (mOFC), anterior cingulate gyrus, inferior parietal lobe, superior and middle temporal gyrus (MTG), middle occipital gyrus, and superior occipital gyrus. Moreover, after applying Bonferroni correction, the Montreal Cognitive Assessment (MoCA) score and VMHC value for the MTG were significantly positively correlated in T2DM patients. In contrast, T2DM patients exhibited higher VMHC in the cerebellum posterior lobe and tonsil and inferior temporal gyrus than the NCs.

CONCLUSIONS: Our study indicates that functional coordination between homotopic brain regions is generally impaired in T2DM patients. In brain regions with decreased VMHC in the default mode network (DMN), MTG impairment could serve as a critical node for T2DM-related cognitive dysfunction. Furthermore, the increased VMHC observed in the cerebellum and inferior temporal gyrus might indicate a functional coordination mechanism.

PMID:34353097 | DOI:10.21037/apm-21-1655

Characterization of cognitive function in survivors of diffuse gliomas using resting-state functional MRI (rs-fMRI)

Thu, 08/05/2021 - 18:00

Brain Imaging Behav. 2021 Aug 5. doi: 10.1007/s11682-021-00497-6. Online ahead of print.

ABSTRACT

As treatments for diffuse gliomas have advanced, survival for patients with gliomas has also increased. However, there remains limited knowledge on the relationships between brain connectivity and the lasting changes to cognitive function that glioma survivors often experience long after completing treatment. This resting-state functional magnetic resonance imaging (rs-fMRI) study explored functional connectivity (FC) alterations associated with cognitive function in survivors of gliomas. In this pilot study, 22 patients (mean age 43.8 ± 11.9) with diffuse gliomas who completed treatment within the past 10 years were evaluated using rs-fMRI and neuropsychological measures. Novel rs-fMRI analysis methods were used to account for missing brain in the resection cavity. FC relationships were assessed between cognitively impaired and non-impaired glioma patients, along with self-reported cognitive impairment, non-work daily functioning, and time with surgery. In the cognitively non-impaired patients, FC was stronger in the medial prefrontal cortex, rostral prefrontal cortex, and intraparietal sulcus compared to the impaired survivors. When examining non-work daily functioning, a positive correlation with FC was observed between the accumbens and the intracalcarine cortices, while a negative correlation with FC was observed between the parietal operculum cortex and the cerebellum. Additionally, worse self-reported cognitive impairment and worse non-work daily functioning were associated with increased FC between regions involved in cognition and sensorimotor processing. These preliminary findings suggest that neural correlates for cognitive and daily functioning in glioma patients can be revealed using rs-fMRI. Resting-state network alterations may serve as a biomarker for patients' cognition and functioning.

PMID:34350525 | DOI:10.1007/s11682-021-00497-6

Brain function state in different phases and its relationship with clinical symptoms of migraine: an fMRI study based on regional homogeneity (ReHo)

Thu, 08/05/2021 - 18:00

Ann Transl Med. 2021 Jun;9(11):928. doi: 10.21037/atm-21-2097.

ABSTRACT

BACKGROUND: Using fMRI to analysis of brain function state in migraineurs at different phases, and combined with the clinical symptoms to explore the mechanisms and outcomes of migraine.

METHODS: It's a case-control study. We analyzed the resting-state brain functional magnetic resonance imaging in 19 patients with episodes, 22 patients with interictal phase, and 22 healthy controls. The ReHo method was used for post-processing. All subjects were evaluated using the Montreal cognitive assessment (MoCA) scale, simple mental state examination (MMSE), Hamilton anxiety (HAMA) scale, and Hamilton depression (HAMD) scale. The subjects' clinical indicators (such as frequency of attack, course of disease, duration of each headache, and severity of headache) were correlated with the ReHo values of brain regions. This study was approved by the ethics committee of Yangtze River Shipping General Hospital.

RESULTS: Compared with the interictal, patients in the episode group had lower activation in bilateral anterior cingulate cortex (ACC), with Montreal Neurological Institute (MNI) (-9, 42, 15); and had stronger activation in bilateral paracentral lobule (PCL), with MNI (-3, -24, 66). Compared with the control group, patients in interictal phase had lower activation in the bilateral cuneus and bilateral lingual gyrus, with MNI scores of (9, -84, 36) and (0, -72, 6), respectively. No significant difference in brain area was found between the episodes group and the control group. In the episodes group, a significant correlation was observed between attack frequency and ReHo value of the bilateral PCL (r=0.492; P=0.038).

