Posture alters human resting-state.
Cortex. 2014 Jun 28;58C:199-205
Authors: Thibault RT, Lifshitz M, Jones JM, Raz A
Neuroimaging is ubiquitous; however, neuroimagers seldom investigate the putative impact of posture on brain activity. Whereas participants in most psychological experiments sit upright, many prominent neuroimaging techniques (e.g., functional magnetic resonance imaging (fMRI)) require participants to lie supine. Such postural discrepancies may hold important implications for brain function in general and for fMRI in particular. We directly investigated the effect of posture on spontaneous brain dynamics by recording scalp electrical activity in four orthostatic conditions (lying supine, inclined at 45°, sitting upright, and standing erect). Here we show that upright versus supine posture increases widespread high-frequency oscillatory activity. Our electroencephalographic findings highlight the importance of posture as a determinant in neuroimaging. When generalizing supine imaging results to ecological human cognition, therefore, cognitive neuroscientists would benefit from considering the influence of posture on brain dynamics.
PMID: 25041937 [PubMed - as supplied by publisher]
[The impact of mood on the intrinsic functional connectivity].
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2014 Apr;31(2):262-6
Authors: Wang Z, Song S, Wang L
Although a great number of studies have investigated the changes of resting-state functional connectivity (rsFC) in patients with mental disorders, such as depression and schizophrenia etc, little is known how stable the changes are, and whether temporal sad or happy mood can modulate the intrinsic rsFC. In our experiments, happy and sad video clips were used to induce temporally happy and sad mood states in 20 healthy young adults. We collected functional magnetic resonance imaging (fMRI) data while participants were watching happy or sad video clips, which were administrated in two consecutive days. Seed-based functional connectivity analyses were conducted using the anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (DLPFC), and amygdala as seeds to investigate neural network related to executive function, attention, and emotion. We also investigated the association of the rsFC changes with emotional arousability level to understand individual differences. There is significantly stronger functional connectivity between the left DLPFC and posterior cingulate cortex (PCC) under sad mood than that under happy mood. The increased connectivity strength was positively correlated with subjects' emotional arousability. The increased positive correlation between the left DLPFC and PCC under sad relative to happy mood might reflect an increased processing of negative emotion-relevant stimuli. The easier one was induced by strong negative emotion (higher emotional arousability), the greater the left DLPFC-PCC connectivity was indicated, the greater the instability of the intrinsic rsFC was shown.
PMID: 25039124 [PubMed - in process]
Impaired functional connectivity of brain reward circuitry in patients with schizophrenia and cannabis use disorder: Effects of cannabis and THC.
Schizophr Res. 2014 Jul 15;
Authors: Fischer AS, Whitfield-Gabrieli S, Roth RM, Brunette MF, Green AI
Cannabis use disorder (CUD) occurs in up to 42% of patients with schizophrenia and substantially worsens disease progression. The basis of CUD in schizophrenia is unclear and available treatments are rarely successful at limiting cannabis use. We have proposed that a dysregulated brain reward circuit (BRC) may underpin cannabis use in these patients. In the present pilot study, we used whole-brain seed-to-voxel resting state functional connectivity (rs-fc) to examine the BRC of patients with schizophrenia and CUD, and to explore the effects of smoked cannabis and orally administered delta-9-tetrahydrocannabinol (THC) on the BRC. 12 patients with schizophrenia and CUD and 12 control subjects each completed two fMRI resting scans, with patients administered either a 3.6% THC cannabis cigarette (n=6) or a 15mg THC capsule (n=6) prior to their second scan. Results revealed significantly reduced connectivity at baseline in patients relative to controls, with most pronounced hypoconnectivity found between the nucleus accumbens and prefrontal cortical BRC regions (i.e., anterior prefrontal cortex, orbitofrontal cortex, and anterior cingulate cortex). Both cannabis and THC administration increased connectivity between these regions, in direct correlation with increases in plasma THC levels. This study is the first to investigate interregional connectivity of the BRC and the effects of cannabis and THC on this circuit in patients with schizophrenia and CUD. The findings from this pilot study support the use of rs-fc as a means of measuring the integrity of the BRC and the effects of pharmacologic agents acting on this circuit in patients with schizophrenia and CUD.
PMID: 25037524 [PubMed - as supplied by publisher]
Lewy body compared with Alzheimer dementia is associated with decreased functional connectivity in resting state networks.
