1
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Burd SG, Lebedeva AV, Rubleva YV, Pantina NV, Efimenko AP, Kovaleva II. [EEG changes in patients with Alzheimer's disease]. Zh Nevrol Psikhiatr Im S S Korsakova 2024; 124:72-76. [PMID: 38696154 DOI: 10.17116/jnevro202412404272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2024]
Abstract
The prevalence of cognitive impairment is steadily increasing compared to previous years. According to the World Health Organization, the number of people living with dementia will increase reaching 82 million in 2030 and 152 million in 2050. The most common cause is Alzheimer's disease (AD). The pathophysiological process in AD begins several years before the onset of clinical symptoms; so identifying it at an early stage would likely improve the clinical prognosis. The article presents EEG changes in patients with AD, and discusses the possibility of using EEG as a screening method for examining patients with cognitive impairment.
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Affiliation(s)
- S G Burd
- Federal Center of Brain Research and Neurotechnologies, Moscow, Russia
- Pirogov Russian National Research Medical University, Moscow, Russia
- Scientific and Practical Center for Child Psychoneurology, Moscow, Russia
| | - A V Lebedeva
- Federal Center of Brain Research and Neurotechnologies, Moscow, Russia
- Pirogov Russian National Research Medical University, Moscow, Russia
| | - Yu V Rubleva
- Federal Center of Brain Research and Neurotechnologies, Moscow, Russia
| | - N V Pantina
- Federal Center of Brain Research and Neurotechnologies, Moscow, Russia
| | - A P Efimenko
- Federal Center of Brain Research and Neurotechnologies, Moscow, Russia
| | - I I Kovaleva
- Federal Center of Brain Research and Neurotechnologies, Moscow, Russia
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2
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Decreased coherence in the model of the dorsal visual pathway associated with Alzheimer's disease. Sci Rep 2023; 13:3495. [PMID: 36859462 PMCID: PMC9977922 DOI: 10.1038/s41598-023-30535-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 02/24/2023] [Indexed: 03/03/2023] Open
Abstract
Decreased coherence in electroencephalogram (EEG) has been reported in Alzheimer's disease (AD) experimentally, which could be considered as a typical electrophysiological characteristic in AD. This work aimed to investigate the effect of AD on coherence in the dorsal visual pathway by the technique of neurocomputation. Firstly, according to the hierarchical organization of the cerebral cortex and the information flows of the dorsal visual pathway, a more physiologically plausible neural mass model including cortical areas v1, v2, and v5 was established in the dorsal visual pathway. The three interconnected cortical areas were connected by ascending and descending projections. Next, the pathological condition of loss of long synaptic projections in AD was simulated by reducing the parameters of long synaptic projections in the model. Then, the loss of long synaptic projections on coherence among different visual cortex areas was explored by means of power spectral analysis and coherence function. The results demonstrate that the coherence between these interconnected cortical areas showed an obvious decline with the gradual decrease of long synaptic projections, i.e. decrease in descending projections from area v2 to v1 and v5 to v2 and ascending projection from area v2 to v5. Hopefully, the results of this study could provide theoretical guidance for understanding the dynamical mechanism of AD.
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3
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Fischer MHF, Zibrandtsen IC, Høgh P, Musaeus CS. Systematic Review of EEG Coherence in Alzheimer's Disease. J Alzheimers Dis 2023; 91:1261-1272. [PMID: 36641665 DOI: 10.3233/jad-220508] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND Magnitude-squared coherence (MSCOH) is an electroencephalography (EEG) measure of functional connectivity. MSCOH has been widely applied to investigate pathological changes in patients with Alzheimer's disease (AD). However, significant heterogeneity exists between the studies using MSOCH. OBJECTIVE We systematically reviewed the literature on MSCOH changes in AD as compared to healthy controls to investigate the clinical utility of MSCOH as a marker of AD. METHODS We searched PubMed, Embase, and Scopus to identify studies reporting EEG MSCOH used in patients with AD. The identified studies were independently screened by two researchers and the data was extracted, which included cognitive scores, preprocessing steps, and changes in MSCOH across frequency bands. RESULTS A total of 35 studies investigating changes in MSCOH in patients with AD were included in the review. Alpha coherence was significantly decreased in patients with AD in 24 out of 34 studies. Differences in other frequency bands were less consistent. Some studies showed that MSCOH may serve as a diagnostic marker of AD. CONCLUSION Reduced alpha MSCOH is present in patients with AD and MSCOH may serve as a diagnostic marker. However, studies validating MSCOH as a diagnostic marker are needed.
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Affiliation(s)
| | | | - Peter Høgh
- Department of Neurology, University Hospital of Zealand, Roskilde, Denmark.,Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Christian Sandøe Musaeus
- Department of Neurology, Danish Dementia Research Centre (DDRC), Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
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4
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Monllor P, Cervera-Ferri A, Lloret MA, Esteve D, Lopez B, Leon JL, Lloret A. Electroencephalography as a Non-Invasive Biomarker of Alzheimer's Disease: A Forgotten Candidate to Substitute CSF Molecules? Int J Mol Sci 2021; 22:10889. [PMID: 34639229 PMCID: PMC8509134 DOI: 10.3390/ijms221910889] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 09/26/2021] [Accepted: 10/05/2021] [Indexed: 12/12/2022] Open
Abstract
Biomarkers for disease diagnosis and prognosis are crucial in clinical practice. They should be objective and quantifiable and respond to specific therapeutic interventions. Optimal biomarkers should reflect the underlying process (pathological or not), be reproducible, widely available, and allow measurements repeatedly over time. Ideally, biomarkers should also be non-invasive and cost-effective. This review aims to focus on the usefulness and limitations of electroencephalography (EEG) in the search for Alzheimer's disease (AD) biomarkers. The main aim of this article is to review the evolution of the most used biomarkers in AD and the need for new peripheral and, ideally, non-invasive biomarkers. The characteristics of the EEG as a possible source for biomarkers will be revised, highlighting its advantages compared to the molecular markers available so far.
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Affiliation(s)
- Paloma Monllor
- CIBERFES, Department of Physiology, Institute INCLIVA, Faculty of Medicine, Health Research University of Valencia, Avda. Blasco Ibanez 17, 46010 Valencia, Spain; (P.M.); (D.E.)
| | - Ana Cervera-Ferri
- Department of Human Anatomy and Embryology, Faculty of Medicine, University of Valencia, 46010 Valencia, Spain;
| | - Maria-Angeles Lloret
- Department of Clinical Neurophysiology, University Clinic Hospital of Valencia, Avda. Blasco Ibanez, 19, 46010 Valencia, Spain;
| | - Daniel Esteve
- CIBERFES, Department of Physiology, Institute INCLIVA, Faculty of Medicine, Health Research University of Valencia, Avda. Blasco Ibanez 17, 46010 Valencia, Spain; (P.M.); (D.E.)
| | - Begoña Lopez
- Department of Neurology, University Clinic Hospital of Valencia, Avda. Blasco Ibanez, 19, 46010 Valencia, Spain;
| | - Jose-Luis Leon
- Ascires Biomedical Group, Department of Neuroradiology, Hospital Clinico Universitario, 46010 Valencia, Spain;
| | - Ana Lloret
- CIBERFES, Department of Physiology, Institute INCLIVA, Faculty of Medicine, Health Research University of Valencia, Avda. Blasco Ibanez 17, 46010 Valencia, Spain; (P.M.); (D.E.)
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5
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Laptinskaya D, Fissler P, Küster OC, Wischniowski J, Thurm F, Elbert T, von Arnim CAF, Kolassa IT. Global EEG coherence as a marker for cognition in older adults at risk for dementia. Psychophysiology 2019; 57:e13515. [PMID: 31840287 DOI: 10.1111/psyp.13515] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 11/18/2019] [Accepted: 11/18/2019] [Indexed: 11/30/2022]
Abstract
Quantitative electroencephalography (EEG) provides useful information about neurophysiological health of the aging brain. Current studies investigating EEG coherence and power for specific brain areas and frequency bands have yielded inconsistent results. This study assessed EEG coherence and power indices at rest measured over the whole skull and for a wide frequency range as global EEG markers for cognition in a sample at risk for dementia. Since global markers are more reliable and less error-prone than region- and frequency-specific indices they might help to overcome previous inconsistencies. Global EEG coherence (1-30 Hz) and an EEG slowing score were assessed. The EEG slowing score was calculated by low-frequency power (1-8 Hz) divided by high-frequency power (9-30 Hz). In addition, the prognostic value of the two EEG indices for cognition and cognitive decline was assessed in a 5-year follow-up pilot study. Baseline global coherence correlated positively with cognition at baseline, but not with cognitive decline or with cognition at the 5-year follow-up. The EEG slowing ratio showed no significant association, neither with cognition at baseline or follow-up, nor with cognitive decline over a period of 5 years. The results indicate that the resting state global EEG coherence might be a useful and easy to assess electrophysiological correlate for neurocognitive health in older adults at risk for dementia. Because of the small statistical power for the follow-up analyses, the prognostic value of global coherence could not be determined in the present study. Future studies should assess its prognostic value with larger sample sizes.