CONCLUSIONS: We need to observe the course of migraine as a whole. In the interictal period, the cuneus and lingual gyrus may affect the development of the disease. The ACC regulates different states of migraine by inducing anti-injury sensation regulation function. The paracentric lobule is not only associated with migraine attacks, but also with the frequency. This may have an effect on the outcome of subsequent migraines, as well as whether the condition becomes chronic, and the remodeling of the brain.

PMID:34350243 | PMC:PMC8263876 | DOI:10.21037/atm-21-2097

Modulation of Working Memory and Resting-State fMRI by tDCS of the Right Frontoparietal Network

Thu, 08/05/2021 - 18:00

Neural Plast. 2021 Jul 26;2021:5594305. doi: 10.1155/2021/5594305. eCollection 2021.

ABSTRACT

Many cognitive functions, including working memory, are processed within large-scale brain networks. We targeted the right frontoparietal network (FPN) with one session of transcranial direct current stimulation (tDCS) in an attempt to modulate the cognitive speed of a visual working memory task (WMT) in 27 young healthy subjects using a double-blind crossover design. We further explored the neural underpinnings of induced changes by performing resting-state fMRI prior to and immediately after each stimulation session with the main focus on the interaction between a task-positive FPN and a task-negative default mode network (DMN). Twenty minutes of 2 mA anodal tDCS was superior to sham stimulation in terms of cognitive speed manipulation of a subtask with processing of objects and tools in unconventional views (i.e., the higher cognitive load subtask of the offline WMT). This result was linked to the magnitude of resting-state functional connectivity decreases between the stimulated FPN seed and DMN seeds. We provide the first evidence for the action reappraisal mechanism of object and tool processing. Modulation of cognitive speed of the task by tDCS was reflected by FPN-DMN cross-talk changes.

PMID:34349797 | PMC:PMC8328716 | DOI:10.1155/2021/5594305

Dynamic Altered Amplitude of Low-Frequency Fluctuations in Patients With Major Depressive Disorder

Thu, 08/05/2021 - 18:00

Front Psychiatry. 2021 Jul 19;12:683610. doi: 10.3389/fpsyt.2021.683610. eCollection 2021.

ABSTRACT

Background: Major depressive disorder (MDD) has demonstrated abnormalities of static intrinsic brain activity measured by amplitude of low-frequency fluctuation (ALFF). Recent studies regarding the resting-state functional magnetic resonance imaging (rs-fMRI) have found the brain activity is inherently dynamic over time. Little is known, however, regarding the temporal dynamics of local neural activity in MDD. Here, we investigated whether temporal dynamic changes in spontaneous neural activity are influenced by MDD. Methods: We recruited 81 first-episode, drug-naive MDD patients and 64 age-, gender-, and education-matched healthy controls who underwent rs-fMRI. A sliding-window approach was then adopted for the estimation of dynamic ALFF (dALFF), which was used to measure time-varying brain activity and then compared between the two groups. The relationship between altered dALFF variability and clinical variables in MDD patients was also analyzed. Results: MDD patients showed increased temporal variability (dALFF) mainly focused on the bilateral thalamus, the bilateral superior frontal gyrus, the right middle frontal gyrus, the bilateral cerebellum posterior lobe, and the vermis. Furthermore, increased dALFF variability values in the right thalamus and right cerebellum posterior lobe were positively correlated with MDD symptom severity. Conclusions: The overall results suggest that altered temporal variability in corticocerebellar-thalamic-cortical circuit (CCTCC), involved in emotional, executive, and cognitive, is associated with drug-naive, first-episode MDD patients. Moreover, our study highlights the vital role of abnormal dynamic brain activity in the cerebellar hemisphere associated with CCTCC in MDD patients. These findings may provide novel insights into the pathophysiological mechanisms of MDD.

PMID:34349681 | PMC:PMC8328277 | DOI:10.3389/fpsyt.2021.683610

Altered Functional Connectivity of the Salience Network in Problematic Smartphone Users

Thu, 08/05/2021 - 18:00

Front Psychiatry. 2021 Jul 19;12:636730. doi: 10.3389/fpsyt.2021.636730. eCollection 2021.

