Most recent paper
J Neurosci. 2021 Aug 10:JN-RM-0316-21. doi: 10.1523/JNEUROSCI.0316-21.2021. Online ahead of print.
The detection of novelty indicates changes in the environment and the need to update existing representations. In response to novelty, interactions across the VTA-hippocampal circuit support experience-dependent plasticity in the hippocampus. While theories have broadly suggested plasticity-related changes are also instantiated in the cortex, research has also shown evidence for functional heterogeneity in cortical networks. It therefore remains unclear how the hippocampal-VTA circuit engages cortical networks, and whether novelty targets specific cortical regions or diffuse, large-scale cortical networks. To adjudicate the role of the VTA and hippocampus in cortical network plasticity, we used fMRI to compare resting-state functional coupling before and following exposure to novel scene images in human subjects of both sexes. Functional coupling between right anterior hippocampus and VTA was enhanced following novelty exposure. However, we also found evidence for a double dissociation, with anterior hippocampus and VTA showing distinct patterns of post-novelty functional coupling enhancements, targeting task-relevant regions versus large-scale networks, respectively. Further, significant correlations between these networks and the novelty-related plasticity in the anterior hippocampal-VTA functional network suggest that the central hippocampal-VTA network may facilitate the interactions with the cortex. These findings support an extended model of novelty-induced plasticity, in which novelty elicits plasticity-related changes in both local and global cortical networks.Significance Statement:Novelty detection is critical for adaptive behavior, signaling the need to update existing representations. By engaging the bidirectional hippocampal-VTA circuit, novelty has been shown to induce plasticity-related changes in the hippocampus. However, it remains an open question how novelty targets such plasticity-related changes in cortical networks. We show that anterior hippocampus and VTA target cortical networks at different spatial scales, with respective enhancements in post-novelty functional coupling with a task-relevant cortical region and a large-scale memory network. The results presented here support an extended model of novelty-related plasticity, in which engaging the anterior hippocampal-VTA circuit through novelty exposure propagates cortical plasticity through hippocampal and VTA functional pathways at distinct scales, targeting specific or diffuse cortical networks.
Neuromarkers from Whole-Brain Functional Connectivity Reveal the Cognitive Recovery Scheme for Overt Hepatic Encephalopathy after Liver Transplantation
eNeuro. 2021 Aug 10:ENEURO.0114-21.2021. doi: 10.1523/ENEURO.0114-21.2021. Online ahead of print.
Neurocognitive impairment is present in cirrhosis and may be more severe in cirrhosis with overt hepatic encephalopathy (OHE). Liver transplantation (LT) can restore liver function, but how it reverses the impaired brain function is still unclear. MRI of resting-state functional connectivity can help reveal the underlying mechanisms that lead to these cognitive deficits and cognitive recovery. In this study, 64 patients with cirrhosis (28 with OHE; 36 without OHE) and 32 healthy control subjects were recruited for resting-state fMRI. The patients were scanned before and after LT. We evaluated presurgical and postsurgical neurocognitive performance in cirrhosis patients using psychomotor tests. Network-based statistics found significant disrupted connectivity in both groups of cirrhotic patients, with OHE and without OHE, compared with control subjects. However, the presurgical connectivity disruption in patients with OHE affected a greater number of connections than those without OHE. The decrease in functional connectivity for both OHE and non-OHE patient groups was reversed after LT to the level of control subjects. An additional hyperconnected network (i.e., higher connected than control subjects) was observed in OHE patients after LT. Regarding the neural-behavior relationship, the functional network that predicted cognitive performance in healthy individuals showed no correlation in presurgical cirrhotic patients. The impaired neural-behavior relationship was re-established after LT for non-OHE patients, but not for OHE patients. OHE patients displayed abnormal hyperconnectivity and a persistently impaired neural-behavior relationship after LT. Our results suggest that patients with OHE may undergo a different trajectory of postsurgical neurofunctional recovery compared with those without, which needs further clarification in future studies.Significance StatementAfter liver transplantation, brain functional impairment induced by cirrhosis shows some recovery in terms of both brain functional connectivity and cognitive task performance. However, cirrhotic patients with and without OHE present different recovery paths. We show that a hyperconnected network emerges for OHE patients only after liver transplantation, within which the connectivity is abnormally higher than that in healthy control subjects. Furthermore, the predictive power of the neuromarkers for cognitive task performance returns to normal in non-OHE patients only, but not in OHE patients. These findings suggest that OHE patients may exhibit functional reorganization in brain functional MRI after liver transplantation. That is, the brain connectivity responsible for cognitive task performance alters, and the brain-behavior relationship is reshaped.
