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  • 1
    In: Human Brain Mapping, Wiley, Vol. 35, No. 9 ( 2014-09), p. 4316-4329
    Abstract: The amygdala and the hippocampus are two adjacent structures in the medial temporal lobe that have been broadly investigated in functional and structural neuroimaging due to their central importance in sensory perception, emotion, and memory. Exact demarcation of the amygdalo‐hippocampal border (AHB) is, however, difficult in conventional structural imaging. Recent evidence suggests that, due to this difficulty, functional activation sites with high probability of being located in the hippocampus may erroneously be assigned to the amygdala, and vice versa. In the present study, we investigated the potential of ultra‐high‐field magnetic resonance imaging (MRI) in single sessions for detecting the AHB in humans. We show for the first time the detailed structure of the AHB as it can be visualized in T1‐weighted 7T in vivo images at 0.5‐mm 3 isotropic resolution. Compared to data acquired at 3T, 7T images revealed considerably more structural detail in the AHB region. Thus, we observed a striking inter‐hemispheric and interindividual variability of the exact anatomical configuration of the AHB that points to the necessity of individual imaging of the AHB as a prerequisite for accurate anatomical assignment in this region. The findings of the present study demonstrate the usefulness of ultra‐high‐field structural MRI to resolve anatomical ambiguities of the human AHB. Highly accurate morphometric and functional investigations in this region at 7T may allow addressing such hitherto unexplored issues as whether the structural configuration of the AHB is related to functional differences in amygdalo‐hippocampal interaction. Hum Brain Mapp 35:4316–4329, 2014 . © 2014 Wiley Periodicals, Inc .
    Type of Medium: Online Resource
    ISSN: 1065-9471 , 1097-0193
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2014
    detail.hit.zdb_id: 1492703-2
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  • 2
    In: Alzheimer's & Dementia, Wiley, Vol. 16, No. S5 ( 2020-12)
    Abstract: The locus coeruleus‐norepinephrine system (LC‐NE system) supports the process of encoding of emotionally salient events. LC integrity varies in healthy elderly and is associated with altered cognitive functions in aging. Post‐mortem as well as structural indicators suggest that the modulation of the LC‐NE system is reduced in elderly. This reduction in ageing is also of note as it might be one of the earliest pre‐symptomatic indicators of dementia‐related brain pathology. Indeed, LC neuron degeneration is already observable in early stages of tau pathology before any cognitive symptoms are clinically notable in Alzheimer´s disease (AD). The main aim of this study was to investigate age differences in functional activations of the LC during (emotionally) salient events. Method A total of 50 people (28 younger, 22 older healthy adults) participated in the experiment. A reversal learning task has been chosen as it provokes the release of NE. The study used neuromelanin (NM) ‐ sensitive magnetic resonance imaging (MRI) and high‐resolution functional MRI (fMRI) to visualise age differences in LC structure and function. Functional indicators can add sensitivity over structural indicators, which is important considering the fact of neuronal function loss before cell death occurs. Result Reduced LC integrity was related to lower memory performance for negative emotional events in elderly only. Moreover, unexpectedly, stronger functional responses of dopaminergic and noradrenergic midbrain structures to (emotionally) salient events during memory encoding were observed in older adults. Conclusion These results are discussed in light of age differences in adapting to high and low levels of task difficulty. The study has shown the feasibility of investigating age differences in neuromodulatory nuclei. Therefore, the observed reduction in LC integrity might be a typical sign of healthy ageing or a sign of mild cognitive impairment (MCI) and thus also for AD.
    Type of Medium: Online Resource
    ISSN: 1552-5260 , 1552-5279
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 2201940-6
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  • 3
    Online Resource
    Online Resource
    Elsevier BV ; 2013
    In:  NeuroImage Vol. 70 ( 2013-04), p. 122-131
    In: NeuroImage, Elsevier BV, Vol. 70 ( 2013-04), p. 122-131
    Type of Medium: Online Resource
    ISSN: 1053-8119
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2013
    detail.hit.zdb_id: 1471418-8
    SSG: 5,2
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  • 4
    In: Brain, Oxford University Press (OUP), Vol. 142, No. 9 ( 2019-09-01), p. 2558-2571
    Abstract: Pathological alterations to the locus coeruleus, the major source of noradrenaline in the brain, are histologically evident in early stages of neurodegenerative diseases. Novel MRI approaches now provide an opportunity to quantify structural features of the locus coeruleus in vivo during disease progression. In combination with neuropathological biomarkers, in vivo locus coeruleus imaging could help to understand the contribution of locus coeruleus neurodegeneration to clinical and pathological manifestations in Alzheimer’s disease, atypical neurodegenerative dementias and Parkinson’s disease. Moreover, as the functional sensitivity of the noradrenergic system is likely to change with disease progression, in vivo measures of locus coeruleus integrity could provide new pathophysiological insights into cognitive and behavioural symptoms. Locus coeruleus imaging also holds the promise to stratify patients into clinical trials according to noradrenergic dysfunction. In this article, we present a consensus on how non-invasive in vivo assessment of locus coeruleus integrity can be used for clinical research in neurodegenerative diseases. We outline the next steps for in vivo, post-mortem and clinical studies that can lay the groundwork to evaluate the potential of locus coeruleus imaging as a biomarker for neurodegenerative diseases.