ABSTRACT

Smartphones provide convenience in everyday life. Smartphones, however, can elicit adverse effects when used excessively. The purpose of this study was to examine the underlying neurobiological alterations that arise from problematic smartphone use. We performed resting state seed-based functional connectivity (FC) analysis of 44 problematic smartphone users and 54 healthy controls. This analysis assessed the salience, central executive, default mode, and affective networks. Compared to controls, problematic smartphone users showed enhanced FC within the salience network and between the salience and default mode network. Moreover, we observed decreased FC between the salience and central executive network in problematic smartphone users, compared to controls. These results imply that problematic smartphone use is associated with aberrant FC in key brain networks. Our results suggest that changes in FC of key networks centered around the salience network might be associated with problematic smartphone use.

PMID:34349676 | PMC:PMC8326368 | DOI:10.3389/fpsyt.2021.636730

Brain reactivity to emotional stimuli in women with premenstrual dysphoric disorder and related personality characteristics

Thu, 08/05/2021 - 18:00

Aging (Albany NY). 2021 Aug 4;13(undefined). doi: 10.18632/aging.203363. Online ahead of print.

ABSTRACT

AIMS: Premenstrual dysphoric disorder (PMDD) is a psychiatric condition that is associated with the menstrual cycle. Elucidation of the neural regulation mechanisms of brain reactivity to emotional stimuli among women with PMDD may inform PMDD treatment.

METHODS: Eighty-six women (42 PMDD, 44 healthy controls) were allocated into two groups (anger-induced group: 23 PMDD vs. 23 controls; depression-induced group: 19 PMDD vs. 21 controls). During the luteal phases of the menstrual cycle, all the women were subjected to functional magnetic resonance imaging (fMRI). fMRI resting-state scans were performed before and after the study participants had performed an emotional stimuli task. After the emotional stimuli task, emotional status of the participants were evaluated by Self-Rating Depression Scales (SDS) and Trait Anger Expression Inventory-II (STAXI-II). In addition, all the participants were requested to complete the Eysenck Personality Questionnaire (EPQ) and the Twenty-Item Toronto Alexithymia Scale (TAS-20).

RESULTS: Compared to healthy controls, all women with PMDD exhibited significantly high scores in Tas-20 (p<0.001), higher neuroticism and psychoticism scores as well as significantly low extraversion and social desirability scores (p<0.05). Compared to the controls, f-MRI revealed that PMDD women had elevated ReHo in the middle frontal gyrus (BA10), temporal lobe (BA42), left cerebellum (BA37), as well as decreased activation in the precuneus (BA7), superior frontal gyrus (BA8), lobulus paracentralis (BA6), and right cerebellum (BA48) (p<0.05). Moreover, depression stimuli showed that women with PMDD had elevated ReHo levels in the middle frontal gyrus (BA11), the middle gyrus (BA47) and in the cingulate gyrus (BA23) vs. healthy controls (p<0.05).

CONCLUSIONS: Women with more neuroticism and psychoticism, less extraversion and social desirability tend to report PMDD symptoms. Women with this condition experience difficulties in regulating emotions during the luteal phase of the menstrual cycle. Abnormal ReHo levels in the precuneus, superior frontal gyrus, lobulus paracentralis, and right cerebellum may contribute to anger dysregulation. Hypoactivation in the middle frontal gyrus, the middle gyrus and the cingulate gyrus may be generally associated with depression dysregulation in PMDD.

PMID:34349039 | DOI:10.18632/aging.203363

Using Electronically Delivered Therapy and Brain Imaging to Understand OCD Pathophysiology: Pilot Protocol

Thu, 08/05/2021 - 18:00

JMIR Res Protoc. 2021 Jul 29. doi: 10.2196/30726. Online ahead of print.

ABSTRACT

BACKGROUND: Obsessive-compulsive disorder (OCD) is a debilitating and prevalent anxiety disorder. While the basal ganglia and frontal cortex are the most hypothesized brain regions involved, the exact pathophysiology is unknown. By observing the effects of proven treatments on brain activation levels, the cause of OCD can be better understood. Currently, the gold standard treatment for OCD is cognitive behavioural therapy (CBT) with exposure and response prevention (ERP). However, this is often temporally and geographically inaccessible, time-consuming, and costly. Fortunately, CBT can be effectively delivered using the internet (e-CBT) due to its structured nature thus addressing these barriers.

OBJECTIVE: This study will implement an e-CBT program for OCD and observe its effects on brain activation levels using functional magnetic resonance imaging (fMRI). It is hypothesized that brain activation levels in the basal ganglia and frontal cortex will decrease following treatment.

