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Michels L, Riese F, Meyer R, Kälin AM, Leh SE, Unschuld PG, Luechinger R, Hock C, O'Gorman R, Kollias S, Gietl A. EEG-fMRI Signal Coupling Is Modulated in Subjects With Mild Cognitive Impairment and Amyloid Deposition. Front Aging Neurosci 2021; 13:631172. [PMID: 33967737 PMCID: PMC8104007 DOI: 10.3389/fnagi.2021.631172] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 03/10/2021] [Indexed: 12/13/2022] Open
Abstract
Cognitive impairment indicates disturbed brain physiology which can be due to various mechanisms including Alzheimer's pathology. Combined functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) recordings (EEG-fMRI) can assess the interplay between complementary measures of brain activity and EEG changes to be localized to specific brain regions. We used a two-step approach, where we first examined changes related to a syndrome of mild cognitive impairment irrespective of pathology and then studied the specific impact of amyloid pathology. After detailed clinical and neuropsychological characterization as well as a positron emission tomography (PET) scans with the tracer 11-[C]-Pittsburgh Compound B to estimate cerebral amyloid deposition, 14 subjects with mild cognitive impairment (MCI) (mean age 75.6 SD: 8.9) according to standard criteria and 21 cognitively healthy controls (HCS) (mean age 71.8 SD: 4.2) were assessed with EEG-fMRI. Thalamo-cortical alpha-fMRI signal coupling was only observed in HCS. Additional EEG-fMRI signal coupling differences between HCS and MCI were observed in parts of the default mode network, salience network, fronto-parietal network, and thalamus. Individuals with significant cerebral amyloid deposition (amyloid-positive MCI and HCS combined compared to amyloid-negative HCS) displayed abnormal EEG-fMRI signal coupling in visual, fronto-parietal regions but also in the parahippocampus, brain stem, and cerebellum. This finding was paralleled by stronger absolute fMRI signal in the parahippocampus and weaker absolute fMRI signal in the inferior frontal gyrus in amyloid-positive subjects. We conclude that the thalamocortical coupling in the alpha band in HCS more closely reflects previous findings observed in younger adults, while in MCI there is a clearly aberrant coupling in several networks dominated by an anticorrelation in the posterior cingulate cortex. While these findings may broadly indicate physiological changes in MCI, amyloid pathology was specifically associated with abnormal fMRI signal responses and disrupted coupling between brain oscillations and fMRI signal responses, which especially involve core regions of memory: the hippocampus, para-hippocampus, and lateral prefrontal cortex.
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Affiliation(s)
- Lars Michels
- Department of Neuroradiology, Clinical Neuroscience Center, University Hospital Zurich, Zurich, Switzerland
| | - Florian Riese
- Department of Geriatric Psychiatry, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland.,University Research Priority Programs (URPP) ≪Dynamics of Healthy Aging≫, University of Zurich, Zurich, Switzerland
| | - Rafael Meyer
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
| | - Andrea M Kälin
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
| | - Sandra E Leh
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
| | - Paul G Unschuld
- Department of Geriatric Psychiatry, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland.,Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland.,Geriatric Psychiatry, Geneva University Hospitals (HUG), Geneva, Switzerland
| | - Roger Luechinger
- Institute of Biomedical Engineering, University and Eidgenössische Technische Hochschule (ETH) Zurich, Zurich, Switzerland
| | - Christoph Hock
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland.,Neurimmune AG, Schlieren, Switzerland
| | - Ruth O'Gorman
- Center for Magnetic Resonance Research, University Children's Hospital Zurich, Zurich, Switzerland
| | - Spyros Kollias
- Department of Neuroradiology, Clinical Neuroscience Center, University Hospital Zurich, Zurich, Switzerland
| | - Anton Gietl
- Department of Geriatric Psychiatry, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland.,Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
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Quevenco FC, Schreiner SJ, Preti MG, van Bergen JMG, Kirchner T, Wyss M, Steininger SC, Gietl A, Leh SE, Buck A, Pruessmann KP, Hock C, Nitsch RM, Henning A, Van De Ville D, Unschuld PG. GABA and glutamate moderate beta-amyloid related functional connectivity in cognitively unimpaired old-aged adults. Neuroimage Clin 2019; 22:101776. [PMID: 30927605 PMCID: PMC6439267 DOI: 10.1016/j.nicl.2019.101776] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 02/03/2019] [Accepted: 03/10/2019] [Indexed: 02/08/2023]
Abstract
Background Effects of beta-amyloid accumulation on neuronal function precede the clinical manifestation of Alzheimer's disease (AD) by years and affect distinct cognitive brain networks. As previous studies suggest a link between beta-amyloid and dysregulation of excitatory and inhibitory neurotransmitters, we aimed to investigate the impact of GABA and glutamate on beta-amyloid related functional connectivity. Methods 29 cognitively unimpaired old-aged adults (age = 70.03 ± 5.77 years) were administered 11C-Pittsburgh Compound B (PiB) positron-emission tomography (PET), and MRI at 7 Tesla (7T) including blood oxygen level dependent (BOLD) functional MRI (fMRI) at rest for measuring static and dynamic functional connectivity. An advanced 7T MR spectroscopic imaging (MRSI) sequence based on the free induction decay acquisition localized by outer volume suppression’ (FIDLOVS) technology was used for gray matter specific measures of GABA and glutamate in the posterior cingulate and precuneus (PCP) region. Results GABA and glutamate MR-spectra indicated significantly higher levels in gray matter than in white matter. A global effect of beta-amyloid on functional connectivity in the frontal, occipital and inferior temporal lobes was observable. Interactive effects of beta-amyloid with gray matter GABA displayed positive PCP connectivity to the frontomedial regions, and the interaction of beta-amyloid with gray matter glutamate indicated positive PCP connectivity to frontal and cerebellar regions. Furthermore, decreased whole-brain but increased fronto-occipital and temporo-parietal dynamic connectivity was found, when GABA interacted with regional beta-amyloid deposits in the amygdala, frontal lobe, hippocampus, insula and striatum. Conclusions GABA, and less so glutamate, may moderate beta-amyloid related functional connectivity. Additional research is needed to better characterize their interaction and potential impact on AD. Combined ultra-high fieldstrength FIDLOVS MRSI at 7 Tesla with 11C-PIB PET. Assessment of gray matter specific levels of GABA and glutamate. Identification of interactive effects of GABA, glutamate and beta-Amyloid. GABA may moderate dysfunctional beta-Amyloid effects on pre-clinical brain pathology.
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Affiliation(s)
- F C Quevenco
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
| | - S J Schreiner
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland; Hospital for Psychogeriatric Medicine, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland
| | - M G Preti
- Department of Radiology and Medical Informatics, Université de Genève, Switzerland; Institute of Bioengineering, École polytechnique fédérale de Lausanne, Switzerland
| | - J M G van Bergen
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
| | - T Kirchner
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - M Wyss
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - S C Steininger
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland; Hospital for Psychogeriatric Medicine, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland
| | - A Gietl
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
| | - S E Leh
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland; Hospital for Psychogeriatric Medicine, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland
| | - A Buck
- Division of Nuclear Medicine, University Hospital Zurich (USZ), Zurich, Switzerland
| | - K P Pruessmann
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland; Neuroscience Center Zurich (ZNZ), Zurich, Switzerland
| | - C Hock
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland; Hospital for Psychogeriatric Medicine, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland; Neuroscience Center Zurich (ZNZ), Zurich, Switzerland
| | - R M Nitsch
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland; Hospital for Psychogeriatric Medicine, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland; Neuroscience Center Zurich (ZNZ), Zurich, Switzerland
| | - A Henning
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland; Max Planck Institute for Biological Cybernetics, Tubingen, Germany
| | - D Van De Ville
- Department of Radiology and Medical Informatics, Université de Genève, Switzerland; Institute of Bioengineering, École polytechnique fédérale de Lausanne, Switzerland
| | - P G Unschuld
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland; Hospital for Psychogeriatric Medicine, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland; Neuroscience Center Zurich (ZNZ), Zurich, Switzerland.