    Type of Medium: Online Resource
    ISSN: 0006-8950 , 1460-2156
    RVK:
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2019
    detail.hit.zdb_id: 1474117-9
    SSG: 12
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  • 5
    In: Alzheimer's & Dementia, Wiley, Vol. 17, No. S4 ( 2021-12)
    Abstract: The noradrenergic locus coeruleus (LC) in the brainstem shows earliest signs of protein pathologies in neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. Its small size (about 3‐4mm in width and 15 mm in length) makes it less suitable for Positron Emission Tomography (PET) investigations, so the past decade has seen a steep rise in structural and functional Magnetic Resonance (MR) studies aiming to characterise the LC's changes in ageing and neurodegeneration. However, given its position in the brainstem and small volume, great care has to be taken to yield methodologically reliable MR results as imprecisions in spatial transformations of functional data in the range of 2‐3mm might make LC activations at the group level effectively disappear (Figure 1B). Here, we suggest a post‐processing pipeline and set of quality control protocols which will allow LC researchers to reach the spatial precision necessary for investigating this small but potentially impactful brain structure. Method Using a combination of available toolboxes (SPM, ANTs, FSL, FreeSurfer), individual 3T scans for structural and functional LC characterisation are transformed into MNI space via a study‐specific template (Figure 1A). Concatenation of independently optimised transformation steps minimises interpolation applied to the data. Following this, spatial misalignment in individual MNI‐transformed are assessed using Euclidean distance (ED) measures using slice‐specific centres of structural LC masks and distance to landmarks defined based on salient anatomical features of mean functional LC images, respectively. Result Median Euclidean Distance of all landmarks on the transformed functional as well as structural LC imaging data were below 2 mm, thereby falling below the typical LC width of 2.5 mm shown in post‐mortem data (Fernandes et al., 2012), or half of the maximum width of the standard‐space LC mask of 4 mm (Keren et al. 2009). Conclusion With the set of spatial post‐processing steps outlined in the poster and available for download soon, we hope to have taken a first step towards establishing reporting standards of LC imaging data and to give readers interested in LC imaging a starting point for more reliable analyses of structural and functional MR data of the LC.
    Type of Medium: Online Resource
    ISSN: 1552-5260 , 1552-5279
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 2201940-6
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  • 6
    In: Communications Biology, Springer Science and Business Media LLC, Vol. 4, No. 1 ( 2021-09-14)
    Abstract: Primary visual cortex (V1) in humans is known to represent both veridically perceived external input and internally-generated contents underlying imagery and mental rotation. However, it is unknown how the brain keeps these contents separate thus avoiding a mixture of the perceived and the imagined which could lead to potentially detrimental consequences. Inspired by neuroanatomical studies showing that feedforward and feedback connections in V1 terminate in different cortical layers, we hypothesized that this anatomical compartmentalization underlies functional segregation of external and internally-generated visual contents, respectively. We used high-resolution layer-specific fMRI to test this hypothesis in a mental rotation task. We found that rotated contents were predominant at outer cortical depth bins (i.e. superficial and deep). At the same time perceived contents were represented stronger at the middle cortical bin. These results identify how through cortical depth compartmentalization V1 functionally segregates rather than confuses external from internally-generated visual contents. These results indicate that feedforward and feedback manifest in distinct subdivisions of the early visual cortex, thereby reflecting a general strategy for implementing multiple cognitive functions within a single brain region.