Psychiatry Res. 2014 Jun 27;
Authors: Lowther ER, O'Brien JT, Firbank MJ, Blamire AM
Resting state functional magnetic resonance imaging (fMRI) was used to measure whole brain functional connectivity within specific networks hypothesised to be more affected in dementia with Lewy bodies (DLB) (a disease characterised by prominent attentional deficits, spontaneous motor features of parkinsonism and depression) than in Alzheimer׳s disease (AD) and controls. This study involved 68 subjects (15 DLB, 13 AD and 40 controls) who were scanned using resting state BOLD (blood-oxygen-level-dependent) fMRI on a 3T MRI scanner. Functional connectivity was measured using a model-free independent component analysis approach that consisted of temporally concatenating the resting state fMRI data of all study subjects and investigating group differences using a back-reconstruction procedure. Resting state functional connectivity was affected in the default mode, salience, executive and basal ganglia networks in DLB subjects compared with AD and controls. Functional connectivity was lower in DLB compared with AD and controls in these networks, except for the basal ganglia network, where connectivity was greater in DLB. No resting state networks showed less connectivity in AD compared with DLB or controls. Our results suggest that functional connectivity of resting state networks can identify differences between DLB and AD subjects that may help to explain why DLB subjects have more frequent attentional deficits, parkinsonian symptoms, and depression than those with AD.
PMID: 25035300 [PubMed - as supplied by publisher]
186 Spinal Cord Stimulation and Functional Magnetic Resonance Imaging: Pain Relief Correlates With Decreased Connectivity Between Somatosensory and Limbic Brain Networks.
Neurosurgery. 2014 Aug;61 Suppl 1:221-222
Authors: Deogaonkar M, Oluigbo C, Nielson D, Yang X, Sharma M, Vera-Portocarrero L, Molnar G, Abduljalil A, Sederberg P, Rezai AR
INTRODUCTION:: The aim of this study was to use resting state functional magnetic resonance imaging (rs-fMRI) to detect changes in cortical networks and cortical processing linked to pain relief from spinal cord stimulation.
METHODS:: Ten patients who have thoracic epidural spinal cord stimulators were enrolled in this Institutional Review Board approved study. Stimulation parameters associated with "optimal" pain reduction and SCS perception threshold were evaluated prior to imaging studies. rs-fMRI was obtained on a 3-Tesla, Philips Achieva MRI. The safety of MRI scanning with spinal cord stimulation (SCS) was determined previously. rsfMRI was performed with stimulator off (300 TRs), at sensory perception threshold (Low, 300 TRs) and at optimum (Opt, 300 TRs) therapeutic settings. Seed-based analysis of the resting state functional connectivity was conducted using seeds in regions linked to the pain networks or in the default mode network. NCUT parcellation was used to generate 100 cortical and subcortical regions of interest in order to expand analysis of changes in functional connections to the entire brain. We corrected for multiple comparisons by limiting the false discovery rate to 5%.
RESULTS:: There were no adverse effects with SCS and fMRI. Significant differences in resting state brain connectivity were seen between several regions related to pain perception, including the left frontal insula, right primary and secondary somatosensory cortices, as well as in regions involved in the default mode network (DMN). Therapeutic SCS resulted in decreased connection strength between somatosensory and limbic areas and increased connection strength between somatosensory and default mode network.
CONCLUSION:: fMRI can be safely performed with SCS. Pain relief from SCS reduces the connectivity between the somatosensory and limbic/affective regions as compared to baseline. This suggests that optimal spinal cord stimulation may be reducing negative emotional processing associated with pain, allowing somatosensory areas to become more integrated into default mode activity and normalization of brain networks.
PMID: 25032637 [PubMed - as supplied by publisher]
Coupling Mechanism and Significance of the BOLD Signal: A Status Report.
