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Manipulation of Subcortical and Deep Cortical Activity in the Primate Brain Using Transcranial Focused Ultrasound Stimulation.

Sun, 02/17/2019 - 00:19
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Manipulation of Subcortical and Deep Cortical Activity in the Primate Brain Using Transcranial Focused Ultrasound Stimulation.

Neuron. 2019 Feb 07;:

Authors: Folloni D, Verhagen L, Mars RB, Fouragnan E, Constans C, Aubry JF, Rushworth MFS, Sallet J

Abstract
The causal role of an area within a neural network can be determined by interfering with its activity and measuring the impact. Many current reversible manipulation techniques have limitations preventing their application, particularly in deep areas of the primate brain. Here, we demonstrate that a focused transcranial ultrasound stimulation (TUS) protocol impacts activity even in deep brain areas: a subcortical brain structure, the amygdala (experiment 1), and a deep cortical region, the anterior cingulate cortex (ACC, experiment 2), in macaques. TUS neuromodulatory effects were measured by examining relationships between activity in each area and the rest of the brain using functional magnetic resonance imaging (fMRI). In control conditions without sonication, activity in a given area is related to activity in interconnected regions, but such relationships are reduced after sonication, specifically for the targeted areas. Dissociable and focal effects on neural activity could not be explained by auditory confounds.

PMID: 30765166 [PubMed - as supplied by publisher]

Circadian phenotype impacts the brain's resting state functional connectivity, attentional performance and sleepiness.

Sat, 02/16/2019 - 00:19
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Circadian phenotype impacts the brain's resting state functional connectivity, attentional performance and sleepiness.

Sleep. 2019 Feb 15;:

Authors: Facer-Childs ER, Campos BM, Middleton B, Skene DJ, Bagshaw AP

Abstract
INTRODUCTION: Functional connectivity (FC) of the human brain's intrinsically connected networks underpins cognitive functioning and disruptions of FC are associated with sleep and neurological disorders. However, there is limited research on the impact of circadian phenotype and time of day on FC.
STUDY OBJECTIVES: The aim of this study was to investigate resting state FC of the default mode network (DMN) in Early and Late circadian phenotypes over a socially constrained day.
METHODS: 38 healthy individuals (14 male, 22.7 ± 4.2 years) categorised as Early (n =16) or Late (n = 22) using the Munich ChronoType Questionnaire took part. Following a two week baseline of actigraphy coupled with saliva samples for melatonin and cortisol rhythms, participants underwent testing at 14.00 h, 20.00 h and 08.00 h the following morning. Testing consisted of resting state functional MRI, a structural T1 scan, attentional cognitive performance tasks and self-reported daytime sleepiness. Seed based FC analysis from the medial prefrontal and posterior cingulate cortices of the DMN was performed, compared between groups and linked with behavioural data.
RESULTS: Fundamental differences in the DMN were observed between Early and Late circadian phenotypes. Resting state FC of the DMN predicted individual differences in attention and subjective ratings of sleepiness.
CONCLUSION: Differences in FC of the DMN may underlie the compromised attentional performance and increased sleepiness commonly associated with Late types when they conform to a societally constrained day that does not match their intrinsic circadian phenotype.

PMID: 30763951 [PubMed - as supplied by publisher]

Resting State Functional Connectivity of Dorsal Raphe Nucleus and Ventral Tegmental Area in Medication-Free Young Adults With Major Depression.

Sat, 02/16/2019 - 00:19
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Resting State Functional Connectivity of Dorsal Raphe Nucleus and Ventral Tegmental Area in Medication-Free Young Adults With Major Depression.

Front Psychiatry. 2018;9:765

Authors: Anand A, Jones SE, Lowe M, Karne H, Koirala P

Abstract
Background: This study has, for the first time, investigated the dorsal raphe nucleus (DRN) and ventral tegmental area (VTA) resting state whole-brain functional connectivity in medication-free young adults with major depression (MDD), at baseline and in relationship to treatment response. Method: A total of 119 subjects: 78 MDD (24 ± 4 years.) and 41 Healthy Controls (HC) (24 ± 3 years) were included in the analysis. DRN and VTA ROIs anatomical templates were used to extract resting state fluctuations and used to derive whole-brain functional connectivity. Differences between MDD and HCs were examined, as well as the correlation of baseline Hamilton Depression and Anxiety scale scores to the baseline DRN and VTA connectivity. The relationship to treatment response was examined by investigating the correlation of the percentage decrease in depression and anxiety scale scores with baseline connectivity measures. Results: There was a significant decrease (p = 0.05; cluster-wise corrected) in DRN connectivity with the prefrontal and mid-cingulate cortex in the MDD group, compared with the HC group. DRN connectivity with temporal areas, including the hippocampus and amygdala, positively correlated with baseline depression scores (p = 0.05; cluster-wise corrected). VTA connectivity with the cuneus-occipital areas correlated with a change in depression scores (p = 0.05; cluster-wise corrected). Conclusion: Our results indicate the presence of DRN-prefrontal and DRN-cingulate cortex connectivity abnormalities in young medication-free depressed subjects when compared to HCs and that the severity of depressive symptoms correlates with DRN-amygdala/hippocampus connectivity. VTA connectivity with the parietal and occipital areas is related to antidepressant treatment associated with a decrease in depressive symptoms. Future studies need to be carried out in larger and different age group populations to confirm the findings of the study.

