Human Brain Mapping
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Mild cognitive impairment in Parkinson's disease is associated with a distributed pattern of brain white matter damage Abstract This study assesses the patterns of gray matter (GM) and white matter (WM) damage in patients with Parkinson's disease and mild cognitive impairment (PD‐MCI) compared with healthy controls and cognitively unimpaired PD patients (PD‐Cu). Three‐dimensional T1‐weighted and diffusion tensor (DT) magnetic resonance imaging (MRI) scans were obtained from 43 PD patients and 33 healthy controls. Cognition was assessed using a neuropsychological battery. Tract‐based spatial statistics was applied to compare DT MRI indices between groups on a voxel‐by‐voxel basis. Voxel‐based morphometry was performed to assess GM atrophy. Thirty PD patients were classified as MCI. Compared with healthy controls, PD‐Cu and PD‐MCI patients did not have GM atrophy. No region of WM damage was found in PD‐Cu patients when compared with healthy controls. Relative to healthy controls and PD‐Cu patients, PD‐MCI patients showed a distributed pattern of WM abnormalities in the anterior and superior corona radiata, genu, and body of the corpus callosum, and anterior inferior fronto‐occipital, uncinate, and superior longitudinal fasciculi, bilaterally. Subtle cognitive decline in PD is associated with abnormalities of frontal and interhemispheric WM connections, and not with GM atrophy. DT MRI might contribute to the identification of structural changes in PD‐MCI patients prior to the development of dementia. Hum Brain Mapp 35:1921–1929, 2014 . © 2013 Wiley Periodicals, Inc.
Human Brain Mapping - Tập 35 Số 5 - Trang 1921-1929 - 2014
Cognitive impairment and resting-state network connectivity in Parkinson's disease
Human Brain Mapping - Tập 36 Số 1 - Trang 199-212 - 2015
Contribution of insula in Parkinson's disease: A quantitative meta‐analysis study Abstract The insula region is known to be an integrating hub interacting with multiple brain networks involved in cognitive, affective, sensory, and autonomic processes. There is growing evidence suggesting that this region may have an important role in Parkinson's disease (PD). Thus, to investigate the functional organization of the insular cortex and its potential role in parkinsonian features, we used a coordinate‐based quantitative meta‐analysis approach, the activation likelihood estimation. A total of 132 insular foci were selected from 96 published experiments comprising the five functional categories: cognition, affective/behavioral symptoms, bodily awareness/autonomic function, sensorimotor function, and nonspecific resting functional changes associated with the disease. We found a significant convergence of activation maxima related to PD in different insular regions including anterior and posterior regions bilaterally. This study provides evidence of an important functional distribution of different domains within the insular cortex in PD, particularly in relation to nonmotor aspects, with an influence of medication effect. Hum Brain Mapp 37:1375‐1392, 2016 . © 2016 Wiley Periodicals, Inc.
Human Brain Mapping - Tập 37 Số 4 - Trang 1375-1392 - 2016
Autoradiographic distribution of serotonin transporters and receptor subtypes in human brain Abstract Several neurochemical in vitro and in vivo imaging studies have been aimed at characterizing the localization of serotonin receptors and transporters in the human brain. In this study, a detailed comparison of the distribution of a number of 5‐HT receptor subtypes and the 5‐HT transporter was carried out in vitro using human postmortem brain tissue. Anatomically adjacent whole hemisphere sections were incubated with specific radioligands for the 5‐HT1A , 5‐HT1B , 5‐HT2A , 5‐HT4 receptors and the 5‐HT transporter. The autoradiograms revealed different laminar and regional distribution patterns in the isocortex, where 5‐HT1A and 5‐HT4 receptor binding showed highest densities in superficial layers and 5‐HT2A receptor binding was most abundant in middle layers. In cortical regions, 5‐HT transporters were concentrated to several limbic lobe structures (posterior uncus, entorhinal, cingulate, insular and temporal polar regions). 5‐HT1A receptor densities were also high in limbic cortical regions (hippocampus, posterior entorhinal cortex, and subcallosal area) compared to the isocortex. Subregionally different distribution patterns were observed in the basal ganglia with a trend toward higher levels in ventral striatal (5‐HT1B receptors) and pallidal (5‐HT transporters and 5‐HT1B receptors) regions. The localization in regions belonging to limbic cortico‐striato‐pallido‐thalamic circuits is in line with the documented role of 5‐HT in modulation of mood and emotion, and the suggested involvement of this system in pathophysiology of various psychiatric disorders. The qualitative and quantitative information reported in this study might provide important complements to in vivo neuroimaging studies of the 5‐HT system. Hum. Brain Mapping 22:246–260, 2004. © 2004 Wiley‐Liss, Inc.