Annu Rev Neurosci. 2014 Jul 8;37:161-181
Authors: Hillman EM
Functional magnetic resonance imaging (fMRI) provides a unique view of the working human mind. The blood-oxygen-level-dependent (BOLD) signal, detected in fMRI, reflects changes in deoxyhemoglobin driven by localized changes in brain blood flow and blood oxygenation, which are coupled to underlying neuronal activity by a process termed neurovascular coupling. Over the past 10 years, a range of cellular mechanisms, including astrocytes, pericytes, and interneurons, have been proposed to play a role in functional neurovascular coupling. However, the field remains conflicted over the relative importance of each process, while key spatiotemporal features of BOLD response remain unexplained. Here, we review current candidate neurovascular coupling mechanisms and propose that previously overlooked involvement of the vascular endothelium may provide a more complete picture of how blood flow is controlled in the brain. We also explore the possibility and consequences of conditions in which neurovascular coupling may be altered, including during postnatal development, pathological states, and aging, noting relevance to both stimulus-evoked and resting-state fMRI studies.
PMID: 25032494 [PubMed - as supplied by publisher]
Shared and distinct intrinsic functional network centrality in autism and attention-deficit/hyperactivity disorder.
Biol Psychiatry. 2013 Oct 15;74(8):623-32
Authors: Di Martino A, Zuo XN, Kelly C, Grzadzinski R, Mennes M, Schvarcz A, Rodman J, Lord C, Castellanos FX, Milham MP
BACKGROUND: Individuals with autism spectrum disorders (ASD) often exhibit symptoms of attention-deficit/hyperactivity disorder (ADHD). Across both disorders, observations of distributed functional abnormalities suggest aberrant large-scale brain network connectivity. Yet, common and distinct network correlates of ASD and ADHD remain unidentified. Here, we aimed to examine patterns of dysconnection in school-age children with ASD and ADHD and typically developing children who completed a resting state functional magnetic resonance imaging scan.
METHODS: We measured voxelwise network centrality, functional connectivity metrics indexing local (degree centrality [DC]) and global (eigenvector centrality) functional relationships across the entire brain connectome, in resting state functional magnetic resonance imaging data from 56 children with ASD, 45 children with ADHD, and 50 typically developing children. A one-way analysis of covariance, with group as fixed factor (whole-brain corrected), was followed by post hoc pairwise comparisons.
RESULTS: Cortical and subcortical areas exhibited centrality abnormalities, some common to both ADHD and ASD, such as in precuneus. Others were disorder-specific and included ADHD-related increases in DC in right striatum/pallidum, in contrast with ASD-related increases in bilateral temporolimbic areas. Secondary analyses differentiating children with ASD into those with or without ADHD-like comorbidity (ASD(+) and ASD(-), respectively) revealed that the ASD(+) group shared ADHD-specific abnormalities in basal ganglia. By contrast, centrality increases in temporolimbic areas characterized children with ASD regardless of ADHD-like comorbidity. At the cluster level, eigenvector centrality group patterns were similar to DC.
CONCLUSIONS: ADHD and ASD are neurodevelopmental disorders with distinct and overlapping clinical presentations. This work provides evidence for both shared and distinct underlying mechanisms at the large-scale network level.
PMID: 23541632 [PubMed - indexed for MEDLINE]
Fast computation of voxel-level brain connectivity maps from resting-state functional MRI using l1-norm as approximation of Pearson's temporal correlation: Proof-of-concept and example vector hardware implementation.
Med Eng Phys. 2014 Jul 8;
Authors: Minati L, Zacà D, D'Incerti L, Jovicich J
An outstanding issue in graph-based analysis of resting-state functional MRI is choice of network nodes. Individual consideration of entire brain voxels may represent a less biased approach than parcellating the cortex according to pre-determined atlases, but entails establishing connectedness for 1(9)-1(11) links, with often prohibitive computational cost. Using a representative Human Connectome Project dataset, we show that, following appropriate time-series normalization, it may be possible to accelerate connectivity determination replacing Pearson correlation with l1-norm. Even though the adjacency matrices derived from correlation coefficients and l1-norms are not identical, their similarity is high. Further, we describe and provide in full an example vector hardware implementation of l1-norm on an array of 4096 zero instruction-set processors. Calculation times <1000s are attainable, removing the major deterrent to voxel-based resting-sate network mapping and revealing fine-grained node degree heterogeneity. L1-norm should be given consideration as a substitute for correlation in very high-density resting-state functional connectivity analyses.
PMID: 25023958 [PubMed - as supplied by publisher]
5.8 clinical and genetic influences on functional brain networks in preterm infants.