PMID: 30761028 [PubMed]

Improved state change estimation in dynamic functional connectivity using hidden semi-Markov models.

Thu, 02/14/2019 - 03:15
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Improved state change estimation in dynamic functional connectivity using hidden semi-Markov models.

Neuroimage. 2019 Feb 09;:

Authors: Shappell H, Caffo BS, Pekar JJ, Lindquist MA

Abstract
The study of functional brain networks has grown rapidly over the past decade. While most functional connectivity (FC) analyses estimate one static network structure for the entire length of the functional magnetic resonance imaging (fMRI) time series, recently there has been increased interest in studying time-varying changes in FC. Hidden Markov models (HMMs) have proven to be a useful modeling approach for discovering repeating graphs of interacting brain regions (brain states). However, a limitation lies in HMMs assuming that the sojourn time, the number of consecutive time points in a state, is geometrically distributed. This may encourage inaccurate estimation of the time spent in a state before switching to another state. We propose a hidden semi-Markov model (HSMM) approach for inferring time-varying brain networks from fMRI data, which explicitly models the sojourn distribution. Specifically, we propose using HSMMs to find each subject's most probable series of network states and the graphs associated with each state, while properly estimating and modeling the sojourn distribution for each state. We perform a simulation study, as well as an analysis on both task-based fMRI data from an anxiety-inducing experiment and resting-state fMRI data from the Human Connectome Project. Our results demonstrate the importance of model choice when estimating sojourn times and reveal their potential for understanding healthy and diseased brain mechanisms.

PMID: 30753927 [PubMed - as supplied by publisher]

A mind-brain-body dataset of MRI, EEG, cognition, emotion, and peripheral physiology in young and old adults.

Thu, 02/14/2019 - 03:15
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A mind-brain-body dataset of MRI, EEG, cognition, emotion, and peripheral physiology in young and old adults.

Sci Data. 2019 Feb 12;6:180308

Authors: Babayan A, Erbey M, Kumral D, Reinelt JD, Reiter AMF, Röbbig J, Schaare HL, Uhlig M, Anwander A, Bazin PL, Horstmann A, Lampe L, Nikulin VV, Okon-Singer H, Preusser S, Pampel A, Rohr CS, Sacher J, Thöne-Otto A, Trapp S, Nierhaus T, Altmann D, Arelin K, Blöchl M, Bongartz E, Breig P, Cesnaite E, Chen S, Cozatl R, Czerwonatis S, Dambrauskaite G, Dreyer M, Enders J, Engelhardt M, Fischer MM, Forschack N, Golchert J, Golz L, Guran CA, Hedrich S, Hentschel N, Hoffmann DI, Huntenburg JM, Jost R, Kosatschek A, Kunzendorf S, Lammers H, Lauckner ME, Mahjoory K, Kanaan AS, Mendes N, Menger R, Morino E, Näthe K, Neubauer J, Noyan H, Oligschläger S, Panczyszyn-Trzewik P, Poehlchen D, Putzke N, Roski S, Schaller MC, Schieferbein A, Schlaak B, Schmidt R, Gorgolewski KJ, Schmidt HM, Schrimpf A, Stasch S, Voss M, Wiedemann A, Margulies DS, Gaebler M, Villringer A

Abstract
We present a publicly available dataset of 227 healthy participants comprising a young (N=153, 25.1±3.1 years, range 20-35 years, 45 female) and an elderly group (N=74, 67.6±4.7 years, range 59-77 years, 37 female) acquired cross-sectionally in Leipzig, Germany, between 2013 and 2015 to study mind-body-emotion interactions. During a two-day assessment, participants completed MRI at 3 Tesla (resting-state fMRI, quantitative T1 (MP2RAGE), T2-weighted, FLAIR, SWI/QSM, DWI) and a 62-channel EEG experiment at rest. During task-free resting-state fMRI, cardiovascular measures (blood pressure, heart rate, pulse, respiration) were continuously acquired. Anthropometrics, blood samples, and urine drug tests were obtained. Psychiatric symptoms were identified with Standardized Clinical Interview for DSM IV (SCID-I), Hamilton Depression Scale, and Borderline Symptoms List. Psychological assessment comprised 6 cognitive tests as well as 21 questionnaires related to emotional behavior, personality traits and tendencies, eating behavior, and addictive behavior. We provide information on study design, methods, and details of the data. This dataset is part of the larger MPI Leipzig Mind-Brain-Body database.

