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Normalization of aberrant pretherapeutic dynamic functional connectivity of extrastriate visual system in patients who underwent thalamotomy with stereotactic radiosurgery for essential tremor: a resting-state functional MRI study.

Sun, 05/12/2019 - 02:00
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Normalization of aberrant pretherapeutic dynamic functional connectivity of extrastriate visual system in patients who underwent thalamotomy with stereotactic radiosurgery for essential tremor: a resting-state functional MRI study.

J Neurosurg. 2019 May 10;:1-10

Authors: Tuleasca C, Bolton TAW, Régis J, Najdenovska E, Witjas T, Girard N, Delaire F, Vincent M, Faouzi M, Thiran JP, Bach Cuadra M, Levivier M, Van De Ville D

Abstract
OBJECTIVEThe tremor circuitry has commonly been hypothesized to be driven by one or multiple pacemakers within the cerebello-thalamo-cortical pathway, including the cerebellum, contralateral motor thalamus, and primary motor cortex. However, previous studies, using multiple methodologies, have advocated that tremor could be influenced by changes within the right extrastriate cortex, at both the structural and functional level. The purpose of this work was to evaluate the role of the extrastriate cortex in tremor generation and further arrest after left unilateral stereotactic radiosurgery thalamotomy (SRS-T).METHODSThe authors considered 12 healthy controls (HCs, group 1); 15 patients with essential tremor (ET, right-sided, drug-resistant; group 2) before left unilateral SRS-T; and the same 15 patients (group 3) 1 year after the intervention, to account for delayed effects. Blood oxygenation level-dependent functional MRI during resting state was used to characterize the dynamic interactions of the right extrastriate cortex, comparing HC subjects against patients with ET before and 1 year after SRS-T. In particular, the authors applied coactivation pattern analysis to extract recurring whole-brain spatial patterns of brain activity over time.RESULTSThe authors found 3 different sets of coactivating regions within the right extrastriate cortex in HCs and patients with pretherapeutic ET, reminiscent of the "cerebello-visuo-motor," "thalamo-visuo-motor" (including the targeted thalamus), and "basal ganglia and extrastriate" networks. The occurrence of the first pattern was decreased in pretherapeutic ET compared to HCs, whereas the other two patterns showed increased occurrences. This suggests a misbalance between the more prominent cerebellar circuitry and the thalamo-visuo-motor and basal ganglia networks. Multiple regression analysis showed that pretherapeutic standard tremor scores negatively correlated with the increased occurrence of the thalamo-visuo-motor network, suggesting a compensatory pathophysiological trait. Clinical improvement after SRS-T was related to changes in occurrences of the basal ganglia and extrastriate cortex circuitry, which returned to HC values after the intervention, suggesting that the dynamics of the extrastriate cortex had a role in tremor generation and further arrest after the intervention.CONCLUSIONSThe data in this study point to a broader implication of the visual system in tremor generation, and not only through visual feedback, given its connections to the dorsal visual stream pathway and the cerebello-thalamo-cortical circuitry, with which its dynamic balance seems to be a crucial feature for reduced tremor. Furthermore, SRS-T seems to bring abnormal pretherapeutic connectivity of the extrastriate cortex to levels comparable to those of HC subjects.

PMID: 31075777 [PubMed - as supplied by publisher]

Aberrant fronto-striatal connectivity and fine motor function in schizophrenia.

Sun, 05/12/2019 - 02:00
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Aberrant fronto-striatal connectivity and fine motor function in schizophrenia.

Psychiatry Res Neuroimaging. 2019 Apr 30;288:44-50

Authors: Viher PV, Docx L, Van Hecke W, Parizel PM, Sabbe B, Federspiel A, Walther S, Morrens M

Abstract
Abnormal fine motor function is a frequent finding in schizophrenia and has been linked to structural and functional brain alterations. However, whether fine motor function is related to functional alterations within the motor system remains unclear. The aim of this study was to assess whether abnormalities in resting-state functional connectivity are present in schizophrenia patients and to investigate how these abnormalities may be related to fine motor function. We examined 19 schizophrenia patients and 16 healthy controls using resting-state functional connectivity for 11 bilateral regions of interest. Fine motor function was assessed on a set of copying tasks and the Symbol-Digit-Substitution Test. We found significantly reduced functional connectivity between the left caudate nucleus and bilateral dorsolateral prefrontal cortex (DLPFC) and between the left putamen and bilateral supplementary motor area (SMA) proper in patients compared to controls. Altered connectivity from DLPFC to caudate nucleus was related to fine motor tasks, which are sensitive to psychomotor speed, whereas aberrant connectivity between the SMA proper and putamen was associated to both, fine motor task, which are sensitive to psychomotor speed and to speed of information processing. Our findings emphasize the role of fronto-striatal connections in the pathogenesis of fine motor impairments in schizophrenia.

