Most recent paper

Subscribe to Most recent paper feed Most recent paper
NCBI: db=pubmed; Term="resting"[All Fields] AND "fMRI"[All Fields]
Updated: 53 min 47 sec ago

Cortical tau deposition follows patterns of entorhinal functional connectivity in aging.

Tue, 09/03/2019 - 22:35
Related Articles

Cortical tau deposition follows patterns of entorhinal functional connectivity in aging.

Elife. 2019 Sep 02;8:

Authors: Adams JN, Maass A, Harrison TM, Baker SL, Jagust WJ

Abstract
Tau pathology first appears in the transentorhinal and anterolateral entorhinal cortex (alEC) in the aging brain. The transition to Alzheimer's disease (AD) is hypothesized to involve amyloid-b (Ab) facilitated tau spread through neural connections. We contrasted functional connectivity (FC) of alEC and posteromedial EC (pmEC), subregions of EC that differ in functional specialization and cortical connectivity, with the hypothesis that alEC-connected cortex would show greater tau deposition than pmEC-connected cortex. We used resting state fMRI to measure FC, and PET to measure tau and Aβ in cognitively normal older adults. Tau preferentially deposited in alEC-connected cortex compared to pmEC-connected or non-connected cortex, and stronger connectivity was associated with increased tau deposition. FC-tau relationships were present regardless of Aβ, though strengthened with Aβ. These results provide an explanation for the anatomic specificity of neocortical tau deposition in the aging brain and reveal relationships between normal aging and the evolution of AD.

PMID: 31475904 [PubMed - as supplied by publisher]

Prolonged Bedtime Smartphone Use is Associated With Altered Resting-State Functional Connectivity of the Insula in Adult Smartphone Users.

Tue, 09/03/2019 - 22:35
Related Articles

Prolonged Bedtime Smartphone Use is Associated With Altered Resting-State Functional Connectivity of the Insula in Adult Smartphone Users.

Front Psychiatry. 2019;10:516

Authors: Paik SH, Park CH, Kim JY, Chun JW, Choi JS, Kim DJ

Abstract
Prolonged bedtime smartphone use is often associated with poor sleep quality and daytime dysfunction. In addition, the unstructured nature of smartphones may lead to excessive and uncontrolled use, which can be a cardinal feature of problematic smartphone use. This study was designed to investigate functional connectivity of insula, which is implicated in salience processing, interoceptive processing, and cognitive control, in association with prolonged bedtime smartphone use. We examined resting-state functional connectivity (rsFC) of insula in 90 adults who used smartphones by functional magnetic resonance imaging (fMRI). Smartphone time in bed was measured by self-report. Prolonged bedtime smartphone use was associated with higher smartphone addiction proneness scale (SAPS) scores, but not with sleep quality. The strength of the rsFC between the left insula and right putamen, and between the right insula and left superior frontal, middle temporal, fusiform, inferior orbitofrontal gyrus and right superior temporal gyrus was positively correlated with smartphone time in bed. The findings imply that prolonged bedtime smartphone use can be an important behavioral measure of problematic smartphone use and altered insula-centered functional connectivity may be associated with it.

PMID: 31474880 [PubMed]

Determinants of Inter-Individual Variability in Corticomotor Excitability Induced by Paired Associative Stimulation.

Tue, 09/03/2019 - 22:35
Related Articles

Determinants of Inter-Individual Variability in Corticomotor Excitability Induced by Paired Associative Stimulation.

Front Neurosci. 2019;13:841

Authors: Minkova L, Peter J, Abdulkadir A, Schumacher LV, Kaller CP, Nissen C, Klöppel S, Lahr J

Abstract
Transcranial magnetic stimulation (TMS) is a well-established tool in probing cortical plasticity in vivo. Changes in corticomotor excitability can be induced using paired associative stimulation (PAS) protocol, in which TMS over the primary motor cortex is conditioned with an electrical peripheral nerve stimulation of the contralateral hand. PAS with an inter-stimulus interval of 25 ms induces long-term potentiation (LTP)-like effects in cortical excitability. However, the response to a PAS protocol tends to vary substantially across individuals. In this study, we used univariate and multivariate data-driven methods to investigate various previously proposed determinants of inter-individual variability in PAS efficacy, such as demographic, cognitive, clinical, neurophysiological, and neuroimaging measures. Forty-one right-handed participants, comprising 22 patients with amnestic mild cognitive impairment (MCI) and 19 healthy controls (HC), underwent the PAS protocol. Prior to stimulation, demographic, genetic, clinical, as well as structural and resting-state functional MRI data were acquired. The two groups did not differ in any of the variables, except by global cognitive status. Univariate analysis showed that only 61% of all participants were classified as PAS responders, irrespective of group membership. Higher PAS response was associated with lower TMS intensity and with higher resting-state connectivity within the sensorimotor network, but only in responders, as opposed to non-responders. We also found an overall positive correlation between PAS response and structural connectivity within the corticospinal tract, which did not differ between groups. A multivariate random forest (RF) model identified age, gender, education, IQ, global cognitive status, sleep quality, alertness, TMS intensity, genetic factors, and neuroimaging measures (functional and structural connectivity, gray matter (GM) volume, and cortical thickness as poor predictors of PAS response. The model resulted in low accuracy of the RF classifier (58%; 95% CI: 42 - 74%), with a higher relative importance of brain connectivity measures compared to the other variables. We conclude that PAS variability in our sample was not well explained by factors known to influence PAS efficacy, emphasizing the need for future replication studies.