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Affiliation(s)
- Daria Laptinskaya
- Clinical and Biological Psychology, Institute of Psychology and Education, Ulm University, Ulm, Germany.,Department of Psychology, University of Konstanz, Konstanz, Germany
| | - Patrick Fissler
- Clinical and Biological Psychology, Institute of Psychology and Education, Ulm University, Ulm, Germany.,Department of Neurology, Ulm University, Ulm, Germany
| | - Olivia Caroline Küster
- Department of Neurology, Ulm University, Ulm, Germany.,Department of Geriatrics, University Medical Center Göttingen, Göttingen, Germany
| | - Jakob Wischniowski
- Clinical and Biological Psychology, Institute of Psychology and Education, Ulm University, Ulm, Germany
| | - Franka Thurm
- Department of Psychology, University of Konstanz, Konstanz, Germany.,Faculty of Psychology, TU Dresden, Dresden, Germany
| | - Thomas Elbert
- Department of Psychology, University of Konstanz, Konstanz, Germany
| | - Christine A F von Arnim
- Department of Neurology, Ulm University, Ulm, Germany.,Department of Geriatrics, University Medical Center Göttingen, Göttingen, Germany
| | - Iris-Tatjana Kolassa
- Clinical and Biological Psychology, Institute of Psychology and Education, Ulm University, Ulm, Germany.,Department of Psychology, University of Konstanz, Konstanz, Germany
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6
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Wu Z, Xu D, Potter T, Zhang Y. Effects of Brain Parcellation on the Characterization of Topological Deterioration in Alzheimer's Disease. Front Aging Neurosci 2019; 11:113. [PMID: 31164815 PMCID: PMC6536693 DOI: 10.3389/fnagi.2019.00113] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 04/30/2019] [Indexed: 12/11/2022] Open
Abstract
Alzheimer's disease (AD) causes the progressive deterioration of neural connections, disrupting structural connectivity (SC) networks within the brain. Graph-based analyses of SC networks have shown that topological properties can reveal the course of AD propagation. Different whole-brain parcellation schemes have been developed to define the nodes of these SC networks, although it remains unclear which scheme can best describe the AD-related deterioration of SC networks. In this study, four whole-brain parcellation schemes with different numbers of parcels were used to define SC network nodes. SC networks were constructed based on high angular resolution diffusion imaging (HARDI) tractography for a mixed cohort that includes 20 normal controls (NC), 20 early mild cognitive impairment (EMCI), 20 late mild cognitive impairment (LMCI), and 20 AD patients, from the Alzheimer's Disease Neuroimaging Initiative. Parcellation schemes investigated in this study include the OASIS-TRT-20 (62 regions), AAL (116 regions), HCP-MMP (180 regions), and Gordon-rsfMRI (333 regions), which have all been widely used for the construction of brain structural or functional connectivity networks. Topological characteristics of the SC networks, including the network strength, global efficiency, clustering coefficient, rich-club, characteristic path length, k-core, rich-club coefficient, and modularity, were fully investigated at the network level. Statistical analyses were performed on these metrics using Kruskal-Wallis tests to examine the group differences that were apparent at different stages of AD progression. Results suggest that the HCP-MMP scheme is the most robust and sensitive to AD progression, while the OASIS-TRT-20 scheme is sensitive to group differences in network strength, global efficiency, k-core, and rich-club coefficient at k-levels from 18 and 39. With the exception of the rich-club and modularity coefficients, AAL could not significantly identify group differences on other topological metrics. Further, the Gordon-rsfMRI atlas only significantly differentiates the groups on network strength, characteristic path length, k-core, and rich-club coefficient. Results show that the topological examination of SC networks with different parcellation schemes can provide important complementary AD-related information and thus contribute to a more accurate and earlier diagnosis of AD.
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Affiliation(s)
- Zhanxiong Wu
- School of Electronic Information, Hangzhou Dianzi University, Hangzhou, China.,Department of Biomedical Engineering, University of Houston, Houston, TX, United States
| | - Dong Xu
- School of Electronic Information, Hangzhou Dianzi University, Hangzhou, China.,Zhejiang Key Laboratory of Equipment Electronics, Hangzhou, China
| | - Thomas Potter
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
| | - Yingchun Zhang
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
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7
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Song Z, Deng B, Wang J, Wang R. Biomarkers for Alzheimer's Disease Defined by a Novel Brain Functional Network Measure. IEEE Trans Biomed Eng 2019; 66:41-49. [DOI: 10.1109/tbme.2018.2834546] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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8
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Bazzigaluppi P, Beckett TL, Koletar MM, Lai AY, Joo IL, Brown ME, Carlen PL, McLaurin J, Stefanovic B. Early-stage attenuation of phase-amplitude coupling in the hippocampus and medial prefrontal cortex in a transgenic rat model of Alzheimer's disease. J Neurochem 2017; 144:669-679. [PMID: 28777881 DOI: 10.1111/jnc.14136] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 06/27/2017] [Accepted: 07/26/2017] [Indexed: 01/21/2023]
Abstract
Alzheimer's disease (AD) is pathologically characterized by amyloid-β peptide (Aβ) accumulation, neurofibrillary tangle formation, and neurodegeneration. Preclinical studies on neuronal impairments associated with progressive amyloidosis have demonstrated some Aβ-dependent neuronal dysfunction including modulation of gamma-aminobutyric acid-ergic signaling. The present work focuses on the early stage of disease progression and uses TgF344-AD rats that recapitulate a broad repertoire of AD-like pathologies to investigate the neuronal network functioning using simultaneous intracranial recordings from the hippocampus (HPC) and the medial prefrontal cortex (mPFC), followed by pathological analyses of gamma-aminobutyric acid (GABAA ) receptor subunits α1, α5, and δ, and glutamic acid decarboxylases (GAD65 and GAD67). Concomitant to amyloid deposition and tau hyperphosphorylation, low-gamma band power was strongly attenuated in the HPC and mPFC of TgF344-AD rats in comparison to those in non-transgenic littermates. In addition, the phase-amplitude coupling of the neuronal networks in both areas was impaired, evidenced by decreased modulation of theta band phase on gamma band amplitude in TgF344-AD animals. Finally, the gamma coherence between HPC and mPFC was attenuated as well. These results demonstrate significant neuronal network dysfunction at an early stage of AD-like pathology. This network dysfunction precedes the onset of cognitive deficits and is likely driven by Aβ and tau pathologies. This article is part of the Special Issue "Vascular Dementia".
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Affiliation(s)
- Paolo Bazzigaluppi
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.,Fundamental Neurobiology, Krembil Research Institute, Toronto, Ontario, Canada
| | - Tina L Beckett
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Margaret M Koletar
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Aaron Y Lai
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Illsung L Joo
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Mary E Brown
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Peter L Carlen
- Fundamental Neurobiology, Krembil Research Institute, Toronto, Ontario, Canada
| | - JoAnne McLaurin
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.,Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Bojana Stefanovic
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Ontario, Canada
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9
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Giovanni A, Capone F, di Biase L, Ferreri F, Florio L, Guerra A, Marano M, Paolucci M, Ranieri F, Salomone G, Tombini M, Thut G, Di Lazzaro V. Oscillatory Activities in Neurological Disorders of Elderly: Biomarkers to Target for Neuromodulation. Front Aging Neurosci 2017; 9:189. [PMID: 28659788 PMCID: PMC5468377 DOI: 10.3389/fnagi.2017.00189] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 05/26/2017] [Indexed: 12/13/2022] Open
Abstract
Non-invasive brain stimulation (NIBS) has been under investigation as adjunct treatment of various neurological disorders with variable success. One challenge is the limited knowledge on what would be effective neuronal targets for an intervention, combined with limited knowledge on the neuronal mechanisms of NIBS. Motivated on the one hand by recent evidence that oscillatory activities in neural systems play a role in orchestrating brain functions and dysfunctions, in particular those of neurological disorders specific of elderly patients, and on the other hand that NIBS techniques may be used to interact with these brain oscillations in a controlled way, we here explore the potential of modulating brain oscillations as an effective strategy for clinical NIBS interventions. We first review the evidence for abnormal oscillatory profiles to be associated with a range of neurological disorders of elderly (e.g., Parkinson's disease (PD), Alzheimer's disease (AD), stroke, epilepsy), and for these signals of abnormal network activity to normalize with treatment, and/or to be predictive of disease progression or recovery. We then ask the question to what extent existing NIBS protocols have been tailored to interact with these oscillations and possibly associated dysfunctions. Our review shows that, despite evidence for both reliable neurophysiological markers of specific oscillatory dis-functionalities in neurological disorders and NIBS protocols potentially able to interact with them, there are few applications of NIBS aiming to explore clinical outcomes of this interaction. Our review article aims to point out oscillatory markers of neurological, which are also suitable targets for modification by NIBS, in order to facilitate in future studies the matching of technical application to clinical targets.
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Affiliation(s)
- Assenza Giovanni
- Clinical Neurology, Campus Biomedico University of RomeRome, Italy
| | | | - Lazzaro di Biase
- Clinical Neurology, Campus Biomedico University of RomeRome, Italy
- Nuffield Department of Clinical Neurosciences, University of OxfordOxford, United Kingdom
| | - Florinda Ferreri
- Clinical Neurology, Campus Biomedico University of RomeRome, Italy
- Department of Clinical Neurophysiology, Kuopio University Hospital, University of Eastern FinlandKuopio, Finland
| | - Lucia Florio
- Clinical Neurology, Campus Biomedico University of RomeRome, Italy
| | - Andrea Guerra
- Clinical Neurology, Campus Biomedico University of RomeRome, Italy
- Nuffield Department of Clinical Neurosciences, University of OxfordOxford, United Kingdom
| | - Massimo Marano
- Clinical Neurology, Campus Biomedico University of RomeRome, Italy
| | - Matteo Paolucci
- Clinical Neurology, Campus Biomedico University of RomeRome, Italy
| | - Federico Ranieri
- Clinical Neurology, Campus Biomedico University of RomeRome, Italy
| | - Gaetano Salomone
- Clinical Neurology, Campus Biomedico University of RomeRome, Italy
| | - Mario Tombini
- Clinical Neurology, Campus Biomedico University of RomeRome, Italy
| | - Gregor Thut
- Centre for Cognitive Neuroimaging (CCNi), Institute of Neuroscience and Psychology, University of GlasgowGlasgow, United Kingdom
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10
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Joo IL, Lai AY, Bazzigaluppi P, Koletar MM, Dorr A, Brown ME, Thomason LAM, Sled JG, McLaurin J, Stefanovic B. Early neurovascular dysfunction in a transgenic rat model of Alzheimer's disease. Sci Rep 2017; 7:46427. [PMID: 28401931 PMCID: PMC5388880 DOI: 10.1038/srep46427] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 03/20/2017] [Indexed: 01/06/2023] Open
Abstract
Alzheimer's disease (AD), pathologically characterized by amyloid-β peptide (Aβ) accumulation, neurofibrillary tangle formation, and neurodegeneration, is thought to involve early-onset neurovascular abnormalities. Hitherto studies on AD-associated neurovascular injury have used animal models that exhibit only a subset of AD-like pathologies and demonstrated some Aβ-dependent vascular dysfunction and destabilization of neuronal network. The present work focuses on the early stage of disease progression and uses TgF344-AD rats that recapitulate a broader repertoire of AD-like pathologies to investigate the cerebrovascular and neuronal network functioning using in situ two-photon fluorescence microscopy and laminar array recordings of local field potentials, followed by pathological analyses of vascular wall morphology, tau hyperphosphorylation, and amyloid plaques. Concomitant to widespread amyloid deposition and tau hyperphosphorylation, cerebrovascular reactivity was strongly attenuated in cortical penetrating arterioles and venules of TgF344-AD rats in comparison to those in non-transgenic littermates. Blood flow elevation to hypercapnia was abolished in TgF344-AD rats. Concomitantly, the phase-amplitude coupling of the neuronal network was impaired, evidenced by decreased modulation of theta band phase on gamma band amplitude. These results demonstrate significant neurovascular network dysfunction at an early stage of AD-like pathology. Our study identifies early markers of pathology progression and call for development of combinatorial treatment plans.