PMID: 31075716 [PubMed - as supplied by publisher]

Longitudinal studies of functional magnetic resonance imaging in first-episode psychosis: A systematic review.

Sun, 05/12/2019 - 02:00
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Longitudinal studies of functional magnetic resonance imaging in first-episode psychosis: A systematic review.

Eur Psychiatry. 2019 May 07;59:60-69

Authors: González-Vivas C, Soldevila-Matías P, Sparano O, García-Martí G, Martí-Bonmatí L, Crespo-Facorro B, Aleman A, Sanjuan J

Abstract
BACKGROUND: Little is known about changes in brain functioning after first-episode psychosis (FEP). Such knowledge is important for predicting the course of disease and adapting interventions. Functional magnetic resonance imaging has become a promising tool for exploring brain function at the time of symptom onset and at follow-up.
METHOD: A systematic review of longitudinal fMRI studies with FEP patients according to PRISMA guidelines. Resting-state and task-activated studies were considered together.
RESULTS: Eleven studies were included. These reported on a total of 236 FEP patients were evaluated by two fMRI scans and clinical assessments. Five studies found hypoactivation at baseline in prefrontal cortex areas, two studies found hypoactivation in the amygdala and hippocampus, and three others found hypoactivation in the basal ganglia. Other hypoactivated areas were the anterior cingulate cortex, thalamus and posterior cingulate cortex. Ten out of eleven studies reported (partial) normalization by increased activation after antipsychotic treatment. A minority of studies observed hyperactivation at baseline.
CONCLUSIONS: This review of longitudinal FEP samples studies reveals a pattern of predominantly hypoactivation in several brain areas at baseline that may normalize to a certain extent after treatment. The results should be interpreted with caution given the small number of studies and their methodological and clinical heterogeneity.

PMID: 31075523 [PubMed - as supplied by publisher]

Hippocampal network abnormalities explain amnesia after VGKCC-Ab related autoimmune limbic encephalitis.

Sun, 05/12/2019 - 02:00
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Hippocampal network abnormalities explain amnesia after VGKCC-Ab related autoimmune limbic encephalitis.

J Neurol Neurosurg Psychiatry. 2019 May 09;:

Authors: Loane C, Argyropoulos GPD, Roca-Fernández A, Lage C, Sheerin F, Ahmed S, Zamboni G, Mackay C, Irani SR, Butler CR

Abstract
OBJECTIVE: Limbic encephalitis associated with antibodies to components of the voltage-gated potassium channel complex (VGKCC-Ab-LE) often leads to hippocampal atrophy and persistent memory impairment. Its long-term impact on regions beyond the hippocampus, and the relationship between brain damage and cognitive outcome, are poorly understood. We investigated the nature of structural and functional brain abnormalities following VGKCC-Ab-LE and its role in residual memory impairment.
METHOD: A cross-sectional group study was conducted. Twenty-four VGKCC-Ab-LE patients (20 male, 4 female; mean (SD) age 63.86 (11.31) years) were recruited post-acutely along with age- and sex-matched healthy controls for neuropsychological assessment, structural MRI and resting-state functional MRI (rs-fMRI). Structural abnormalities were determined using volumetry and voxel-based morphometry; rs-fMRI data were analysed to investigate hippocampal functional connectivity (FC). Associations of memory performance with neuroimaging measures were examined.
RESULTS: Patients showed selective memory impairment. Structural analyses revealed focal hippocampal atrophy within the medial temporal lobes, correlative atrophy in the mediodorsal thalamus, and additional volume reduction in the posteromedial cortex. There was no association between regional volumes and memory performance. Instead, patients demonstrated reduced posteromedial cortico-hippocampal and inter-hippocampal FC, which correlated with memory scores (r = 0.553; r = 0.582, respectively). The latter declined as a function of time since the acute illness (r = -0.531).
CONCLUSION: VGKCC-Ab-LE results in persistent isolated memory impairment. Patients have hippocampal atrophy with further reduced mediodorsal thalamic and posteromedial cortical volumes. Crucially, reduced FC of remaining hippocampal tissue correlates more closely with memory function than does regional atrophy.

PMID: 31072956 [PubMed - as supplied by publisher]

Functional connectivity and the sleep-deprived brain.

Sun, 05/12/2019 - 02:00
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Functional connectivity and the sleep-deprived brain.

Prog Brain Res. 2019;246:159-176

Authors: Chee MWL, Zhou J

Abstract
Resting state functional connectivity (rsFC) evaluated by detecting temporal co-variation of BOLD signals across multiple brain regions undergoes three major changes following sleep deprivation that indicate the occurrence of sleep intrusions; a loss of integration within networks like the default mode network as well as between networks like the salience and dorsal attention systems; a loss of segregation between networks, for example, between the dorsal attention and default mode networks; and an increase in global signal. Changes in vigilance affect rsFC and these likely occur in many scans involving persons with neuropsychiatric conditions. Ensuring "healthy" or "control" participants do not fall asleep in the scanner is increasingly acknowledged as a being important for proper inference in fMRI studies. Dynamic functional connectivity analyses evaluating the relative proportion of time spent in "low" or "high" arousal states during the well-rested state can predict propensity for vigilance decline when sleep deprived.