PMID: 30747911 [PubMed - in process]

Offline impact of transcranial focused ultrasound on cortical activation in primates.

Thu, 02/14/2019 - 03:15
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Offline impact of transcranial focused ultrasound on cortical activation in primates.

Elife. 2019 Feb 12;8:

Authors: Verhagen L, Gallea C, Folloni D, Constans C, Jensen DE, Ahnine H, Roumazeilles L, Santin M, Ahmed B, Lehericy S, Klein-Flügge MC, Krug K, Mars RB, Rushworth MF, Pouget P, Aubry JF, Sallet J

Abstract
To understand brain circuits it is necessary both to record and manipulate their activity. Transcranial ultrasound stimulation (TUS) is a promising non-invasive brain stimulation technique. To date, investigations report short-lived neuromodulatory effects, but to deliver on its full potential for research and therapy, ultrasound protocols are required that induce longer-lasting 'offline' changes. Here, we present a TUS protocol that modulates brain activation in macaques for more than one hour after 40 s of stimulation, while circumventing auditory confounds. Normally activity in brain areas reflects activity in interconnected regions but TUS caused stimulated areas to interact more selectively with the rest of the brain. In a within-subject design, we observe regionally specific TUS effects for two medial frontal brain regions - supplementary motor area and frontal polar cortex. Independently of these site-specific effects, TUS also induced signal changes in the meningeal compartment. TUS effects were temporary and not associated with microstructural changes.

PMID: 30747105 [PubMed - in process]

Hierarchical Heterogeneity across Human Cortex Shapes Large-Scale Neural Dynamics.

Thu, 02/14/2019 - 03:15
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Hierarchical Heterogeneity across Human Cortex Shapes Large-Scale Neural Dynamics.

Neuron. 2019 Feb 05;:

Authors: Demirtaş M, Burt JB, Helmer M, Ji JL, Adkinson BD, Glasser MF, Van Essen DC, Sotiropoulos SN, Anticevic A, Murray JD

Abstract
The large-scale organization of dynamical neural activity across cortex emerges through long-range interactions among local circuits. We hypothesized that large-scale dynamics are also shaped by heterogeneity of intrinsic local properties across cortical areas. One key axis along which microcircuit properties are specialized relates to hierarchical levels of cortical organization. We developed a large-scale dynamical circuit model of human cortex that incorporates heterogeneity of local synaptic strengths, following a hierarchical axis inferred from magnetic resonance imaging (MRI)-derived T1- to T2-weighted (T1w/T2w) mapping and fit the model using multimodal neuroimaging data. We found that incorporating hierarchical heterogeneity substantially improves the model fit to functional MRI (fMRI)-measured resting-state functional connectivity and captures sensory-association organization of multiple fMRI features. The model predicts hierarchically organized higher-frequency spectral power, which we tested with resting-state magnetoencephalography. These findings suggest circuit-level mechanisms linking spatiotemporal levels of analysis and highlight the importance of local properties and their hierarchical specialization on the large-scale organization of human cortical dynamics.

PMID: 30744986 [PubMed - as supplied by publisher]

Alexithymia and frontal-amygdala functional connectivity in North Korean refugees.

Thu, 02/14/2019 - 03:15
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Alexithymia and frontal-amygdala functional connectivity in North Korean refugees.

Psychol Med. 2019 Feb 12;:1-8

Authors: Kim N, Park I, Lee YJ, Jeon S, Kim S, Lee KH, Park J, Kim HK, Gwaq AR, Jun JY, Yoo SY, Lee SH, Kim SJ

Abstract
BACKGROUND: Refugees commonly experience difficulties with emotional processing, such as alexithymia, due to stressful or traumatic experiences. However, the functional connectivity of the amygdala, which is central to emotional processing, has yet to be assessed in refugees. Thus, the present study investigated the resting-state functional connectivity of the amygdala and its association with emotional processing in North Korean (NK) refugees.
METHODS: This study included 45 NK refugees and 40 native South Koreans (SK). All participants were administered the Toronto Alexithymia Scale (TAS), Beck Depression Inventory (BDI), and Clinician-administered PTSD Scale (CAPS), and differences between NK refugees and native SK in terms of resting-state functional connectivity of the amygdala were assessed. Additionally, the association between the strength of amygdala connectivity and the TAS score was examined.
RESULTS: Resting-state connectivity values from the left amygdala to the bilateral dorsolateral prefrontal cortex (dlPFC) and dorsal anterior cingulate cortex (dACC) were higher in NK refugees than in native SK. Additionally, the strength of connectivity between the left amygdala and right dlPFC was positively associated with TAS score after controlling for the number of traumatic experiences and BDI and CAPS scores.
CONCLUSIONS: The present study found that NK refugees exhibited heightened frontal-amygdala connectivity, and that this connectivity was correlated with alexithymia. The present results suggest that increased frontal-amygdala connectivity in refugees may represent frontal down-regulation of the amygdala, which in turn may produce alexithymia.