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Affiliation(s)
- Illsung L. Joo
- Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, Ontario, M5G 2M9, Canada
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
| | - Aaron Y. Lai
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
| | - Paolo Bazzigaluppi
- Fundamental Neurobiology, Krembil Research Institute, University Health Network, 60 Leonard Avenue, Toronto, Ontario, M5T 2R1, Canada
| | - Margaret M. Koletar
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
| | - Adrienne Dorr
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
| | - Mary E. Brown
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
| | - Lynsie A. M. Thomason
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
| | - John G. Sled
- Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, Ontario, M5G 2M9, Canada
- Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8, Canada
| | - JoAnne McLaurin
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, 1 King’s College Circle, Toronto, Ontario, M5S 1A1, Canada
| | - Bojana Stefanovic
- Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, Ontario, M5G 2M9, Canada
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
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11
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Barzegaran E, van Damme B, Meuli R, Knyazeva MG. Perception-related EEG is more sensitive to Alzheimer's disease effects than resting EEG. Neurobiol Aging 2016; 43:129-39. [DOI: 10.1016/j.neurobiolaging.2016.03.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 03/28/2016] [Accepted: 03/30/2016] [Indexed: 01/06/2023]
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12
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Babiloni C, Lizio R, Marzano N, Capotosto P, Soricelli A, Triggiani AI, Cordone S, Gesualdo L, Del Percio C. Brain neural synchronization and functional coupling in Alzheimer's disease as revealed by resting state EEG rhythms. Int J Psychophysiol 2016; 103:88-102. [PMID: 25660305 DOI: 10.1016/j.ijpsycho.2015.02.008] [Citation(s) in RCA: 201] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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13
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Waser M, Garn H, Schmidt R, Benke T, Dal-Bianco P, Ransmayr G, Schmidt H, Seiler S, Sanin G, Mayer F, Caravias G, Grossegger D, Frühwirt W, Deistler M. Quantifying synchrony patterns in the EEG of Alzheimer's patients with linear and non-linear connectivity markers. J Neural Transm (Vienna) 2016; 123:297-316. [PMID: 26411482 PMCID: PMC4766239 DOI: 10.1007/s00702-015-1461-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 09/11/2015] [Indexed: 11/25/2022]
Abstract
We analyzed the relation of several synchrony markers in the electroencephalogram (EEG) and Alzheimer's disease (AD) severity as measured by Mini-Mental State Examination (MMSE) scores. The study sample consisted of 79 subjects diagnosed with probable AD. All subjects were participants in the PRODEM-Austria study. Following a homogeneous protocol, the EEG was recorded both in resting state and during a cognitive task. We employed quadratic least squares regression to describe the relation between MMSE and the EEG markers. Factor analysis was used for estimating a potentially lower number of unobserved synchrony factors. These common factors were then related to MMSE scores as well. Most markers displayed an initial increase of EEG synchrony with MMSE scores from 26 to 21 or 20, and a decrease below. This effect was most prominent during the cognitive task and may be owed to cerebral compensatory mechanisms. Factor analysis provided interesting insights in the synchrony structures and the first common factors were related to MMSE scores with coefficients of determination up to 0.433. We conclude that several of the proposed EEG markers are related to AD severity for the overall sample with a wide dispersion for individual subjects. Part of these fluctuations may be owed to fluctuations and day-to-day variability associated with MMSE measurements. Our study provides a systematic analysis of EEG synchrony based on a large and homogeneous sample. The results indicate that the individual markers capture different aspects of EEG synchrony and may reflect cerebral compensatory mechanisms in the early stages of AD.
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Affiliation(s)
- Markus Waser
- AIT Austrian Institute of Technology GmbH, Vienna, Austria.
| | - Heinrich Garn
- AIT Austrian Institute of Technology GmbH, Vienna, Austria
| | - Reinhold Schmidt
- Department of Neurology, Clinical Section of Neurogeriatrics, Graz Medical University, Graz, Austria
| | - Thomas Benke
- Department of Neurology, Innsbruck Medical University, Innsbruck, Austria
| | - Peter Dal-Bianco
- Department of Neurology, Vienna Medical University, Vienna, Austria
| | - Gerhard Ransmayr
- Department of Neurology and Psychiatry, Linz General Hospital, Linz, Austria
| | - Helena Schmidt
- Institute of Molecular Biology and Biochemistry, Graz Medical University, Graz, Austria
| | - Stephan Seiler
- Department of Neurology, Clinical Section of Neurogeriatrics, Graz Medical University, Graz, Austria
| | - Günter Sanin
- Department of Neurology, Innsbruck Medical University, Innsbruck, Austria
| | - Florian Mayer
- Department of Neurology, Vienna Medical University, Vienna, Austria
| | - Georg Caravias
- Department of Neurology and Psychiatry, Linz General Hospital, Linz, Austria
| | | | | | - Manfred Deistler
- Institute for Mathematical Methods in Economics, Vienna University of Technology, Vienna, Austria
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Neuronal Network Oscillations in Neurodegenerative Diseases. Neuromolecular Med 2015; 17:270-84. [PMID: 25920466 DOI: 10.1007/s12017-015-8355-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Accepted: 04/16/2015] [Indexed: 10/23/2022]
Abstract
Cognitive and behavioral acts go along with highly coordinated spatiotemporal activity patterns in neuronal networks. Most of these patterns are synchronized by coherent membrane potential oscillations within and between local networks. By entraining multiple neurons into a common time regime, such network oscillations form a critical interface between cellular activity and large-scale systemic functions. Synaptic integrity is altered in neurodegenerative diseases, and it is likely that this goes along with characteristic changes of coordinated network activity. This notion is supported by EEG recordings from human patients and from different animal models of such disorders. However, our knowledge about the pathophysiology of network oscillations in neurodegenerative diseases is surprisingly incomplete, and increased research efforts are urgently needed. One complicating factor is the pronounced diversity of network oscillations between different brain regions and functional states. Pathological changes must, therefore, be analyzed separately in each condition and affected area. However, cumulative evidence from different diseases may result, in the future, in more unifying "oscillopathy" concepts of neurodegenerative diseases. In this review, we report present evidence for pathological changes of network oscillations in Alzheimer's disease (AD), one of the most prominent and challenging neurodegenerative disorders. The heterogeneous findings from AD are contrasted to Parkinson's disease, where motor-related changes in specific frequency bands do already fulfill criteria of a valid biomarker.
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Impaired cortical oscillatory coupling in mild cognitive impairment: anatomical substrate and ApoE4 effects. Brain Struct Funct 2014; 220:1721-37. [PMID: 24682246 DOI: 10.1007/s00429-014-0757-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 03/16/2014] [Indexed: 01/04/2023]
Abstract
Our current knowledge about the anatomical substrate of impaired resting-state cortical oscillatory coupling in mild cognitive impairment is still rudimentary. Here, we show that both resting-state oscillatory coupling and its anatomical correlates clearly distinguish healthy older (HO) adults from individuals with amnestic mild cognitive impairment (aMCI). aMCI showed failures in neural-phase coupling of resting-state electroencephalographic alpha activity mostly evident between fronto-temporal and parietal regions. As oligomers of amyloid-beta (Aβ) are linked to synaptic dysfunction in Alzheimer's disease (AD), we further investigated whether plasma concentrations of these oligomers (Aβ40 and Aβ42) accounted for impaired patterns of oscillatory coupling in aMCI. Results revealed that decreased plasma Aβ42 was associated with augmented coupling of parieto-temporal regions in HO subjects, but no relationship was found in aMCI. Oscillatory coupling of frontal regions was also significantly reduced in aMCI carriers of the ε4 allele of the Apolipoprotein E (ApoE) compared to ε4 noncarriers, although neither neuroanatomical nor plasma Aβ changes accounted for this difference. However, the abnormal pattern of oscillatory coupling in aMCI was negatively related to volume of the angular gyrus, and positively related to volume of the precuneus and the splenium of the corpus callosum. Previous evidence suggests that all these regions are neuropathological targets of AD. The current study takes that scenario one step further, suggesting that this anatomical damage could be responsible for disrupted cortical oscillatory coupling in aMCI. Together, these data shed light on how the MCI status modifies anatomo-functional relationships underlying coordination of large-scale cortical systems in the resting-state.