PMID: 31072560 [PubMed - in process]

Maximal flexibility in dynamic functional connectivity with critical dynamics revealed by fMRI data analysis and brain network modelling.

Fri, 05/10/2019 - 19:58
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Maximal flexibility in dynamic functional connectivity with critical dynamics revealed by fMRI data analysis and brain network modelling.

J Neural Eng. 2019 May 09;:

Authors: Song B, Ma N, Liu G, Zhang H, Yu L, Liu L, Zhang J

Abstract
OBJECTIVE: The exploration of time-varying functional connectivity (FC) through human neuroimaging techniques provides important new insights on the spatio-temporal organization of functional communication in the brain's networks and its alterations in diseased brains. However, little is known about the underlying dynamic mechanism with which such a dynamic FC is flexibly organized under the constraint of structural connections. In this work, we explore the relationship between critical dynamics and FC flexibility based on both functional magnetic resonance imaging data and computer models.
APPROACH: First, we proposed the connectivity number entropy (CNE), which was an entropy measure for the flexibility of FC. Through an analysis of resting-state fMRI (rs-fMRI) data from 95 healthy participants, we explored the correlation between CNE and long-range temporal correlations (LRTCs), which can represent the critical dynamics. Then, we employed a whole-brain computer model based on diffusion tensor imaging (DTI) to further demonstrate this relationship.
MAIN RESULTS: We found that the most flexible FC is present when the brain is operating close to the critical point of a phase transition. Additionally, around this point, our model can yield the best prediction for the regional distribution of CNE because structural information is reflected the most by the CNE through critical dynamics.
SIGNIFICANCE: Our results not only reveal the underlying dynamic mechanism for the organization of time-dependent FC but also provide a possible pathway to model the flexible functional organization in the human brain and may have potential application in the analysis of altered dynamic FC in diseased brains.

PMID: 31071699 [PubMed - as supplied by publisher]

Cortical-Basal Ganglia-Cerebellar Networks in Unilateral Vocal Fold Paralysis: A Pilot Study.

Fri, 05/10/2019 - 19:58
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Cortical-Basal Ganglia-Cerebellar Networks in Unilateral Vocal Fold Paralysis: A Pilot Study.

Laryngoscope. 2019 May 09;:

Authors: Perez PL, Cueva KL, Rosen CA, Young VN, Naunheim ML, Yung KC, Schneider SL, Mizuiri D, Klein DJ, Houde JF, Hinkley LB, Nagarajan SS, Cheung SW

Abstract
OBJECTIVES/HYPOTHESIS: To evaluate differences in cortical-basal ganglia-cerebellar functional connectivity between treated unilateral vocal fold paralysis (UVFP) and healthy control cohorts using resting-state functional magnetic resonance imaging (RS-fMRI).
STUDY DESIGN: Cross-sectional.
METHODS: Ten UVFP study patients treated by type I thyroplasty and 12 control subjects underwent RS-fMRI on a 3-Tesla scanner to evaluate differences in functional connectivity of whole-brain networks. Spontaneous RS-fMRI data were collected using a gradient echo planar pulse sequence, preprocessed, and analyzed to compare seed-to-voxel maps between the two cohorts. Seeds were placed in the caudate, putamen, and globus pallidus divisions of the basal ganglia in both hemispheres. Group contrasts were tested for statistical significance using two-tailed unpaired t tests corrected for multiple comparisons with a cluster false discovery rate threshold of P < .05.
RESULTS: UVFP patients demonstrated increased connectivity between both caudate nuclei and the precuneus, a node of the default mode network, compared to healthy controls. Both caudate nuclei also showed decreased connectivity with the left cerebellar hemisphere. The putamen and globus pallidus divisions of the basal ganglia were not abnormally connected to other brain structures.
CONCLUSIONS: UVFP patients treated by type I thyroplasty exhibited long-term alterations of cortical-basal ganglia-cerebellar networks thought to be important for self-referential voice quality awareness and learning processes that compensate for changes to the paralyzed hemilarynx. This pilot study on relatively small cohorts adds to growing evidence for persistent central nervous system changes in treated UVFP. Replication studies with larger numbers of subjects will be essential to validate and extend findings.
LEVEL OF EVIDENCE: 3b Laryngoscope, 2019.

PMID: 31070785 [PubMed - as supplied by publisher]

How does methylphenidate affect default mode network? A systematic review.

Fri, 05/10/2019 - 19:58
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How does methylphenidate affect default mode network? A systematic review.