METHODS: Individuals with OCD will be offered a 16-week e-CBT program with ERP mirroring in-person CBT content that will be administered through a secure online platform. Efficacy of treatment will be evaluated using clinically validated symptomology questionnaires at baseline, week 8, and post-treatment (week 16). Using fMRI at baseline and post-treatment, brain activation levels will be assessed at resting state, and while exposed to anxiety-inducing images (i.e., dirty dishes if cleanliness is an obsession). The effects of treatment on brain activation levels and the correlation between symptom changes and activation levels will be analyzed.

RESULTS: The study received initial ethics approval in December 2020 and participant recruitment began in January 2021. Participant recruitment has been conducted through social media advertisements, physical advertisements, and physician referrals. To date, there have been 5 participants recruited. Data collection is expected to conclude by January 2022, and data analysis is expected to be completed by February 2022.

CONCLUSIONS: The findings from this study can further our understanding of the causation of OCD, helping to develop more effective treatments for this disorder.

CLINICALTRIAL: ClinicalTrials.gov NCT04630197; clinicaltrials.gov/ct2/show/NCT04630197.

PMID:34348889 | DOI:10.2196/30726

Early motor network connectivity after stroke: An interplay of general reorganization and state-specific compensation

Wed, 08/04/2021 - 18:00

Hum Brain Mapp. 2021 Aug 4. doi: 10.1002/hbm.25612. Online ahead of print.

ABSTRACT

Motor recovery after stroke relies on functional reorganization of the motor network, which is commonly assessed via functional magnetic resonance imaging (fMRI)-based resting-state functional connectivity (rsFC) or task-related effective connectivity (trEC). Measures of either connectivity mode have been shown to successfully explain motor impairment post-stroke, posing the question whether motor impairment is more closely reflected by rsFC or trEC. Moreover, highly similar changes in ipsilesional and interhemispheric motor network connectivity have been reported for both rsFC and trEC after stroke, suggesting that altered rsFC and trEC may capture similar aspects of information integration in the motor network reflecting principle, state-independent mechanisms of network reorganization rather than state-specific compensation strategies. To address this question, we conducted the first direct comparison of rsFC and trEC in a sample of early subacute stroke patients (n = 26, included on average 7.3 days post-stroke). We found that both rsFC and trEC explained motor impairment across patients, stressing the clinical potential of fMRI-based connectivity. Importantly, intrahemispheric connectivity between ipsilesional M1 and premotor areas depended on the activation state, whereas interhemispheric connectivity between homologs was state-independent. From a mechanistic perspective, our results may thus arise from two distinct aspects of motor network plasticity: task-specific compensation within the ipsilesional hemisphere and a more fundamental form of reorganization between hemispheres.

PMID:34346531 | DOI:10.1002/hbm.25612

Subcortical structures and visual divergent thinking: a resting-state functional MRI analysis

Tue, 08/03/2021 - 18:00

Brain Struct Funct. 2021 Aug 3. doi: 10.1007/s00429-021-02355-z. Online ahead of print.

ABSTRACT

An increasing number of studies have found that a few, specific subcortical regions are involved in creative visual divergent thinking. In addition, creative thinking is heavily reliant on the fronto-striatal dopaminergic pathways. This study aimed to explore whether spontaneous fluctuations in the subcortex, which contribute to our creative abilities, showed significant differences between individuals with different levels of creativity based on resting-state functional magnetic resonance imaging data. We calculated subcortical regions' seed-wise and dynamic functional connectivity (dFC), and then examined the differences between the high and low visual creativity groups. Furthermore, the topological properties of the subcortical network were measured, and their relationship with creative visual divergent thinking was calculated using brain-behavior correlation analyses. The results showed that functional connectivity (FC) between the putamen, pallidum, and thalamus indicated group differences within the subcortex. Whole-brain FC results showed group differences across subcortical (i.e., the thalamus and pallidum) and cerebral regions (i.e., the insula, middle frontal gyrus, and middle temporal gyrus). In addition, subcortical FC demonstrated a positive correlation with visual divergent thinking scores across the pallidum, putamen, and thalamus. Our findings provide novel insights into the relationship between visual divergent thinking and the activities of the subcortex. It is likely that not only fronto-striatal dopaminergic pathways, but also "motor" pathways, are involved in creative visual divergent thinking processing.

PMID:34342689 | DOI:10.1007/s00429-021-02355-z

Structural and functional brain connectivity in moderate-late preterm infants with low-grade intraventricular hemorrhage

Tue, 08/03/2021 - 18:00

Neuroradiology. 2021 Aug 3. doi: 10.1007/s00234-021-02770-3. Online ahead of print.