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Babiloni C, Vecchio F, Altavilla R, Tibuzzi F, Lizio R, Altamura C, Palazzo P, Maggio P, Ursini F, Ercolani M, Soricelli A, Noce G, Rossini PM, Vernieri F. Hypercapnia affects the functional coupling of resting state electroencephalographic rhythms and cerebral haemodynamics in healthy elderly subjects and in patients with amnestic mild cognitive impairment. Clin Neurophysiol 2013; 125:685-693. [PMID: 24238990 DOI: 10.1016/j.clinph.2013.10.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 10/03/2013] [Accepted: 10/03/2013] [Indexed: 10/26/2022]
Abstract
OBJECTIVE Cerebral vasomotor reactivity (VMR) and coherence of resting state electroencephalographic (EEG) rhythms are impaired in Alzheimer's disease (AD) patients. Here we tested the hypothesis that these two variables could be related. METHODS We investigated VMR and coherence of resting state EEG rhythms in nine normal elderly (Nold) and in 10 amnesic mild cognitive impairment (MCI) subjects. Resting state eyes-closed EEG data were recorded at baseline pre-CO₂ (ambient air, 2 min), during 7% CO₂/air mixture inhalation (hypercapnia, 90 s) and post-CO₂ (ambient air, 2 min) conditions. Simultaneous frontal bilateral near-infrared spectroscopy (NIRS) was performed to assess VMR by cortical oxy- and deoxy-haemoglobin concentration changes. EEG coherence across all electrodes was computed at delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), beta 2 (20-30 Hz) and gamma (30-40 Hz) bands. RESULTS In Nold subjects, 'total coherence' of EEG across all frequency bands and electrode pairs decreased during hypercapnia, with full recovery during post-CO₂. Total coherence resulted lower in pre-CO₂ and post-CO₂ and presented poor reactivity during CO₂ inhalation in MCI patients compared with Nold subjects. Hypercapnia increased oxy-haemoglobin and decreased deoxy-haemoglobin concentrations in both groups. Furthermore, the extent of changes in these variables during CO₂ challenge was correlated with the EEG coherence, as a reflection of neurovascular coupling. CONCLUSIONS Hypercapnia induced normal frontal VMR that was detected by NIRS in both Nold and amnesic MCI groups, while it produced a reactivity of global functional coupling of resting state EEG rhythms only in the Nold group. SIGNIFICANCE In amnesic MCI patients, global EEG functional coupling is basically low in amplitude and does not react to hypercapnia.
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Affiliation(s)
- Claudio Babiloni
- Department of Physiology and Pharmacology, University of Rome "La Sapienza", Rome, Italy; IRCCS San Raffaele Pisana, Rome, Italy.
| | - Fabrizio Vecchio
- IRCCS San Raffaele Pisana, Rome, Italy; A.Fa.R. Dip. Neurosci, Ospedale 'San Giovanni Calibita' Fatebenefratelli, Isola Tiberina, Rome, Italy
| | | | - Francesco Tibuzzi
- A.Fa.R. Dip. Neurosci, Ospedale 'San Giovanni Calibita' Fatebenefratelli, Isola Tiberina, Rome, Italy
| | | | - Claudia Altamura
- Unità di Neurologia, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Paola Palazzo
- Unità di Neurologia, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Paola Maggio
- Unità di Neurologia, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Francesca Ursini
- Unità di Neurologia, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Matilde Ercolani
- A.Fa.R. Dip. Neurosci, Ospedale 'San Giovanni Calibita' Fatebenefratelli, Isola Tiberina, Rome, Italy
| | - Andrea Soricelli
- IRCCS SDN, Napoli, Italy; Department of Studies of Institutions and Territorial Systems, University of Naples Parthenope, Naples, Italy
| | | | - Paolo Maria Rossini
- IRCCS San Raffaele Pisana, Rome, Italy; Department of Geriatrics, Neuroscience & Orthopedics, Institute of Neurology Catholic University "Sacro Cuore", Rome, Italy
| | - Fabrizio Vernieri
- Unità di Neurologia, Università Campus Bio-Medico di Roma, Rome, Italy
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Chen G, Zhang HY, Xie C, Chen G, Zhang ZJ, Teng GJ, Li SJ. Modular reorganization of brain resting state networks and its independent validation in Alzheimer's disease patients. Front Hum Neurosci 2013; 7:456. [PMID: 23950743 PMCID: PMC3739061 DOI: 10.3389/fnhum.2013.00456] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 07/22/2013] [Indexed: 12/05/2022] Open
Abstract
Previous studies have demonstrated disruption in structural and functional connectivity occurring in the Alzheimer's Disease (AD). However, it is not known how these disruptions alter brain network reorganization. With the modular analysis method of graph theory, and datasets acquired by the resting-state functional connectivity MRI (R-fMRI) method, we investigated and compared the brain organization patterns between the AD group and the cognitively normal control (CN) group. Our main finding is that the largest homotopic module (defined as the insula module) in the CN group was broken down to the pieces in the AD group. Specifically, it was discovered that the eight pairs of the bilateral regions (the opercular part of inferior frontal gyrus, area triangularis, insula, putamen, globus pallidus, transverse temporal gyri, superior temporal gyrus, and superior temporal pole) of the insula module had lost symmetric functional connection properties, and the corresponding gray matter concentration (GMC) was significant lower in AD group. We further quantified the functional connectivity changes with an index (index A) and structural changes with the GMC index in the insula module to demonstrate their great potential as AD biomarkers. We further validated these results with six additional independent datasets (271 subjects in six groups). Our results demonstrated specific underlying structural and functional reorganization from young to old, and for diseased subjects. Further, it is suggested that by combining the structural GMC analysis and functional modular analysis in the insula module, a new biomarker can be developed at the single-subject level.
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Affiliation(s)
- Guangyu Chen
- Department of Biophysics, Medical College of Wisconsin Milwaukee, WI, USA
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18
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Liu Q, Li A, Gong L, Zhang L, Wu N, Xu F. Decreased coherence between the two olfactory bulbs in Alzheimer's disease model mice. Neurosci Lett 2013; 545:81-5. [DOI: 10.1016/j.neulet.2013.04.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 04/07/2013] [Accepted: 04/08/2013] [Indexed: 10/26/2022]
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Toga AW, Thompson PM. Connectomics sheds new light on Alzheimer's disease. Biol Psychiatry 2013; 73:390-2. [PMID: 23399468 PMCID: PMC3661406 DOI: 10.1016/j.biopsych.2013.01.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 01/07/2013] [Indexed: 11/30/2022]
Affiliation(s)
- Arthur W Toga
- Laboratory of Neuro Imaging, University of California, Los Angeles, School of Medicine, Los Angeles, California.
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20
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Chan HL, Chu JH, Fung HC, Tsai YT, Meng LF, Huang CC, Hsu WC, Chao PK, Wang JJ, Lee JD, Wai YY, Tsai MT. Brain connectivity of patients with Alzheimer's disease by coherence and cross mutual information of electroencephalograms during photic stimulation. Med Eng Phys 2013; 35:241-52. [DOI: 10.1016/j.medengphy.2011.10.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 10/02/2011] [Accepted: 10/12/2011] [Indexed: 10/15/2022]
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21
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Seo EH, Lee DY, Lee JM, Park JS, Sohn BK, Lee DS, Choe YM, Woo JI. Whole-brain functional networks in cognitively normal, mild cognitive impairment, and Alzheimer's disease. PLoS One 2013; 8:e53922. [PMID: 23335980 PMCID: PMC3545923 DOI: 10.1371/journal.pone.0053922] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Accepted: 12/04/2012] [Indexed: 12/29/2022] Open
Abstract
The conceptual significance of understanding functional brain alterations and cognitive deficits associated with Alzheimer's disease (AD) process has been widely established. However, the whole-brain functional networks of AD and its prodromal stage, mild cognitive impairment (MCI), are not well clarified yet. In this study, we compared the characteristics of the whole-brain functional networks among cognitively normal (CN), MCI, and AD individuals by applying graph theoretical analyses to [(18)F] fluorodeoxyglucose positron emission tomography (FDG-PET) data. Ninety-four CN elderly, 183 with MCI, and 216 with AD underwent clinical evaluation and FDG-PET scan. The overall small-world property as seen in the CN whole-brain network was preserved in MCI and AD. In contrast, individual parameters of the network were altered with the following patterns of changes: local clustering of networks was lower in both MCI and AD compared to CN, while path length was not different among the three groups. Then, MCI had a lower level of local clustering than AD. Subgroup analyses for AD also revealed that very mild AD had lower local clustering and shorter path length compared to mild AD. Regarding the local properties of the whole-brain networks, MCI and AD had significantly decreased normalized betweenness centrality in several hubs regionally associated with the default mode network compared to CN. Our results suggest that the functional integration in whole-brain network progressively declines due to the AD process. On the other hand, functional relatedness between neighboring brain regions may not gradually decrease, but be the most severely altered in MCI stage and gradually re-increase in clinical AD stages.
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Affiliation(s)
- Eun Hyun Seo
- Department of Neuropsychiatry and Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea
- Interdisciplinary Program of Cognitive Science, Seoul National University, Seoul, Korea
| | - Dong Young Lee
- Department of Neuropsychiatry and Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea
- Interdisciplinary Program of Cognitive Science, Seoul National University, Seoul, Korea
| | - Jong-Min Lee
- Department of Biomedical Engineering, Hanyang University, Seoul, Korea
| | - Jun-Sung Park
- Department of Biomedical Engineering, Hanyang University, Seoul, Korea
| | - Bo Kyung Sohn
- Department of Neuropsychiatry and Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea
| | - Dong Soo Lee
- Department of Nuclear Medicine, Seoul National University Hospital, Seoul, Korea
| | - Young Min Choe
- Department of Neuropsychiatry and Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea
| | - Jong Inn Woo
- Department of Neuropsychiatry and Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea
- Interdisciplinary Program of Cognitive Science, Seoul National University, Seoul, Korea
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22
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Vecchio F, Babiloni C, Lizio R, Fallani FDV, Blinowska K, Verrienti G, Frisoni G, Rossini PM. Resting state cortical EEG rhythms in Alzheimer's disease: toward EEG markers for clinical applications: a review. SUPPLEMENTS TO CLINICAL NEUROPHYSIOLOGY 2013; 62:223-36. [PMID: 24053043 DOI: 10.1016/b978-0-7020-5307-8.00015-6] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The human brain contains an intricate network of about 100 billion neurons. Aging of the brain is characterized by a combination of synaptic pruning, loss of cortico-cortical connections, and neuronal apoptosis that provoke an age-dependent decline of cognitive functions. Neural/synaptic redundancy and plastic remodeling of brain networking, also secondary to mental and physical training, promote maintenance of brain activity and cognitive status in healthy elderly subjects for everyday life. However, age is the main risk factor for neurodegenerative disorders such as Alzheimer's disease (AD) that impact on cognition. Growing evidence supports the idea that AD targets specific and functionally connected neuronal networks and that oscillatory electromagnetic brain activity might be a hallmark of the disease. In this line, digital electroencephalography (EEG) allows noninvasive analysis of cortical neuronal synchronization, as revealed by resting state brain rhythms. This review provides an overview of the studies on resting state eyes-closed EEG rhythms recorded in amnesic mild cognitive impairment (MCI) and AD subjects. Several studies support the idea that spectral markers of these EEG rhythms, such as power density, spectral coherence, and other quantitative features, differ among normal elderly, MCI, and AD subjects, at least at group level. Regarding the classification of these subjects at individual level, the most previous studies showed a moderate accuracy (70-80%) in the classification of EEG markers relative to normal and AD subjects. In conclusion, resting state EEG makers are promising for large-scale, low-cost, fully noninvasive screening of elderly subjects at risk of AD.