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3
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Hua J, Lee S, Blair NIS, Wyss M, van Bergen JMG, Schreiner SJ, Kagerer SM, Leh SE, Gietl AF, Treyer V, Buck A, Nitsch RM, Pruessmann KP, Lu H, Van Zijl PCM, Albert M, Hock C, Unschuld PG. Increased cerebral blood volume in small arterial vessels is a correlate of amyloid-β-related cognitive decline. Neurobiol Aging 2019; 76:181-193. [PMID: 30738323 DOI: 10.1016/j.neurobiolaging.2019.01.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 01/01/2019] [Accepted: 01/02/2019] [Indexed: 12/22/2022]
Abstract
The protracted accumulation of amyloid-β (Aβ) is a major pathologic hallmark of Alzheimer's disease and may trigger secondary pathological processes that include neurovascular damage. This study was aimed at investigating long-term effects of Aβ burden on cerebral blood volume of arterioles and pial arteries (CBVa), possibly present before manifestation of dementia. Aβ burden was assessed by 11C Pittsburgh compound-B positron emission tomography in 22 controls and 18 persons with mild cognitive impairment (MCI), [ages: 75(±6) years]. After 2 years, inflow-based vascular space occupancy at ultra-high field strength of 7-Tesla was administered for measuring CBVa, and neuropsychological testing for cognitive decline. Crushing gradients were incorporated during MR-imaging to suppress signals from fast-flowing blood in large arteries, and thereby sensitize inflow-based vascular space occupancy to CBVa in pial arteries and arterioles. CBVa was significantly elevated in MCI compared to cognitively normal controls and regional CBVa related to local Aβ deposition. For both MCI and controls, Aβ burden and follow-up CBVa in several brain regions synergistically predicted cognitive decline over 2 years. Orbitofrontal CBVa was positively associated with apolipoprotein E e4 carrier status. Increased CBVa may reflect long-term effects of region-specific pathology associated with Aβ deposition. Additional studies are needed to clarify the role of the arteriolar system and the potential of CBVa as a biomarker for Aβ-related vascular downstream pathology.
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Affiliation(s)
- Jun Hua
- Neurosection, Division of MRI Research, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - SeungWook Lee
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Nicholas I S Blair
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Michael Wyss
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Jiri M G van Bergen
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland
| | - Simon J Schreiner
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland; Hospital for Psychogeriatric Medicine, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland
| | - Sonja M Kagerer
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland; Hospital for Psychogeriatric Medicine, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland
| | - Sandra E Leh
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland
| | - Anton F Gietl
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland
| | - Valerie Treyer
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland; Department of Nuclear Medicine, University Hospital Zurich, Switzerland
| | - Alfred Buck
- Department of Nuclear Medicine, University Hospital Zurich, Switzerland
| | - Roger M Nitsch
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland
| | - Klaas P Pruessmann
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Hanzhang Lu
- Neurosection, Division of MRI Research, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Peter C M Van Zijl
- Neurosection, Division of MRI Research, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Marilyn Albert
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Christoph Hock
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland
| | - Paul G Unschuld
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland; Hospital for Psychogeriatric Medicine, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland.
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4
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van Bergen JMG, Li X, Quevenco FC, Gietl AF, Treyer V, Leh SE, Meyer R, Buck A, Kaufmann PA, Nitsch RM, van Zijl PCM, Hock C, Unschuld PG. Low cortical iron and high entorhinal cortex volume promote cognitive functioning in the oldest-old. Neurobiol Aging 2017; 64:68-75. [PMID: 29351872 DOI: 10.1016/j.neurobiolaging.2017.12.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 11/09/2017] [Accepted: 12/13/2017] [Indexed: 10/18/2022]
Abstract
The aging brain is characterized by an increased presence of neurodegenerative and vascular pathologies. However, there is substantial variation regarding the relationship between an individual's pathological burden and resulting cognitive impairment. To identify correlates of preserved cognitive functioning at highest age, the relationship between β-amyloid plaque load, presence of small vessel cerebrovascular disease (SVCD), iron-burden, and brain atrophy was investigated. Eighty cognitively unimpaired participants (44 oldest-old, aged 85-96 years; 36 younger-old, aged 55-80 years) were scanned by integrated positron emission tomography-magnetic resonance imaging for assessing beta regional amyloid plaque load (18F-flutemetamol), white matter hyperintensities as an indicator of SVCD (fluid-attenuated inversion recovery-magnetic resonance imaging), and iron load (quantitative susceptibility mapping). For the oldest-old group, lower cortical volume, increased β-amyloid plaque load, prevalence of SVCD, and lower cognitive performance in the normal range were found. However, compared to normal-old, cortical iron burden was lower in the oldest-old. Moreover, only in the oldest-old, entorhinal cortex volume positively correlated with β-amyloid plaque load. Our data thus indicate that the co-occurrence of aging-associated neuropathologies with reduced quantitative susceptibility mapping measures of cortical iron load constitutes a lower vulnerability to cognitive loss.
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Affiliation(s)
- Jiri M G van Bergen
- Institute for Regenerative Medicine (IREM), University of Zürich, Zürich, Switzerland.
| | - Xu Li
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Frances C Quevenco
- Institute for Regenerative Medicine (IREM), University of Zürich, Zürich, Switzerland
| | - Anton F Gietl
- Institute for Regenerative Medicine (IREM), University of Zürich, Zürich, Switzerland; Hospital for Psychogeriatric Medicine, University of Zürich, Zürich, Switzerland
| | - Valerie Treyer
- Institute for Regenerative Medicine (IREM), University of Zürich, Zürich, Switzerland; Department of Nuclear Medicine, University Hospital Zürich and University of Zürich, Zürich, Switzerland
| | - Sandra E Leh
- Hospital for Psychogeriatric Medicine, University of Zürich, Zürich, Switzerland
| | - Rafael Meyer
- Institute for Regenerative Medicine (IREM), University of Zürich, Zürich, Switzerland; Hospital for Psychogeriatric Medicine, University of Zürich, Zürich, Switzerland
| | - Alfred Buck
- Department of Nuclear Medicine, University Hospital Zürich and University of Zürich, Zürich, Switzerland
| | - Philipp A Kaufmann
- Department of Nuclear Medicine, University Hospital Zürich and University of Zürich, Zürich, Switzerland
| | - Roger M Nitsch
- Institute for Regenerative Medicine (IREM), University of Zürich, Zürich, Switzerland; Hospital for Psychogeriatric Medicine, University of Zürich, Zürich, Switzerland
| | - Peter C M van Zijl
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Christoph Hock
- Institute for Regenerative Medicine (IREM), University of Zürich, Zürich, Switzerland; Hospital for Psychogeriatric Medicine, University of Zürich, Zürich, Switzerland
| | - Paul G Unschuld
- Institute for Regenerative Medicine (IREM), University of Zürich, Zürich, Switzerland; Hospital for Psychogeriatric Medicine, University of Zürich, Zürich, Switzerland
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5
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Schreiner SJ, Kirchner T, Narkhede A, Wyss M, Van Bergen JMG, Steininger SC, Gietl A, Leh SE, Treyer V, Buck A, Pruessmann KP, Nitsch RM, Hock C, Henning A, Brickman AM, Unschuld PG. Brain amyloid burden and cerebrovascular disease are synergistically associated with neurometabolism in cognitively unimpaired older adults. Neurobiol Aging 2017; 63:152-161. [PMID: 29310864 DOI: 10.1016/j.neurobiolaging.2017.12.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 11/16/2017] [Accepted: 12/04/2017] [Indexed: 01/08/2023]
Abstract
Alzheimer's disease (AD) is the most common cause of cognitive dysfunction in older adults. The pathological hallmarks of AD such as beta amyloid (Aβ) aggregation and neurometabolic change, as indicated by altered myo-inositol (mI) and N-acetylaspartate (NAA) levels, typically precede the onset of cognitive dysfunction by years. Furthermore, cerebrovascular disease occurs early in AD, but the interplay between vascular and neurometabolic brain change is largely unknown. Thirty cognitively normal older adults (age = 70 ± 5.6 years, Mini-Mental State Examination = 29.2 ± 1) received 11-C-Pittsburgh Compound B positron emission tomography for estimating Aβ-plaque density, 7 Tesla fluid-attenuated inversion recovery magnetic resonance imaging for quantifying white matter hyperintensity volume as a marker of small vessel cerebrovascular disease and high-resolution magnetic resonance spectroscopic imaging at 7 Tesla, based on free induction decay acquisition localized by outer volume suppression to investigate tissue-specific neurometabolism in the posterior cingulate and precuneus. Aβ (β = 0.45, p = 0.018) and white matter hyperintensities (β = 0.40, p = 0.046) were independently and interactively (β = -0.49, p = 0.026) associated with a higher ratio of mI over NAA (mI/NAA) in the posterior cingulate and precuneus gray matter but not in the white matter. Our data suggest that cerebrovascular disease and Aβ burden are synergistically associated with AD-related gray matter neurometabolism in older adults.