Rev Neurol. 2019 May 16;68(10):417-425

Authors: Santos PH, Goncalves R, Pedroso S

Abstract
INTRODUCTION: Methylphenidate is a widely-used drug for the treatment of attention deficit/hyperactivity disorder (ADHD) and other neuropsychiatric disorders. Sustained-attention deficits and poorer task performance in these disorders have been associated with default mode network (DMN) dysfunction in fMRI studies. DMN is a set of brain areas more activated during the resting-state. Under the execution of external tasks, there is an attenuation of DMN activity. In healthy individuals, DMN and task-positive network are anticorrelated. It has been suggested that methylphenidate could normalize the attenuated task-related DMN deactivation in attention- and inhibitory control-related disorders and that such normalization could improve task performance.
PATIENTS AND METHODS: To explore the hypothesis of DMN deactivation after methylphenidate administration, we conducted a systematic review of the literature.
RESULTS: After a systematic search, 12 studies were included in this review. For eligibility, studies were required to measure the effects of methylphenidate administration on the DMN activity. Eleven studies showed evidence of MPH-induced improvements in brain areas related to DMN. The results suggest a normalization of brain circuits in individuals with DMN dysfunction.
CONCLUSIONS: Our preliminary findings strongly suggest methylphenidate improves DMN dysfunction presented in ADHD and other neuropsychiatric disorders. Further studies are needed to better understand this effect and expand comprehension of methylphenidate action mechanisms.

PMID: 31070233 [PubMed - in process]

Why is Clinical fMRI in a Resting State?

Fri, 05/10/2019 - 19:58
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Why is Clinical fMRI in a Resting State?

Front Neurol. 2019;10:420

Authors: O'Connor EE, Zeffiro TA

Abstract
While resting state fMRI (rs-fMRI) has gained widespread application in neuroimaging clinical research, its penetration into clinical medicine has been more limited. We surveyed a neuroradiology professional group to ascertain their experience with rs-fMRI, identify perceived barriers to using rs-fMRI clinically and elicit suggestions about ways to facilitate its use in clinical practice. The electronic survey also collected information about demographics and work environment using Likert scales. We found that 90% of the respondents had adequate equipment to conduct rs-fMRI and 82% found rs-fMRI data easy to collect. Fifty-nine percent have used rs-fMRI in their past research and 72% reported plans to use rs-fMRI for research in the next year. Nevertheless, only 40% plan to use rs-fMRI in clinical practice in the next year and 82% agreed that their clinical fMRI use is largely confined to pre-surgical planning applications. To explore the reasons for the persistent low utilization of rs-fMRI in clinical applications, we identified barriers to clinical rs-fMRI use related to the availability of robust denoising procedures, single-subject analysis techniques, demonstration of functional connectivity map reliability, regulatory clearance, reimbursement, and neuroradiologist training opportunities. In conclusion, while rs-fMRI use in clinical neuroradiology practice is limited, enthusiasm appears to be quite high and there are several possible avenues in which further research and development may facilitate its penetration into clinical practice.

PMID: 31068901 [PubMed]

Verbal Creativity Is Correlated With the Dynamic Reconfiguration of Brain Networks in the Resting State.

Fri, 05/10/2019 - 19:58
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Verbal Creativity Is Correlated With the Dynamic Reconfiguration of Brain Networks in the Resting State.

Front Psychol. 2019;10:894

Authors: Feng Q, He L, Yang W, Zhang Y, Wu X, Qiu J

Abstract
Creativity is the foundation of human culture. All inventions and innovations in history rely upon us to break with the traditional thinking and create something novel. A number of neuroimaging studies have explored the neural mechanism of creativity. However, a majority of researches have focused only on the stationary functional connectivity in resting-state fMRI and task-related fMRI, neglecting the dynamic variation of brain networks. Here, we used dynamic network analysis to investigate the relation between the dynamic reorganization of brain networks and verbal creativity in 370 healthy subjects. We found that the integration of the left lingual gyrus and left middle temporal gyrus (MTG) in default mode network (DMN) and the integration of the DMN and cerebellum, frontoparietal task control network (FPTC) and auditory network (Aud) showed positive correlation with verbal creativity performance. In addition, the recruitment of the bilateral postcentral gyrus from the sensory/somatomotor network (SMN) and the recruitment of the SMN in general displayed a significant correlation with verbal creativity scores. Taken together, these results suggested that the dynamic reorganization among the brain networks involved multiple cognitive processes, such as memory retrieval, imaginative process, cognitive control - these are all important for verbal creativity. These findings provided direct evidence that verbal creativity was related to the dynamic variation of brain mechanism during resting-state, extending past research on the neural mechanism of creativity. Meanwhile, these results bought about new perspectives for verbal creative training and rehabilitation training of depression.

PMID: 31068873 [PubMed]

Altered Brain Function in Drug-Naïve Major Depressive Disorder Patients With Early-Life Maltreatment: A Resting-State fMRI Study.