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Affiliation(s)
- Fabrizio Vecchio
- A.Fa.R., Dipartimento di Neuroscienze, Ospedale Fatebenefratelli, Isola Tiberina, 00186 Rome, Italy
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23
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Daianu M, Jahanshad N, Nir TM, Toga AW, Jack CR, Weiner MW, Thompson PM. Breakdown of brain connectivity between normal aging and Alzheimer's disease: a structural k-core network analysis. Brain Connect 2013; 3:407-22. [PMID: 23701292 PMCID: PMC3749712 DOI: 10.1089/brain.2012.0137] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Brain connectivity analyses show considerable promise for understanding how our neural pathways gradually break down in aging and Alzheimer's disease (AD). Even so, we know very little about how the brain's networks change in AD, and which metrics are best to evaluate these changes. To better understand how AD affects brain connectivity, we analyzed anatomical connectivity based on 3-T diffusion-weighted images from 111 subjects (15 with AD, 68 with mild cognitive impairment, and 28 healthy elderly; mean age, 73.7±7.6 SD years). We performed whole brain tractography based on the orientation distribution functions, and compiled connectivity matrices showing the proportions of detected fibers interconnecting 68 cortical regions. We computed a variety of measures sensitive to anatomical network topology, including the structural backbone--the so-called "k-core"--of the anatomical network, and the nodal degree. We found widespread network disruptions, as connections were lost in AD. Among other connectivity measures showing disease effects, network nodal degree, normalized characteristic path length, and efficiency decreased with disease, while normalized small-worldness increased, in the whole brain and left and right hemispheres individually. The normalized clustering coefficient also increased in the whole brain; we discuss factors that may cause this effect. The proportions of fibers intersecting left and right cortical regions were asymmetrical in all diagnostic groups. This asymmetry may intensify as disease progressed. Connectivity metrics based on the k-core may help understand brain network breakdown as cognitive impairment increases, revealing how degenerative diseases affect the human connectome.
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Affiliation(s)
- Madelaine Daianu
- Department of Neurology, Imaging Genetics Center, Laboratory of Neuro Imaging, UCLA School of Medicine, Los Angeles, California
| | - Neda Jahanshad
- Department of Neurology, Imaging Genetics Center, Laboratory of Neuro Imaging, UCLA School of Medicine, Los Angeles, California
| | - Talia M. Nir
- Department of Neurology, Imaging Genetics Center, Laboratory of Neuro Imaging, UCLA School of Medicine, Los Angeles, California
| | - Arthur W. Toga
- Department of Neurology, Imaging Genetics Center, Laboratory of Neuro Imaging, UCLA School of Medicine, Los Angeles, California
| | | | - Michael W. Weiner
- Department of Radiology, Medicine, and Psychiatry, University of California San Francisco, San Francisco, California
- San Francisco VA Medical Center, U.S. Department of Veteran Affairs, San Francisco, California
| | - Paul M. Thompson
- Department of Neurology, Imaging Genetics Center, Laboratory of Neuro Imaging, UCLA School of Medicine, Los Angeles, California
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24
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Adaptive reorganization of cortical networks in Alzheimer’s disease. Clin Neurophysiol 2013; 124:35-43. [DOI: 10.1016/j.clinph.2012.05.028] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 05/16/2012] [Accepted: 05/31/2012] [Indexed: 11/24/2022]
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25
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Rodriguez G, Arnaldi D, Picco A. Brain functional network in Alzheimer's disease: diagnostic markers for diagnosis and monitoring. Int J Alzheimers Dis 2011; 2011:481903. [PMID: 21629749 PMCID: PMC3100570 DOI: 10.4061/2011/481903] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 03/08/2011] [Accepted: 03/22/2011] [Indexed: 11/29/2022] Open
Abstract
Alzheimer's disease (AD) is the most common type of dementia that is clinically characterized by the presence of memory impairment and later by impairment in other cognitive domains. The clinical diagnosis is based on interviews with the patient and his/her relatives and on neuropsychological assessment, which are also used to monitor cognitive decline over time. Several biomarkers have been proposed for detecting AD in its earliest stages, that is, in the predementia stage. In an attempt to find noninvasive biomarkers, researchers have investigated the feasibility of neuroimaging tools, such as MR, SPECT, and FDG-PET imaging, as well as neurophysiological measurements using EEG. In this paper, we investigate the brain functional networks in AD, focusing on main neurophysiological techniques, integrating with most relevant functional brain imaging findings.
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Affiliation(s)
- Guido Rodriguez
- Department of Neurosciences, Ophthalmology, and Genetics, Clinical Neurophysiology Unit, University of Genoa, De Toni street 5, 16132 Genoa, Italy
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26
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Lizio R, Vecchio F, Frisoni GB, Ferri R, Rodriguez G, Babiloni C. Electroencephalographic rhythms in Alzheimer's disease. Int J Alzheimers Dis 2011; 2011:927573. [PMID: 21629714 PMCID: PMC3100729 DOI: 10.4061/2011/927573] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 03/13/2011] [Indexed: 11/20/2022] Open
Abstract
Physiological brain aging is characterized by synapses loss and neurodegeneration that slowly lead to an age-related decline of cognition. Neural/synaptic redundancy and plastic remodelling of brain networking, also due to mental and physical training, promotes maintenance of brain activity in healthy elderly subjects for everyday life and good social behaviour and intellectual capabilities. However, age is the major risk factor for most common neurodegenerative disorders that impact on cognition, like Alzheimer's disease (AD). Brain electromagnetic activity is a feature of neuronal network function in various brain regions. Modern neurophysiological techniques, such as electroencephalography (EEG) and event-related potentials (ERPs), are useful tools in the investigation of brain cognitive function in normal and pathological aging with an excellent time resolution. These techniques can index normal and abnormal brain aging analysis of corticocortical connectivity and neuronal synchronization of rhythmic oscillations at various frequencies. The present review suggests that discrimination between physiological and pathological brain aging clearly emerges at the group level, with suggested applications also at the level of single individual. The possibility of combining the use of EEG together with biological/neuropsychological markers and structural/functional imaging is promising for a low-cost, non-invasive, and widely available assessment of groups of individuals at-risk.
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27
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Vecchio F, Babiloni C. Direction of Information Flow in Alzheimer's Disease and MCI Patients. Int J Alzheimers Dis 2011; 2011:214580. [PMID: 21547216 PMCID: PMC3087446 DOI: 10.4061/2011/214580] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 02/13/2011] [Indexed: 11/20/2022] Open
Abstract
Is directionality of electroencephalographic (EEG) synchronization abnormal in amnesic mild cognitive impairment (MCI) and Alzheimer's disease (AD)? And, do cerebrovascular and AD lesions represent additive factors in the development of MCI as a putative preclinical stage of AD? Here we reported two studies that tested these hypotheses. EEG data were recorded in normal elderly (Nold), amnesic MCI, and mild AD subjects at rest condition (closed eyes). Direction of information flow within EEG electrode pairs was performed by directed transfer function (DTF) at δ (2-4 Hz), θ (4-8 Hz), α1 (8-10 Hz), α2 (10-12 Hz), β1 (13-20 Hz), β2 (20-30 Hz), and γ (30-40 Hz). Parieto-to-frontal direction was stronger in Nold than in MCI and/or AD subjects for α and β rhythms. In contrast, the directional flow within interhemispheric EEG functional coupling did not discriminate among the groups. More interestingly, this coupling was higher at θ, α1, α2, and β1 in MCI with higher than in MCI with lower vascular load. These results suggest that directionality of parieto-to-frontal EEG synchronization is abnormal not only in AD but also in amnesic MCI, supporting the additive model according to which MCI state would result from the combination of cerebrovascular and neurodegenerative lesions.
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Affiliation(s)
- Fabrizio Vecchio
- AfaR, Department of Neuroscience, Fatebenefratelli Hospital, Isola Tiberina, 00186 Rome, Italy
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Abstract
Alzheimer's disease (AD) is the most common form of dementia. As an incurable, progressive, and neurodegenerative disease, it causes cognitive and memory deficits. However, the biological mechanisms underlying the disease are not thoroughly understood. In recent years, non-invasive neuroimaging and neurophysiological techniques [e.g., structural magnetic resonance imaging (MRI), diffusion MRI, functional MRI, and EEG/MEG] and graph theory based network analysis have provided a new perspective on structural and functional connectivity patterns of the human brain (i.e., the human connectome) in health and disease. Using these powerful approaches, several recent studies of patients with AD exhibited abnormal topological organization in both global and regional properties of neuronal networks, indicating that AD not only affects specific brain regions, but also alters the structural and functional associations between distinct brain regions. Specifically, disruptive organization in the whole-brain networks in AD is involved in the loss of small-world characters and the re-organization of hub distributions. These aberrant neuronal connectivity patterns were associated with cognitive deficits in patients with AD, even with genetic factors in healthy aging. These studies provide empirical evidence to support the existence of an aberrant connectome of AD. In this review we will summarize recent advances discovered in large-scale brain network studies of AD, mainly focusing on graph theoretical analysis of brain connectivity abnormalities. These studies provide novel insights into the pathophysiological mechanisms of AD and could be helpful in developing imaging biomarkers for disease diagnosis and monitoring.