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Affiliation(s)
- Simon J Schreiner
- Institute for Regenerative Medicine, University of Zurich, Schlieren, Switzerland; Hospital for Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Thomas Kirchner
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Atul Narkhede
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Department of Neurology, College of Physicians and Surgeons, Columbia University, NY
| | - Michael Wyss
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Jiri M G Van Bergen
- Institute for Regenerative Medicine, University of Zurich, Schlieren, Switzerland; Hospital for Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Stephanie C Steininger
- Institute for Regenerative Medicine, University of Zurich, Schlieren, Switzerland; Hospital for Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Anton Gietl
- Institute for Regenerative Medicine, University of Zurich, Schlieren, Switzerland; Hospital for Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Sandra E Leh
- Institute for Regenerative Medicine, University of Zurich, Schlieren, Switzerland; Hospital for Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Valerie Treyer
- Institute for Regenerative Medicine, University of Zurich, Schlieren, Switzerland; Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Alfred Buck
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Klaas P Pruessmann
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Roger M Nitsch
- Institute for Regenerative Medicine, University of Zurich, Schlieren, Switzerland; Hospital for Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Christoph Hock
- Institute for Regenerative Medicine, University of Zurich, Schlieren, Switzerland; Hospital for Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Anke Henning
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland; Max Planck Institute for Biological Cybernetics, Tubingen, Germany
| | - Adam M Brickman
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Department of Neurology, College of Physicians and Surgeons, Columbia University, NY.
| | - Paul G Unschuld
- Institute for Regenerative Medicine, University of Zurich, Schlieren, Switzerland; Hospital for Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
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6
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Michels L, Muthuraman M, Anwar AR, Kollias S, Leh SE, Riese F, Unschuld PG, Siniatchkin M, Gietl AF, Hock C. Changes of Functional and Directed Resting-State Connectivity Are Associated with Neuronal Oscillations, ApoE Genotype and Amyloid Deposition in Mild Cognitive Impairment. Front Aging Neurosci 2017; 9:304. [PMID: 29081745 PMCID: PMC5646353 DOI: 10.3389/fnagi.2017.00304] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 09/04/2017] [Indexed: 01/03/2023] Open
Abstract
The assessment of effects associated with cognitive impairment using electroencephalography (EEG) power mapping allows the visualization of frequency-band specific local changes in oscillatory activity. In contrast, measures of coherence and dynamic source synchronization allow for the study of functional and effective connectivity, respectively. Yet, these measures have rarely been assessed in parallel in the context of mild cognitive impairment (MCI) and furthermore it has not been examined if they are related to risk factors of Alzheimer’s disease (AD) such as amyloid deposition and apolipoprotein ε4 (ApoE) allele occurrence. Here, we investigated functional and directed connectivities with Renormalized Partial Directed Coherence (RPDC) in 17 healthy controls (HC) and 17 participants with MCI. Participants underwent ApoE-genotyping and Pittsburgh compound B positron emission tomography (PiB-PET) to assess amyloid deposition. We observed lower spectral source power in MCI in the alpha and beta bands. Coherence was stronger in HC than MCI across different neuronal sources in the delta, theta, alpha, beta and gamma bands. The directed coherence analysis indicated lower information flow between fronto-temporal (including the hippocampus) sources and unidirectional connectivity in MCI. In MCI, alpha and beta RPDC showed an inverse correlation to age and gender; global amyloid deposition was inversely correlated to alpha coherence, RPDC and beta and gamma coherence. Furthermore, the ApoE status was negatively correlated to alpha coherence and RPDC, beta RPDC and gamma coherence. A classification analysis of cognitive state revealed the highest accuracy using EEG power, coherence and RPDC as input. For this small but statistically robust (Bayesian power analyses) sample, our results suggest that resting EEG related functional and directed connectivities are sensitive to the cognitive state and are linked to ApoE and amyloid burden.
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Affiliation(s)
- Lars Michels
- Clinic of Neuroradiology, University Hospital of ZurichZurich, Switzerland.,MR-Center, University Children's Hospital ZurichZurich, Switzerland
| | - Muthuraman Muthuraman
- Clinic for Neurology, University of KielKiel, Germany.,Clinic for Neurology, University of MainzMainz, Germany
| | - Abdul R Anwar
- Clinic for Neurology, University of KielKiel, Germany
| | - Spyros Kollias
- Clinic of Neuroradiology, University Hospital of ZurichZurich, Switzerland
| | - Sandra E Leh
- Division of Psychiatry Research and Psychogeriatric Medicine, University of ZurichZurich, Switzerland
| | - Florian Riese
- Division of Psychiatry Research and Psychogeriatric Medicine, University of ZurichZurich, Switzerland
| | - Paul G Unschuld
- Division of Psychiatry Research and Psychogeriatric Medicine, University of ZurichZurich, Switzerland
| | - Michael Siniatchkin
- Institute of Medical Psychology and Medical Sociology, Christian-Albrechts-University of KielKiel, Germany
| | - Anton F Gietl
- Division of Psychiatry Research and Psychogeriatric Medicine, University of ZurichZurich, Switzerland
| | - Christoph Hock
- Division of Psychiatry Research and Psychogeriatric Medicine, University of ZurichZurich, Switzerland
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7
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Leh SE, Schroeder C, Chen JK, Mallar Chakravarty M, Park MTM, Cheung B, Huntgeburth SC, Gosselin N, Hock C, Ptito A, Petrides M. Microstructural Integrity of Hippocampal Subregions Is Impaired after Mild Traumatic Brain Injury. J Neurotrauma 2017; 34:1402-1411. [DOI: 10.1089/neu.2016.4591] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- Sandra E. Leh
- Institute for Regenerative Medicine, University of Zurich, Switzerland
| | - Clemens Schroeder
- Institute for Regenerative Medicine, University of Zurich, Switzerland
| | - Jen-Kai Chen
- Cognitive Neuroscience Unit, Montreal Neurological Institute, Montreal, Quebec, Canada
- Department of Psychology, McGill University Health Centre, Montreal, Quebec, Canada
| | - M. Mallar Chakravarty
- Cerebral Imaging Centre, Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada
- Departments of Psychiatry and Biomedical Engineering, McGill University, Montreal, Quebec, Canada
| | - Min Tae M. Park
- Cerebral Imaging Centre, Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada
- Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Bob Cheung
- Defense Research and Development Canada (DRDC) Toronto, Ontario, Canada
| | - Sonja C. Huntgeburth
- Cognitive Neuroscience Unit, Montreal Neurological Institute, Montreal, Quebec, Canada
- Department of Psychology, McGill University, Montreal, Quebec, Canada
| | - Nadia Gosselin
- Research Center, Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada
| | - Christoph Hock
- Institute for Regenerative Medicine, University of Zurich, Switzerland
| | - Alain Ptito
- Cognitive Neuroscience Unit, Montreal Neurological Institute, Montreal, Quebec, Canada
- Department of Psychology, McGill University Health Centre, Montreal, Quebec, Canada
| | - Michael Petrides
- Cognitive Neuroscience Unit, Montreal Neurological Institute, Montreal, Quebec, Canada
- Department of Psychology, McGill University, Montreal, Quebec, Canada
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8
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Quevenco FC, Preti MG, van Bergen JMG, Hua J, Wyss M, Li X, Schreiner SJ, Steininger SC, Meyer R, Meier IB, Brickman AM, Leh SE, Gietl AF, Buck A, Nitsch RM, Pruessmann KP, van Zijl PCM, Hock C, Van De Ville D, Unschuld PG. Memory performance-related dynamic brain connectivity indicates pathological burden and genetic risk for Alzheimer's disease. Alzheimers Res Ther 2017; 9:24. [PMID: 28359293 PMCID: PMC5374623 DOI: 10.1186/s13195-017-0249-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 02/27/2017] [Indexed: 11/10/2022]
Abstract
BACKGROUND The incidence of Alzheimer's disease (AD) strongly relates to advanced age and progressive deposition of cerebral amyloid-beta (Aβ), hyperphosphorylated tau, and iron. The purpose of this study was to investigate the relationship between cerebral dynamic functional connectivity and variability of long-term cognitive performance in healthy, elderly subjects, allowing for local pathology and genetic risk. METHODS Thirty seven participants (mean (SD) age 74 (6.0) years, Mini-Mental State Examination 29.0 (1.2)) were dichotomized based on repeated neuropsychological test performance within 2 years. Cerebral Aβ was measured by 11C Pittsburgh Compound-B positron emission tomography, and iron by quantitative susceptibility mapping magnetic resonance imaging (MRI) at an ultra-high field strength of 7 Tesla (7T). Dynamic functional connectivity patterns were investigated by resting-state functional MRI at 7T and tested for interactive effects with genetic AD risk (apolipoprotein E (ApoE)-ε4 carrier status). RESULTS A relationship between low episodic memory and a lower expression of anterior-posterior connectivity was seen (F(9,27) = 3.23, p < 0.008), moderated by ApoE-ε4 (F(9,27) = 2.22, p < 0.005). Inherent node-strength was related to local iron (F(5,30) = 13.2; p < 0.022). CONCLUSION Our data indicate that altered dynamic anterior-posterior brain connectivity is a characteristic of low memory performance in the subclinical range and genetic risk for AD in the elderly. As the observed altered brain network properties are associated with increased local iron, our findings may reflect secondary neuronal changes due to pathologic processes including oxidative stress.