PMID: 31474818 [PubMed]

Low Frequency Systemic Hemodynamic "Noise" in Resting State BOLD fMRI: Characteristics, Causes, Implications, Mitigation Strategies, and Applications.

Tue, 09/03/2019 - 22:35
Related Articles

Low Frequency Systemic Hemodynamic "Noise" in Resting State BOLD fMRI: Characteristics, Causes, Implications, Mitigation Strategies, and Applications.

Front Neurosci. 2019;13:787

Authors: Tong Y, Hocke LM, Frederick BB

Abstract
Advances in functional magnetic resonance imaging (fMRI) acquisition have improved signal to noise to the point where the physiology of the subject is the dominant noise source in resting state fMRI data (rsfMRI). Among these systemic, non-neuronal physiological signals, respiration and to some degree cardiac fluctuations can be removed through modeling, or in the case of newer, faster acquisitions such as simultaneous multislice acquisition, simple spectral filtering. However, significant low frequency physiological oscillation (∼0.01-0.15 Hz) remains in the signal. This is problematic, as it is the precise frequency band occupied by the neuronally modulated hemodynamic responses used to study brain connectivity, precluding its removal by spectral filtering. The source of this signal, and its method of production and propagation in the body, have not been conclusively determined. Here, we summarize the defining characteristics of the systemic low frequency noise signal, and review some current theories about the signal source and the evidence supporting them. The strength and distribution of the systemic LFO signal make characterizing and removing it essential for accurate quantification, especially for resting state connectivity, when no stimulation can be compared with the signal. Widespread correlated non-neuronal signals obscure and distort the more localized patterns of neuronal correlations between interacting brain regions; they may even cause apparent connectivity between regions with no neuronal interaction. Here, we discuss a simple method we have developed to parse the global, moving, blood-borne signal from the stationary, neuronal connectivity signals, substantially reducing the negative correlations that result from global signal regression. Finally, we will discuss some of the uses to which the moving systemic low frequency oscillation can be put if we consider it a "signal" carrying information, rather than simply "noise" complicating the interpretation of resting state connectivity. Properly utilizing this signal may offer insights into subtle hemodynamic alterations that can be used as early indicators of circulatory dysfunction in a number of neuropsychiatric conditions, such as prodromal stroke, moyamoya, and Alzheimer's disease.

PMID: 31474815 [PubMed]

Resting-state fMRI dynamic functional network connectivity and associations with psychopathy traits.

Mon, 09/02/2019 - 22:32
Related Articles

Resting-state fMRI dynamic functional network connectivity and associations with psychopathy traits.

Neuroimage Clin. 2019 Aug 05;24:101970

Authors: Espinoza FA, Anderson NE, Vergara VM, Harenski CL, Decety J, Rachakonda S, Damaraju E, Koenigs M, Kosson DS, Harenski K, Calhoun VD, Kiehl KA

Abstract
Studies have used resting-state functional magnetic resonance imaging (rs-fMRI) to examine associations between psychopathy and brain connectivity in selected regions of interest as well as networks covering the whole-brain. One of the limitations of these approaches is that brain connectivity is modeled as a constant state through the scan duration. To address this limitation, we apply group independent component analysis (GICA) and dynamic functional network connectivity (dFNC) analysis to uncover whole-brain, time-varying functional network connectivity (FNC) states in a large forensic sample. We then examined relationships between psychopathic traits (PCL-R total scores, Factor 1 and Factor 2 scores) and FNC states obtained from dFNC analysis. FNC over the scan duration was better represented by five states rather than one state previously shown in static FNC analysis. Consistent with prior findings, psychopathy was associated with networks from paralimbic regions (amygdala and insula). In addition, whole-brain FNC identified 15 networks from nine functional domains (subcortical, auditory, sensorimotor, cerebellar, visual, salience, default mode network, executive control and attentional) related to psychopathy traits (Factor 1 and PCL-R scores). Results also showed that individuals with higher Factor 1 scores (affective and interpersonal traits) spend more time in a state with weaker connectivity overall, and changed states less frequently compared to those with lower Factor 1 scores. On the other hand, individuals with higher Factor 2 scores (impulsive and antisocial behaviors) showed more dynamism (changes to and from different states) than those with lower scores.