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Affiliation(s)
- Teng Xie
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University Beijing, China
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Dauwels J, Vialatte F, Musha T, Cichocki A. A comparative study of synchrony measures for the early diagnosis of Alzheimer's disease based on EEG. Neuroimage 2010; 49:668-93. [PMID: 19573607 DOI: 10.1016/j.neuroimage.2009.06.056] [Citation(s) in RCA: 222] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Revised: 06/08/2009] [Accepted: 06/17/2009] [Indexed: 11/18/2022] Open
Affiliation(s)
- J Dauwels
- Laboratory for Information and Decision Systems, Massachusetts Institute of Technology, Cambridge, MA, USA.
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Increasing Hippocampal Atrophy and Cerebrovascular Damage Is Differently Associated With Functional Cortical Coupling in MCI Patients. Alzheimer Dis Assoc Disord 2009; 23:323-32. [DOI: 10.1097/wad.0b013e31819d4a9d] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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31
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Inter-hemispheric functional coupling of eyes-closed resting EEG rhythms in adolescents with Down syndrome. Clin Neurophysiol 2009; 120:1619-27. [PMID: 19643663 DOI: 10.1016/j.clinph.2009.06.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 05/13/2009] [Accepted: 06/18/2009] [Indexed: 11/20/2022]
Abstract
OBJECTIVE We tested the hypothesis that inter-hemispheric directional functional coupling of eyes-closed resting EEG rhythms is abnormal in adolescents with Down syndrome (DS). METHODS Eyes-closed resting EEG data were recorded in 38 DS adolescents (18.7 years +/-0.67 SE, IQ=49+/-1.9 SE) and in 17 matched normal control subjects (NYoung=19.1 years +/-0.39 SE). The EEG data were recorded from 8 electrodes (Fp1, Fp2, C3, C4, T3, T4, O1, O2) referenced to vertex. EEG rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). Power of EEG rhythms was evaluated by FFT for control purposes, whereas inter-hemispheric directional EEG functional coupling was computed by directed transfer function (DTF). RESULTS As expected, alpha, beta, and gamma power was widely higher in NYoung than DS subjects, whereas the opposite was true for delta power. As a novelty, DTF (directionality) values globally prevailed from right to left occipital areas in NYoung subjects and in the opposite direction in DS patients. A control experiment showed that this DTF difference could not be observed in the comparison between DS adults with mild cognitive impairment and normal age-matched adults. CONCLUSIONS These results indicate a peculiar abnormal directional inter-hemispheric interplay in visual occipital areas of DS adolescents. SIGNIFICANCE Direction of inter-hemispheric EEG functional coupling unveils a new abnormal brain network feature in DS adolescents.
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Abstract
Alzheimer's disease (AD) is a progressive, neurodegenerative disease that can be clinically characterized by impaired memory and many other cognitive functions. Previous studies have demonstrated that the impairment is accompanied by not only regional brain abnormalities but also changes in neuronal connectivity between anatomically distinct brain regions. Specifically, using neurophysiological and neuroimaging techniques as well as advanced graph theory-based computational approaches, several recent studies have suggested that AD patients have disruptive neuronal integrity in large-scale structural and functional brain systems underlying high-level cognition, as demonstrated by a loss of small-world network characteristics. Small world is an attractive model for the description of complex brain networks because it can support both segregated and integrated information processing. The altered small-world organization thus reflects aberrant neuronal connectivity in the AD brain that is most likely to explain cognitive deficits caused by this disease. In this review, we will summarize recent advances in the brain network research on AD, focusing mainly on the large-scale structural and functional descriptions. The literature reviewed here suggests that AD patients are associated with integrative abnormalities in the distributed neuronal networks, which could provide new insights into the disease mechanism in AD and help us to uncover an imaging-based biomarker for the diagnosis and monitoring of the disease.
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Affiliation(s)
- Yong He
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
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33
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Babiloni C, Frisoni GB, Pievani M, Vecchio F, Infarinato F, Geroldi C, Salinari S, Ferri R, Fracassi C, Eusebi F, Rossini PM. White matter vascular lesions are related to parietal-to-frontal coupling of EEG rhythms in mild cognitive impairment. Hum Brain Mapp 2009; 29:1355-67. [PMID: 17979121 DOI: 10.1002/hbm.20467] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Do cerebrovascular and Alzheimer's disease (AD) lesions represent additive factors in the development of mild cognitive impairment (MCI) as a putative preclinical stage of AD? Here we tested the hypothesis that directionality of fronto-parietal functional coupling of electroencephalographic (EEG) rhythms is relatively preserved in amnesic MCI subjects in whom the cognitive decline is mainly explained by white-matter vascular load. Resting EEG was recorded in 40 healthy elderly (Nold) and 78 amnesic MCI. In the MCI subjects, white-matter vascular load was quantified based on magnetic resonance images (0-30 visual rating scale). EEG rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha1 (8-10.5 Hz), alpha2 (10.5-13 Hz), beta1 (13-20 Hz), and beta2 (20-30 Hz). Directionality of fronto-parietal functional coupling of EEG rhythms was estimated by directed transfer function software. As main results, (i) fronto-parietal functional coupling of EEG rhythms was higher in magnitude in the Nold than in the MCI subjects; (ii) more interestingly, that coupling was higher at theta, alpha1, alpha2, and beta1 in MCI V+ (high vascular load; N = 42; MMSE = 26) than in MCI V- group (low vascular load; N = 36; MMSE= 26.7). These results are interpreted as supporting the additive model according to which MCI state would result from the combination of cerebrovascular and neurodegenerative lesions.
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Affiliation(s)
- Claudio Babiloni
- Dip. Fisiologia Umana e Farmacologia, University La Sapienza, Rome, Italy
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Babiloni C, Frisoni G, Vecchio F, Lizio R, Pievani M, Geroldi C, Fracassi C, Vernieri F, Ursini F, Rodriguez G, Nobili F, Salinari S, Van Dijkman S, Ferri R, Rossini PM. Global Functional Coupling of Resting EEG Rhythms is Abnormal in Mild Cognitive Impairment and Alzheimer’s Disease. J PSYCHOPHYSIOL 2009. [DOI: 10.1027/0269-8803.23.4.224] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Alzheimer’s disease (AD) is typically associated with an impairment of brain networks and global cognitive function in aging. In this vein, the present study tested the hypothesis that the functional coupling of resting cortical electroencephalographic (EEG) rhythms is progressively abnormal in amnesic mild cognitive impairment (MCI) and AD subjects. Eyes-closed resting EEG data were recorded (10–20 system) in 33 mild AD, 52 amnesic MCI, and 47 normal elderly subjects (Nold). EEG rhythms of interest were delta (2–4 Hz), theta (4–8 Hz), alpha1 (8–10 Hz), alpha2 (10–13 Hz), beta1 (13–20 Hz), beta2 (20–30 Hz), and gamma (30–40 Hz). The global functional coupling of the EEG rhythms was indexed by means of spectral coherence for all combinations of electrode pairs (i.e., total coherence). The main results showed that the total coherence of delta rhythms was higher in the AD than the MCI group. It was also higher in the MCI than the Nold group. Furthermore, the delta total coherence was negatively correlated with global cognition (Mini Mental State Examination score) across the Nold, MCI, and AD subjects. Finally, the alpha1 total coherence was lower in the AD group than in the MCI and Nold groups. These results suggest that in the AD process an impairment of brain networks and global cognition is associated with a frequency-specific modulation of the global functional coupling of resting EEG rhythms.
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Affiliation(s)
- Claudio Babiloni
- Department of Biomedical Sciences, University of Foggia, Italy
- Casa di Cura San Raffaele Cassino, Italy
| | | | - Fabrizio Vecchio
- IRCCS “S. Giovanni di Dio-F.B.F.,” Brescia, Italy
- A.Fa.R., Dip. Neurosci. Osp. FBF; Isola Tiberina, Rome, Italy
| | | | | | | | | | | | | | - Guido Rodriguez
- Neurofisiologia Clinica (DiNOG; DipTeC), Azienda Ospedale-Universita’ S. Martino di Genova, Italy
| | - Flavio Nobili
- Neurofisiologia Clinica (DiNOG; DipTeC), Azienda Ospedale-Universita’ S. Martino di Genova, Italy
| | - Serenella Salinari
- Dipartimento Informatica e Sistemistica Univ. “La Sapienza,” Rome, Italy
| | - Sven Van Dijkman
- Department of Physiology and Pharmacology, University of Rome “Sapienza,” Rome, Italy
| | - Raffaele Ferri
- Dept of Neurology, IRCCS Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Troina, Italy
| | - Paolo M. Rossini
- Casa di Cura San Raffaele Cassino, Italy
- Clin. Neurol. University “Campus Biomedico”, Rome, Italy
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Bobkova N, Vorobyov V, Medvinskaya N, Aleksandrova I, Nesterova I. Interhemispheric EEG differences in olfactory bulbectomized rats with different cognitive abilities and brain beta-amyloid levels. Brain Res 2008; 1232:185-94. [PMID: 18687318 DOI: 10.1016/j.brainres.2008.07.036] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2008] [Revised: 07/09/2008] [Accepted: 07/09/2008] [Indexed: 10/21/2022]
Abstract
Alterations in electroencephalogram (EEG) asymmetry and deficits in interhemispheric integration of information have been shown in patients with Alzheimer's disease (AD). However, no direct evidence of an association between EEG asymmetry, morphological markers in the brain, and cognition was found either in AD patients or in AD models. In this study we used rats with bilateral olfactory bulbectomy (OBX) as one of the AD models and measured their learning/memory abilities, brain beta-amyloid levels and EEG spectra in symmetrical frontal and occipital cortices. One year after OBX or sham-surgery, the rats were tested with the Morris water paradigm and assigned to three groups: sham-operated rats, SO, and OBX rats with virtually normal, OBX(+), or abnormal, OBX(-), learning (memory) abilities. In OBX vs. SO, the theta EEG activity was enhanced to a higher extent in the right frontal cortex and in the left occipital cortex. This produced significant interhemispheric differences in the frontal cortex of the OBX(-) rats and in the occipital cortex of both OBX groups. The beta1 EEG asymmetry in SO was attenuated in OBX(+) and completely eliminated in OBX(-). OBX produced highly significant beta2 EEG decline in the right frontal cortex, with OBX(-)>OBX(+) rank order of strength. The beta-amyloid level, examined by post-mortem immunological DOT-analysis in the cortex-hippocampus samples, was about six-fold higher in OBX(-) than in SO, but significantly less (enhanced by 82% vs. SO) in OBX(+) than in OBX(-). The involvement of the brain mediatory systems in the observed EEG asymmetry differences is discussed.