PMID: 30744720 [PubMed - as supplied by publisher]

Increased amygdala-visual cortex connectivity in youth with persecutory ideation.

Thu, 02/14/2019 - 03:15
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Increased amygdala-visual cortex connectivity in youth with persecutory ideation.

Psychol Med. 2019 Feb 12;:1-11

Authors: DeCross SN, Farabaugh AH, Holmes AJ, Ward M, Boeke EA, Wolthusen RPF, Coombs G, Nyer M, Fava M, Buckner RL, Holt DJ

Abstract
BACKGROUND: Subclinical delusional ideas, including persecutory beliefs, in otherwise healthy individuals are heritable symptoms associated with increased risk for psychotic illness, possibly representing an expression of one end of a continuum of psychosis severity. The identification of variation in brain function associated with these symptoms may provide insights about the neurobiology of delusions in clinical psychosis.
METHODS: A resting-state functional magnetic resonance imaging scan was collected from 131 young adults with a wide range of severity of subclinical delusional beliefs, including persecutory ideas. Because of evidence for a key role of the amygdala in fear and paranoia, resting-state functional connectivity of the amygdala was measured.
RESULTS: Connectivity between the amygdala and early visual cortical areas, including striate cortex (V1), was found to be significantly greater in participants with high (n = 43) v. low (n = 44) numbers of delusional beliefs, particularly in those who showed persistence of those beliefs. Similarly, across the full sample, the number of and distress associated with delusional beliefs were positively correlated with the strength of amygdala-visual cortex connectivity. Moreover, further analyses revealed that these effects were driven by those who endorsed persecutory beliefs.
CONCLUSIONS: These findings are consistent with the hypothesis that aberrant assignments of threat to sensory stimuli may lead to the downstream development of delusional ideas. Taken together with prior findings of disrupted sensory-limbic coupling in psychosis, these results suggest that altered amygdala-visual cortex connectivity could represent a marker of psychosis-related pathophysiology across a continuum of symptom severity.

PMID: 30744715 [PubMed - as supplied by publisher]

Variation in the CACNB2 gene is associated with functional connectivity of the Hippocampus in bipolar disorder.

Thu, 02/14/2019 - 03:15
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Variation in the CACNB2 gene is associated with functional connectivity of the Hippocampus in bipolar disorder.

BMC Psychiatry. 2019 Feb 11;19(1):62

Authors: Liu F, Gong X, Yao X, Cui L, Yin Z, Li C, Tang Y, Wang F

Abstract
BACKGROUND: Calcium voltage-gated channel auxiliary subunit β2 is a protein that, in humans, is encoded by the CACNB2 gene. The β2 subunit is an auxiliary protein of voltage-gated calcium channels, which is predominantly expressed in hippocampal pyramidal neurons. A single-nucleotide polymorphism at the CACNB2 gene (rs11013860) has been reported in genome-wide association studies to be associated with bipolar disorder (BD). However, the neural effects of rs11013860 expression are unknown. Thus, the current study investigated the mechanisms of how the CACNB2 gene influences hippocampal-cortical limbic circuits in patients with bipolar disorder (BD).
METHODS: A total of 202 subjects were studied [69 BD patients and 133 healthy controls (HC)]. Participants agreed to undergo resting-state functional magnetic resonance imaging (rs-fMRI) and have blood drawn for genetic testing. Participants were found to belong to either a CC group homozygous for the C-allele (17 BD, 41 HC), or an A-carrier group carrying the high risk A-allele (AA/CA genotypes; 52 BD, 92 HC). Brain activity was assessed using resting-state functional connectivity (rs-FC) analyses.
RESULTS: A main effect of genotype showed that the rs-FC of the AA/CA group was elevated more than that of the CC-group between the hippocampus and the regions of right-inferior temporal, fusiform, and left-inferior occipital gyri. Additionally, a significant diagnosis × genotype interaction was noted between the hippocampus and right pars triangularis. Furthermore, in BD patients, the AA/CA group showed lower rs-FC when compared to that of the CC group. Additionally, individuals from HC within the AA/CA group showed higher rs-FC than that of the CC group. Finally, within C-allele-carrying groups, individuals with BD showed significantly increased rs-FC compared to that of HC.
CONCLUSIONS: Our study demonstrates that BD patients with the CACNB2 rs11013860 AA/CA genotype may exhibit altered hippocampal-cortical connectivity.