ABSTRACT

PURPOSE: Brain functional connectivity (FC) changes and microstructural abnormalities are reported in infants born moderate and late preterm (MLPT). We evaluated the effect of low-grade (grades I, II) intraventricular hemorrhage (IVH) in MLPT babies on brain structural connectivity (SC) and FC.

METHODS: Babies born MLPT between January 2014 and May 2017 underwent brain ultrasound (US) at 72 h and 7 days after birth, and MRI at around term equivalent. The MRI protocol comprised T1- and T2-weighted sequences, diffusion tensor imaging (DTI), and resting-state functional MRI (fMRI). SC and FC were assessed using graph analysis.

RESULTS: Of 350 MLPT neonates, 15 showed low-grade IVH on US at 72 h, for which brain MRI was available in 10. These 10 infants, with mean gestational age (GA) 34.0 ± 0.8 weeks, comprised the study group, and 10 MLPT infants of mean GA 33.9 ± 1.1 weeks, with no abnormalities on brain US and MRI, were control subjects. All study subjects presented modularity, small world topology, and rich club organization for both SC and FC. The patients with low-grade IVH had lower FC rich club coefficient and lower SC betweenness centrality in the left frontoparietal operculum, and lower SC rich club coefficient in the right superior orbitofrontal cortex than the control subjects.

CONCLUSIONS: Topological and functional properties of mature brain connectivity are present in MLPT infants. IVH in these infants was associated with structural and functional abnormalities in the left frontoparietal operculum and right orbitofrontal cortex, regions related to language and cognition.

PMID:34342681 | DOI:10.1007/s00234-021-02770-3

Physiological and motion signatures in static and time-varying functional connectivity and their subject identifiability

Tue, 08/03/2021 - 18:00

Elife. 2021 Aug 3;10:e62324. doi: 10.7554/eLife.62324. Online ahead of print.

ABSTRACT

Human brain connectivity yields significant potential as a noninvasive biomarker. Several studies have used fMRI-based connectivity fingerprinting to characterize individual patterns of brain activity. However, it is not clear whether these patterns mainly reflect neural activity or the effect of physiological and motion processes. To answer this question, we capitalize on a large data sample from the Human Connectome Project and rigorously investigate the contribution of the aforementioned processes on functional connectivity (FC) and time-varying FC, as well as their contribution to subject identifiability. We find that head motion, as well as heart rate and breathing fluctuations, induce artifactual connectivity within distinct resting-state networks and that they correlate with recurrent patterns in time-varying FC. Even though the spatiotemporal signatures of these processes yield above-chance levels in subject identifiability, removing their effects at the preprocessing stage improves identifiability, suggesting a neural component underpinning the inter-individual differences in connectivity.

PMID:34342582 | DOI:10.7554/eLife.62324

Disruptions in global network segregation and integration in adolescents and young adults with fetal alcohol spectrum disorder

Tue, 08/03/2021 - 18:00

Alcohol Clin Exp Res. 2021 Aug 2. doi: 10.1111/acer.14673. Online ahead of print.

ABSTRACT

BACKGROUND: Fetal alcohol spectrum disorder (FASD) is a significant public health problem that is associated with a broad range of physical, neurocognitive, and behavioral effects resulting from prenatal alcohol exposure (PAE). Magnetic resonance imaging (MRI) has been an important tool for advancing our knowledge of abnormal brain structure and function in individuals with FASD. However, whereas only a small number of studies have applied graph theory-based network analysis to resting-state functional MRI (fMRI) data in individuals with FASD additional research in this area is needed.

METHODS: Resting-state fMRI data were collected from adolescent and young adult participants (ages 12-22) with fetal alcohol syndrome (FAS) or alcohol-related neurodevelopmental disorder (ARND) and neurotypically developing controls (CNTRL) from previous studies. Group independent components analysis (gICA) was applied to fMRI data to extract components representing functional brain networks. Functional network connectivity (FNC), measured by Pearson correlation of the average independent component (IC) time series, was analyzed under a graph theory framework to compare network modularity, the average clustering coefficient, characteristic path length, and global efficiency between groups. Cognitive intelligence, measured by the Wechsler Abbreviated Scale of Intelligence (WASI), was compared and correlated to global network measures.

RESULTS: Group comparisons revealed significant differences in the average clustering coefficient, characteristic path length, and global efficiency. Modularity was not significantly different between groups. The FAS and ARND groups scored significantly lower than the CNTRL group on Full Scale IQ (FS-IQ) and the Vocabulary subtest, but not the Matrix Reasoning subtest. No significant associations between intelligence and graph theory measures were detected.