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Affiliation(s)
- Natalia Bobkova
- Institute of Cell Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
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36
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Structural insights into aberrant topological patterns of large-scale cortical networks in Alzheimer's disease. J Neurosci 2008; 28:4756-66. [PMID: 18448652 DOI: 10.1523/jneurosci.0141-08.2008] [Citation(s) in RCA: 718] [Impact Index Per Article: 44.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Recent research on Alzheimer's disease (AD) has shown that cognitive and memory decline in this disease is accompanied by disrupted changes in the coordination of large-scale brain functional networks. However, alterations in coordinated patterns of structural brain networks in AD are still poorly understood. Here, we used cortical thickness measurement from magnetic resonance imaging to investigate large-scale structural brain networks in 92 AD patients and 97 normal controls. Brain networks were constructed by thresholding cortical thickness correlation matrices of 54 regions and analyzed using graph theoretical approaches. Compared with controls, AD patients showed decreased cortical thickness intercorrelations between the bilateral parietal regions and increased intercorrelations in several selective regions involving the lateral temporal and parietal cortex as well as the cingulate and medial frontal cortex regions. Specially, AD patients showed abnormal small-world architecture in the structural cortical networks (increased clustering and shortest paths linking individual regions), implying a less optimal topological organization in AD. Moreover, AD patients were associated with reduced nodal centrality predominantly in the temporal and parietal heteromodal association cortex regions and increased nodal centrality in the occipital cortex regions. Finally, the brain networks of AD were about equally as robust to random failures as those of controls, but more vulnerable against targeted attacks, presumably because of the effects of pathological topological organization. Our findings suggest that the coordinated patterns of cortical morphology are widely altered in AD patients, thus providing structural evidence for disrupted integrity in large-scale brain networks that underlie cognition. This work has implications for our understanding of how functional deficits in patients are associated with their underlying structural (morphological) basis.
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Sampaio I, Puga F, Veiga H, Cagy M, Piedade R, Ribeiro P. Influence of bromazepam on cortical interhemispheric coherence. ARQUIVOS DE NEURO-PSIQUIATRIA 2008; 65:77-81. [PMID: 17420832 DOI: 10.1590/s0004-282x2007000100017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Accepted: 09/20/2006] [Indexed: 11/21/2022]
Abstract
Benzodiazepines are among the most commonly prescribed medications due to their therapeutic efficacy in reducing anxiety and inducing sleep. Consequently, they have been widely employed in the pharmacological treatment of several disorders. Nevertheless, few studies have analyzed the effects of bromazepam in electroencephalographic activity (EEG). The present study aimed at investigating the modulatory effects of this drug on brain dynamics. Specifically, the effects of bromazepam (3mg) on EEG coherence were tested in a double-blind experiment. The sample, consisting of 10 healthy subjects (5 male and 5 female), was submitted to ten minutes of EEG recording. The electrophysiological measure (coherence) was analyzed across three experimental conditions: bromazepam, placebo 1, and placebo 2. Results indicate that bromazepam significantly increases cortical interhemispheric coherence.
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Affiliation(s)
- Isabel Sampaio
- Laboratório de Mapeamento Cerebral e Integração Sensório-Motora, Instituto de Psiquiatria, Universidade Federal do Rio de Janeiro, Avenida Venceslau Brás 71/Fundos, 22290-140 Rio de Janeiro, RJ, Brazil.
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38
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Rossini PM, Rossi S, Babiloni C, Polich J. Clinical neurophysiology of aging brain: from normal aging to neurodegeneration. Prog Neurobiol 2007; 83:375-400. [PMID: 17870229 DOI: 10.1016/j.pneurobio.2007.07.010] [Citation(s) in RCA: 328] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 05/03/2007] [Accepted: 07/26/2007] [Indexed: 02/06/2023]
Abstract
Physiological brain aging is characterized by a loss of synaptic contacts and neuronal apoptosis that provokes age-dependent decline of sensory processing, motor performance, and cognitive function. Neural redundancy and plastic remodelling of brain networking, also secondary to mental and physical training, promotes maintenance of brain activity in healthy elderly for everyday life and fully productive affective and intellectual capabilities. However, age is the main risk factor for neurodegenerative disorders such as Alzheimer's disease (AD) that impact on cognition. Oscillatory electromagnetic brain activity is a hallmark of neuronal network function in various brain regions. Modern neurophysiological techniques including electroencephalography (EEG), event-related potential (ERP), magnetoencephalography (MEG), and transcranial magnetic stimulation (TMS) can accurately index normal and abnormal brain aging to facilitate non-invasive analysis of cortico-cortical connectivity and neuronal synchronization of firing and coherence of rhythmic oscillations at various frequencies. The present review provides a perspective of these issues by assaying different neurophysiological methods and integrating the results with functional brain imaging findings. It is concluded that discrimination between physiological and pathological brain aging clearly emerges at the group level, with applications at the individual level also suggested. Integrated approaches utilizing neurophysiological techniques together with biological markers and structural and functional imaging are promising for large-scale, low-cost and non-invasive evaluation of at-risk populations. Practical implications of the methods are emphasized.
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Affiliation(s)
- Paolo M Rossini
- Clinica Neurologica University Campus Bio-Medico, Rome, Italy.
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39
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Babiloni C, Ferri R, Binetti G, Vecchio F, Frisoni GB, Lanuzza B, Miniussi C, Nobili F, Rodriguez G, Rundo F, Cassarino A, Infarinato F, Cassetta E, Salinari S, Eusebi F, Rossini PM. Directionality of EEG synchronization in Alzheimer's disease subjects. Neurobiol Aging 2007; 30:93-102. [PMID: 17573161 DOI: 10.1016/j.neurobiolaging.2007.05.007] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Revised: 04/27/2007] [Accepted: 05/04/2007] [Indexed: 10/23/2022]
Abstract
Is directionality of electroencephalographic (EEG) synchronization abnormal in amnesic mild cognitive impairment (MCI) and Alzheimer's disease (AD)? EEG data were recorded in 64 normal elderly (Nold), 69 amnesic MCI, and 73 mild AD subjects at rest condition (closed eyes). Direction of information flux within EEG functional coupling at electrode pairs was performed by directed transfer function (DTF) at delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10 Hz), alpha 2 (10-12 Hz), beta 1 (13-20 Hz), beta 2 (20-30 Hz), and gamma (30-40 Hz). Parietal to frontal direction of the information flux within EEG functional coupling was stronger in Nold than in MCI and/or AD subjects, namely for alpha and beta rhythms. In contrast, the directional flow within inter-hemispheric EEG functional coupling did not discriminate among the three groups. These results suggest that directionality of parieto-to-frontal EEG synchronization is abnormal not only in AD but also in amnesic MCI.
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Affiliation(s)
- Claudio Babiloni
- Department of Human Physiology and Pharmacology, University La Sapienza, Rome, Italy.
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40
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Delbeuck X, Collette F, Van der Linden M. Is Alzheimer's disease a disconnection syndrome? Neuropsychologia 2007; 45:3315-23. [PMID: 17765932 DOI: 10.1016/j.neuropsychologia.2007.05.001] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2006] [Revised: 04/19/2007] [Accepted: 05/03/2007] [Indexed: 11/28/2022]
Abstract
In Alzheimer's disease (AD), loss of connectivity in the patient's brain has been evidenced by a range of electrophysiological and neuroimaging studies. However, few neuropsychological research projects have sought to interpret the cognitive modifications following the appearance of AD in terms of a disconnection syndrome. In this paper, we sought to investigate brain connectivity in AD via the study of a crossmodal effect. More precisely, we examined the integration of auditory and visual speech information (the McGurk effect) in AD patients and matched control subjects. Our results revealed impaired crossmodal integration during speech perception in AD, which was not associated with disturbances in the separate processing of auditory and visual speech stimuli. In conclusion, our data suggest the occurrence of a specific, audio-visual integration deficit in AD, which might be the consequence of a connectivity breakdown and corroborate the observation from other studies of crossmodal deficits between the auditory and visual modalities in this population.
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Affiliation(s)
- X Delbeuck
- Memory, Resources & Research Centre, EA 2691, Lille University Hospital, Lille, France.
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41
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Jiang ZY, Zheng LL. Inter- and intra-hemispheric EEG coherence in patients with mild cognitive impairment at rest and during working memory task. J Zhejiang Univ Sci B 2006; 7:357-64. [PMID: 16615165 PMCID: PMC1462929 DOI: 10.1631/jzus.2006.b0357] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE To assess functional relationship by calculating inter- and intra-hemispheric electroencephalography (EEG) coherence at rest and during a working memory task of patients with mild cognitive impairment (MCI). METHODS The sample consisted of 69 subjects: 35 patients (n=17 males, n=18 females; 52-71 years old) and 34 normal controls (n=17 males, n=17 females; 51~63 years old). Mini-mental state examination (MMSE) of two groups revealed that the scores of MCI patients did not differ significantly from those of normal controls (P>0.05). In EEG recording, subjects were performed at rest and during working memory task. EEG signals from F3-F4, C3-C4, P3-P4, T5-T6 and O1-O2 electrode pairs are resulted from the inter-hemispheric action, and EEG signals from F3-C3, F4-C4, C3-P3, C4-P4, P3-O1, P4-O2, T5-C3, T6-C4, T5-P3 and T6-P4 electrode pairs are resulted from the intra-hemispheric action for delta (1.0-3.5 Hz), theta (4.0-7.5 Hz), alpha-1 (8.0-10.0 Hz), alpha-2 (10.5-13.0 Hz), beta-1 (13.5-18.0 Hz) and beta-2 (18.5-30.0 Hz) frequency bands. The influence of inter- and intra-hemispheric coherence on EEG activity with eyes closed was examined using fast Fourier transformation from the 16 sampled channels. RESULTS During working memory tasks, the inter- and intra-hemispheric EEG coherences in all bands were significantly higher in the MCI group in comparison with those in the control group (P<0.05). However, there was no significant difference in inter- and intra-hemispheric EEG coherences between two groups at rest. CONCLUSION Experimental results comprise evidence that MCI patients have higher degree of functional connectivity between hemispheres and in hemispheres during working condition. It suggests that MCI may be associated with compensatory processes during working memory tasks between hemispheres and in hemispheres. Moreover, failure of normal cortical connections may exist in MCI patients.