Arch Dis Child Fetal Neonatal Ed. 2014 Jun;99 Suppl 1:A6
Authors: Smith-Collins A, Heep A, Kauppinen R, Váradi A, Rajatileka S, Molnar E, Luyt K
: Preterm birth is associated with adverse neurodevelopmental outcomes. The pathological mechanisms leading to adverse outcomes involve several pathways, which are not fully understood. Current methods of assessing neurological injury associated with preterm birth have limited scope and low prognostic value. Whilst structural MRI may provide detailed anatomical information about the neonatal brain, there is imperfect mapping between structure and function. A supplementary approach is the use of functional MRI (fMRI) to infer functional connectivity (FC), evaluating integration of neural activity within the brain. There is emerging evidence that children who were born preterm show long term changes in FC, and early detection of such changes offers potential to improve understanding of pathophysiology of preterm brain injury. These functional changes may be influenced by both neonatal course and underlying susceptibilities to abnormal development, including genetic risk factors. We used resting state fMRI (rs-fMRI) at 3T to examine functional brain connectivity in 20 infants born at <32 weeks of gestation, scanned at term. Infants also had genetic testing to examine polymorphisms in the EAAT2 glutamate transporter, previously associated with variation in preterm neurodevelopmental outcomes. Using a multivariate model to examine the independent contributions of demographic, genetic and clinical characteristics of the infants to FC, we identified multiple dissociable influences on functional brain networks. This is the first report of genetic variability in cerebral glutamate homeostasis influencing neonatal brain connectivity. We discuss the impact on understanding preterm brain injury, and the potential for predicting neurodevelopmental outcome by non-invasive measurement of functional brain connectivity.
PMID: 25021297 [PubMed - in process]
Preserving subject variability in group fMRI analysis: performance evaluation of GICA vs. IVA.
Front Syst Neurosci. 2014;8:106
Authors: Michael AM, Anderson M, Miller RL, Adalı T, Calhoun VD
Independent component analysis (ICA) is a widely applied technique to derive functionally connected brain networks from fMRI data. Group ICA (GICA) and Independent Vector Analysis (IVA) are extensions of ICA that enable users to perform group fMRI analyses; however a full comparison of the performance limits of GICA and IVA has not been investigated. Recent interest in resting state fMRI data with potentially higher degree of subject variability makes the evaluation of the above techniques important. In this paper we compare component estimation accuracies of GICA and an improved version of IVA using simulated fMRI datasets. We systematically change the degree of inter-subject spatial variability of components and evaluate estimation accuracy over all spatial maps (SMs) and time courses (TCs) of the decomposition. Our results indicate the following: (1) at low levels of SM variability or when just one SM is varied, both GICA and IVA perform well, (2) at higher levels of SM variability or when more than one SMs are varied, IVA continues to perform well but GICA yields SM estimates that are composites of other SMs with errors in TCs, (3) both GICA and IVA remove spatial correlations of overlapping SMs and introduce artificial correlations in their TCs, (4) if number of SMs is over estimated, IVA continues to perform well but GICA introduces artifacts in the varying and extra SMs with artificial correlations in the TCs of extra components, and (5) in the absence or presence of SMs unique to one subject, GICA produces errors in TCs and IVA estimates are accurate. In summary, our simulation experiments (both simplistic and realistic) and our holistic analyses approach indicate that IVA produces results that are closer to ground truth and thereby better preserves subject variability. The improved version of IVA is now packaged into the GIFT toolbox (http://mialab.mrn.org/software/gift).
PMID: 25018704 [PubMed]
Functional plasticity before the cradle: a review of neural functional imaging in the human fetus.
Neurosci Biobehav Rev. 2013 Nov;37(9 Pt B):2220-32
Authors: Anderson AL, Thomason ME
The organization of the brain is highly plastic in fetal life. Establishment of healthy neural functional systems during the fetal period is essential to normal growth and development. Across the last several decades, remarkable progress has been made in understanding the development of human fetal functional brain systems. This is largely due to advances in imaging methodologies. Fetal neuroimaging began in the 1950-1970's with fetal electroencephalography (EEG) applied during labor. Later, in the 1980's, magnetoencephalography (MEG) emerged as an effective approach for investigating fetal brain function. Most recently, functional magnetic resonance imaging (fMRI) has arisen as an additional powerful approach for examining fetal brain function. This review will discuss major developmental findings from fetal imaging studies such as the maturation of prenatal sensory system functions, functional hemispheric asymmetry, and sensory-driven neurodevelopment. We describe how with improved imaging and analysis techniques, functional imaging of the fetus has the potential to assess the earliest point of neural maturation and provide insight into the patterning and sequence of normal and abnormal brain development.