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Affiliation(s)
- Frances C Quevenco
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
| | - Maria G Preti
- Department of Radiology and Medical Informatics, Université de Genève, Geneva, Switzerland.,Institute of Bioengineering, École polytechnique fédérale de Lausanne, Lausanne, Switzerland
| | - Jiri M G van Bergen
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
| | - Jun Hua
- Department of Radiology, Johns Hopkins School of Medicine and F.M. Kirby Center for Functional Brain Imaging at Kennedy Krieger Institute, Baltimore, MD, USA
| | - Michael Wyss
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Xu Li
- Department of Radiology, Johns Hopkins School of Medicine and F.M. Kirby Center for Functional Brain Imaging at Kennedy Krieger Institute, Baltimore, MD, USA
| | - Simon J Schreiner
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland.,Hospital for Psychogeriatric Medicine, University of Zurich, Minervastr.145, CH-8032, Zurich, Switzerland
| | - Stefanie C Steininger
- Hospital for Psychogeriatric Medicine, University of Zurich, Minervastr.145, CH-8032, Zurich, Switzerland
| | - Rafael Meyer
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland.,Hospital for Psychogeriatric Medicine, University of Zurich, Minervastr.145, CH-8032, Zurich, Switzerland
| | - Irene B Meier
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland
| | - Adam M Brickman
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, USA
| | - Sandra E Leh
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland.,Hospital for Psychogeriatric Medicine, University of Zurich, Minervastr.145, CH-8032, Zurich, Switzerland
| | - Anton F Gietl
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland.,Hospital for Psychogeriatric Medicine, University of Zurich, Minervastr.145, CH-8032, Zurich, Switzerland
| | - Alfred Buck
- Division of Nuclear Medicine, University of Zurich, Zurich, Switzerland
| | - Roger M Nitsch
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland.,Hospital for Psychogeriatric Medicine, University of Zurich, Minervastr.145, CH-8032, Zurich, Switzerland
| | - Klaas P Pruessmann
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Peter C M van Zijl
- Department of Radiology, Johns Hopkins School of Medicine and F.M. Kirby Center for Functional Brain Imaging at Kennedy Krieger Institute, Baltimore, MD, USA
| | - Christoph Hock
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland.,Hospital for Psychogeriatric Medicine, University of Zurich, Minervastr.145, CH-8032, Zurich, Switzerland
| | - Dimitri Van De Ville
- Department of Radiology and Medical Informatics, Université de Genève, Geneva, Switzerland.,Institute of Bioengineering, École polytechnique fédérale de Lausanne, Lausanne, Switzerland
| | - Paul G Unschuld
- Institute for Regenerative Medicine (IREM), University of Zurich, Zurich, Switzerland. .,Hospital for Psychogeriatric Medicine, University of Zurich, Minervastr.145, CH-8032, Zurich, Switzerland.
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9
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Kälin AM, Park MTM, Chakravarty MM, Lerch JP, Michels L, Schroeder C, Broicher SD, Kollias S, Nitsch RM, Gietl AF, Unschuld PG, Hock C, Leh SE. Subcortical Shape Changes, Hippocampal Atrophy and Cortical Thinning in Future Alzheimer's Disease Patients. Front Aging Neurosci 2017; 9:38. [PMID: 28326033 PMCID: PMC5339600 DOI: 10.3389/fnagi.2017.00038] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Accepted: 02/13/2017] [Indexed: 11/13/2022] Open
Abstract
Efficacy of future treatments depends on biomarkers identifying patients with mild cognitive impairment at highest risk for transitioning to Alzheimer's disease. Here, we applied recently developed analysis techniques to investigate cross-sectional differences in subcortical shape and volume alterations in patients with stable mild cognitive impairment (MCI) (n = 23, age range 59–82, 47.8% female), future converters at baseline (n = 10, age range 66–84, 90% female) and at time of conversion (age range 68–87) compared to group-wise age and gender matched healthy control subjects (n = 23, age range 61–81, 47.8% female; n = 10, age range 66–82, 80% female; n = 10, age range 68–82, 70% female). Additionally, we studied cortical thinning and global and local measures of hippocampal atrophy as known key imaging markers for Alzheimer's disease. Apart from bilateral striatal volume reductions, no morphometric alterations were found in cognitively stable patients. In contrast, we identified shape alterations in striatal and thalamic regions in future converters at baseline and at time of conversion. These shape alterations were paralleled by Alzheimer's disease like patterns of left hemispheric morphometric changes (cortical thinning in medial temporal regions, hippocampal total and subfield atrophy) in future converters at baseline with progression to similar right hemispheric alterations at time of conversion. Additionally, receiver operating characteristic curve analysis indicated that subcortical shape alterations may outperform hippocampal volume in identifying future converters at baseline. These results further confirm the key role of early cortical thinning and hippocampal atrophy in the early detection of Alzheimer's disease. But first and foremost, and by distinguishing future converters but not patients with stable cognitive abilities from cognitively normal subjects, our results support the value of early subcortical shape alterations and reduced hippocampal subfield volumes as potential markers for the early detection of Alzheimer's disease.