PMID: 31473543 [PubMed - as supplied by publisher]

Alterations in the functional brain network in a rat model of epileptogenesis: A longitudinal resting state fMRI study.

Mon, 09/02/2019 - 22:32
Related Articles

Alterations in the functional brain network in a rat model of epileptogenesis: A longitudinal resting state fMRI study.

Neuroimage. 2019 Aug 29;:116144

Authors: Christiaen E, Goossens MG, Raedt R, Descamps B, Larsen LE, Craey E, Carrette E, Vonck K, Boon P, Vanhove C

Abstract
Epilepsy is a neurological disorder characterized by recurrent epileptic seizures. Electrophysiological and neuroimaging studies in patients with epilepsy suggest that abnormal functional brain networks play a role in the development of epilepsy, i.e. epileptogenesis, resulting in the generation of spontaneous seizures and cognitive impairment. In this longitudinal study, we investigated changes in functional brain networks during epileptogenesis in the intraperitoneal kainic acid (IPKA) rat model of temporal lobe epilepsy (TLE) using resting state functional magnetic resonance imaging (rsfMRI) and graph theory. Additionally, we investigated whether these changes are related to the frequency of occurrence of spontaneous epileptic seizures in the chronic phase of epilepsy. Using a 7T MRI system, rsfMRI images were acquired under medetomidine anaesthesia before and 1, 3, 6, 10 and 16 weeks after status epilepticus (SE) induction in 20 IPKA animals and 7 healthy control animals. To obtain a functional network, correlation between fMRI time series of 38 regions of interest (ROIs) was calculated. Then, several graph theoretical network measures were calculated to describe and quantify the network changes. At least 17 weeks post-SE, IPKA animals were implanted with electrodes in the left and right dorsal hippocampus, EEG was measured for 7 consecutive days and spontaneous seizures were counted. Our results show that correlation coefficients of fMRI time series shift to lower values during epileptogenesis, indicating weaker whole brain network connections. Segregation and integration in the functional brain network also decreased, indicating a lower local interconnectivity and a lower overall communication efficiency. Secondly, this study demonstrated that the largest decrease in functional connectivity was observed for the retrosplenial cortex. Finally, post-SE changes in functional connectivity, segregation and integration were correlated with seizure frequency in the IPKA rat model.

PMID: 31473355 [PubMed - as supplied by publisher]

Different exercise modalities relieve pain syndrome in patients with knee osteoarthritis and modulate the dorsolateral prefrontal cortex: a multiple mode MRI study.

Sun, 09/01/2019 - 19:30
Related Articles

Different exercise modalities relieve pain syndrome in patients with knee osteoarthritis and modulate the dorsolateral prefrontal cortex: a multiple mode MRI study.

Brain Behav Immun. 2019 Aug 28;:

Authors: Liu J, Chen L, Tu Y, Chen X, Hu K, Tu Y, Lin M, Xie G, Chen S, Huang J, Liu W, Wu J, Xiao T, Wilson G, Lang C, Park J, Tao J, Kong J

Abstract
OBJECTIVES: Knee osteoarthritis (KOA) is a common degenerative joint disease with no satisfactory intervention. Recently, both physical and mindfulness exercises have received considerable attention for their implications in KOA pain management, and the dorsolateral prefrontal cortex (DLPFC) has displayed a critical role in pain modulation. This study aimed to comparatively investigate the modulation effects of different exercises using multidisciplinary measurements.
METHODS: 140 KOA patients were randomized into Tai Chi, Baduanjin, stationary cycling, or health education control groups for 12 weeks. Knee Injury and Osteoarthritis Outcome Score (KOOS), resting state functional magnetic resonance imaging (fMRI), structural MRI, and serum biomarkers were measured at baseline and at the end of the study.
RESULTS: We found: 1) increased KOOS pain subscores (pain reduction) and serum programmed cell death protein 1 (PD-1) levels in the three exercise groups compared to the control group; 2) decreased resting state functional connectivity (rsFC) of the DLPFC-supplementary motor area (SMA) and increased rsFC between the DLPFC and anterior cingulate cortex in all exercise groups compared to the control group; 3) significant associations between DLPFC-SMA rsFC with KOOS pain subscores and serum PD-1 levels at baseline; 4) significantly increased grey matter volume in the SMA in the Tai Chi and stationary cycling groups, and a trend towards significant increase in the Baduanjin group compared to the control group; 5) significant DLPFC rsFC differences among different exercise groups; and 6) that baseline DLPFC-SMA rsFC can predict the effect of mind-body exercise on pain improvement in KOA.
CONCLUSION: Our results suggest that different exercises can modulate both common and unique DLPFC (cognitive control) pathways, and altered DLPFC-SMA rsFC is associated with serum biomarker levels. Our findings also highlight the potentials of neuroimaging biomarkers in predicting the therapeutic effect of mind-body exercises on KOA pain.