PMID: 23542738 [PubMed - indexed for MEDLINE]
Motor Imagery Learning Induced Changes in Functional Connectivity of the Default Mode Network.
IEEE Trans Neural Syst Rehabil Eng. 2014 Jul 8;
Authors: Ge R, Zhang H, Yao L, Long Z
Numerous studies provide evidences that motor skill learning changes the activity of some brain regions during task as well as some resting networks during rest. However, it is still unclear how motor learning affects the resting-state default-mode network (DMN). Using functional magnetic resonance imaging (fMRI), this study investigated the alteration of the DMN after motor skill learning with mental imagery practice. 14 participants in the experimental group learned to imagine a sequential finger movement over a 2-week period while 12 control participants did not undergo motor imagery learning. For the experimental group, interregional connectivity, estimated by the graph theory method, between the medial temporal lobe, lateral temporal, and lateral parietal cortex within the DMN was increased after learning, whereas activity of the DMN network, estimated by the independent component analysis (ICA) method, remained stable. Moreover, the experimental group showed significant improvement in motor performance after learning and a negative correlation between the alteration of the execution rate and changes in activity in the lateral parietal cortex. These results indicate that the DMN could be sculpted by motor learning in a manner of altering interregional connectivity and may imply that the DMN plays a role in improving behavioral performance.
PMID: 25014958 [PubMed - as supplied by publisher]
The Value of Resting-State Functional Magnetic Resonance Imaging in Stroke.
Stroke. 2014 Jul 10;
Authors: Ovadia-Caro S, Margulies DS, Villringer A
PMID: 25013022 [PubMed - as supplied by publisher]
The alterations in inter-hemispheric functional coordination of patients with panic disorder: The findings in the posterior sub-network of default mode network.
J Affect Disord. 2014 Sep;166:279-84
Authors: Lai CH, Wu YT
OBJECTIVE: Voxel-mirrored homotopic connectivity (VMHC) has been studied in several neuropsychiatric illnesses. The inter-hemispheric interactions probably could explain the important aspects for the pathophysiology of panic disorder (PD). Therefore, we initiated this study to estimate the differences in VMHC values between the PD patients and controls.
METHODS: Thirty first-episode medication-naïve patients with PD and 21 controls were enrolled with age and gender controlled. All the participants received the scanning of resting-state functional magnetic resonance imaging (R-FMRI). The R-FMRI images were preprocessed and analyzed to obtain the VMHC values. The two-sample t test of VMHC data between PD patients and controls was performed. We also explored the relationship between the VMHC values and clinical characteristics.
RESULTS: The controls had significantly higher VMHC values than patients in the posterior cingulate cortex and precuneus (false discovery rate corrected p<0.005). The one-sided results by the unilateral hemisphere mask also confirmed that the results were indeed found in the right hemisphere. The VMHC value in the posterior cingulate cortex was also negatively correlated with panic severity.
CONCLUSION: The alterations of inter-hemispheric coordination in cingulate-precuneus may play a role in the pathophysiology of PD.
PMID: 25012442 [PubMed - in process]
Alterations in resting state brain networks in concussed adolescent athletes.
J Neurotrauma. 2014 Jul 10;
Authors: Borich M, Babul AN, Huang PH, Boyd L, Virji-Babul N
Sports related concussion in adolescents is a major public health issue; however, little is known about the underlying changes in functional brain connectivity. We evaluated connectivity of resting state brain networks to determine whether alterations in specific networks distinguish adolescents with sports related concussion from a group of healthy, active control adolescents. Twelve adolescents with a clinical diagnosis of subacute concussion and ten healthy adolescents matched for age, gender and physical activity completed functional MRI (fMRI) scanning. Functional connectivity of resting state brain networks was evaluated in both groups using probabilistic independent component analysis (ICA). Altered functional connectivity was found within three resting state networks in adolescents with concussion. Specifically we noted: a) alterations within the default mode network, b) increased connectivity in the right frontal pole in the executive function network and c) increased connectivity in the left frontal operculum cortex associated with the ventral attention network. This preliminary report shows that whole brain functional connectivity is altered in networks related to cognition and attention in adolescents in the subacute phase following sports related concussion. This first report in adolescents should be used to inform future studies in larger cohorts of adolescents with sports-related concussion. Increased knowledge of these changes may lead to improvements in clinical management and help to develop rehabilitation programs.