Dimensional personality impairment is associated with disruptions in intrinsic intralimbic functional connectivity
Psychol Med. 2021 Aug 11:1-11. doi: 10.1017/S0033291721002865. Online ahead of print.
BACKGROUND: Recently proposed alternative dimensional models of personality disorder (PD) place the severity of impairments in self and interpersonal functioning at the core of personality pathology. However, associations of these impairments with disturbances in social, cognitive, and affective brain networks remain uninvestigated.
METHODS: The present study examined patterns of resting-state functional connectivity (rsFC) in a sample of 74 age- and sex-matched participants (45 inpatients with PD and 29 healthy controls). At a minimum, PD patients carried a diagnosis of borderline PD, although the majority of the sample had one or more additional PDs. rsFC patterns in the following networks were compared between groups and in association with dimensional personality impairments: default mode network (DMN)/core mentalization, frontolimbic, salience, and central executive. Further, the extent to which variation in rsFC was explained by levels of personality impairment as compared to typology-specific borderline PD symptom severity was explored.
RESULTS: Relative to controls, the PD group showed disruptions in rsFC within the DMN/core mentalization and frontolimbic networks. Among PD patients, greater severity of dimensional self-interpersonal impairment was associated with stronger intralimbic rsFC. In contrast, severity of borderline PD-specific typology was not associated with any rsFC patterns.
CONCLUSIONS: Disruptions in core mentalization and affective networks are present in PD. Higher intralimbic functional connectivity may underlie self-interpersonal personality impairment in PD regardless of diagnostic typology-specific PD symptoms, providing initial neurobiological evidence supporting alternative dimensional conceptualizations of personality pathology.
Biol Psychiatry Cogn Neurosci Neuroimaging. 2021 Aug 7:S2451-9022(21)00208-1. doi: 10.1016/j.bpsc.2021.07.014. Online ahead of print.
BACKGROUND: Obsessive compulsive symptomatology (OCS) is common in adolescence but usually does not meet the diagnostic threshold for obsessive compulsive disorder. Nevertheless, both OCD and subthreshold OCS are associated with increased likelihood of experiencing other serious psychiatric conditions including depression and suicidal ideation. Unfortunately, there is limited information on the neurobiology of OCS.
METHODS: Here we undertook one of the first brain imaging studies of OCS in a large adolescent sample (analyzed n=832) from the Philadelphia Neurodevelopmental Cohort. We investigated resting-state fMRI functional connectivity using complementary analytic approaches that focus on different neuroanatomical scales, from known functional systems to connectome-wide tests.
RESULTS: We found a robust pattern of connectome-wide, OCS-related differences, as well as evidence of specific abnormalities involving known functional systems, including dorsal and ventral attention, frontoparietal and default mode systems. Analysis of cerebral perfusion imaging and high resolution structural imaging did not show OCS-related differences, consistent with domain specificity to functional connectivity.
CONCLUSIONS: The brain connectomic associations with OCS reported here, together with early studies of its clinical relevance, support the potential for OCS as an early marker of psychiatric risk that may enhance our understanding of mechanisms underlying the onset of adolescent psychopathology.
Altered thalamo-cortical functional connectivity in patients with vestibular migraine: a resting-state fMRI study
Neuroradiology. 2021 Aug 10. doi: 10.1007/s00234-021-02777-w. Online ahead of print.
PURPOSE: To explore the functional connectivity (FC) between the bilateral thalamus and the other brain regions in patients with vestibular migraine (VM).
METHODS: Resting-state fMRI and 3D-T1 data were collected from 37 patients with VM during the interictal period and 44 age-, gender-, and years of education-matched healthy controls (HC). The FC of the bilateral thalamus was analyzed using a standard seed-based whole-brain correlation method. Furthermore, the correlations between thalamus FC and clinical characteristics of patients were investigated using Pearson's partial correlation.
RESULTS: Compared with HC, VM patients showed decreased FC between the left thalamus and the left anterior cingulate cortex (ACC), bilateral insular and right supplementary motor cortex. We also observed decreased FC between the right thalamus and the left insular and ACC in VM patients. Furthermore, patients with VM also exhibited increased FC between the left thalamus and the right precuneus and middle frontal gyrus, between the right thalamus and superior parietal lobule. FC between the right thalamus and the left insular was negatively correlated with disease duration (p = 0.019, r = - 0.399), FC between the left thalamus and the left ACC was negatively correlated with HIT-6 score (p = 0.004, r = - 0.484).