PMID: 31472246 [PubMed - as supplied by publisher]

Correlated Resting-State Functional MRI Activity of Frontostriatal, Thalamic, Temporal, and Cerebellar Brain Regions Differentiates Stroke Survivors with High Compared to Low Depressive Symptom Scores.

Sat, 08/31/2019 - 22:28
Related Articles

Correlated Resting-State Functional MRI Activity of Frontostriatal, Thalamic, Temporal, and Cerebellar Brain Regions Differentiates Stroke Survivors with High Compared to Low Depressive Symptom Scores.

Neural Plast. 2019;2019:2357107

Authors: Goodin P, Lamp G, Vidyasagar R, Connelly A, Rose S, Campbell BCV, Tse T, Ma H, Howells D, Hankey GJ, Davis S, Donnan G, Carey LM

Abstract
Background: One in three survivors of stroke experience poststroke depression (PSD). PSD has been linked with poorer recovery of function and cognition, yet our understanding of potential mechanisms is currently limited. Alterations in resting-state functional MRI have been investigated to a limited extent. Fluctuations in low frequency signal are reported, but it is unknown if interactions are present between the level of depressive symptom score and intrinsic brain activity in varying brain regions.
Objective: To investigate potential interaction effects between whole-brain resting-state activity and depressive symptoms in stroke survivors with low and high levels of depressive symptoms.
Methods: A cross-sectional analysis of 63 stroke survivors who were assessed at 3 months poststroke for depression, using the Montgomery-Åsberg Depression Rating Scale (MÅDRS-SIGMA), and for brain activity using fMRI. A MÅDRS-SIGMA score of >8 was classified as high depressive symptoms. Fractional amplitude of frequency fluctuations (fALFF) data across three frequency bands (broadband, i.e., ~0.01-0.08; subbands, i.e., slow-5: ~0.01-0.027 Hz, slow-4: 0.027-0.07) was examined.
Results: Of the 63 stroke survivors, 38 were classified as "low-depressive symptoms" and 25 as "high depressive symptoms." Six had a past history of depression. We found interaction effects across frequency bands in several brain regions that differentiated the two groups. The broadband analysis revealed interaction effects in the left insula and the left superior temporal lobe. The subband analysis showed contrasting fALFF response between the two groups in the left thalamus, right caudate, and left cerebellum. Across the three frequency bands, we found contrasting fALFF response in areas within the fronto-limbic-thalamic network and cerebellum.
Conclusions: We provide evidence that fALFF is sensitive to changes in poststroke depressive symptom severity and implicates frontostriatal and cerebellar regions, consistent with previous studies. The use of multiband analysis could be an effective method to examine neural correlates of depression after stroke. The START-PrePARE trial is registered with the Australian New Zealand Clinical Trial Registry, number ACTRN12610000987066.

PMID: 31467520 [PubMed - in process]

In vivo magnetic resonance imaging reveals the effect of gonadal hormones on morphological and functional brain sexual dimorphisms in adult sheep.

Fri, 08/30/2019 - 19:27

In vivo magnetic resonance imaging reveals the effect of gonadal hormones on morphological and functional brain sexual dimorphisms in adult sheep.

Psychoneuroendocrinology. 2019 Aug 13;109:104387

Authors: Barrière DA, Ella A, Adriaensen H, Roselli CE, Chemineau P, Keller M

Abstract
Sex differences in the brain and behavior are produced by the perinatal action of testosterone, which is converted into estradiol by the enzyme aromatase in the brain. Although magnetic resonance imaging (MRI) has been widely used in humans to study these differences, the use of animal models, where hormonal status can be properly manipulated, is necessary to explore the mechanisms involved. We used sheep, a recognized model in the field of neuroendocrinology, to assess brain morphological and functional sex differences and their regulation by adult gonadal hormones. To this end, we performed voxel-based morphometry and a resting-state functional MRI approach to assess sex differences in gonadally intact animals. We demonstrated significant sex differences in gray matter concentration (GMC) at the level of the gonadotropic axis, i.e., not only within the hypothalamus and pituitary but also within the hippocampus and the amygdala of intact animals. We then performed the same analysis one month after gonadectomy and found that some of these differences were reduced, especially in the hypothalamus and amygdala. By contrast, we found few differences in the organization of the functional connectome between males and females either before or after gonadectomy. As a whole, our study identifies brain regions that are sexually dimorphic in the sheep brain at the resolution of the MRI and highlights the role of gonadal hormones in the maintenance of these differences.