Human Brain Mapping - Tập 22 Số 3 - Trang 246-260 - 2004
Resting state sensorimotor functional connectivity in multiple sclerosis inversely correlates with transcallosal motor pathway transverse diffusivity Abstract Recent studies indicate that functional connectivity using low‐frequency BOLD fluctuations (LFBFs) is reduced between the bilateral primary sensorimotor regions in multiple sclerosis. In addition, it has been shown that pathway‐dependent measures of the transverse diffusivity of water in white matter correlate with related clinical measures of functional deficit in multiple sclerosis. Taken together, these methods suggest that MRI methods can be used to probe both functional connectivity and anatomic connectivity in subjects with known white matter impairment. We report the results of a study comparing anatomic connectivity of the transcallosal motor pathway, as measured with diffusion tensor imaging (DTI) and functional connectivity of the bilateral primary sensorimotor cortices (SMC), as measured with LFBFs in the resting state. High angular resolution diffusion imaging was combined with functional MRI to define the transcallosal white matter pathway connecting the bilateral primary SMC. Maps were generated from the probabilistic tracking employed and these maps were used to calculate the mean pathway diffusion measures fractional anisotropy 〈FA〉, mean diffusivity 〈MD〉, longitudinal diffusivity 〈λ1 〉, and transverse diffusivity 〈λ2 〉. These were compared with LFBF‐based functional connectivity measures (F c ) obtained at rest in a cohort of 11 multiple sclerosis patients and ∼10 age‐ and gender‐matched control subjects. The correlation between 〈FA〉 and F c for MS patients was r = −0.63, P < 0.04. The correlation between all subjects 〈λ2 〉 and F c was r = 0.42, P < 0.05. The correlation between all subjects 〈λ2 〉 and F c was r = −0.50, P < 0.02. None of the control subject correlations were significant, nor were 〈FA〉, 〈λ1 〉, or 〈MD〉 significantly correlated with F c for MS patients. This constitutes the first in vivo observation of a correlation between measures of anatomic connectivity and functional connectivity using spontaneous LFBFs. Hum Brain Mapp, 2008. © 2008 Wiley‐Liss, Inc.
Human Brain Mapping - Tập 29 Số 7 - Trang 818-827 - 2008
Decreased basal fMRI functional connectivity in epileptogenic networks and contralateral compensatory mechanisms Abstract A better understanding of interstructure relationship sustaining drug‐resistant epileptogenic networks is crucial for surgical perspective and to better understand the consequences of epileptic processes on cognitive functions. We used resting‐state fMRI to study basal functional connectivity within temporal lobes in medial temporal lobe epilepsy (MTLE) during interictal period. Two hundred consecutive single‐shot GE‐EPI acquisitions were acquired in 37 right‐handed subjects (26 controls, eight patients presenting with left and three patients with right MTLE). For each hemisphere, normalized correlation coefficients were computed between pairs of time‐course signals extracted from five regions involved in MTLE epileptogenic networks (Brodmann area 38, amygdala, entorhinal cortex (EC), anterior hippocampus (AntHip), and posterior hippocampus (PostHip)). In controls, an asymmetry was present with a global higher connectivity in the left temporal lobe. Relative to controls, the left MTLE group showed disruption of the left EC‐AntHip link, and a trend of decreased connectivity of the left AntHip‐PostHip link. In contrast, a trend of increased connectivity of the right AntHip‐PostHip link was observed and was positively correlated to memory performance. At the individual level, seven out of the eight left MTLE patients showed decreased or disrupted functional connectivity. In this group, four patients with left TLE showed increased basal functional connectivity restricted to the right temporal lobe spared by seizures onset. A reverse pattern was observed at the individual level for patients with right TLE. This is the first demonstration of decreased basal functional connectivity within epileptogenic networks with concomitant contralateral increased connectivity possibly reflecting compensatory mechanisms. Hum Brain Mapp 2009. © 2008 Wiley‐Liss, Inc.