CONCLUSION: VM patients showed altered FC between thalamus and brain regions involved in pain, vestibular and visual processing, which are associated with specific clinical features. Specifically, VM patients showed reduced thalamo-pain and thallamo-vestibular pathways, while exhibited enhanced thalamo-visual pathway, which provided first insight into the underlying functional brain connectivity in VM patients.
J Magn Reson Imaging. 2021 Aug 9. doi: 10.1002/jmri.27853. Online ahead of print.
BACKGROUND: The pathophysiology of rigidity in Parkinson's disease (PD) is poorly understood. Multi-sequence functional and structural brain MRI may further clarify the origin of this clinical characteristic.
PURPOSE: To examine both joint and unique relationships of MRI-based functional and structural imaging modalities to rigidity and other clinical features of PD.
STUDY TYPE: Retrospective cross-sectional study.
POPULATION: 31 PD subjects (aged 68.0 ± 5.9 years, 21 males) with average disease duration 9.3 ± 5.4 years.
FIELD STRENGTH/SEQUENCE: Multi-echo GRASE, diffusion-weighted echo planar imaging (EPI), and blood oxygen level dependent contrast EPI T2*-weighted sequences on a 3T scanner.
ASSESSMENT: Myelin water fraction (MWF) and fractional anisotropy (FA) of 20 white-matter regions of interest (ROIs), and functional connectivity derived from resting-state fMRI among 56 ROIs were assessed. The Unified Parkinson's Disease Rating Scale-Part III, Montreal Cognitive Assessment, Beck Depression Index, and Apathy Rating Scales were used to assess motor and non-motor symptoms.
STATISTICAL TESTS: Multiset canonical correlation analysis (MCCA) and canonical correlation analysis (CCA) were utilized to examine the joint and unique relationships of multiple imaging measures with clinical symptoms of PD. A permutation test was used to determine statistical significance (P < 0.05).
RESULTS: MCCA revealed a single significant component jointly linking MWF, FA, and functional connectivity to age, bradykinesia, and leg agility, non-motor symptoms of cognition, depression, and apathy, but not rigidity (P = 0.77), tremor (P = 0.50 and 0.67 on the left and right side), or sex (P = 0.54). After controlling for this joint component, CCA found a unique significant association between MWF and rigidity, but no other associations were detected, including with FA (P = 0.87).
DATA CONCLUSION: MWF, FA, and functional connectivity can serve as multi-sequence imaging markers to characterize many PD symptoms. However, rigidity in PD is additionally associated with widespread myelin changes.
EVIDENCE LEVEL: 4 TECHNICAL EFFICACY: Stage 3.
Graph-theory based degree centrality combined with machine learning algorithms can predict response to treatment with antiepileptic medications in children with epilepsy
J Clin Neurosci. 2021 Sep;91:276-282. doi: 10.1016/j.jocn.2021.07.016. Epub 2021 Jul 26.
BACKGROUND AND PURPOSE: The purpose of the current study is to detect changes of graph-theory-based degree centrality (DC) and their relationship with the clinical treatment effects of anti-epileptic drugs (AEDs) for patients with childhood absence epilepsy (CAE) using resting-state functional MRI (RS-fMRI).
METHODS: RS-fMRI data from 35 CAE patients were collected and compared with findings from 35 age and gender matched healthy controls (HCs). The patients were treated with AEDs for 46.03 weeks before undergoing a second RS-fMRI scan.
RESULTS: CAE children at baseline showed increased DC in thalamus, postcentral and precentral and reduced DC in medial frontal cortex, superior frontal cortex, middle temporal cortex, angular and precuneus. However, those abnormalities showed a clear renormalization after AEDs treatments. We then explored the viability of graph-theory-based degree centrality to accurately classify effectiveness to AEDs. Support Vector Machine analysis using leave-one-out cross-validation achieved a correct classification rate of 84.22% [sensitivity 78.76%, specificity 89.65%, and area under the receiver operating characteristic curve (AUC) 0.96] for differentiating effective subjects from ineffective subjects. Brain areas that contributed most to the classification model were mainly located within the right thalamus, bilateral middle temporal gyrus, right medial frontal gyrus, right inferior frontal gyrus, left precuneus, bilateral angular right precentral and left postcentral. Furthermore, the DC change within the bilateral angular are positively correlated with the symptom improvements after AEDs treatment.
CONCLUSION: These findings suggest that graph-theory-based measures, such as DC, combined with machine-learning algorithms, can provide crucial insights into pathophysiological mechanisms and the effectiveness of AEDs.