PMID: 31465941 [PubMed - as supplied by publisher]

The predictive potential of altered spontaneous brain activity patterns in diabetic retinopathy and nephropathy.

Fri, 08/30/2019 - 19:27
Related Articles

The predictive potential of altered spontaneous brain activity patterns in diabetic retinopathy and nephropathy.

EPMA J. 2019 Sep;10(3):249-259

Authors: Wang Y, Shao Y, Shi WQ, Jiang L, Wang XY, Zhu PW, Yuan Q, Gao G, Lv JL, Wang GX

Abstract
Objective: The amplitude of low-frequency fluctuation (ALFF) fMRI technique was used to study the changes of spontaneous brain activity in patients with diabetic retinopathy and nephropathy (DRN), and to explore the application of ALFF technique in the potential prediction and the targeted prevention of diabetic microangiopathy.
Methods: Nineteen patients with diabetic retinopathy and nephropathy and 19 healthy controls (HCs) were matched for age and gender. Spontaneous cerebral activity variations were investigated using the ALFF technique. The average ALFF values of the DRN patients and the HCs were classified utilizing receiver operating characteristic (ROC) curves.
Results: In contrast to the results in the HCs, the patients with DRN had significantly higher ALFF values in the cerebellum (bilaterally in the posterior and anterior lobes) and the left inferior temporal gyrus, but the ALFF values of the bilateral medial frontal gyrus, right superior temporal gyrus, right middle frontal gyrus, left middle/inferior frontal gyrus, bilateral precuneus, and left inferior parietal lobule were lower. ROC curve analysis of each brain region showed the accuracy of AUC was excellent. However, the mean ALFF values in the different regions did not correlate with clinical performance. The subjects showed abnormal neuronal synchronization in many areas of the brain, which is consistent with cognitive and visual functional deficits.
Conclusion: Abnormal spontaneous activity was detected in many areas of the brain, which may provide useful information for understanding the pathology of DRN. Abnormal ALFF values of these brain regions may be of predictive value in the development of early DRN and be a targeted intervention indicator for individualized treatment of diabetic microvascular diseases.

PMID: 31462942 [PubMed]

[The correlation of functional connectivity and structural connectivity between hippocampus and thalamus in Alzheimer's disease and amnestic mild cognitive impairment].

Thu, 08/29/2019 - 19:26

[The correlation of functional connectivity and structural connectivity between hippocampus and thalamus in Alzheimer's disease and amnestic mild cognitive impairment].

Zhonghua Nei Ke Za Zhi. 2019 Sep 01;58(9):662-667

Authors: Feng F, Zhou B, Wang L, Yao HX, Guo YE, An NY, Wang LN, Zhang X

Abstract
Objective: To investigate the correlation of functional connectivity (FC) and the integrity of connective fibres between hippocampus and thalamus in Alzheimer's disease(AD) and amnestic mild cognitive impairment (aMCI). Methods: Both resting-state functional magnetic resonance imaging (rs-fMRI) and diffusion tensor imaging (DTI) data of 40 AD patients, 37 aMCI patients and 41 normal control subjects matching with age and educational level were collected. These subjects were all recruited from outpatient Department of Neurology in the Second Medical Center of Chinese PLA General Hospital, as well as poster, from May 2016 to January 2018. The FC strength between bilateral hippocampus and thalamus, as well as the parameters representing integrity of connective fibres, including fractional anisotropy (FA) and mean diffusivity(MD),were analyzed. Also, the correlations between FC strength and FA or MD strength were analyzed in the study. Results: Compared to that of normal control subjects, the FC strength between billateral hippocampus and thalamus in patients with AD, aMCI were not significantly different(P>0.05). The integrity of bilateral connective fibres between hippocampus and thalamus were damaged in AD patients when compared to normal control subjects(P<0.01). A positive correlation of connective fibres integrity with FC strength between hippocampus and thalamus was found in the left side(r=0.25,P<0.05) but rather in the right side. Conclusion: In AD and aMCI patients, structural connectivity between left hippocampus and thalamus affects the functional connectivity between them.

PMID: 31461817 [PubMed - in process]

Imaging the spontaneous flow of thought: Distinct periods of cognition contribute to dynamic functional connectivity during rest.

Thu, 08/29/2019 - 19:26

Imaging the spontaneous flow of thought: Distinct periods of cognition contribute to dynamic functional connectivity during rest.