CONCLUSION: Our results partially agree with previous studies examining global graph theory metrics in children and adolescents with FASD and suggest that the exposure to alcohol during prenatal development leads to disruptions in aspects of functional network segregation and integration.

PMID:34342371 | DOI:10.1111/acer.14673

Unveiling the neural underpinnings of optimism: a systematic review

Tue, 08/03/2021 - 18:00

Cogn Affect Behav Neurosci. 2021 Aug 2. doi: 10.3758/s13415-021-00931-8. Online ahead of print.

ABSTRACT

Optimism is a personality trait strongly associated with physical and psychological well-being, with correlates in nonhuman species. Optimistic individuals hold positive expectancies for their future, have better physical and psychological health, recover faster after heart disease and other ailments, and cope more effectively with stress and anxiety. We performed a systematic review of neuroimaging studies focusing on neural correlates of optimism. A search identified 14 papers eligible for inclusion. Two key brain areas were linked to optimism: the anterior cingulate cortex (ACC), involved in imagining the future and processing of self-referential information; and the inferior frontal gyrus (IFG), involved in response inhibition and processing relevant cues. ACC activity was positively correlated with trait optimism and with the probability estimations of future positive events. Behavioral measures of optimistic tendencies investigated through the belief update task correlated positively with IFG activity. Elucidating the neural underpinnings of optimism may inform both the development of prevention and treatment strategies for several mental disorders negatively associated with optimism, such as depression, as well as help to foster new resilience promotion interventions targeting healthy, vulnerable, and mentally ill individuals.

PMID:34341967 | DOI:10.3758/s13415-021-00931-8

Neural network modelling reveals changes in directional connectivity between cortical and hypothalamic regions with increased BMI

Tue, 08/03/2021 - 18:00

Int J Obes (Lond). 2021 Aug 2. doi: 10.1038/s41366-021-00918-y. Online ahead of print.

ABSTRACT

BACKGROUND/OBJECTIVES: Obesity has been ascribed to corticostriatal regions taking control over homeostatic areas. To test this assumption, we applied an effective connectivity approach to reveal the direction of information flow between brain regions and the valence of connections (excitatory versus inhibitory) as a function of increased BMI and homeostatic state.

SUBJECTS/METHODS: Forty-one participants (21 overweight/obese) underwent two resting-state fMRI scans: after overnight fasting (hunger) and following a standardised meal (satiety). We used spectral dynamic causal modelling to unravel hunger and increased BMI-related changes in directed connectivity between cortical, insular, striatal and hypothalamic regions.

RESULTS: During hunger, as compared to satiety, we found increased excitation of the ventromedial prefrontal cortex over the ventral striatum and hypothalamus, suggesting enhanced top-down modulation compensating energy depletion. Increased BMI was associated with increased excitation of the anterior insula over the hypothalamus across the hunger and satiety conditions. The interaction of hunger and increased BMI yielded decreased intra-cortical excitation from the dorso-lateral to the ventromedial prefrontal cortex.

CONCLUSIONS: Our findings suggest that excess weight and obesity is associated with persistent top-down excitation of the hypothalamus, regardless of homeostatic state, and hunger-related reductions of dorso-lateral to ventromedial prefrontal inputs. These findings are compatible with eating without hunger and reduced self-regulation views of obesity.

PMID:34341471 | DOI:10.1038/s41366-021-00918-y

Hyper- and hypo-connectivity in sensorimotor network of drug-naïve patients with cervical dystonia

Mon, 08/02/2021 - 18:00

Parkinsonism Relat Disord. 2021 Jul 22;90:15-20. doi: 10.1016/j.parkreldis.2021.07.020. Online ahead of print.

ABSTRACT

BACKGROUND: Cervical dystonia (CD) is the most common form of focal dystonia with involuntary movements and postures of the head. The pathogenesis and neural mechanisms underlying CD have not been fully elucidated.

METHODS: Twenty-seven newly drug-naïve patients with CD and 21 healthy controls (HCs) were recruited with clinical assessment and resting-state functional magnetic resonance imaging (rs-fMRI) scanning. Severity of CD was measured by Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) and Tsui scores. Whole-brain voxel-wise intrinsic connectivity (IC) and seed-based functional connectivity (FC) analyses were performed for detection of changes in the CD group relative to HCs, controlling for age, gender, and global time series correlation, followed by correlation analyses of IC, seed-based FC and clinically relevant features, respectively.