Effect of acupuncture on pain-emotion related brain regions in patients with cervical spondylosis of cervical type: a fMRI study
Zhongguo Zhen Jiu. 2021 Aug 12;41(8):906-12. doi: 10.13703/j.0255-2930.20201022-k0007.
OBJECTIVE: To observe the changes of functional connectivity of brain pain-emotion regulation region in patients with cervical spondylosis of cervical type by functional magnetic resonance imaging (fMRI).
METHODS: Thirty-two subjects were selected. Of them, 16 patients with cervical spondylosis of cervical type were divided into an observation group and 16 healthy subjects into a control group. The patients in the observation group were treated with acupuncture at Tianzhu (BL 10), Jingbailao (EX-HN 15), Jianzhongshu (SI 15) and ashi points for 30 min. The rest-state fMRI data was collected before and after acupuncture in the observation group. The subjects in the control group received no treatment, and the rest-state fMRI data was collected once. The visual analogue scale (VAS) score before and after treatment and the pain catastrophizing scale (PCS) score before treatment in the observation group were recorded. The resting-state brain functional imaging characteristics between the observation group and control group before treatment, between the observation group before and after treatment, were compared. Based on the brain functional connectivity of region of interest (ROI) the changes of functional connectivity in insula and ventral tegmental area (VTA) in emotional regulation brain region were observed, and the correlation between functional connectivity changes and VAS、PCS scores in patients of the observation group was analyzed.
RESULTS: In the observation group, the VAS score was (1.94±1.12) after the treatment, which was lower than (5.62±1.20) before treatment (P<0.05). The PCS score before treatment was (19.18±8.42) in the observation group. Compared with the control group, the areas with increased functional connectivity with insula in the observation group before acupuncture included bilateral dorsolateral prefrontal lobe and right middle cingulate gyrus, and the areas with increased functional connectivity with VTA included right central posterior gyrus and right insula. In the observation group, the connectivity coefficient of left insula and left dorsolateral prefrontal lobe (r=0.438, P<0.05), the connectivity coefficient of right insula and right dorsolateral prefrontal lobe (r=0.483, P<0.05) were positively associated with the VAS score. In the observation group, the connectivity coefficient between the right insula and the right middle cingulate gyrus (r=-0.560, P<0.05), the connectivity coefficient between the right VTA and the right insula (r=-0.525, P<0.05) were negatively associated with the PCS score. After acupuncture, the areas with decreased functional connectivity with insula included bilateral posterior central gyrus, right anterior central gyrus, middle cingulate gyrus and left corpus callosum, while the bilateral suboccipital gyrus and left cerebellum showed increased functional connectivity with right insula. The areas with decreased functional connectivity with VTA included bilateral dorsomedial prefrontal cortex, left anterior cingulate gyrus, right middle temporal gyrus and left anterior cingulate gyrus. After acupuncture in the observation group, the functional connectivity of left VTA left dorsomedial prefrontal cortex and left anterior cingulate cortex (r=-0.548, P<0.05), the functional connectivity of right VTA-bilateral dorsomedial prefrontal cortex and left anterior cingulate cortex (r=-0.547, P<0.05) were negatively associated with the PCS score.
CONCLUSION: Pain involves the formation and expression of "pain-emotion-cognition". Acupuncture can systematically regulate the brain functional connections between cognitive regions such as dorsal prefrontal lobe and anterior cingulate gyrus and emotional regions such as insula and VTA in patients with cervical spondylosis of cervical type, suggesting that acupuncture has a multi-dimensional and comprehensive regulation effect on pain.
Construction of embedded fMRI resting-state functional connectivity networks using manifold learning
Cogn Neurodyn. 2021 Aug;15(4):585-608. doi: 10.1007/s11571-020-09645-y. Epub 2020 Nov 3.
We construct embedded functional connectivity networks (FCN) from benchmark resting-state functional magnetic resonance imaging (rsfMRI) data acquired from patients with schizophrenia and healthy controls based on linear and nonlinear manifold learning algorithms, namely, Multidimensional Scaling, Isometric Feature Mapping, Diffusion Maps, Locally Linear Embedding and kernel PCA. Furthermore, based on key global graph-theoretic properties of the embedded FCN, we compare their classification potential using machine learning. We also assess the performance of two metrics that are widely used for the construction of FCN from fMRI, namely the Euclidean distance and the cross correlation metric. We show that diffusion maps with the cross correlation metric outperform the other combinations.
Front Psychiatry. 2021 Jul 23;12:694394. doi: 10.3389/fpsyt.2021.694394. eCollection 2021.