Fri, 05/10/2019 - 19:58
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Altered Brain Function in Drug-Naïve Major Depressive Disorder Patients With Early-Life Maltreatment: A Resting-State fMRI Study.

Front Psychiatry. 2019;10:255

Authors: Xu Z, Zhang J, Wang D, Wang T, Zhang S, Ren X, Zhu X, Kamiya A, Fang J, Qu M

Abstract
Childhood Maltreatment (CM) is an important risk factor for major depressive disorder (MDD). Previous studies using emotional task-state functional magnetic resonance (task-state fMRI) found that altered brain function in prefrontal-limbic regions was the key neuropathological mechanism in adult MDD patients with experience of early-life maltreatment. However, to the best of our knowledge, there is no published study investigating brain function in MDD patients with CM experience using resting-state fMRI (rs-fMRI). In present study, we aimed to detect altered resting-state brain activity in MDD patients with CM experience, and identify significantly activated brain regions, which may provide new insights into the neural mechanism underlying the relationship between MDD and CM experience. The results showed MDD patients with CM experience were associated with increased amplitude of low-frequency fluctuation (ALFF) and altered function connection (FC) in the prefrontal cortex, when compared to MDD patients without CM. Of note, left frontal middle gyrus (LFEG) was found as a specific brain region which differentiates MDD patients with CM from patients without CM. These results suggest that rs-fMRI is a useful method in studying the correlation between MDD and CM experience and altered function of LFEG in resting-state may explain the correlation between MDD and CM experience.

PMID: 31068844 [PubMed]

Hub distribution of the brain functional networks of newborns prenatally exposed to maternal depression and SSRI antidepressants.

Thu, 05/09/2019 - 19:57
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Hub distribution of the brain functional networks of newborns prenatally exposed to maternal depression and SSRI antidepressants.

Depress Anxiety. 2019 May 08;:

Authors: Rotem-Kohavi N, Williams LJ, Muller AM, Abdi H, Virji-Babul N, Bjornson BH, Brain U, Werker JF, Grunau RE, Miller SP, Oberlander TF

Abstract
BACKGROUND: Prenatal maternal depression (PMD) and selective serotonin reuptake inhibitor (SSRI) antidepressants are associated with increased developmental risk in infants. Reports suggest that PMD is associated with hyperconnectivity of the insula and the amygdala, while SSRI exposure is associated with hyperconnectivity of the auditory network in the infant brain. However, associations between functional brain organization and PMD and/or SSRI exposure are not well understood.
METHODS: We examined the relation between PMD or SSRI exposure and neonatal brain functional organization. Infants of control (n = 17), depressed SSRI-treated (n = 20) and depressed-only (HAM-D ≥ 8) (n = 16) women, underwent resting-state functional magnetic resonance imaging at postnatal Day 6. At 6 months, temperament was assessed using Infant Behavioral Questionnaire (IBQ). We applied GTA and partial least square regression (PLSR) to the resting-state time series to assess group differences in modularity, and connector and provincial hubs.
RESULTS: Modularity was similar across all groups. The depressed-only group showed higher connector hub values in the left anterior cingulate, insula, and caudate as well as higher provincial hub values in the amygdala compared to the control group. The SSRI group showed higher provincial hub values in Heschl's gyrus relative to the depressed-only group. PLSR showed that newborns' hub values predicted 10% of the variability in infant temperament at 6 months, suggesting different developmental patterns between groups.
CONCLUSIONS: Prenatal exposures to maternal depression and SSRIs have differential impacts on neonatal functional brain organization. Hub values at 6 days predict variance in temperament between infant groups at 6 months of age.

PMID: 31066992 [PubMed - as supplied by publisher]

Duloxetine effects on striatal resting-state functional connectivity in patients with major depressive disorder.

Thu, 05/09/2019 - 19:57
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Duloxetine effects on striatal resting-state functional connectivity in patients with major depressive disorder.

Hum Brain Mapp. 2019 May 08;:

Authors: Wang L, An J, Gao HM, Zhang P, Chen C, Li K, Mitchell PB, Si TM

Abstract
Reward deficits and associated striatal circuitry disturbances have been implicated in the onset and progression of major depressive disorder (MDD). However, no studies have been conducted to investigate how the striatal circuitry changes during standard antidepressant, which is important for development of novel and targeted treatments for MDD. We examined the seed-to-whole-brain functional connectivity (FC) for six striatal subregions based on resting-state fMRI data of 23 MDD patients before and after 8-week duloxetine, a serotonin, and noradrenaline reuptake inhibitor. Twenty-three healthy controls (HCs) were also scanned twice with an 8-week interval. After the analysis of covariance, we observed significant group-by-time interaction on FC of the dorsal caudate (DC), ventral striatum (VS), and putamen seeds. Post hoc analyses revealed that the FC between several right striatal seeds and left superior frontal gyrus (SFG), between right DC and left precuneus, between right superior VS and left inferior parietal lobe, were significantly higher in MDD patients compared to HCs at baseline and were reduced after treatment. Conversely, the FC between right inferior VS and left cerebellum was lower in MDD patients and was increased after treatment. Patients with larger reduction in right superior VS-left SFG FC exhibited larger alleviation of rumination. These findings suggest that duloxetine modulates the striatal FC with dorsolateral prefrontal cortex, posterior default mode network, and cerebellum, and partly, these changes underlie symptomatic improvement. This study adds to our understanding of antidepressant mechanism and future therapeutic development might benefit from considering these striatal circuitry as potential targets.