PMID: 25010041 [PubMed - as supplied by publisher]
Resting state fMRI in the moving fetus: A robust framework for motion, bias field and spin history correction.
Neuroimage. 2014 Jul 6;
Authors: Ferrazzi G, Murgasova MK, Arichi T, Malamateniou C, Fox MJ, Makropoulos A, Allsop J, Rutherford M, Malik S, Aljabar P, Hajnal JV
There is growing interest in exploring fetal functional brain development, particularly with Resting State fMRI. However, during a typical fMRI acquisition, the womb moves due to maternal respiration and the fetus may perform large-scale and unpredictable movements. Conventional fMRI processing pipelines, which assume that brain movements are infrequent or at least small, are not suitable. Previous published studies have tackled this problem by adopting conventional methods and discarding as much as 40% or more of the acquired data. In this work, we developed and tested a processing framework for fetal Resting State fMRI, capable of correcting gross motion. The method comprises bias field and spin history corrections in the scanner frame of reference, combined with slice to volume registration and scattered data interpolation to place all data into a consistent anatomical space. The aim is to recover an ordered set of samples suitable for further analysis using standard tools such as Group Independent Component Analysis (Group ICA). We have tested the approach using simulations and in vivo data acquired at 1.5T. After full motion correction, Group ICA performed on a population of 8 fetuses extracted 20 networks, 6 of which were identified as matching those previously observed in preterm babies.
PMID: 25008959 [PubMed - as supplied by publisher]
Connectomics and neuroticism: an altered functional network organization.
Neuropsychopharmacology. 2014 Jul 9;
Authors: Servaas MN, Geerligs L, Jan Renken R, Marsman JB, Ormel J, Riese H, Aleman A
The personality trait neuroticism is a potent risk marker for psychopathology. Although the neurobiological basis remains unclear, studies have suggested that alterations in connectivity may underlie it. Therefore, the aim of the current study was to shed more light on the functional network organization in neuroticism. To this end, we applied graph theory on resting-state fMRI data in 120 women selected based on their neuroticism score. Binary and weighted brain-wide graphs were constructed to examine changes in the functional network structure and functional connectivity strength. Furthermore, graphs were partitioned into modules to specifically investigate connectivity within and between functional subnetworks related to emotion processing and cognitive control. Subsequently, complex network measures (i.a. efficiency and modularity) were calculated on the brain-wide graphs and modules, and correlated with neuroticism scores. Compared to low neurotic individuals, high neurotic individuals exhibited a whole-brain network structure resembling more that of a random network and had overall weaker functional connections. Furthermore, in these high neurotic individuals, functional subnetworks could be delineated less clearly and the majority of these subnetworks showed lower efficiency, while the affective subnetwork showed higher efficiency. In addition, the cingulo-operculum subnetwork demonstrated more ties with other functional subnetworks in association with neuroticism. In conclusion, the 'neurotic brain' has a less than optimal functional network organization and shows signs of functional disconnectivity. Moreover, in high compared to low neurotic individuals, emotion and salience subnetworks play a more prominent role in the information exchange, while sensory(-motor) and cognitive control subnetworks play a less prominent role.Neuropsychopharmacology accepted article preview online, 09 July 2014; doi:10.1038/npp.2014.169.
PMID: 25005250 [PubMed - as supplied by publisher]
Cortico-striatal-thalamic network functional connectivity in hemiparkinsonism.
Neurobiol Aging. 2014 Jun 11;
Authors: Agosta F, Caso F, Stankovic I, Inuggi A, Petrovic I, Svetel M, Kostic VS, Filippi M
Cortico-striatal-thalamic network functional connectivity (FC) and its relationship with levodopa (L-dopa) were investigated in 69 patients with hemiparkinsonism (25 drug-naïve [n-PD] and 44 under stable/optimized dopaminergic treatment [t-PD]) and 27 controls. Relative to controls, n-PD patients showed an increased FC between the left and the right basal ganglia, and a decreased connectivity of the affected caudate nucleus and thalamus with the ipsilateral frontal and insular cortices. Compared with both controls and n-PD patients, t-PD patients showed a decreased FC among the striatal and thalamic regions, and an increased FC between the striatum and temporal cortex, and between the thalamus and several sensorimotor, parietal, temporal, and occipital regions. In both n-PD and t-PD, patients with more severe motor disability had an increased striatal and/or thalamic FC with temporal, parietal, occipital, and cerebellar regions. Cortico-striatal-thalamic functional abnormalities occur in patients with hemiparkinsonism, antecede the onset of the motor symptoms on the opposite body side and are modulated by L-dopa. In patients with hemiparkinsonism, L-dopa is likely to facilitate a compensation of functional abnormalities possibly through an increased thalamic FC.