Neuroimage. 2019 Aug 25;:116129

Authors: Gonzalez-Castillo J, Caballero-Gaudes C, Topolski N, Handwerker DA, Pereira F, Bandettini PA

Abstract
Brain functional connectivity (FC) changes have been measured across seconds using fMRI. This is true for both rest and task scenarios. Moreover, it is well accepted that task engagement alters FC, and that dynamic estimates of FC during and before task events can help predict their nature and performance. Yet, when it comes to dynamic FC (dFC) during rest, there is no consensus about its origin or significance. Some argue that rest dFC reflects fluctuations in on-going cognition, or is a manifestation of intrinsic brain maintenance mechanisms, which could have predictive clinical value. Conversely, others have concluded that rest dFC is mostly the result of sampling variability, head motion or fluctuating sleep states. Here, we present novel analyses suggesting that rest dFC is influenced by short periods of spontaneous cognitive-task-like processes, and that the cognitive nature of such mental processes can be inferred blindly from the data. As such, several different behaviorally relevant whole-brain FC configurations may occur during a single rest scan even when subjects were continuously awake and displayed minimal motion. In addition, using low dimensional embeddings as visualization aids, we show how FC states-commonly used to summarize and interpret resting dFC-can accurately and robustly reveal periods of externally imposed tasks; however, they may be less effective in capturing periods of distinct cognition during rest.

PMID: 31461679 [PubMed - as supplied by publisher]

Effects of Neural Mechanisms of Pretask Resting EEG Alpha Information on Situational Awareness: A Functional Connectivity Approach.

Thu, 08/29/2019 - 19:26

Effects of Neural Mechanisms of Pretask Resting EEG Alpha Information on Situational Awareness: A Functional Connectivity Approach.

Hum Factors. 2019 Aug 28;:18720819869129

Authors: Kaur A, Chaujar R, Chinnadurai V

Abstract
OBJECTIVE: In this study, the influence of pretask resting neural mechanisms on situational awareness (SA)-task is studied.
BACKGROUND: Pretask electroencephalography (EEG) information and Stroop effect are known to influence task engagement independently. However, neural mechanisms of pretask resting absolute alpha (PRAA) and pretask resting alpha frontal asymmetry (PRAFA) in influencing SA-task which is undergoing Stroop effect is still not understood.
METHOD: The study involved pretask resting EEG measurements from 18 healthy individuals followed by functional magnetic resonance imaging (fMRI) acquisition during SA-task. To understand the effect of pretask alpha information and Stroop effect on SA, a robust correlation between mean reaction time, SA Index, PRAA, and PRAFA were assessed. Furthermore, neural underpinnings of PRAA, PRAFA in SA-task, and functional connectivity were analyzed through the EEG-informed fMRI approach.
RESULTS: Significant robust correlation of reaction time was observed with SA Index (Pearson: r = .50, pcorr = .05) and PRAFA (Pearson: r = .63; pcorr = .01), respectively. Similarly, SA Index significantly correlated with PRAFA (Pearson: r = .56, pcorr = .01; Spearman: r = .61, pcorr = .007), and PRAA (Pearson: r = .59, pcorr = .005; Spearman: r = .59, pcorr = .002). Neural underpinnings of SA-task revealed regions involved in visual-processing and higher-order cognition. PRAA was primarily underpinned at frontal-temporal areas and functionally connected to SA-task regions pertaining to the emotional regulation. PRAFA has correlated with limbic and parietal regions, which are involved in integration of visual, emotion, and memory information of SA-task.
CONCLUSION: The results suggest a strong association of reaction time with SA-task and PRAFA and strongly support the hypothesis that PRAFA, PRAA, and associated neural mechanisms significantly influence the outcome of SA-task.
APPLICATION: It is beneficial to study the effect of pretask resting information on SA-task to improve SA.

PMID: 31461374 [PubMed - as supplied by publisher]

Lower Functional Connectivity in Vestibular-Limbic Networks in Individuals With Subclinical Agoraphobia.

Thu, 08/29/2019 - 19:26

Lower Functional Connectivity in Vestibular-Limbic Networks in Individuals With Subclinical Agoraphobia.