PMID: 30744588 [PubMed - in process]

Investigation of the emotional network in depression after stroke: A study of multivariate Granger causality analysis of fMRI data.

Wed, 02/13/2019 - 03:14
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Investigation of the emotional network in depression after stroke: A study of multivariate Granger causality analysis of fMRI data.

J Affect Disord. 2019 Feb 06;249:35-44

Authors: Shi Y, Liu W, Liu R, Zeng Y, Wu L, Huang S, Cai G, Yang J, Wu W

Abstract
OBJECTIVE: Depression after stroke (DAS) is a serious complication of stroke that significantly restricts rehabilitation. Brain imaging technology is an important method for studying the emotional network of DAS. However, few studies have focused on dynamic interactions within the network. The aim of this study was to investigate the emotional network of frontal lobe DAS using the multivariate Granger causality analysis (GCA) method, a technique that can estimate the association among the brain areas to analyze functional magnetic resonance imaging (fMRI) data collected from DAS and no depression after stroke (NDAS).
METHOD: Thirty-six first-time ischemic right frontal lobe stroke patients underwent resting-state fMRI (rs-fMRI) scans. The clinical assessment scale used for screening subjects was as follows: the 24-item Hamilton Rating Scale for Depression (HAMD-24), the National Institutes of Health Stroke Scale (NIHSS), the Mini-Mental State Examination (MMSE), and the Barthel Index (BI). The multivariate GCA method was used to analyze fMRI data collected from DAS and NDAS.
RESULTS: The results showed positive regulations in the order from the ventromedial prefrontal cortex (VMPFC), the anterior cingulate cortex (ACC), and the amygdala (AMYG) to the thalamus, and when the interaction order is opposite, the moderating effect is negative. The thalamus could predict the negative activity of the insular (IC) via the ACC. The dorsolateral prefrontal cortex (DLPFC) could predict the activity of the ACC via the temporal pole (TP).
CONCLUSION: This study found a VMPFC-ACC-AMYG-thalamus emotional circuit to explain the network between different brain regions associated with DAS. The DLPFC and TP play an important role in the emotional regulation of DAS, and the function of the IC is regulated negatively by the thalamus. These findings advance the neural theory of DAS, which is based on the functional relationship between different brain areas.

PMID: 30743020 [PubMed - as supplied by publisher]

Correspondence between cerebral glucose metabolism and BOLD reveals relative power and cost in human brain.

Wed, 02/13/2019 - 03:14
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Correspondence between cerebral glucose metabolism and BOLD reveals relative power and cost in human brain.

Nat Commun. 2019 Feb 11;10(1):690

Authors: Shokri-Kojori E, Tomasi D, Alipanahi B, Wiers CE, Wang GJ, Volkow ND

Abstract
The correspondence between cerebral glucose metabolism (indexing energy utilization) and synchronous fluctuations in blood oxygenation (indexing neuronal activity) is relevant for neuronal specialization and is affected by brain disorders. Here, we define novel measures of relative power (rPWR, extent of concurrent energy utilization and activity) and relative cost (rCST, extent that energy utilization exceeds activity), derived from FDG-PET and fMRI. We show that resting-state networks have distinct energetic signatures and that brain could be classified into major bilateral segments based on rPWR and rCST. While medial-visual and default-mode networks have the highest rPWR, frontoparietal networks have the highest rCST. rPWR and rCST estimates are generalizable to other indexes of energy supply and neuronal activity, and are sensitive to neurocognitive effects of acute and chronic alcohol exposure. rPWR and rCST are informative metrics for characterizing brain pathology and alternative energy use, and may provide new multimodal biomarkers of neuropsychiatric disorders.

PMID: 30741935 [PubMed - in process]

Abnormal fronto-striatal intrinsic connectivity reflects executive dysfunction in alcohol use disorders.

Tue, 02/12/2019 - 00:14
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Abnormal fronto-striatal intrinsic connectivity reflects executive dysfunction in alcohol use disorders.

Cortex. 2019 Jan 23;115:27-42

Authors: Galandra C, Basso G, Manera M, Crespi C, Giorgi I, Vittadini G, Poggi P, Canessa N