RESULTS: In comparison with HCs, CD patients showed significantly increased IC measurement in the anterior part of the left supramarginal gyrus and extended to the inferior left postcentral gyrus (AL-SMG/IL-PCG). With this cluster as a seed, decreased FC was found in the right precentral and postcentral gyrus. Moreover, the regional IC value in the AL-SMG/IL-PCG was significantly positively correlated with TWSTRS-1 (severity) score, and significantly negatively correlated with the associated seed-based FC strength.

CONCLUSIONS: Our results showed signs of both hyper- and hypo-connectivity in bilateral regions of the sensorimotor network related to CD. The imbalance of functional connectivity (both hyper- and hypo-) may hint both overloading and disrupted somatosensory or sensorimotor integration dysfunction within the sensorimotor network underlying the pathophysiology of CD, thus providing a network target for future therapies.

PMID:34340003 | DOI:10.1016/j.parkreldis.2021.07.020

Imbalance Between Prefronto-Thalamic and Sensorimotor-Thalamic Circuitries Associated with Working Memory Deficit in Schizophrenia

Mon, 08/02/2021 - 18:00

Schizophr Bull. 2021 Aug 2:sbab086. doi: 10.1093/schbul/sbab086. Online ahead of print.

ABSTRACT

BACKGROUND: Thalamocortical circuit imbalance characterized by prefronto-thalamic hypoconnectivity and sensorimotor-thalamic hyperconnectivity has been consistently documented at rest in schizophrenia (SCZ). However, this thalamocortical imbalance has not been studied during task engagement to date, limiting our understanding of its role in cognitive dysfunction in schizophrenia.

METHODS: Both n-back working memory (WM) task-fMRI and resting-state fMRI data were collected from 172 patients with SCZ and 103 healthy control subjects (HC). A replication sample with 49 SCZ and 48 HC was independently obtained. Sixteen thalamic subdivisions were employed as seeds for the analysis.

RESULTS: During both task-performance and rest, SCZ showed thalamic hyperconnectivity with sensorimotor cortices, but hypoconnectivity with prefrontal-cerebellar regions relative to controls. Higher sensorimotor-thalamic connectivity and lower prefronto-thalamic connectivity both relate to poorer WM performance (lower task accuracy and longer response time) and difficulties in discriminating target from nontarget (lower d' score) in n-back task. The prefronto-thalamic hypoconnectivity and sensorimotor-thalamic hyperconnectivity were anti-correlated both in SCZ and HCs; this anti-correlation was more pronounced with less cognitive demand (rest>0-back>2-back). These findings replicated well in the second sample. Finally, the hypo- and hyper-connectivity patterns during resting-state positively correlated with the hypo- and hyper-connectivity during 2-back task-state in SCZ respectively.

CONCLUSIONS: The thalamocortical imbalance reflected by prefronto-thalamic hypoconnectivity and sensorimotor-thalamic hyperconnectivity is present both at rest and during task engagement in SCZ and relates to working memory performance. The frontal reduction, sensorimotor enhancement pattern of thalamocortical imbalance is a state-invariant feature of SCZ that affects a core cognitive function.

PMID:34337670 | DOI:10.1093/schbul/sbab086

Fast Independent Component Analysis Algorithm-Based Diagnosis of L5 Nerve Root Compression and Changes of Brain Functional Areas Using 3D Functional Magnetic Resonance Imaging

Mon, 08/02/2021 - 18:00

J Healthc Eng. 2021 Jul 22;2021:5063021. doi: 10.1155/2021/5063021. eCollection 2021.