Front Neurol. 2019;10:874

Authors: Indovina I, Conti A, Lacquaniti F, Staab JP, Passamonti L, Toschi N

Abstract
Background: Agoraphobia was described in 1871 as a condition of fear-related alterations in spatial orientation and locomotor control triggered by places or situations that might cause a patient to panic and feel trapped. In contemporary nosology, however, this original concept of agoraphobia was split into two diagnostic entities, i.e., the modern anxiety disorder of agoraphobia, consisting solely of phobic/avoidant symptoms in public spaces, and the recently defined vestibular disorder of persistent postural perceptual dizziness (PPPD), characterized by dizziness, and unsteadiness exacerbated by visual motion stimuli. Previous neuroimaging studies found altered brain activity and connectivity in visual-vestibular networks of patients with PPPD vs. healthy controls. Neuroticism and introversion, which pre-dispose to both agoraphobia and PPPD, influenced brain responses to vestibular and visual motion stimuli in patients with PPPD. Similar neuroimaging studies have not been undertaken in patients with agoraphobia in its current definition. Given their shared history and pre-disposing factors, we sought to test the hypotheses that individuals with agoraphobic symptoms have alterations in visual-vestibular networks similar to those of patients with PPPD, and that these alterations are influenced by neuroticism and introversion. Methods: Drawing from the Human Connectome Project (HCP) database, we matched 52 participants with sub-clinical agoraphobia and 52 control subjects without agoraphobic symptoms on 19 demographic and psychological/psychiatric variables. We then employed a graph-theoretical framework to compare resting-state functional magnetic resonance images between groups and evaluated the interactive effects of neuroticism and introversion on the brain signatures of agoraphobia. Results: Individuals with subclinical agoraphobia had lower global clustering, efficiency and transitivity relative to controls. They also had lower connectivity metrics in two brain networks, one positioned to process incoming visual space-motion information, assess threat, and initiate/inhibit behavioral responses (visuospatial-emotional network) and one positioned to control and monitor locomotion (vestibular-navigational network). Introversion interacted with agoraphobic symptoms to lower the connectivity of the visuospatial-emotional network. This contrasted with previous findings describing neuroticism-associated higher connectivity in a narrower visual-spatial-frontal network in patients with PPPD. Conclusion: Functional connectivity was lower in two brain networks in subclinical agoraphobia as compared to healthy controls. These networks integrate visual vestibular and emotional response to guide movement in space.

PMID: 31456740 [PubMed]

Resting State fMRI: Going Through the Motions.

Thu, 08/29/2019 - 19:26

Resting State fMRI: Going Through the Motions.

Front Neurosci. 2019;13:825

Authors: Maknojia S, Churchill NW, Schweizer TA, Graham SJ

Abstract
Resting state functional magnetic resonance imaging (rs-fMRI) has become an indispensable tool in neuroscience research. Despite this, rs-fMRI signals are easily contaminated by artifacts arising from movement of the head during data collection. The artifacts can be problematic even for motions on the millimeter scale, with complex spatiotemporal properties that can lead to substantial errors in functional connectivity estimates. Effective correction methods must be employed, therefore, to distinguish true functional networks from motion-related noise. Research over the last three decades has produced numerous correction methods, many of which must be applied in combination to achieve satisfactory data quality. Subject instruction, training, and mild restraints are helpful at the outset, but usually insufficient. Improvements come from applying multiple motion correction algorithms retrospectively after rs-fMRI data are collected, although residual artifacts can still remain in cases of elevated motion, which are especially prevalent in patient populations. Although not commonly adopted at present, "real-time" correction methods are emerging that can be combined with retrospective methods and that promise better correction and increased rs-fMRI signal sensitivity. While the search for the ideal motion correction protocol continues, rs-fMRI research will benefit from good disclosure practices, such as: (1) reporting motion-related quality control metrics to provide better comparison between studies; and (2) including motion covariates in group-level analyses to limit the extent of motion-related confounds when studying group differences.

PMID: 31456656 [PubMed]

Task-evoked reconfiguration of the fronto-parietal network is associated with cognitive performance in brain tumor patients.

Thu, 08/29/2019 - 19:26
Related Articles

Task-evoked reconfiguration of the fronto-parietal network is associated with cognitive performance in brain tumor patients.

Brain Imaging Behav. 2019 Aug 27;:

Authors: De Baene W, Jansma MJ, Schouwenaars IT, Rutten GM, Sitskoorn MM

Abstract
In healthy participants, the strength of task-evoked network reconfigurations is associated with cognitive performance across several cognitive domains. It is, however, unclear whether the capacity for network reconfiguration also plays a role in cognitive deficits in brain tumor patients. In the current study, we examined whether the level of reconfiguration of the fronto-parietal ('FPN') and default mode network ('DMN') during task execution is correlated with cognitive performance in patients with different types of brain tumors. For this purpose, we combined data from a resting state and task-fMRI paradigm in patients with a glioma or meningioma. Cognitive performance was measured using the in-scanner working memory task, as well as an out-of-scanner cognitive flexibility task. Task-evoked changes in functional connectivity strength (defined as the mean of the absolute values of all connections) and in functional connectivity patterns within and between the FPN and DMN did not differ significantly across meningioma and fast (HGG) and slowly growing glioma (LGG) patients. Across these brain tumor patients, a significant and positive correlation was found between the level of task-evoked reconfiguration of the FPN and cognitive performance. This suggests that the capacity for FPN reconfiguration also plays a role in cognitive deficits in brain tumor patients, as was previously found for normal cognitive performance in healthy controls.