    Type of Medium: Online Resource
    ISSN: 2399-3642
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 2919698-X
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  • 7
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2017
    In:  Scientific Data Vol. 4, No. 1 ( 2017-03-14)
    In: Scientific Data, Springer Science and Business Media LLC, Vol. 4, No. 1 ( 2017-03-14)
    Abstract: We present an ultrahigh resolution in vivo human brain magnetic resonance imaging (MRI) dataset. It consists of T 1 -weighted whole brain anatomical data acquired at 7 Tesla with a nominal isotropic resolution of 250 μm of a single young healthy Caucasian subject and was recorded using prospective motion correction. The raw data amounts to approximately 1.2 TB and was acquired in eight hours total scan time. The resolution of this dataset is far beyond any previously published in vivo structural whole brain dataset. Its potential use is to build an in vivo MR brain atlas. Methods for image reconstruction and image restoration can be improved as the raw data is made available. Pre-processing and segmentation procedures can possibly be enhanced for high magnetic field strength and ultrahigh resolution data. Furthermore, potential resolution induced changes in quantitative data analysis can be assessed, e.g., cortical thickness or volumetric measures, as high quality images with an isotropic resolution of 1 and 0.5 mm of the same subject are included in the repository as well.
    Type of Medium: Online Resource
    ISSN: 2052-4463
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2017
    detail.hit.zdb_id: 2775191-0
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  • 8
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2017
    In:  Scientific Data Vol. 4, No. 1 ( 2017-05-09)
    In: Scientific Data, Springer Science and Business Media LLC, Vol. 4, No. 1 ( 2017-05-09)
    Abstract: Scientific Data 4:170032 doi: 10.1038/sdata.2017.32 (2017); Published 14 March 2017; Updated 9 May 2017 The original HTML version of this Data Descriptor incorrectly included Oliver Speck’s name in the Data Citations as ‘Speck, C.’ instead of ‘Speck, O.’ This has now been corrected in the HTML version.
    Type of Medium: Online Resource
    ISSN: 2052-4463
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2017
    detail.hit.zdb_id: 2775191-0
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  • 9
    In: Scientific Data, Springer Science and Business Media LLC, Vol. 8, No. 1 ( 2021-05-25)
    Abstract: Here, we present an extension to our previously published structural ultrahigh resolution T 1 -weighted magnetic resonance imaging (MRI) dataset with an isotropic resolution of 250 µm, consisting of multiple additional ultrahigh resolution contrasts. Included are up to 150 µm Time-of-Flight angiography, an updated 250 µm structural T 1 -weighted reconstruction, 330 µm quantitative susceptibility mapping, up to 450 µm structural T 2 -weighted imaging, 700 µm T 1 -weighted back-to-back scans, 800 µm diffusion tensor imaging, one hour continuous resting-state functional MRI with an isotropic spatial resolution of 1.8 mm as well as more than 120 other structural T 1 -weighted volumes together with multiple corresponding proton density weighted acquisitions collected over ten years. All data are from the same participant and were acquired on the same 7 T scanner. The repository contains the unprocessed data as well as (pre-)processing results. The data were acquired in multiple studies with individual goals. This is a unique and comprehensive collection comprising a “human phantom” dataset. Therefore, we compiled, processed, and structured the data, making them publicly available for further investigation.
    Type of Medium: Online Resource
    ISSN: 2052-4463
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 2775191-0
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  • 10
    Online Resource
    Online Resource
    Wiley ; 2019
    In:  Magnetic Resonance in Medicine Vol. 81, No. 3 ( 2019-03), p. 1605-1619
    In: Magnetic Resonance in Medicine, Wiley, Vol. 81, No. 3 ( 2019-03), p. 1605-1619
    Abstract: Recent literature has shown the potential of high‐resolution quantitative susceptibility mapping (QSM) with ultra‐high field MRI for imaging the anatomy, the vasculature, and investigating their magnetostatic properties. Higher spatial resolutions, however, translate to longer scans resulting, therefore, in higher vulnerability to, and likelihood of, subject movement. We propose a gradient‐recalled echo sequence with prospective motion correction (PMC) to address such limitation. Methods Data from 4 subjects were acquired at 7T. The effect of small and large motion on QSM with and without PMC was assessed qualitatively and quantitatively. Full brain QSM and QSM‐based venograms with up to 0.33 mm isotropic voxel size were reconstructed. Results With PMC, motion artifacts in QSM and QSM‐based venograms were largely eliminated, enabling—in both large‐ and small‐amplitude motion regimes—accurate depiction of the cortex, vasculature, and other small anatomical structures that are often blurred as a result of head movement or indiscernible at lower image resolutions. Quantitative analyses demonstrated that uncorrected motion could bias regional susceptibility distributions, a trend that was greatly reduced with PMC. Conclusion Qualitatively, PMC prevented image degradation because of motion artifacts, providing highly detailed QSM images and venograms. Quantitatively, PMC increased the reproducibility of susceptibility measures.
    Type of Medium: Online Resource
    ISSN: 0740-3194 , 1522-2594
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 1493786-4
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