PMID: 25004890 [PubMed - as supplied by publisher]
A review of the use of magnetic resonance imaging in Parkinson's disease.
Ther Adv Neurol Disord. 2014 Jul;7(4):206-20
Authors: Pyatigorskaya N, Gallea C, Garcia-Lorenzo D, Vidailhet M, Lehericy S
To date, the most frequently used Parkinson's disease (PD) biomarkers are the brain imaging measures of dopaminergic dysfunction using positron emission tomography and single photon emission computed tomography. However, major advances have occurred in the development of magnetic resonance imaging (MRI) biomarkers for PD in the past decade. Although conventional structural imaging remains normal in PD, advanced techniques have shown changes in the substantia nigra and the cortex. The most well-developed MRI markers in PD include diffusion imaging and iron load using T2/T2* relaxometry techniques. Other quantitative biomarkers such as susceptibility-weighted imaging for iron load, magnetization transfer and ultra-high-field MRI have shown great potential. More sophisticated techniques such as tractography and resting state functional connectivity give access to anatomical and functional connectivity changes in the brain, respectively. Brain perfusion can be assessed using non-contrast-agent techniques such as arterial spin labelling and spectroscopy gives access to metabolites concentrations. However, to date these techniques are not yet fully validated and standardized quantitative metrics for PD are still lacking. This review presents an overview of new structural, perfusion, metabolic and anatomo-functional connectivity biomarkers, their use in PD and their potential applications to improve the clinical diagnosis of Parkinsonian syndromes and the quality of clinical trials.
PMID: 25002908 [PubMed]
Structural and functional brain connectivity in presymptomatic familial frontotemporal dementia.
Neurology. 2014 Jul 8;83(2):e19-26
Authors: Dopper EG, Rombouts SA, Jiskoot LC, den Heijer T, de Graaf JR, de Koning I, Hammerschlag AR, Seelaar H, Seeley WW, Veer IM, van Buchem MA, Rizzu P, van Swieten JC
OBJECTIVE: We aimed to investigate whether cognitive deficits and structural and functional connectivity changes can be detected before symptom onset in a large cohort of carriers of MAPT (microtubule-associated protein tau) or GRN (progranulin) mutations.
METHODS: In this case-control study, 75 healthy individuals (aged 20-70 years) with 50% risk of frontotemporal dementia (FTD) underwent DNA screening, neuropsychological assessment, structural MRI, and fMRI. We used voxel-based morphometry and tract-based spatial statistics for voxel-wise analyses of gray matter volume and diffusion tensor imaging measures. Using resting-state fMRI scans, we assessed whole-brain functional connectivity to frontoinsular, anterior midcingulate, and posterior cingulate cortices.
RESULTS: Carriers (n = 39) and noncarriers (n = 36) had similar neuropsychological performance, except for lower Letter Digit Substitution Test scores in carriers. Worse performance on Stroop III, Rivermead Behavioral Memory Test, and Happé Cartoons correlated with higher age in carriers, but not controls. Reduced fractional anisotropy in the right uncinate fasciculus was found in carriers compared with controls. Reductions in functional connectivity between anterior midcingulate cortex and frontoinsula and several other brain regions were found in carriers compared with controls and correlated with higher age in carriers, but not controls. We found no significant differences or age correlations in posterior cingulate cortex connectivity. No differences in regional gray matter volume were found, except for a small cluster of higher volume in the precentral gyrus in carriers.
CONCLUSIONS: This study demonstrates that alterations in structural and functional connectivity develop before the first symptoms of FTD arise. These findings suggest that diffusion tensor imaging and resting-state fMRI may have the potential to become sensitive biomarkers for early FTD in future clinical trials.
PMID: 25002573 [PubMed - in process]