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Affiliation(s)
- Andrea M Kälin
- Institute for Regenerative Medicine, University of Zurich Schlieren, Switzerland
| | - Min T M Park
- Cerebral Imaging Centre, Douglas Mental Health University InstituteMontreal, QC, Canada; Schulich School of Medicine and Dentistry, Western UniversityLondon, ON, Canada
| | - M Mallar Chakravarty
- Cerebral Imaging Centre, Douglas Mental Health University InstituteMontreal, QC, Canada; Departments of Psychiatry and Biological and Biomedical Engineering, McGill UniversityMontreal, QC, Canada
| | - Jason P Lerch
- The Hospital for Sick ChildrenToronto, ON, Canada; Department of Medical Biophysics, The University of TorontoToronto, ON, Canada
| | - Lars Michels
- Clinic of Neuroradiology, University Hospital Zurich, University of ZurichZurich, Switzerland; Center for MR Research, University Children's Hospital ZurichZurich, Switzerland
| | - Clemens Schroeder
- Institute for Regenerative Medicine, University of Zurich Schlieren, Switzerland
| | - Sarah D Broicher
- Neuropsychology Unit, Department of Neurology, University Hospital Zurich Zurich, Switzerland
| | - Spyros Kollias
- Clinic of Neuroradiology, University Hospital Zurich, University of Zurich Zurich, Switzerland
| | - Roger M Nitsch
- Institute for Regenerative Medicine, University of Zurich Schlieren, Switzerland
| | - Anton F Gietl
- Institute for Regenerative Medicine, University of Zurich Schlieren, Switzerland
| | - Paul G Unschuld
- Institute for Regenerative Medicine, University of Zurich Schlieren, Switzerland
| | - Christoph Hock
- Institute for Regenerative Medicine, University of Zurich Schlieren, Switzerland
| | - Sandra E Leh
- Institute for Regenerative Medicine, University of Zurich Schlieren, Switzerland
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10
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Schreiner SJ, Kirchner T, Wyss M, Van Bergen JM, Quevenco FC, Steininger SC, Griffith EY, Meier I, Michels L, Gietl AF, Leh SE, Brickman AM, Hock C, Nitsch RM, Pruessmann KP, Henning A, Unschuld PG. Low episodic memory performance in cognitively normal elderly subjects is associated with increased posterior cingulate gray matter N-acetylaspartate: a 1H MRSI study at 7 Tesla. Neurobiol Aging 2016; 48:195-203. [DOI: 10.1016/j.neurobiolaging.2016.08.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 08/03/2016] [Accepted: 08/24/2016] [Indexed: 11/30/2022]
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11
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van Bergen JMG, Li X, Hua J, Schreiner SJ, Steininger SC, Quevenco FC, Wyss M, Gietl AF, Treyer V, Leh SE, Buck F, Nitsch RM, Pruessmann KP, van Zijl PCM, Hock C, Unschuld PG. Colocalization of cerebral iron with Amyloid beta in Mild Cognitive Impairment. Sci Rep 2016; 6:35514. [PMID: 27748454 PMCID: PMC5066274 DOI: 10.1038/srep35514] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 09/26/2016] [Indexed: 01/21/2023] Open
Abstract
Quantitative Susceptibility Mapping (QSM) MRI at 7 Tesla and 11-Carbon Pittsburgh-Compound-B PET were used for investigating the relationship between brain iron and Amyloid beta (Aβ) plaque-load in a context of increased risk for Alzheimer's disease (AD), as reflected by the Apolipoprotein E ε4 (APOE-e4) allele and mild cognitive impairment (MCI) in elderly subjects. Carriers of APOE-e4 with normal cognition had higher cortical Aβ-plaque-load than non-carriers. In MCI an association between APOE-e4 and higher Aβ-plaque-load was observable both for cortical and subcortical brain-regions. APOE-e4 and MCI was also associated with higher cortical iron. Moreover, cerebral iron significantly affected functional coupling, and was furthermore associated with increased Aβ-plaque-load (R2-adjusted = 0.80, p < 0.001) and APOE-e4 carrier status (p < 0.001) in MCI. This study confirms earlier reports on an association between increased brain iron-burden and risk for neurocognitive dysfunction due to AD, and indicates that disease-progression is conferred by spatial colocalization of brain iron deposits with Aβ-plaques.
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Affiliation(s)
- J M G van Bergen
- Institute for Regenerative Medicine, University of Zürich, Switzerland
| | - X Li
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - J Hua
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - S J Schreiner
- Institute for Regenerative Medicine, University of Zürich, Switzerland.,Hospital for Psychogeriatric Medicine, University of Zürich, Switzerland
| | - S C Steininger
- Institute for Regenerative Medicine, University of Zürich, Switzerland.,Hospital for Psychogeriatric Medicine, University of Zürich, Switzerland
| | - F C Quevenco
- Institute for Regenerative Medicine, University of Zürich, Switzerland
| | - M Wyss
- Institute for Biomedical Engineering, University of Zürich and ETH Zürich, Zürich, Switzerland
| | - A F Gietl
- Institute for Regenerative Medicine, University of Zürich, Switzerland.,Hospital for Psychogeriatric Medicine, University of Zürich, Switzerland
| | - V Treyer
- Institute for Regenerative Medicine, University of Zürich, Switzerland.,Department of Nuclear Medicine, University Hospital Zürich and University of Zürich, Zürich, Switzerland
| | - S E Leh
- Institute for Regenerative Medicine, University of Zürich, Switzerland.,Hospital for Psychogeriatric Medicine, University of Zürich, Switzerland
| | - F Buck
- Department of Nuclear Medicine, University Hospital Zürich and University of Zürich, Zürich, Switzerland
| | - R M Nitsch
- Institute for Regenerative Medicine, University of Zürich, Switzerland.,Hospital for Psychogeriatric Medicine, University of Zürich, Switzerland
| | - K P Pruessmann
- Institute for Biomedical Engineering, University of Zürich and ETH Zürich, Zürich, Switzerland
| | - P C M van Zijl
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - C Hock
- Institute for Regenerative Medicine, University of Zürich, Switzerland
| | - P G Unschuld
- Institute for Regenerative Medicine, University of Zürich, Switzerland.,Hospital for Psychogeriatric Medicine, University of Zürich, Switzerland
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12
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Schroeder C, Park MTM, Germann J, Chakravarty MM, Michels L, Kollias S, Kroll SL, Buck A, Treyer V, Savaskan E, Unschuld PG, Nitsch RM, Kälin AM, Hock C, Gietl AF, Leh SE. Hippocampal shape alterations are associated with regional Aβ load in cognitively normal elderly individuals. Eur J Neurosci 2016; 45:1241-1251. [PMID: 27646656 DOI: 10.1111/ejn.13408] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 09/09/2016] [Accepted: 09/16/2016] [Indexed: 01/18/2023]
Abstract
Aβ deposition is a driving force of Alzheimer's disease pathology and can be detected early by amyloid positron emission tomography. Identifying presymptomatic structural brain changes associated with Aβ deposition might lead to a better understanding of its consequences and provide early diagnostic information. In this respect we analyzed measures of cortical thickness and subcortical volumes along with hippocampal, thalamic and striatal shape and surface area by applying novel analysis strategies for structural magnetic resonance imaging. We included 69 cognitively normal elderly subjects after careful clinical and neuropsychological workup. Standardized uptake value ratios (cerebellar reference) for uptake of 11-C-Pittsburgh Compound B (PiB) were calculated from positron emission tomographic data for a cortical measurement and for bilateral hippocampus, thalamus and striatum. Associations to shape, surface area, volume and cortical thickness were tested using regression models that included significant predictors as covariates. Left anterior hippocampal shape was associated with regional PiB uptake (P < 0.05, FDR corrected), whereas volumes of the hippocampi and their subregions were not associated with cortical or regional PiB uptake (all P > 0.05, FDR corrected). Within the entorhinal cortical region of both hemispheres, thickness was negatively associated with cortical PiB uptake (P < 0.05, FDR corrected). Hence, localized shape measures and cortical thickness may be potential biomarkers of presymptomatic Alzheimer's disease.