Background: People with schizophrenia are more likely to develop cannabis use disorder (CUD) and experience worse outcomes with use. Yet as cannabis is legalized for medical and recreational use, there is interest in its therapeutic potential. Objectives: To conduct a systematic review summarizing the design and results of controlled trials using defined doses of THC and CBD in schizophrenia. Method: A keyword search of eight online literature databases identified 11 eligible reports. Results: One placebo controlled trial (13 stable patients without CUD) found that intravenous THC increased psychosis and worsened learning/recall. Two reports of a functional magnetic resonance (fMRI) study of smoked or oral THC in 12 abstinent patients with schizophrenia and CUD found no change in symptoms and cognition, and an amelioration of impaired resting state brain function in areas implicated in reward function and the default mode network. One 4 week trial in acutely psychotic inpatients without CUD (mean age 30 y) found 800 mg CBD to be similarly efficacious to amisupride in improving psychosis and cognition. Two 6 week studies of CBD augmentation of antipsychotics in stable outpatients reported mixed results: CBD 600 mg was not more effective than placebo; CBD 1,000 mg reduced symptoms in a sample that did not exclude cannabis use and CUD. A brain fMRI and proton magnetic resonance spectroscopy study of single dose CBD in a sample that did not exclude CUD and cannabis use found that CBD improved symptoms and brain function during a learning/recall task and was associated with increased hippocampal glutamate. Discussion: There is substantial heterogeneity across studies in dose, method of drug delivery, length of treatment, patient age, whether patients with cannabis use/CUD were included or excluded, and whether patients were using antipsychotic medication. Conclusion: There is insufficient evidence for an effect of THC or CBD on symptoms, cognition, and neuroimaging measures of brain function in schizophrenia. At this time, research does not support recommending medical cannabis (THC or CBD) for treating patients with schizophrenia. Further research should examine THC and CBD in schizophrenia with and without comorbid CUD and consider the role of CBD in mitigating symptom exacerbation from THC.
Severities in persistent mild traumatic brain injury related headache is associated with changes in supraspinal pain modulatory functions
Mol Pain. 2021 Jan-Dec;17:17448069211037881. doi: 10.1177/17448069211037881.
Emerging evidence suggests mild traumatic brain injury related headache (MTBI-HA) is a form of neuropathic pain state. Previous supraspinal mechanistic studies indicate patients with MTBI-HA demonstrate a dissociative state with diminished levels of supraspinal prefrontal pain modulatory functions and enhanced supraspinal sensory response to pain in comparison to healthy controls. However, the relationship between supraspinal pain modulatory functional deficit and severity of MTBI-HA is largely unknown. Understanding this relationship may provide enhanced levels of insight about MTBI-HA and facilitate the development of treatments. This study assessed pain related supraspinal resting states among MTBI-HA patients with various headache intensity phenotypes with comparisons to controls via functional magnetic resonance imaging (fMRI). Resting state fMRI data was analyzed with self-organizing-group-independent-component-analysis in three MTBI-HA intensity groups (mild, moderate, and severe) and one control group (n = 16 per group) within a pre-defined supraspinal pain network based on prior studies. In the mild-headache group, significant increases in supraspinal function were observed in the right premotor cortex (T = 3.53, p < 0.001) and the left premotor cortex (T = 3.99, p < 0.0001) when compared to the control group. In the moderate-headache group, a significant (T = -3.05, p < 0.01) decrease in resting state activity was observed in the left superior parietal cortex when compared to the mild-headache group. In the severe-headache group, significant decreases in resting state supraspinal activities in the right insula (T = -3.46, p < 0.001), right premotor cortex (T = -3.30, p < 0.01), left premotor cortex (T = -3.84, p < 0.001), and left parietal cortex (T = -3.94, p < 0.0001), and an increase in activity in the right secondary somatosensory cortex (T = 4.05, p < 0.0001) were observed when compared to the moderate-headache group. The results of the study suggest that the increase in MTBI-HA severity may be associated with an imbalance in the supraspinal pain network with decline in supraspinal pain modulatory function and enhancement of sensory/pain decoding.
Global fractional anisotropy: effect on resting-state neural activity and brain networking in healthy participants
Neuroscience. 2021 Aug 5:S0306-4522(21)00375-4. doi: 10.1016/j.neuroscience.2021.07.021. Online ahead of print.