PMID: 31066977 [PubMed - as supplied by publisher]

Aberrant brain network topology in fronto-limbic circuitry differentiates euthymic bipolar disorder from recurrent major depressive disorder.

Thu, 05/09/2019 - 19:57
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Aberrant brain network topology in fronto-limbic circuitry differentiates euthymic bipolar disorder from recurrent major depressive disorder.

Brain Behav. 2019 May 07;:e01257

Authors: Dvorak J, Hilke M, Trettin M, Wenzler S, Hagen M, Ghirmai N, Müller M, Kraft D, Reif A, Oertel V

Abstract
INTRODUCTION: Previous studies have established graph theoretical analysis of functional network connectivity (FNC) as a potential tool to detect neurobiological underpinnings of psychiatric disorders. Despite the promising outcomes in studies that examined FNC aberrancies in bipolar disorder (BD) and major depressive disorder (MDD), there is still a lack of research comparing both mood disorders, especially in a nondepressed state. In this study, we used graph theoretical network analysis to compare brain network properties of euthymic BD, euthymic MDD and healthy controls (HC) to evaluate whether these groups showed distinct features in FNC.
METHODS: We collected resting-state functional magnetic resonance imaging (fMRI) data from 20 BD patients, 15 patients with recurrent MDD as well as 30 age- and gender-matched HC. Graph theoretical analyses were then applied to investigate functional brain networks on a global and regional network level.
RESULTS: Global network analysis revealed a significantly higher mean global clustering coefficient in BD compared to HC. We further detected frontal, temporal and subcortical nodes in emotion regulation areas such as the limbic system and associated regions exhibiting significant differences in network integration and segregation in BD compared to MDD patients and HC. Participants with MDD and HC only differed in frontal and insular network centrality.
CONCLUSION: In conclusion, our findings indicate that a significantly altered brain network topology in the limbic system might be a trait marker specific to BD. Brain network analysis in these regions may therefore be used to differentiate euthymic BD not only from HC but also from patients with MDD.

PMID: 31066228 [PubMed - as supplied by publisher]

Accurate neuroimaging biomarkers to predict body mass index in adolescents: a longitudinal study.

Thu, 05/09/2019 - 19:57
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Accurate neuroimaging biomarkers to predict body mass index in adolescents: a longitudinal study.

Brain Imaging Behav. 2019 May 07;:

Authors: Park BY, Chung CS, Lee MJ, Park H

Abstract
Obesity is often associated with cardiovascular complications. Adolescent obesity is a risk factor for cardiovascular disease in adulthood; thus, intensive management is warranted in adolescence. The brain state contributes to the development of obesity in addition to metabolic conditions, and hence neuroimaging is an important tool for accurately assessing an individual's risk of developing obesity. Here, we aimed to predict body mass index (BMI) progression in adolescents with neuroimaging features using machine learning approaches. From an open database, we adopted 76 resting-state functional magnetic resonance imaging (rs-fMRI) datasets from adolescents with longitudinal BMI scores. Functional connectivity analyses were performed on cortical surfaces and subcortical volumes. We identified baseline functional connectivity features in the prefrontal-, posterior cingulate-, sensorimotor-, and inferior parietal-cortices as significant determinants of BMI changes. A BMI prediction model based on the identified fMRI biomarkers exhibited a high accuracy (intra-class correlation = 0.98) in predicting BMI at the second visit (1~2 years later). The identified brain regions were significantly correlated with the eating disorder-, anxiety-, and depression-related scores. Based on these results, we concluded that these functional connectivity features in brain regions related to eating disorders and emotional processing could be important neuroimaging biomarkers for predicting BMI progression.

PMID: 31065926 [PubMed - as supplied by publisher]

Connectivity of the Cingulate Sulcus Visual Area (CSv) in the Human Cerebral Cortex.

Thu, 05/09/2019 - 19:57
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Connectivity of the Cingulate Sulcus Visual Area (CSv) in the Human Cerebral Cortex.