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Affiliation(s)
- Clemens Schroeder
- Institute for Regenerative Medicine, University of Zurich, Wagistrasse 12, CH-8952, Schlieren, Switzerland
| | - Min Tae M Park
- Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Cerebral Imaging Centre, Douglas Mental Health University Institute, McGill University, Montréal, QC, Canada
| | - Jürgen Germann
- Cerebral Imaging Centre, Douglas Mental Health University Institute, McGill University, Montréal, QC, Canada
| | - M Mallar Chakravarty
- Cerebral Imaging Centre, Douglas Mental Health University Institute, McGill University, Montréal, QC, Canada.,Departments of Psychiatry and Biomedical Engineering, McGill University, Montreal, QC, Canada
| | - Lars Michels
- Institute of Neuroradiology, University of Zurich, Zurich, Switzerland
| | - Spyros Kollias
- Institute of Neuroradiology, University of Zurich, Zurich, Switzerland
| | - Sara L Kroll
- Department of Psychiatry, Psychotherapy and Psychosomatics, University of Zurich, Zurich, Switzerland
| | - Alfred Buck
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Valerie Treyer
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Egemen Savaskan
- Clinic for Gerontopsychiatry, Psychiatric University Hospital Zurich, Zurich, Switzerland
| | - Paul G Unschuld
- Institute for Regenerative Medicine, University of Zurich, Wagistrasse 12, CH-8952, Schlieren, Switzerland
| | - Roger M Nitsch
- Institute for Regenerative Medicine, University of Zurich, Wagistrasse 12, CH-8952, Schlieren, Switzerland
| | - Andrea M Kälin
- Institute for Regenerative Medicine, University of Zurich, Wagistrasse 12, CH-8952, Schlieren, Switzerland
| | - Christoph Hock
- Institute for Regenerative Medicine, University of Zurich, Wagistrasse 12, CH-8952, Schlieren, Switzerland
| | - Anton F Gietl
- Institute for Regenerative Medicine, University of Zurich, Wagistrasse 12, CH-8952, Schlieren, Switzerland
| | - Sandra E Leh
- Institute for Regenerative Medicine, University of Zurich, Wagistrasse 12, CH-8952, Schlieren, Switzerland.,Clinic for Gerontopsychiatry, Psychiatric University Hospital Zurich, Zurich, Switzerland
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13
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Leh SE, Kälin AM, Schroeder C, Park MTM, Chakravarty MM, Freund P, Gietl AF, Riese F, Kollias S, Hock C, Michels L. Volumetric and shape analysis of the thalamus and striatum in amnestic mild cognitive impairment. J Alzheimers Dis 2016; 49:237-49. [PMID: 26444755 DOI: 10.3233/jad-150080] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Alterations in brain structures, including progressive neurodegeneration, are a hallmark in patients with Alzheimer's disease (AD). However, pathological mechanisms, such as the accumulation of amyloid and the proliferation of tau, are thought to begin years, even decades, before the initial clinical manifestations of AD. In this study, we compare the brain anatomy of amnestic mild cognitive impairment patients (aMCI, n = 16) to healthy subjects (CS, n = 22) using cortical thickness, subcortical volume, and shape analysis, which we believe to be complimentary to volumetric measures. We were able to replicate "classical" cortical thickness alterations in aMCI in the hippocampus, amygdala, putamen, insula, and inferior temporal regions. Additionally, aMCI showed significant thalamic and striatal shape differences. We observed higher global amyloid deposition in aMCI, a significant correlation between striatal displacement and global amyloid, and an inverse correlation between executive function and right-hemispheric thalamic displacement. In contrast, no volumetric differences were detected in thalamic, striatal, and hippocampal regions. Our results provide new evidence for early subcortical neuroanatomical changes in patients with aMCI, which are linked to cognitive abilities and amyloid deposition. Hence, shape analysis may aid in the identification of structural biomarkers for identifying individuals at highest risk of conversion to AD.
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Affiliation(s)
- Sandra E Leh
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Switzerland
| | - Andrea M Kälin
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Switzerland
| | - Clemens Schroeder
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Switzerland
| | - Min Tae M Park
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Canada.,Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Canada
| | - M Mallar Chakravarty
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Canada.,Departments of Psychiatry and Biomedical Engineering, McGill University, Montreal, Canada
| | - Patrick Freund
- Spinal Cord Injury Center, University Hospital Balgrist, Switzerland.,Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, University College London, London, UK.,Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, University College London, London, UK.,Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Anton F Gietl
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Switzerland
| | - Florian Riese
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Switzerland
| | - Spyros Kollias
- Institute of Neuroradiology, University of Zurich, Switzerland
| | - Christoph Hock
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Switzerland
| | - Lars Michels
- Institute of Neuroradiology, University of Zurich, Switzerland
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14
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Abstract
Blindsight is a visual phenomenon whereby hemianopic patients are able to process visual information in their blind visual field without awareness. Previous research demonstrating the existence of blindsight in hemianopic patients has been criticized for the nature of the paradigms used, for the presence of methodological artifacts, and for the possibility that spared islands of visual cortex may have sustained the phenomenon because the patients generally had small circumscribed lesions. To respond to these criticisms, the authors have been investigating for several years now residual visual abilities in the blind field of hemispherectomized patients in whom a whole cerebral hemisphere has been removed or disconnected from the rest of the brain. These patients have offered a unique opportunity to establish the existence of blindsight and to investigate its underlying neuronal mechanisms because in these cases, spared islands of visual cortex cannot be evoked to explain the presence of visual abilities in the blind field. In addition, the authors have been using precise behavioral paradigms, strict control for potential methodological artifacts such as light scatter, fixation, criterion effects, and macular sparing, and they have utilized new neuroimaging techniques such as diffusion tensor imaging tractography to enhance their understanding of the phenomenon. The following article is a review of their research on the involvement of the superior colliculi in blindsight in hemispherectomized patients. NEUROSCIENTIST 13(5):506—518, 2007.
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Affiliation(s)
- Alain Ptito
- Cognitive Neuroscience Unit, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada.
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15
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Michels L, Warnock G, Buck A, Macauda G, Leh SE, Kaelin AM, Riese F, Meyer R, O'Gorman R, Hock C, Kollias S, Gietl AF. Arterial spin labeling imaging reveals widespread and Aβ-independent reductions in cerebral blood flow in elderly apolipoprotein epsilon-4 carriers. J Cereb Blood Flow Metab 2016; 36:581-95. [PMID: 26661143 PMCID: PMC4794091 DOI: 10.1177/0271678x15605847] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Accepted: 10/07/2015] [Indexed: 12/11/2022]
Abstract
Changes in cerebral blood flow are an essential feature of Alzheimer's disease and have been linked to apolipoprotein E-genotype and cerebral amyloid-deposition. These factors could be interdependent or influence cerebral blood flow via different mechanisms. We examined apolipoprotein E-genotype, amyloid beta-deposition, and cerebral blood flow in amnestic mild cognitive impairment using pseudo-continuous arterial spin labeling MRI in 27 cognitively normal elderly and 16 amnestic mild cognitive impairment participants. Subjects underwent Pittsburgh Compound B (PiB) positron emission tomography and apolipoprotein E-genotyping. Global cerebral blood flow was lower in apolipoprotein E ɛ4-allele carriers (apolipoprotein E4+) than in apolipoprotein E4- across all subjects (including cognitively normal participants) and within the group of cognitively normal elderly. Global cerebral blood flow was lower in subjects with mild cognitive impairment compared with cognitively normal. Subjects with elevated cerebral amyloid-deposition (PiB+) showed a trend for lower global cerebral blood flow. Apolipoprotein E-status exerted the strongest effect on global cerebral blood flow. Regional analysis indicated that local cerebral blood flow reductions were more widespread for the contrasts apolipoprotein E4+ versus apolipoprotein E4- compared with the contrasts PiB+ versus PiB- or mild cognitive impairment versus cognitively normal. These findings suggest that apolipoprotein E-genotype exerts its impact on cerebral blood flow at least partly independently from amyloid beta-deposition, suggesting that apolipoprotein E also contributes to cerebral blood flow changes outside the context of Alzheimer's disease.