ABSTRACT

In this paper, the application of 3-dimensional (3D) functional magnetic resonance imaging (FMRI) in the diagnosis of the 5th lumbar (L5) nerve root compression and brain functional areas in patients with lumbar disc herniation (LDH) was analyzed. The traditional fast independent component analysis (Fast ICA) algorithm was optimized based on the modified whitening matrix to establish a new type of Modified-Fast ICA (M-Fast ICA) algorithm that was compared with the introduced traditional Fast ICA and ICA. M-Fast ICA was applied to the 3D FMRI diffusion tensor imaging (DTI) evaluation of 65 patients with L5 nerve root pain due to LDH (group A) and 50 healthy volunteers (group B). The values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) in the lumbar nerve roots (L3, L4, L5, and the 1st sacral vertebra (S1)) were recorded among subjects from the two groups. Besides, the score of edema degree in the lumbar nerve roots (L5 and S1) and activity of brain functional areas were also recorded among all subjects of the two groups. The results showed that the mean square error of M-Fast ICA was smaller than that of traditional Fast ICA and ICA, while its signal-to-noise ratio (SNR) was greater than that of Fast ICA and ICA (P < 0.05). The FA of L5 and S1 nerve roots in patients of group A was sharply lower than the values of group B, while the ADC of patients in group A was greater than that of the control group (P < 0.05). Besides, the score of edema in L5 and S1 nerve roots of patients in group A increased in contrast to group B (P < 0.05). The brain areas were activated after surgery including bilateral temporal lobe, left thalamus, splenium of corpus callosum, and right internal capsule. In conclusion, the 3D image denoising performance of M-Fast ICA optimized and constructed in this study was superior to that of the traditional Fast ICA and ICA. The FA of patients with L5 nerve root pain due to LDH decreased steeply, while the ADC increased dramatically. L5 nerve root pain caused by LDH resulted in changes in brain functional areas of the patients to inhibit the resting state default network activity, and the corresponding brain functional areas could be activated through treatment.

PMID:34336154 | PMC:PMC8321732 | DOI:10.1155/2021/5063021

Abnormal Functional Connectivity of the Amygdala in Mild Cognitive Impairment Patients With Depression Symptoms Revealed by Resting-State fMRI

Mon, 08/02/2021 - 18:00

Front Psychiatry. 2021 Jul 15;12:533428. doi: 10.3389/fpsyt.2021.533428. eCollection 2021.

ABSTRACT

Convergent evidence indicates that individuals with symptoms of depression exhibit altered functional connectivity (FC) of the amygdala, which is a key brain region in processing emotions. At present, the characteristics of amygdala functional circuits in patients with mild cognitive impairment (MCI) with and without depression are not clear. The current study examined the features of amygdala FC in patients with MCI with depression symptoms (D-MCI) using resting-state functional magnetic resonance imaging. We acquired resting-state functional magnetic resonance imaging data from 16 patients with D-MCI, 18 patients with MCI with no depression (nD-MCI), and 20 healthy controls (HCs) using a 3T scanner and compared the strength of amygdala FC between the three groups. Patients with D-MCI exhibited significant FC differences in the amygdala-medial prefrontal cortex and amygdala-sensorimotor networks. These results suggest that the dysfunction of the amygdala-medial prefrontal cortex network and the amygdala-sensorimotor network might be involved in the neural mechanism underlying depression in MCI.

PMID:34335316 | PMC:PMC8319717 | DOI:10.3389/fpsyt.2021.533428

Brain Frequency-Specific Changes in the Spontaneous Neural Activity Are Associated With Cognitive Impairment in Patients With Presbycusis

Mon, 08/02/2021 - 18:00

Front Aging Neurosci. 2021 Jul 14;13:649874. doi: 10.3389/fnagi.2021.649874. eCollection 2021.

ABSTRACT

Presbycusis (PC) is characterized by preferential hearing loss at high frequencies and difficulty in speech recognition in noisy environments. Previous studies have linked PC to cognitive impairment, accelerated cognitive decline and incident Alzheimer's disease. However, the neural mechanisms of cognitive impairment in patients with PC remain unclear. Although resting-state functional magnetic resonance imaging (rs-fMRI) studies have explored low-frequency oscillation (LFO) connectivity or amplitude of PC-related neural activity, it remains unclear whether the abnormalities occur within all frequency bands or within specific frequency bands. Fifty-one PC patients and fifty-one well-matched normal hearing controls participated in this study. The LFO amplitudes were investigated using the amplitude of low-frequency fluctuation (ALFF) at different frequency bands (slow-4 and slow-5). PC patients showed abnormal LFO amplitudes in the Heschl's gyrus, dorsolateral prefrontal cortex (dlPFC), frontal eye field and key nodes of the speech network exclusively in slow-4, which suggested that abnormal spontaneous neural activity in PC was frequency dependent. Our findings also revealed that stronger functional connectivity between the dlPFC and the posterodorsal stream of auditory processing, as well as lower functional coupling between the PCC and key nodes of the DMN, which were associated with cognitive impairments in PC patients. Our study might underlie the cross-modal plasticity and higher-order cognitive participation of the auditory cortex after partial hearing deprivation. Our findings indicate that frequency-specific analysis of ALFF could provide valuable insights into functional alterations in the auditory cortex and non-auditory regions involved in cognitive impairment associated with PC.

PMID:34335224 | PMC:PMC8316979 | DOI:10.3389/fnagi.2021.649874