Cereb Cortex. 2018 02 01;28(2):713-725

Authors: Smith AT, Beer AL, Furlan M, Mars RB

Abstract
The human cingulate sulcus visual area (CSv) responds selectively to visual and vestibular cues to self-motion. Although it is more selective for visual self-motion cues than any other brain region studied, it is not known whether CSv mediates perception of self-motion. An alternative hypothesis, based on its location, is that it provides sensory information to the motor system for use in guiding locomotion. To evaluate this hypothesis we studied the connectivity pattern of CSv, which is completely unknown, with a combination of diffusion MRI and resting-state functional MRI. Converging results from the 2 approaches suggest that visual drive is provided primarily by areas hV6, pVIP (putative intraparietal cortex) and PIC (posterior insular cortex). A strong connection with the medial portion of the somatosensory cortex, which represents the legs and feet, suggests that CSv may receive locomotion-relevant proprioceptive information as well as visual and vestibular signals. However, the dominant connections of CSv are with specific components of the motor system, in particular the cingulate motor areas and the supplementary motor area. We propose that CSv may provide a previously unknown link between perception and action that serves the online control of locomotion.

PMID: 28108496 [PubMed - indexed for MEDLINE]

[Effect of Flurbiprofen Axetil on Low-frequency Fluctuation Amplitude of Resting-state Functional Magnetic Resonance Imaging in Trigeminal Neuralgia].

Wed, 05/08/2019 - 22:56
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[Effect of Flurbiprofen Axetil on Low-frequency Fluctuation Amplitude of Resting-state Functional Magnetic Resonance Imaging in Trigeminal Neuralgia].

Zhongguo Yi Xue Ke Xue Yuan Xue Bao. 2019 Apr 28;41(2):228-233

Authors: Cai N, Fu Q, Zhang YY, Yu GX

Abstract
Objective To observe the changes of brain function in patients with trigeminal neuralgia after administration of flurbiprofen axetil by using the resting-state functional magnetic resonance imaging(fMRI)and based on the amplitude of low-frequency fluctuation(ALFF). Methods Resting fMRI data of 20 patients with trigeminal neuralgia before and after treatment with flurbiprofen axetil were collected by 1.5T magnetic resonance imaging system.The resting fMRI data were pretreated by Statistical Parametric Mapping and DPABI(a toolbox for Data Processing and Analysis for Brain Imaging)software,and the difference of low-frequency oscillation amplitude of brain spontaneous activity before and after treatment with flurbiprofen axetil was analyzed by ALFF. Results The Visual Analogue Scale of pain intensity after flurbiprofen axetil injection was significantly lower than that before administration,and the pain relieved significantly(P=0.000).The ALFF values of right dorsolateral prefrontal lobe,bilateral medial prefrontal lobe,and right middle cingulate gyrus in patients treated with flurbiprofen axetil at rest were significantly lower than those before administration(P=0.000). Conclusions The analgesic effect of flurbiprofen axetil is exerted on the central system.This agent can inhibit the abnormal brain function caused by chronic pain stimulation and thus reduce pain.However,the specific mechanism needs further investigations.

PMID: 31060679 [PubMed - in process]

Functional disconnectivity of the hippocampal network and neural correlates of memory impairment in treatment-resistant depression.

Tue, 05/07/2019 - 19:55
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Functional disconnectivity of the hippocampal network and neural correlates of memory impairment in treatment-resistant depression.

J Affect Disord. 2019 Apr 29;253:248-256

Authors: Ge R, Torres I, Brown JJ, Gregory E, McLellan E, Downar JH, Blumberger DM, Daskalakis ZJ, Lam RW, Vila-Rodriguez F

Abstract
BACKGROUND: Major depressive disorder (MDD) is a disabling neuropsychiatric condition associated with cognitive impairment. Neuroimaging studies have consistently linked memory deficits with hippocampal atrophy in MDD patients. However, there has been a paucity of research examining how the hippocampus functionally contributes to memory impairments in MDD. The present study examined whether hippocampal networks distinguish treatment-resistant depression (TRD) patients from healthy controls (HCs), and whether these networks underlie declarative memory deficits in TRD. We hypothesized that functional connectivity (FC) of the posterior hippocampus would correlate preferentially with memory in patients, whereas FC pattern of the anterior and intermediate hippocampus would correlate with emotion-mediated regions and show a significant correlation with memory.
METHODS: Resting-state functional magnetic resonance imaging (fMRI) scans were acquired in 56 patients and 42 age- and sex-matched HCs. We parcellated the hippocampus into three subregions based on a sparse representation-based method recently developed by our group. FC networks of hippocampal subregions were compared between patients and HCs and correlated with clinical measures and cognitive performance.
RESULTS: Decreased connectivity of the right intermediate hippocampus (RIH) with the limbic regions was a distinguishing feature between TRD and HCs. These functional abnormalities were present in the absence of structural volumetric differences. Furthermore, lower right amygdalar connectivity to the RIH related to a longer current depressive episode. Declarative memory deficits in TRD were significantly associated with left posterior and right intermediate hippocampal FC patterns.
LIMITATIONS: Our patient samples were treatment-resistant, the conclusions from this study cannot be generalized to all MDD patients directly. Task-based imaging studies are needed to demonstrate hippocampal engagement in the memory deficits of patients. Finally, our findings are strongly in need of replication in independent validation samples.
CONCLUSIONS: These findings demonstrate a transitional property of the intermediate hippocampal subregion between its anterior and posterior counterparts in TRD patients, and provide new insights into the neural network-level dysfunction of the hippocampus in TRD.