PMID: 31456158 [PubMed - as supplied by publisher]

Endogenous fluctuations in the dopaminergic midbrain drive behavioral choice variability.

Thu, 08/29/2019 - 01:26
Related Articles

Endogenous fluctuations in the dopaminergic midbrain drive behavioral choice variability.

Proc Natl Acad Sci U S A. 2019 Aug 26;:

Authors: Chew B, Hauser TU, Papoutsi M, Magerkurth J, Dolan RJ, Rutledge RB

Abstract
Human behavior is surprisingly variable, even when facing the same problem under identical circumstances. A prominent example is risky decision making. Economic theories struggle to explain why humans are so inconsistent. Resting-state studies suggest that ongoing endogenous fluctuations in brain activity can influence low-level perceptual and motor processes, but it remains unknown whether endogenous fluctuations also influence high-level cognitive processes including decision making. Here, using real-time functional magnetic resonance imaging, we tested whether risky decision making is influenced by endogenous fluctuations in blood oxygenation level-dependent (BOLD) activity in the dopaminergic midbrain, encompassing ventral tegmental area and substantia nigra. We show that low prestimulus brain activity leads to increased risky choice in humans. Using computational modeling, we show that increased risk taking is explained by enhanced phasic responses to offers in a decision network. Our findings demonstrate that endogenous brain activity provides a physiological basis for variability in complex human behavior.

PMID: 31451671 [PubMed - as supplied by publisher]

Functional Connectivity Signatures of Parkinson's Disease.

Thu, 08/29/2019 - 01:26
Related Articles

Functional Connectivity Signatures of Parkinson's Disease.

J Parkinsons Dis. 2019 Aug 23;:

Authors: Tessitore A, Cirillo M, De Micco R

Abstract
 Resting-state functional magnetic resonance imaging (RS-fMRI) studies have been extensively applied to analyze the pathophysiology of neurodegenerative disorders such as Parkinson's disease (PD). In the present narrative review, we attempt to summarize the most recent RS-fMRI findings highlighting the role of brain networks re-organization and adaptation in the course of PD. We also discuss limitations and potential definition of early functional connectivity signatures to track and predict future PD progression. Understanding the neural correlates and potential predisposing factors of clinical progression and complication will be crucial to guide novel clinical trials and to foster preventive strategies.

PMID: 31450512 [PubMed - as supplied by publisher]

Quantitative Susceptibility Mapping and Resting State Network Analyses in Parkinsonian Phenotypes-A Systematic Review of the Literature.

Wed, 08/28/2019 - 01:24
Related Articles

Quantitative Susceptibility Mapping and Resting State Network Analyses in Parkinsonian Phenotypes-A Systematic Review of the Literature.

Front Neural Circuits. 2019;13:50

Authors: Pelzer EA, Florin E, Schnitzler A

Abstract
An imbalance of iron metabolism with consecutive aggregation of α-synuclein and axonal degeneration of neurons has been postulated as the main pathological feature in the development of Parkinson's disease (PD). Quantitative susceptibility mapping (QSM) is a new imaging technique, which enables to measure structural changes caused by defective iron deposition in parkinsonian brains. Due to its novelty, its potential as a new imaging technique remains elusive for disease-specific characterization of motor and non-motor symptoms (characterizing the individual parkinsonian phenotype). Functional network changes associated with these symptoms are however frequently described for both magnetoencephalography (MEG) and resting state functional magnetic imaging (rs-fMRI). Here, we performed a systematic review of the current literature about QSM imaging, MEG and rs-fMRI in order to collect existing data about structural and functional changes caused by motor and non-motor symptoms in PD. Whereas all three techniques provide an effect in the motor domain, the understanding of network changes caused by non-motor symptoms is much more lacking for MEG and rs-fMRI, and does not yet really exist for QSM imaging. In order to better understand the influence of pathological iron distribution onto the functional outcome, whole-brain QSM analyses should be integrated in functional analyses (especially for the non-motor domain), to enable a proper pathophysiological interpretation of MEG and rs-fMRI network changes in PD. Herewith, a better understanding of the relationship between neuropathological changes, functional network changes and clinical phenotype might become possible.

PMID: 31447651 [PubMed - in process]

A Neurophysiological Event of Arousal Modulation May Underlie fMRI-EEG Correlations.

Wed, 08/28/2019 - 01:24
Related Articles

A Neurophysiological Event of Arousal Modulation May Underlie fMRI-EEG Correlations.

Front Neurosci. 2019;13:823

Authors: Han F, Gu Y, Liu X

PMID: 31447638 [PubMed]