Abstract
The neural bases of cognitive impairment(s) in alcohol use disorders (AUDs) have been explained either with the specific involvement of frontal regions mostly affected by alcohol neurotoxic effects, or with a global brain damage underlying different neuro-cognitive alterations. Novel insights into this issue might come from the analysis of resting-state brain activity, representing a baseline level of intrinsic connectivity within and between the networks underlying cognitive performance. We thus addressed the neural bases of cognitive impairment(s) in 22 AUD patients, compared with 18 healthy controls, by coupling resting-state fMRI with an in-depth neuropsychological assessment of the main cognitive domains. We assessed a relationship between AUD patients' cognitive impairment and two complementary facets of intrinsic brain functioning, i.e., intensity of activation and functional network connectivity, related to the strength of connectivity within and between resting-state networks, respectively. Alcoholic patients' decreased cognitive performance involved specifically an executive domain associated with attentional and working-memory tasks. This impairment reflected an abnormal relationship, in patients versus controls, between cognitive performance and the intensity of intrinsic activity in the dorsolateral prefrontal and striatal nodes of the executive control network. Functional connectivity between the same structures was positively correlated with executive performance in the whole sample, but significantly reduced in patients. The present data suggest that AUD patients' executive impairment reflects dysfunctional connectivity between the cortical and subcortical nodes of the networks underlying cognitive control on goal-directed behavior. This evidence provides a baseline for future studies addressing the abnormal neural architecture underlying cognitive impairment in AUDs and the outcome of rehabilitative treatment.

PMID: 30738999 [PubMed - as supplied by publisher]

Editorial: To Eat or Not to Eat: Advancing the Neuroscience of Hedonic Versus Controlled Eating Across Weight and Eating Disorders.

Tue, 02/12/2019 - 00:14
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Editorial: To Eat or Not to Eat: Advancing the Neuroscience of Hedonic Versus Controlled Eating Across Weight and Eating Disorders.

J Am Acad Child Adolesc Psychiatry. 2019 Feb;58(2):151-153

Authors: Ehrlich S, King JA, Boehm I

Abstract
Excessive weight and obesity, especially with childhood onset, is associated with long-term morbidity and mortality and places a major burden on the health care system. In the United States, 17% of children and adolescents are obese (32% overweight). By adulthood, the number rises to 34% or even 68% when also considering overweight individuals.1 Conventional nonsurgical treatments are often ineffective, and weight loss achieved with behaviorally oriented therapy programs is usually small (∼5%) and short-lived.2 A better understanding of the associated psychological mechanisms and their neurobiological underpinnings may allow for the development of more efficient, potentially brain-based, therapeutic interventions. A growing number of human functional magnetic resonance imaging (fMRI) studies point to alterations in reward-related corticostriatal circuity and the hypothalamus, a key area in energy homeostasis.3 Recent studies have analyzed resting state functional connectivity (rsFC), a technique sensitive to changes in the interaction between distant brain regions, which is particularly advantageous in clinical samples, as it requires little compliance and as scanning time is relatively short.

PMID: 30738539 [PubMed - in process]

Human caudate nucleus subdivisions in tinnitus modulation.

Sun, 02/10/2019 - 21:13
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Human caudate nucleus subdivisions in tinnitus modulation.

J Neurosurg. 2019 Feb 08;:1-7

Authors: Perez PL, Wang SS, Heath S, Henderson-Sabes J, Mizuiri D, Hinkley LB, Nagarajan SS, Larson PS, Cheung SW

Abstract
OBJECTIVEThe object of this study was to define caudate nucleus locations responsive to intraoperative direct electrical stimulation for tinnitus loudness modulation and relate those locations to functional connectivity maps between caudate nucleus subdivisions and auditory cortex.METHODSSix awake study participants who underwent bilateral deep brain stimulation (DBS) electrode placement in the caudate nucleus as part of a phase I clinical trial were analyzed for tinnitus modulation in response to acute stimulation at 20 locations. Resting-state 3-T functional MRI (fMRI) was used to compare connectivity strength between centroids of tinnitus loudness-reducing or loudness-nonreducing caudate locations and the auditory cortex in the 6 DBS phase I trial participants and 14 other neuroimaging participants with a Tinnitus Functional Index > 50.RESULTSAcute tinnitus loudness reduction was observed at 5 caudate locations, 4 positioned at the body and 1 at the head of the caudate nucleus in normalized Montreal Neurological Institute space. The remaining 15 electrical stimulation interrogations of the caudate head failed to reduce tinnitus loudness. Compared to the caudate head, the body subdivision had stronger functional connectivity to the auditory cortex on fMRI (p < 0.05).CONCLUSIONSAcute tinnitus loudness reduction was more readily achieved by electrical stimulation of the caudate nucleus body. Compared to the caudate head, the caudate body has stronger functional connectivity to the auditory cortex. These first-in-human findings provide insight into the functional anatomy of caudate nucleus subdivisions and may inform future target selection in a basal ganglia-centric neuromodulation approach to treat medically refractory tinnitus.Clinical trial registration no.: NCT01988688 (clinicaltrials.gov).

PMID: 30738400 [PubMed - as supplied by publisher]

Neurophysiological markers of network dysfunction in neurodegenerative diseases.

Sun, 02/10/2019 - 21:13
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Neurophysiological markers of network dysfunction in neurodegenerative diseases.