PMID: 31060011 [PubMed - as supplied by publisher]

The voxel-wise analysis of false negative fMRI activation in regions of provoked impaired cerebrovascular reactivity.

Tue, 05/07/2019 - 19:55
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The voxel-wise analysis of false negative fMRI activation in regions of provoked impaired cerebrovascular reactivity.

PLoS One. 2019;14(5):e0215294

Authors: van Niftrik CHB, Piccirelli M, Muscas G, Sebök M, Fisher JA, Bozinov O, Stippich C, Valavanis A, Regli L, Fierstra J

Abstract
Task-evoked Blood-oxygenation-level-dependent (BOLD-fMRI) signal activation is widely used to interrogate eloquence of brain areas. However, data interpretation can be improved, especially in regions with absent BOLD-fMRI signal activation. Absent BOLD-fMRI signal activation may actually represent false-negative activation due to impaired cerebrovascular reactivity (BOLD-CVR) of the vascular bed. The relationship between impaired BOLD-CVR and BOLD-fMRI signal activation may be better studied in healthy subjects where neurovascular coupling is known to be intact. Using a model-based prospective end-tidal carbon dioxide (CO2) targeting algorithm, we performed two controlled 3 tesla BOLD-CVR studies on 17 healthy subjects: 1: at the subjects' individual resting end-tidal CO2 baseline. 2: Around +6.0 mmHg CO2 above the subjects' individual resting baseline. Two BOLD-fMRI finger-tapping experiments were performed at similar normo- and hypercapnic levels. Relative BOLD fMRI signal activation and t-values were calculated for BOLD-CVR and BOLD-fMRI data. For each component of the cerebral motor-network (precentral gyrus, postcentral gyrus, supplementary motor area, cerebellum und fronto-operculum), the correlation between BOLD-CVR and BOLD-fMRI signal changes and t-values was investigated. Finally, a voxel-wise quantitative analysis of the impact of BOLD-CVR on BOLD-fMRI was performed. For the motor-network, the linear correlation coefficient between BOLD-CVR and BOLD-fMRI t-values were significant (p<0.01) and in the range 0.33-0.55, similar to the correlations between the CVR and fMRI Δ%signal (p<0.05; range 0.34-0.60). The linear relationship between CVR and fMRI is challenged by our voxel-wise analysis of Δ%signal and t-value change between normo- and hypercapnia. Our main finding is that BOLD fMRI signal activation maps are markedly dampened in the presence of impaired BOLD-CVR and highlights the importance of a complementary BOLD-CVR assessment in addition to a task-evoked BOLD fMRI to identify brain areas at risk for false-negative BOLD-fMRI signal activation.

PMID: 31059517 [PubMed - in process]

Stronger Functional Connectivity in the Default Mode and Salience Networks Is Associated With Youthful Memory in Superaging.

Tue, 05/07/2019 - 19:55
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Stronger Functional Connectivity in the Default Mode and Salience Networks Is Associated With Youthful Memory in Superaging.

Cereb Cortex. 2019 May 06;:

Authors: Zhang J, Andreano JM, Dickerson BC, Touroutoglou A, Barrett LF

Abstract
"Superagers" are older adults who, despite their advanced age, maintain youthful memory. Previous morphometry studies revealed multiple default mode network (DMN) and salience network (SN) regions whose cortical thickness is greater in superagers and correlates with memory performance. In this study, we examined the intrinsic functional connectivity within DMN and SN in 41 young (24.5 ± 3.6 years old) and 40 older adults (66.9 ± 5.5 years old). Superaging was defined as youthful performance on a memory recall task, the California Verbal Learning Test (CVLT). Participants underwent a resting-state functional magnetic resonance imaging (fMRI) scan and performed a separate visual-verbal recognition memory task. As predicted, within both DMN and SN, superagers had stronger connectivity compared with typical older adults and similar connectivity compared with young adults. Superagers also performed similarly to young adults and better than typical older adults on the recognition task, demonstrating youthful episodic memory that generalized across memory tasks. Stronger connectivity within each network independently predicted better performance on both the CVLT and recognition task in older adults. Variation in intrinsic connectivity explained unique variance in memory performance, above and beyond youthful neuroanatomy. These results extend our understanding of the neural basis of superaging as a model of successful aging.

PMID: 31058917 [PubMed - as supplied by publisher]