The global fractional anisotropy (gFA) is a structural marker of white matter myelination and integrity. Previous studies already evidenced that aging-related reduced integrity of specific white matter tracts is associated with decreased functional connectivity in several hubs. However, the correlations between gFA and functional brain connectivity remain unknown. In this cross-sectional study, we analyzed structural and functional MR datasets of 79 healthy participants from the Leipzig Study for Mind-Body-Emotion Interactions. DTI model-based method was used to quantify gFA values. We tested associations between gFA, age, and gender. The fractional amplitude of low-frequency fluctuations (fALFF) and ROI-to-ROI connectivity waere analyzed in a regression model for evaluating the effects of gFA on brain activity and networking, respectively. A negative correlation was found between gFA and age (ρ= -0.343; p = 0.002). No statistically significant correlation as found between gFA and gender (p = 0.229). Higher values of gFA were associated with increased brain regional activity, including areas of the default mode network. There was a higher degree of correlation between some regions, particularly those that conform to the limbic system. Our study demonstrates that gFA influences regional neural activity and brain networking on resting, particularly the limbic system.
Exploration of the influence of body mass index on intra-network resting-state connectivity in chronic cigarette smokers
Drug Alcohol Depend. 2021 Jul 21;227:108911. doi: 10.1016/j.drugalcdep.2021.108911. Online ahead of print.
BACKGROUND: Obesity and cigarette smoking are two leading preventable causes of death. Previous research suggests that comorbid smoking and obesity likely share neurobehavioral underpinnings; however, the influence of body mass index (BMI) on resting-state functional connectivity (rsFC) in smokers remains unknown. In this study, we explore how BMI affects rsFC and associations between rsFC and smoking-related behavior.
METHODS: Treatment-seeking cigarette smokers (N = 87; 54 % men) completed a BOLD resting-state fMRI scan session. We grouped smokers into BMI groups (N = 23 with obesity, N = 33 with overweight, N = 31 lean) and used independent components analysis (ICA) to identify the resting state networks commonly associated with cigarette smoking: salience network (SN), right and left executive control networks (ECN) and default mode network (DMN). Average rsFC values were extracted (p < 0.001, k = 100) to determine group differences in rsFC and relationship to self-reported smoking and dependence.
RESULTS: Analyses revealed a significant relationship between BMI and connectivity in the SN and a significant quadratic effect of BMI on DMN connectivity. Heavier smoking was related to greater rsFC in the SN among lean and obese groups but reduced rsFC in the overweight group.
CONCLUSIONS: Findings build on research suggesting an influence of BMI on the neurobiology of smokers. In particular, dysfunction of SN-DMN-ECN circuitry in smokers with overweight may lead to a failure to modulate attention and behavior and subsequent difficulty quitting smoking. Future research is needed to elucidate the mechanism underlying the interaction of BMI and smoking and its impact on treatment.
High Thought Control Ability, High Resilience: The Effect of Temporal Cortex and Insula Connectivity
Neuroscience. 2021 Aug 4:S0306-4522(21)00388-2. doi: 10.1016/j.neuroscience.2021.07.034. Online ahead of print.
Psychological resilience is always portrayed as the ability to rebound from adversity, which is essential for human mental health. Whereas thought control ability (TCA) is a reliable indicator of perceptual cognitive control and has a predictive effect on psychopathology. Whether and how resilience correlates with thought control are still unclear. The current study explored the whole-brain functional connectivity underlying resilience and its role in the association between resilience and TCA using resting-state fMRI. Results reveled a significant positive correlation between resilience and the functional connectivity of temporal cortex-insula, suggesting that individuals with high resilient ability exhibit flexible interaction between these two regions to facilitate emotional information processing. More importantly, a significant positive correlation between TCA and resilience was observed, and the functional connectivity of temporal cortex-insula has a significant mediation effect on the association between TCA and psychological resilience, revealing that individuals with high TCA show high levels of resilience ability through robust cognitive control on unwanted thoughts. In short, these results extended previous findings by shedding novel insights into the close relationship between resilience and TCA and the underlying neural mechanism.
When functional blurring becomes deleterious: Reduced system segregation is associated with less white matter integrity and cognitive decline in aging
Neuroimage. 2021 Aug 3:118449. doi: 10.1016/j.neuroimage.2021.118449. Online ahead of print.
Healthy aging is accompanied by progressive decline in cognitive performance and concomitant changes in brain structure and functional architecture. Age-accompanied alterations in brain function have been characterized on a network level as weaker functional connections within brain networks along with stronger interactions between networks. This phenomenon has been described as age-related differences in functional network segregation. It has been suggested that functional networks related to associative processes are particularly sensitive to age-related deterioration in segregation, possibly related to cognitive decline in aging. However, there have been only a few longitudinal studies with inconclusive results. Here, we used a large longitudinal sample of 284 participants between 25 to 80 years of age at baseline, with cognitive and neuroimaging data collected at up to three time points over a 10-year period. We investigated age-related changes in functional segregation among two large-scale systems comprising associative and sensorimotor-related resting-state networks. We found that functional segregation of associative systems declines in aging with exacerbated deterioration from the late fifties. Changes in associative segregation were positively associated with changes in global cognitive ability, suggesting that decreased segregation has negative consequences for domain-general cognitive functions. Age-related changes in system segregation were partly accounted for by changes in white matter integrity, but white matter integrity only weakly influenced the association between segregation and cognition. Together, these novel findings suggest a cascade where reduced white-matter integrity leads to less distinctive functional systems which in turn contributes to cognitive decline in aging.