Neuroimage Clin. 2019 Feb 02;22:101706

Authors: McMackin R, Bede P, Pender N, Hardiman O, Nasseroleslami B

Abstract
There is strong clinical, imaging and pathological evidence that neurodegeneration is associated with altered brain connectivity. While functional imaging (fMRI) can detect resting and activated states of metabolic activity, its use is limited by poor temporal resolution, cost and confounding vascular parameters. By contrast, electrophysiological (e.g. EEG/MEG) recordings provide direct measures of neural activity with excellent temporal resolution, and source localization methodologies can address problems of spatial resolution, permitting measurement of functional activity of brain networks with a spatial resolution similar to that of fMRI. This opens an exciting therapeutic approach focussed on pharmacological and physiological modulation of brain network activity. This review describes current neurophysiological approaches towards evaluating cortical network dysfunction in common neurodegenerative disorders. It explores how modern neurophysiologic tools can provide markers for diagnosis, prognosis, subcategorization and clinical trial outcome measures, and how modulation of brain networks can contribute to new therapeutic approaches.

PMID: 30738372 [PubMed - as supplied by publisher]

Multimodal neuroimaging study reveals dissociable processes between structural and functional networks in patients with subacute intracerebral hemorrhage.

Sun, 02/10/2019 - 21:13
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Multimodal neuroimaging study reveals dissociable processes between structural and functional networks in patients with subacute intracerebral hemorrhage.

Med Biol Eng Comput. 2019 Feb 09;:

Authors: Zhang X, Yu X, Bao Q, Yang L, Sun Y, Qi P

Abstract
Emerging evidence has revealed widespread stroke-induced brain dysconnectivity, which leads to abnormal network organization. However, there are apparent discrepancies in dysconnectivity between structural connectivity and functional connectivity studies. In this work, resting-state fMRI and structural diffusion tensor imaging were obtained from 26 patients with subacute (10-14 days) intracerebral hemorrhage (ICH) and 20 matched healthy participants (patients/controls = 21/18 after head motion rejection). Graph theoretical approaches were applied to multimodal brain networks to quantitatively compare topological properties between both groups. Prominent small-world properties were found in the structural and functional brain networks of both groups. However, a significant deficit in global integration was revealed in the structural brain networks of the patient group and was associated with more severe clinical manifestations of ICH. Regarding ICH-related nodal deficits, reduced nodal interconnectivity was mainly detected in motor-related regions. Moreover, in the functional brain network, topological properties were mostly comparable between patients with ICH and healthy participants. Beyond the prominent small-world architecture in multimodal brain networks, there are dissociable alterations between structural and functional brain networks in patients with ICH. These findings highlight the potential for using aberrant network metrics as neural biomarkers for evaluation of the severity of ICH. Graphical abstract Intracerebral hemorrhage (ICH) also known as cerebral bleed, a major type of stroke, would significantly affect brain structure and function. Using multimodal neuroimaging, Zhang et al. investigate the ICH-related dysconnectivity in structural and functional brain networks and show a significantly disintegrated structural brain network with a preserved functional network topology in subacute phase (10-14 days).

PMID: 30737626 [PubMed - as supplied by publisher]

Dopaminergic mechanisms underlying normal variation in trait anxiety.

Sun, 02/10/2019 - 21:13
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Dopaminergic mechanisms underlying normal variation in trait anxiety.

J Neurosci. 2019 Feb 08;:

Authors: Berry AS, White RL, Furman DJ, Naskolnakorn JR, Shah VD, D'Esposito M, Jagust WJ

Abstract
Trait anxiety has been associated with altered activity within corticolimbic pathways connecting the amygdala and rostral anterior cingulate cortex (rACC), which receive rich dopaminergic input. Though the popular culture uses the term "chemical imbalance" to describe the pathophysiology of psychiatric conditions such as anxiety disorders, we know little about how individual differences in human dopamine neurochemistry are related to variation in anxiety and activity within corticolimbic circuits. We addressed this issue by examining inter-individual variability in dopamine release at rest using [11C]raclopride positron emission tomography (PET), functional connectivity between amygdala and rACC using resting-state functional magnetic resonance imaging (fMRI), and trait anxiety measures in healthy adult male and female humans. To measure endogenous dopamine release, we collected two [11C]raclopride PET scans per participant. We contrasted baseline [11C]raclopride D2/3 receptor binding and D2/3 receptor binding following oral methylphenidate administration. Methylphenidate blocks the dopamine transporter, which increases extracellular dopamine and leads to reduced [11C]raclopride D2/3 receptor binding via competitive displacement. We found that individuals with higher dopamine release in the amygdala and rACC self-reported lower trait anxiety. Lower trait anxiety was also associated with reduced rACC-amygdala functional connectivity at baseline. Further, functional connectivity showed a modest negative relationship with dopamine release such that reduced rACC-amygdala functional connectivity was accompanied by higher levels of dopamine release in these regions. Together, these findings contribute to hypodopaminergic models of anxiety and support the utility of combining fMRI and PET measures of neurochemical function to advance our understanding of basic affective processes in humans.SIGNIFICANCE STATEMENTIt is common wisdom that individuals vary in their baseline levels of anxiety. We all have a friend or colleague we know to be more "tightly wound" than others, or, perhaps, we are the ones marveling at others' ability to "just go with the flow." While such observations about individual differences within non-clinical populations are commonplace, the neural mechanisms underlying normal variation in trait anxiety have not been established. Using multimodal brain imaging in humans, this study takes initial steps in linking intrinsic measures of neuromodulator release and functional connectivity within regions implicated in anxiety disorders. Our findings suggest that in healthy adults, higher levels of trait anxiety may arise, at least in part, from reduced dopamine neurotransmission.