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Affiliation(s)
- Lars Michels
- Institute of Neuroradiology, University Hospital Zurich, Zurich, Switzerland Center of MR-Research, University Children's Hospital Zurich, Zurich, Switzerland
| | - Geoffrey Warnock
- Clinic of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Alfred Buck
- Clinic of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Gianluca Macauda
- Institute of Neuroradiology, University Hospital Zurich, Zurich, Switzerland Neuropsychology Unit, Department of Neurology, University Hospital Zurich, Zurich, Switzerland
| | - Sandra E Leh
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Andrea M Kaelin
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Florian Riese
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Rafael Meyer
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Ruth O'Gorman
- Center of MR-Research, University Children's Hospital Zurich, Zurich, Switzerland
| | - Christoph Hock
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Spyros Kollias
- Institute of Neuroradiology, University Hospital Zurich, Zurich, Switzerland
| | - Anton F Gietl
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
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16
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Schreiner SJ, Liu X, Gietl AF, Wyss M, Steininger SC, Gruber E, Treyer V, Meier IB, Kälin AM, Leh SE, Buck A, Nitsch RM, Pruessmann KP, Hock C, Unschuld PG. Regional Fluid-Attenuated Inversion Recovery (FLAIR) at 7 Tesla correlates with amyloid beta in hippocampus and brainstem of cognitively normal elderly subjects. Front Aging Neurosci 2014; 6:240. [PMID: 25249977 PMCID: PMC4159032 DOI: 10.3389/fnagi.2014.00240] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 08/22/2014] [Indexed: 11/13/2022] Open
Abstract
Background: Accumulation of amyloid beta (Aβ) may occur during healthy aging and is a risk factor for Alzheimer Disease (AD). While individual Aβ-accumulation can be measured non-invasively using Pittsburgh Compund-B positron emission tomography (PiB-PET), Fluid-attenuated inversion recovery (FLAIR) is a Magnetic Resonance Imaging (MRI) sequence, capable of indicating heterogeneous age-related brain pathologies associated with tissue-edema. In the current study cognitively normal elderly subjects were investigated for regional correlation of PiB- and FLAIR intensity. Methods: Fourteen healthy elderly subjects without known history of cognitive impairment received 11C-PiB-PET for estimation of regional Aβ-load. In addition, whole brain T1-MPRAGE and FLAIR-MRI sequences were acquired at high field strength of 7 Tesla (7T). Volume-normalized intensities of brain regions were assessed by applying an automated subcortical segmentation algorithm for spatial definition of brain structures. Statistical dependence between FLAIR- and PiB-PET intensities was tested using Spearman's rank correlation coefficient (rho), followed by Holm–Bonferroni correction for multiple testing. Results: Neuropsychological testing revealed normal cognitive performance levels in all participants. Mean regional PiB-PET and FLAIR intensities were normally distributed and independent. Significant correlation between volume-normalized PiB-PET signals and FLAIR intensities resulted for Hippocampus (right: rho = 0.86; left: rho = 0.84), Brainstem (rho = 0.85) and left Basal Ganglia vessel region (rho = 0.82). Conclusions: Our finding of a significant relationship between PiB- and FLAIR intensity mainly observable in the Hippocampus and Brainstem, indicates regional Aβ associated tissue-edema in cognitively normal elderly subjects. Further studies including clinical populations are necessary to clarify the relevance of our findings for estimating individual risk for age-related neurodegenerative processes such as AD.
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Affiliation(s)
- Simon J Schreiner
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland
| | - Xinyang Liu
- Department of Radiology, Harvard Medical School, Brigham and Women's Hospital Boston, MA, USA
| | - Anton F Gietl
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland
| | - Michael Wyss
- Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University of Zürich and ETH Zürich Zürich, Switzerland
| | - Stefanie C Steininger
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland
| | - Esmeralda Gruber
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland
| | - Valerie Treyer
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland ; Division of Nuclear Medicine, University of Zürich Zürich, Switzerland
| | - Irene B Meier
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland ; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University Medical Center New York, NY, USA
| | - Andrea M Kälin
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland
| | - Sandra E Leh
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland
| | - Alfred Buck
- Division of Nuclear Medicine, University of Zürich Zürich, Switzerland
| | - Roger M Nitsch
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland
| | - Klaas P Pruessmann
- Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University of Zürich and ETH Zürich Zürich, Switzerland
| | - Christoph Hock
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland
| | - Paul G Unschuld
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland
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Riese F, Gietl A, Zölch N, Henning A, O'Gorman R, Kälin AM, Leh SE, Buck A, Warnock G, Edden RAE, Luechinger R, Hock C, Kollias S, Michels L. Posterior cingulate γ-aminobutyric acid and glutamate/glutamine are reduced in amnestic mild cognitive impairment and are unrelated to amyloid deposition and apolipoprotein E genotype. Neurobiol Aging 2014; 36:53-9. [PMID: 25169676 DOI: 10.1016/j.neurobiolaging.2014.07.030] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 07/18/2014] [Accepted: 07/23/2014] [Indexed: 02/08/2023]
Abstract
The biomarker potential of the inhibitory neurotransmitter γ-aminobutyric acid (GABA) for the in vivo characterization of preclinical stages in Alzheimer's disease has not yet been explored. We measured GABA, glutamate + glutamine (Glx), and N-acetyl-aspartate (NAA) levels by single-voxel MEGA-PRESS magnetic resonance spectroscopy in the posterior cingulate cortex of 21 elderly subjects and 15 patients with amnestic mild cognitive impairment. Participants underwent Pittsburgh Compound B positron emission tomography, apolipoprotein E (APOE) genotyping, and neuropsychological examination. GABA, Glx, and NAA levels were significantly lower in patients. NAA was lower in Pittsburgh Compound B-positive subjects and APOE ε4 allele carriers. GABA, Glx, and NAA levels were positively correlated to CERAD word learning scores. Reductions in GABA, Glx, and NAA levels may serve as metabolic biomarkers for cognitive impairment in amnestic mild cognitive impairment. Because GABA and Glx do not seem to reflect amyloid β deposition or APOE genotype, they are less likely biomarker candidates for preclinical Alzheimer's disease.
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Affiliation(s)
- Florian Riese
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Anton Gietl
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Niklaus Zölch
- Institute of Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Anke Henning
- Institute of Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland; Max-Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Ruth O'Gorman
- Center of MR-Research, University Children's Hospital Zurich, Zurich, Switzerland
| | - Andrea M Kälin
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Sandra E Leh
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Alfred Buck
- Institute of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Geoffrey Warnock
- Institute of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Richard A E Edden
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Center for Functional Brain Imaging, Kenneddy Krieger Institute, Baltimore, MD, USA
| | - Roger Luechinger
- Institute of Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Christoph Hock
- Division of Psychiatry Research and Psychogeriatric Medicine, University of Zurich, Zurich, Switzerland
| | - Spyros Kollias
- Clinic of Neuroradiology, University Hospital Zurich, Zurich, Switzerland
| | - Lars Michels
- Clinic of Neuroradiology, University Hospital Zurich, Zurich, Switzerland.
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18
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Riese F, Gietl A, Zölch N, Henning A, O'Gorman R, Kälin AM, Leh SE, Buck A, Warnock G, Luechinger R, Hock C, Kollias S, Michels L. P3‐225: POSTERIOR CINGULATE GABA AND GLX ARE REDUCED IN AMNESTIC MILD COGNITIVE IMPAIRMENT. Alzheimers Dement 2014. [DOI: 10.1016/j.jalz.2014.05.1316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
| | | | | | | | - Ruth O'Gorman
- University Children's Hospital ZurichZurichSwitzerland
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19
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Ogourtsova T, Korner-Bitensky N, Leh SE, Eskes G, Ptito A. Superior colliculi involvement in poststroke unilateral spatial neglect: a pilot study. Top Stroke Rehabil 2012; 18:770-85. [PMID: 22436314 DOI: 10.1310/tsr1806-770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE The neural mechanisms underlying unilateral spatial neglect (USN) are unclear. The superior colliculi (SC) may be involved in USN expression, and the spatial summation effect (SSE), where reaction times to bilateral stimuli are faster than to unilateral, may be a behavioral index of SC function. We determined the feasibility of investigating SC contribution to poststroke USN using the SSE in 3 groups. METHODS Seven participants with left near-extrapersonal space USN (USN+) following right hemisphere stroke, 10 without (USN-), and 10 controls were tested under binocular/monocular (right eye patched) conditions while responding to unilateral/bilateral stimuli. Control and USN- groups completed the SSE paradigm. RESULTS Most USN+ participants were unable to initiate the SSE paradigm due to poor visual fi xation and demonstrated higher contrast sensitivity for left-sided stimuli. Controls showed an SSE (under both viewing conditions) while the USN- showed an abnormal SSE whereby reaction times to bilateral stimuli were faster than to unilateral-left but not to unilateral-right stimuli (under both binocular/monocular conditions). CONCLUSION This study is the fi rst to investigate SC contribution in poststroke USN using the SSE; we identifi ed higher contrast sensitivity to left-sided stimuli and poor fi xation in the USN+ group. These fi ndings suggest avenues for research that may lead to novel rehabilitation interventions.