Human Brain Mapping - Tập 30 Số 5 - Trang 1580-1591 - 2009
Functional cortical changes of the sensorimotor network are associated with clinical recovery in multiple sclerosis Abstract Objective: To assess the early cortical changes following an acute motor relapse secondary to a pseudotumoral lesion in MS patients, the longitudinal cortical functional correlates of clinical recovery, and the evolution over time of cortical reorganization. Methods: FMRI during the performance of a simple motor task were obtained from 12 MS patients (after a clinical attack involving the motor system secondary to a pseudotumoral lesion) and 15 matched controls. In six patients and five controls, a longitudinal fMRI study was also performed. Results: In patients, at baseline, the primary sensorimotor cortex (SMC) of the ipsilateral (contralesional) hemisphere was significantly more active during task performance with the impaired than the unimpaired hand. During task performance with the unimpaired hand, the ipsilateral cerebellum and several motor areas in the contralateral hemisphere were significantly more active. Pseudotumoral lesion volume was correlated with activation of the primary SMC bilaterally (r = −0.86 and −0.85) and the nine‐hole peg test score with activation of the primary SMC of the affected hemisphere (r = 0.88). A recovery of function of the primary SMC of the affected hemisphere was found in the four patients with clinical improvement. In the two patients without clinical recovery, there was a persistent recruitment of the primary SMC of the unaffected hemisphere. Conclusions: Pseudotumoral MS lesions affecting the motor system can determine short‐term cortical changes characterized by the recruitment of pathways in the unaffected hemisphere. The regain of function of motor areas of the affected hemisphere seems to be a critical factor for a favorable recovery. Hum Brain Mapp 2008. © 2007 Wiley‐Liss, Inc.
Human Brain Mapping - Tập 29 Số 5 - Trang 562-573 - 2008
Application of neuroanatomical features to tractography clustering
Human Brain Mapping - Tập 34 Số 9 - Trang 2089-2102 - 2013
Atypical age‐dependent effects of autism on white matter microstructure in children of 2–7 years Abstract Atypical age‐dependent changes of white matter (WM) microstructure play a central role in abnormal brain maturation of the children with autism spectrum disorder (ASD), but their early manifestations have not been systematically characterized. The entire brain core WM voxels were surveyed to detect differences in WM microstructural development between 31 children with ASD of 2–7 years and 19 age‐matched children with typical development (TD), using measurements of fractional anisotropy (FA) and radial diffusivity (RD) from diffusion tensor imaging (DTI). The anatomical locations, distribution, and extent of the core WM voxels with atypical age‐dependent changes in a specific tract or tract group were delineated and evaluated by integrating the skeletonized WM with a digital atlas. Exclusively, unidirectional FA increases and RD decreases in widespread WM tracts were revealed in children with ASD before 4 years, with bi‐directional changes found for children with ASD of 2–7 years. Compared to progressive development that raised FA and lowered RD during 2–7 years in the TD group, flattened curves of WM maturation were found in multiple major WM tracts of all five tract groups, particularly associational and limbic tracts, in the ASD group with trend lines of ASD and TD crossed around 4 years. We found atypical age‐dependent changes of FA and RD widely and heterogeneously distributed in WM tracts of children with ASD. The early higher WM microstructural integrity before 4 years reflects abnormal neural patterning, connectivity, and pruning that may contribute to aberrant behavioral and cognitive development in ASD. Hum Brain Mapp 37:819–832, 2016 . © 2015 Wiley Periodicals, Inc.
Human Brain Mapping - Tập 37 Số 2 - Trang 819-832 - 2016
Sensation‐to‐cognition cortical streams in attention‐deficit/hyperactivity disorder Abstract We sought to determine whether functional connectivity streams that link sensory, attentional, and higher‐order cognitive circuits are atypical in attention‐deficit/hyperactivity disorder (ADHD). We applied a graph‐theory method to the resting‐state functional magnetic resonance imaging data of 120 children with ADHD and 120 age‐matched typically developing children (TDC). Starting in unimodal primary cortex—visual, auditory, and somatosensory—we used stepwise functional connectivity to calculate functional connectivity paths at discrete numbers of relay stations (or link‐step distances). First, we characterized the functional connectivity streams that link sensory, attentional, and higher‐order cognitive circuits in TDC and found that systems do not reach the level of integration achieved by adults. Second, we searched for stepwise functional connectivity differences between children with ADHD and TDC. We found that, at the initial steps of sensory functional connectivity streams, patients display significant enhancements of connectivity degree within neighboring areas of primary cortex, while connectivity to attention‐regulatory areas is reduced. Third, at subsequent link‐step distances from primary sensory cortex, children with ADHD show decreased connectivity to executive processing areas and increased degree of connections to default mode regions. Fourth, in examining medication histories in children with ADHD, we found that children medicated with psychostimulants present functional connectivity streams with higher degree of connectivity to regions subserving attentional and executive processes compared to medication‐naïve children. We conclude that predominance of local sensory processing and lesser influx of information to attentional and executive regions may reduce the ability to organize and control the balance between external and internal sources of information in ADHD. Hum Brain Mapp 36:2544–2557, 2015 . © 2015 Wiley Periodicals, Inc .
Human Brain Mapping - Tập 36 Số 7 - Trang 2544-2557 - 2015
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