Behavioral and neural correlates of social network size: the unique and common contributions of face recognition and extraversion
J Pers. 2021 Aug 6. doi: 10.1111/jopy.12666. Online ahead of print.
Humans are inherently social creatures and can gain advantages from larger network size. Researches have shown that different cognitive and personality factors may result in individual differences of social network size (SNS). Here, we focused on whether face recognition ability and extraversion were related to SNS and the neural basis underlying the relations. Behaviorally, we adopted the face-inversion task, NEO personality inventory, and computerized SNS test, and found that individuals with better face recognition ability and more extraverted personality had larger size of social network, and the unique and common contributions of face recognition and extraversion to SNS were depicted. Neurally, we used resting state functional magnetic resonance imaging (rs-fMRI) method and found that SNS was positively associated with the fractional amplitude of low-frequency fluctuation (fALFF) in the ventromedial prefrontal cortex (vmPFC), right superior temporal sulcus (rSTS), and precuneus. Interestingly, the fALFF in the vmPFC significantly correlated with face recognition ability. Our study suggests that both face recognition and extraversion may be important correlates of SNS, and the underlying spontaneous neural substrates are partially dissociable.
J Pers Med. 2021 Jul 19;11(7):679. doi: 10.3390/jpm11070679.
Apathy is a neuropsychiatric condition characterized by reduced motivation, initiative, and interest in daily life activities, and it is commonly reported in several neurodegenerative disorders. The study aims to investigate large-scale brain networks involved in apathy syndrome in patients with frontotemporal dementia (FTD) and Parkinson's disease (PD) compared to a group of healthy controls (HC). The study sample includes a total of 60 subjects: 20 apathetic FTD and PD patients, 20 non apathetic FTD and PD patients, and 20 HC matched for age. Two disease-specific apathy-evaluation scales were used to measure the presence of apathy in FTD and PD patients; in the same day, a 3T brain magnetic resonance imaging (MRI) with structural and resting-state functional (fMRI) sequences was acquired. Differences in functional connectivity (FC) were assessed between apathetic and non-apathetic patients with and without primary clinical diagnosis revealed, using a whole-brain, seed-to-seed approach. A significant hypoconnectivity between apathetic patients (both FTD and PD) and HC was detected between left planum polare and both right pre- or post-central gyrus. Finally, to investigate whether such neural alterations were due to the underlying neurodegenerative pathology, we replicated the analysis by considering two independent patients' samples (i.e., non-apathetic PD and FTD). In these groups, functional differences were no longer detected. These alterations may subtend the involvement of neural pathways implicated in a specific reduction of information/elaboration processing and motor outcome in apathetic patients.
Parietal Lobe Reorganization and Widespread Functional Connectivity Integration in Upper-Limb Amputees: A rs-fMRI Study
Front Neurosci. 2021 Jul 20;15:704079. doi: 10.3389/fnins.2021.704079. eCollection 2021.
The right parietal lobe plays an important role in body image, and disorders of body image emerge after lesions in the parietal lobe or with parietal lobe epilepsy. Body image disorder also often accompanies upper-limb amputation, in which the patient misperceives that their missing limb is still part of their body. Cortical reorganization is known to occur after upper-limb amputation, but it is not clear how widespread and to what degree functional connectivity (FC) is reorganized post-amputation, nor whether such changes might be related to misperceptions of body image. Twenty-four subjects who had a traumatically upper-limb amputees (ULAs) and 24 age-matched healthy controls (HCs) underwent resting-state functional magnetic resonance imaging (rs-fMRI) scans. Regions of interest (ROIs) in the right superior parietal gyrus (SPG_R) and right inferior parietal lobule (IPL_R) were defined using BrainNet Viewer. We calculated the amplitude of low-frequency fluctuations (ALFF) in ROIs and correlated the ROI mean amplitude of low-frequency fluctuations (mALFF) and mean scores on the phantom limb sensation (PLS) scale and beck depression index (BDI). We also calculated ROIs and whole-brain FC. Compared to the HC group, we observed significantly increased activation (mALFF) in ROIs of the ULA group. Moreover, correlation analyses revealed a significant positive correlation between ROI mALFF and scores on the PLS. There was a significant negative correlation between the SPG_R mALFF and BDI scores. Seed-based, whole-brain FC analysis revealed that FC in the ULA group significantly decreased in many brain regions across the entire brain. The right parietal lobe appears to be involved in some aspect of body awareness and depression in amputation patients. Upper-limb amputation results not only in reorganization in the local brain area formerly representing the missing limb, but also results in more widespread reorganization through FC changes in whole brain.