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Affiliation(s)
- Tatiana Ogourtsova
- School of Physical and Occupational Therapy, McGill University, Montreal, Quebec, Canada
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20
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Leh SE, Ptito A, Schönwiesner M, Chakravarty MM, Mullen KT. Blindsight mediated by an S-cone-independent collicular pathway: an fMRI study in hemispherectomized subjects. J Cogn Neurosci 2010; 22:670-82. [PMID: 19309296 DOI: 10.1162/jocn.2009.21217] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The purpose of our study was to investigate the ability to process achromatic and short-wavelength-sensitive cone (S-cone)-isolating (blue-yellow) stimuli in the blind visual field of hemispherectomized subjects and to demonstrate that blindsight is mediated by a collicular pathway that is independent of S-cone inputs. Blindsight has been described as the ability to respond to visual stimuli in the blind visual field without conscious awareness [Weiskrantz, L., Warrington, E. K., Sanders, M. D., & Marshall, J. Visual capacity in the hemianopic field following a restricted occipital ablation. Brain, 97, 709-728, 1974]. The roles of the subcortical neural structures in blindsight, such as the pulvinar and the superior colliculus, have been debated and an underlying neural correlate has yet to be confirmed. Using fMRI, we tested the ability to process visual stimuli that isolated the achromatic and short-wavelength-sensitive (S-)-cone pathways in three subjects: one control subject, one hemispherectomized subject with blindsight, and one hemispherectomized subject without blindsight. We demonstrated that (1) achromatic and S-cone-isolating stimuli presented to the normal visual hemifield of hemispherectomized subjects and to both visual hemifields of the control subject activated contralateral visual areas (V1/V2), as expected; (2) achromatic stimulus presentation but not S-cone-isolating stimulus presentation to the blind hemifield of the subject with blindsight activated visual areas FEF/V5; (3) whereas the cortical activation of the control subject was enhanced by an additional stimulus (achromatic and S-cone isolating) presented in the contralateral visual field, activation pattern of the subject with blindsight was enhanced by achromatic stimuli only. We conclude that the human superior colliculus is blind to the S-cone-isolating stimuli, and blindsight is mediated by an S-cone-independent collicular pathway.
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21
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Abstract
In our constantly changing environment, we are frequently faced with altered circumstances requiring generation and monitoring of appropriate strategies, when novel plans of action must be formulated and conducted. The abilities that we call upon to respond accurately to novel situations are referred to as 'executive functions', and are frequently engaged to deal with conditions in which routine activation of behavior would not be sufficient for optimal performance. Here, we summarize important findings that may help us understand executive functions and their underlying neuronal correlates. We focus particularly on observations from imaging technology, such as functional magnetic resonance imaging, position emission tomography, diffusion tensor imaging, and transcranial magnetic stimulation, which in the past few years have provided the bulk of information on the neurobiological underpinnings of the executive functions. Further, emphasis will be placed on recent insights from Parkinson's disease (PD), in which the underlying dopaminergic abnormalities have provided new exciting information into basic molecular mechanisms of executive dysfunction, and which may help to disentangle the cortical/subcortical networks involved in executive processes.
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Affiliation(s)
- Sandra E Leh
- Division of Brain Imaging and Behaviour—Systems Neuroscience, Toronto Western Research Institute (TWRI), UHN, University of Toronto, Toronto, ON, Canada
| | - Michael Petrides
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Antonio P Strafella
- Division of Brain Imaging and Behaviour—Systems Neuroscience, Toronto Western Research Institute (TWRI), UHN, University of Toronto, Toronto, ON, Canada,Division of Neurology, Toronto Western Hospital, UHN, University of Toronto, Toronto, ON, Canada,PET Imaging Centre, Centre for Addiction and Mental Health (CAMH), University of Toronto, Toronto, ON, Canada,Division of Neurology, CAMH-PET imaging center, Toronto Western Hospital/Research Institute, University of Toronto, Toronto, ON, Canada M5T2S8. Tel: +416 603 5706, Fax: +416 603 5004, E-mail: or
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22
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23
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Leh SE, Ptito A, Chakravarty MM, Strafella AP. Fronto-striatal connections in the human brain: a probabilistic diffusion tractography study. Neurosci Lett 2007; 419:113-8. [PMID: 17485168 PMCID: PMC5114128 DOI: 10.1016/j.neulet.2007.04.049] [Citation(s) in RCA: 271] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 04/02/2007] [Accepted: 04/12/2007] [Indexed: 01/11/2023]
Abstract
Anatomical studies in animals have described multiple striatal circuits and suggested that sub-components of the striatum, although functionally related, project to distinct cortical areas. To date, anatomical investigations in humans have been limited by methodological constraints such that most of our knowledge of fronto-striatal networks relies on nonhuman primate studies. To better identify the fronto-striatal pathways in the human brain, we used Diffusion Tensor Imaging (DTI) tractography to reconstruct neural connections between the frontal cortex and the caudate nucleus and putamen in vivo. We demonstrate that the human caudate nucleus is interconnected with the prefrontal cortex, inferior and middle temporal gyrus, frontal eye fields, cerebellum and thalamus; the putamen is interconnected with the prefrontal cortex, primary motor area, primary somatosensory cortex, supplementary motor area, premotor area, cerebellum and thalamus. A connectivity-based seed classification analysis identified connections between the dorsolateral prefrontal areas (DLPFC) and the dorsal-posterior caudate nucleus and between the ventrolateral prefrontal areas (VLPFC) and the ventral-anterior caudate nucleus. For the putamen, connections exist between the supplementary motor area (SMA) and dorsal-posterior putamen while the premotor area projects to medial putamen, and the primary motor area to the lateral putamen. Identifying the anatomical organization of the fronto-striatal network has important implications for understanding basal ganglia function and associated disease processes.
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Affiliation(s)
- Sandra E Leh
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Qc., Canada.
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24
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Abstract
Destruction of the occipital cortex presumably leads to permanent blindness in the contralateral visual field. Residual abilities to respond to visual stimuli in the blind field without consciously experiencing them have, however, been described in cortically blind patients and are termed 'blindsight'. Although the neuronal basis of blindsight remains unknown, possible neuronal correlates have been proposed based on the nature of the residual vision observed. The most prominent but still controversial hypothesis postulates the involvement of the superior colliculi in blindsight. Here we demonstrate, using a computer-based reaction time test in a group of hemispherectomized subjects, that human 'attention-blindsight' can be measured for achromatic stimuli but disappears for stimuli that solely activate S-cones. Given that primate data have shown that the superior colliculi lacks input from S-cones, our results lend strong support to the hypothesis that 'attention-blindsight' is mediated through a collicular pathway. The contribution of a direct geniculo-extrastriate-koniocellular projection was ruled out by testing hemispherectomized subjects in whom a whole hemisphere has been removed or disconnected for the treatment of epilepsy. A direct retino-pulvinar-cortical connection is also unlikely as the pulvinar nucleus is known to receive input from S-cones as well as from L/M-cone-driven colour-opponent ganglion cells.
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Affiliation(s)
- Sandra E Leh
- Neuropsychology/Cognitive Neuroscience Unit, Montreal Neurological Institute, 3801 University Street, Montreal, Quebec, Canada H3A 2B4.
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25
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Abstract
The existence of several types of unconscious vision, or 'blindsight', has convincingly been demonstrated in numerous studies, and their neuronal correlates have been hypothesized according to the nature of the residual vision observed. We used diffusion tensor imaging (DTI) tractography to demonstrate an association between the presence of 'Type I'- blindsight or 'attention blindsight' and reconstructed superior colliculi (SC) fibre tracts in hemispherectomized subjects, in support of the hypothesis that this subcortical structure plays a pivotal role in this type of blindsight. Before the DTI study, 'Type I' blindsight was identified in two of four hemispherectomized subjects by using a spatial summation effect paradigm, an indirect behavioural method, in which subjects were unaware of a stimulus presented in their blind visual field and were required to respond to an identical stimulus presented simultaneously in their intact field. SC tracts were then reconstructed in six control subjects, the two hemispherectomized subjects with blindsight and the two hemispherectomized subjects without blindsight. Whereas control subjects demonstrated mainly ipsilateral connections to visual association areas, parietal cortex, prefrontal areas and to an area close to the frontal eye fields, hemispherectomized subjects with blindsight showed ipsi- and contralateral connections from the SC to visual association areas, primary visual areas, parietal areas, prefrontal areas and to the posterior part of the internal capsule. In contrast, no projections from the SC on the hemispherectomized side were observed in hemispherectomized subjects without blindsight, in support of a key role of this structure in 'Type-I' or 'attention blindsight'.
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Affiliation(s)
- Sandra E Leh
- Cognitive Neuroscience Unit, Montreal Neurological Institute and Hospital, McGill University Montreal, Canada
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