PMID: 30737306 [PubMed - as supplied by publisher]

On the analysis of rapidly sampled fMRI data.

Sat, 02/09/2019 - 21:13
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On the analysis of rapidly sampled fMRI data.

Neuroimage. 2019 Feb 05;:

Authors: Chen JE, Polimeni JR, Bollmann S, Glover GH

Abstract
Recent advances in parallel imaging and simultaneous multi-slice techniques have permitted whole-brain fMRI acquisitions at sub-second sampling intervals, without significantly sacrificing the spatial coverage and resolution. Apart from probing brain function at finer temporal scales, faster sampling rates may potentially lead to enhanced functional sensitivity, owing possibly to both cleaner neural representations (due to less aliased physiological noise) and additional statistical benefits (due to more degrees of freedom for a fixed scan duration). Accompanying these intriguing aspects of fast acquisitions, however, confusion has also arisen regarding (1) how to preprocess/analyze these fast fMRI data, and (2) what exactly is the extent of benefits with fast acquisitions, i.e., how fast is fast enough for a specific research aim? The first question is motivated by the altered spectral distribution and noise characteristics at short sampling intervals, while the second question seeks to reconcile the complicated trade-offs between the functional contrast-to-noise ratio and the effective degrees of freedom. Although there have been recent efforts to empirically approach different aspects of these two questions, in this work we discuss, from a theoretical perspective accompanied by some illustrative, proof-of-concept experimental in vivo human fMRI data, a few considerations that are rarely mentioned, yet are important for both preprocessing and optimizing statistical inferences for studies that employ acquisitions with sub-second sampling intervals. Several summary recommendations include concerns regarding advisability of relying on low-pass filtering to de-noise physiological contributions, employment of statistical models with sufficient complexity to account for the substantially increased serial correlation, and cautions regarding using rapid sampling to enhance functional sensitivity given that different analysis models may associate with distinct trade-offs between contrast-to-noise ratios and the effective degrees of freedom. As an example, we demonstrate that as TR shortens, the intrinsic differences in how noise is accommodated in general linear models and Pearson correlation analyses (assuming Gaussian distributed stochastic signals and noise) can result in quite different outcomes, either gaining or losing statistical power.

PMID: 30735828 [PubMed - as supplied by publisher]

Graph-based network analysis of resting-state fMRI: test-retest reliability of binarized and weighted networks.

Sat, 02/09/2019 - 21:13
Related Articles

Graph-based network analysis of resting-state fMRI: test-retest reliability of binarized and weighted networks.

Brain Imaging Behav. 2019 Feb 08;:

Authors: Xiang J, Xue J, Guo H, Li D, Cui X, Niu Y, Yan T, Cao R, Ma Y, Yang Y, Wang B

Abstract
In the past decade, resting-state functional magnetic resonance imaging (rs-fMRI) and graph-based measures have been widely used to quantitatively characterize the architectures of brain functional networks in healthy individuals and in patients with abnormalities related to psychopathic and neurological disorders. To accurately evaluate the topological organization of brain functional networks, the definition of the nodes and edges for the construction of functional networks is critical. Furthermore, both types of brain functional networks (binarized networks and weighted networks) are widely used to analyze topological organization. However, how to best select the network type is still debated. Consequently, we investigated the test-retest reliability of brain functional networks with binarized and weighted edges using two independent datasets and four strategies for defining nodes. We revealed fair to good reliability for a majority of network topological attributes and overall higher reliabilities for weighted networks than for binarized networks. For regional nodal efficiency, weighted networks also showed higher reliability across nodes. Thus, our findings imply that weighted networks contain more information, leading to more stable results. In addition, we found that the reliability of brain functional networks was influenced by the node definition strategy and that more precise of nodal definition were associated with higher reliability. The time effect of reliability was restricted, as no differences between long-term and short-term reliability were observed. In conclusion, our results suggest that weighted networks have better reliability because they reflect more topological information, implying broader applications of weighted networks related to normal and disordered function of the human brain.

PMID: 30734917 [PubMed - as supplied by publisher]