Multimodal Neuroimaging Predictors of Learning Performance of Sensorimotor Rhythm Up-Regulation Neurofeedback
Front Neurosci. 2021 Jul 20;15:699999. doi: 10.3389/fnins.2021.699999. eCollection 2021.
Electroencephalographic (EEG) neurofeedback (NFB) is a popular neuromodulation method to help one selectively enhance or inhibit his/her brain activities by means of real-time visual or auditory feedback of EEG signals. Sensory motor rhythm (SMR) NFB protocol has been applied to improve cognitive performance, but a large proportion of participants failed to self-regulate their brain activities and could not benefit from NFB training. Therefore, it is important to identify the neural predictors of SMR up-regulation NFB training performance for a better understanding the mechanisms of individual difference in SMR NFB. Twenty-seven healthy participants (12 males, age: 23.1 ± 2.36) were enrolled to complete three sessions of SMR up-regulation NFB training and collection of multimodal neuroimaging data [resting-state EEG, structural magnetic resonance imaging (MRI), and resting-state functional MRI (fMRI)]. Correlation analyses were performed between within-session NFB learning index and anatomical and functional brain features extracted from multimodal neuroimaging data, in order to identify the neuroanatomical and neurophysiological predictors for NFB learning performance. Lastly, machine learning models were trained to predict NFB learning performance using features from each modality as well as multimodal features. According to our results, most participants were able to successfully increase the SMR power and the NFB learning performance was significantly correlated with a set of neuroimaging features, including resting-state EEG powers, gray/white matter volumes from MRI, regional and functional connectivity (FC) of resting-state fMRI. Importantly, results of prediction analysis indicate that NFB learning index can be better predicted using multimodal features compared with features of single modality. In conclusion, this study highlights the importance of multimodal neuroimaging technique as a tool to explain the individual difference in within-session NFB learning performance, and could provide a theoretical framework for early identification of individuals who cannot benefit from NFB training.
Altered Spontaneous Neural Activity and Functional Connectivity in Parkinson's Disease With Subthalamic Microlesion
Front Neurosci. 2021 Jul 20;15:699010. doi: 10.3389/fnins.2021.699010. eCollection 2021.
BACKGROUND: Transient improvement in motor symptoms are immediately observed in patients with Parkinson's disease (PD) after an electrode has been implanted into the subthalamic nucleus (STN) for deep brain stimulation (DBS). This phenomenon is known as the microlesion effect (MLE). However, the underlying mechanisms of MLE is poorly understood.
PURPOSE: We utilized resting state functional MRI (rs-fMRI) to evaluate changes in spontaneous brain activity and networks in PD patients during the microlesion period after DBS.
METHOD: Overall, 37 PD patients and 13 gender- and age-matched healthy controls (HCs) were recruited for this study. Rs-MRI information was collected from PD patients three days before DBS and one day after DBS, whereas the HCs group was scanned once. We utilized the amplitude of low-frequency fluctuation (ALFF) method in order to analyze differences in spontaneous whole-brain activity among all subjects. Furthermore, functional connectivity (FC) was applied to investigate connections between other brain regions and brain areas with significantly different ALFF before and after surgery in PD patients.
RESULT: Relative to the PD-Pre-DBS group, the PD-Post-DBS group had higher ALFF in the right putamen, right inferior frontal gyrus, right precentral gyrus and lower ALFF in right angular gyrus, right precuneus, right posterior cingulate gyrus (PCC), left insula, left middle temporal gyrus (MTG), bilateral middle frontal gyrus and bilateral superior frontal gyrus (dorsolateral). Functional connectivity analysis revealed that these brain regions with significantly different ALFF scores demonstrated abnormal FC, largely in the temporal, prefrontal cortices and default mode network (DMN).
CONCLUSION: The subthalamic microlesion caused by DBS in PD was found to not only improve the activity of the basal ganglia-thalamocortical circuit, but also reduce the activity of the DMN and executive control network (ECN) related brain regions. Results from this study provide new insights into the mechanism of MLE.