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Affiliation(s)
- Zheng-yan Jiang
- Department of Psychiatry, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China.
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42
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Rossini PM, Del Percio C, Pasqualetti P, Cassetta E, Binetti G, Dal Forno G, Ferreri F, Frisoni G, Chiovenda P, Miniussi C, Parisi L, Tombini M, Vecchio F, Babiloni C. Conversion from mild cognitive impairment to Alzheimer's disease is predicted by sources and coherence of brain electroencephalography rhythms. Neuroscience 2006; 143:793-803. [PMID: 17049178 DOI: 10.1016/j.neuroscience.2006.08.049] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Revised: 07/25/2006] [Accepted: 08/16/2006] [Indexed: 10/23/2022]
Abstract
Objective. Can quantitative electroencephalography (EEG) predict the conversion from mild cognitive impairment (MCI) to Alzheimer's disease (AD)? Methods. Sixty-nine subjects fulfilling criteria for MCI were enrolled; cortical connectivity (spectral coherence) and (low resolution brain electromagnetic tomography) sources of EEG rhythms (delta=2-4 Hz; theta=4-8 Hz; alpha 1=8-10.5 Hz; alpha 2=10.5-13 Hz: beta 1=13-20 Hz; beta 2=20-30 Hz; and gamma=30-40) were evaluated at baseline (time of MCI diagnosis) and follow up (about 14 months later). At follow-up, 45 subjects were still MCI (MCI Stable) and 24 subjects were converted to AD (MCI Converted). Results. At baseline, fronto-parietal midline coherence as well as delta (temporal), theta (parietal, occipital and temporal), and alpha 1 (central, parietal, occipital, temporal, limbic) sources were stronger in MCI Converted than stable subjects (P<0.05). Cox regression modeling showed low midline coherence and weak temporal source associated with 10% annual rate AD conversion, while this rate increased up to 40% and 60% when strong temporal delta source and high midline gamma coherence were observed respectively. Interpretation. Low-cost and diffuse computerized EEG techniques are able to statistically predict MCI to AD conversion.
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Affiliation(s)
- P M Rossini
- IRCCS "Centro S. Giovanni di Dio-F.B.F.," Brescia, Italy.
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Babiloni C, Ferri R, Binetti G, Cassarino A, Dal Forno G, Ercolani M, Ferreri F, Frisoni GB, Lanuzza B, Miniussi C, Nobili F, Rodriguez G, Rundo F, Stam CJ, Musha T, Vecchio F, Rossini PM. Fronto-parietal coupling of brain rhythms in mild cognitive impairment: a multicentric EEG study. Brain Res Bull 2005; 69:63-73. [PMID: 16464686 DOI: 10.1016/j.brainresbull.2005.10.013] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Revised: 10/21/2005] [Accepted: 10/24/2005] [Indexed: 11/16/2022]
Abstract
Electroencephalographic (EEG) data were recorded in 69 normal elderly (Nold), 88 mild cognitive impairment (MCI), and 109 mild Alzheimer's disease (AD) subjects at rest condition, to test whether the fronto-parietal coupling of EEG rhythms is in line with the hypothesis that MCI can be considered as a pre-clinical stage of the disease at group level. Functional coupling was estimated by synchronization likelihood of Laplacian-transformed EEG data at electrode pairs, which accounts for linear and non-linear components of that coupling. Cortical rhythms of interest were delta (2-4Hz), theta (4-8Hz), alpha 1 (8-10.5Hz), alpha 2 (10.5-13Hz), beta 1 (13-20Hz), beta 2 (20-30Hz), and gamma (30-40Hz). Compared to the Nold subjects, the AD patients presented a marked reduction of the synchronization likelihood (delta to gamma) at both fronto-parietal and inter-hemispherical (delta to beta 2) electrodes. As a main result, alpha 1 synchronization likelihood progressively decreased across Nold, MCI, and mild AD subjects at midline (Fz-Pz) and right (F4-P4) fronto-parietal electrodes. The same was true for the delta synchronization likelihood at right fronto-parietal electrodes (F4-P4). For these EEG bands, the synchronization likelihood correlated with global cognitive status as measured by the Mini Mental State Evaluation. The present results suggest that at group level, fronto-parietal coupling of the delta and alpha rhythms progressively becomes abnormal though MCI and mild AD. Future longitudinal research should evaluate whether the present EEG approach is able to predict the cognitive decline in individual MCI subjects.
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Affiliation(s)
- Claudio Babiloni
- Dipartimento di Fisiologia Umana e Farmacologia, Università degli Studi di Roma La Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy.
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Cichocki A, Shishkin SL, Musha T, Leonowicz Z, Asada T, Kurachi T. EEG filtering based on blind source separation (BSS) for early detection of Alzheimer's disease. Clin Neurophysiol 2005; 116:729-37. [PMID: 15721088 DOI: 10.1016/j.clinph.2004.09.017] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2004] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Development of an EEG preprocessing technique for improvement of detection of Alzheimer's disease (AD). The technique is based on filtering of EEG data using blind source separation (BSS) and projection of components which are possibly sensitive to cortical neuronal impairment found in early stages of AD. METHODS Artifact-free 20s intervals of raw resting EEG recordings from 22 patients with Mild Cognitive Impairment (MCI) who later proceeded to AD and 38 age-matched normal controls were decomposed into spatio-temporally decorrelated components using BSS algorithm 'AMUSE'. Filtered EEG was obtained by back projection of components with the highest linear predictability. Relative power of filtered data in delta, theta, alpha 1, alpha 2, beta 1, and beta 2 bands were processed with Linear Discriminant Analysis (LDA). RESULTS Preprocessing improved the percentage of correctly classified patients and controls computed with jack-knifing cross-validation from 59 to 73% and from 76 to 84%, correspondingly. CONCLUSIONS The proposed approach can significantly improve the sensitivity and specificity of EEG based diagnosis. SIGNIFICANCE Filtering based on BSS can improve the performance of the existing EEG approaches to early diagnosis of Alzheimer's disease. It may also have potential for improvement of EEG classification in other clinical areas or fundamental research. The developed method is quite general and flexible, allowing for various extensions and improvements.
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Affiliation(s)
- Andrzej Cichocki
- Laboratory for Advanced Brain Signal Processing, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
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45
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Anghinah R, Caramelli P, Takahashi DY, Nitrini R, Sameshima K. Estudo da coerência do eletrencefalograma na banda de frequência alfa em indivíduos adultos normais: resultados preliminares em 10 casos. ARQUIVOS DE NEURO-PSIQUIATRIA 2005; 63:83-6. [PMID: 15830070 DOI: 10.1590/s0004-282x2005000100015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A coerência espectral inter-hemisférica do eletrencefalograma da região occipital do escalpo (eletrodos O1 e O2) foi estimada usando a transformada rápida de Fourier. As médias de coerências na banda de freqüência alfa (alfa1 - 8,0 a 10,0 Hz e alfa2 -10,1 a 12,5 Hz) em indivíduos normais com mais de 50 anos foram comparadas com as obtidas em adultos jovens com idade inferior a 50 anos. Nossos resultados mostraram que não há diferença significativa dos níveis de coerência na banda alfa entre indivíduos em faixas etárias mais avançadas comparados aos adultos jovens.
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Affiliation(s)
- Renato Anghinah
- Departamento de Neurologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil.
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46
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Pijnenburg YAL, v d Made Y, van Cappellen van Walsum AM, Knol DL, Scheltens P, Stam CJ. EEG synchronization likelihood in mild cognitive impairment and Alzheimer's disease during a working memory task. Clin Neurophysiol 2004; 115:1332-9. [PMID: 15134700 DOI: 10.1016/j.clinph.2003.12.029] [Citation(s) in RCA: 202] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/30/2003] [Indexed: 01/22/2023]
Abstract
OBJECTIVE Synchronization likelihood analysis of resting state EEG has shown that cognitive dysfunction in Alzheimer's disease (AD) and its precursor mild cognitive impairment (MCI) are associated with a loss of functional connectivity in high (upper alpha and beta) frequency bands. Working memory tasks are known to change functional connectivity, but it is unknown whether this increases the differences between AD, MCI and healthy controls. Our objective was to investigate the behavior of synchronization likelihood of multichannel EEG in AD, MCI and cognitively healthy controls, both at rest and during a working memory task. METHODS EEGs (200 Hz sample frequency, 21 channels, average reference) were recorded at rest as well as during a visual working memory task in 14 patients with AD according to the NINCDS-ADRDA criteria (mean age 76.4; SD 13.6), 11 patients with MCI according to the criteria of Petersen (mean age 78.4; SD 6.4) and 14 with subjective memory complaints but no demonstrable memory disturbance (mean age 61.6; SD 26.6). The synchronization likelihood was computed over 19 channels, comparing each channel with all the other channels for the 0.5-4, 4-8, 8-10, 10-12, 12-30, 30-50 Hz frequency bands. RESULTS The synchronization likelihood was significantly decreased in the upper alpha (10-12) and beta (12-30) bands in AD compared to persons with subjective memory complaints. The working memory task scores strongly correlated with Mini-Mental State Examination scores. During the working memory task the synchronization likelihood was significantly higher in MCI compared to the control subjects in the lower alpha band (8-10 Hz). CONCLUSIONS Decrease of beta band synchronization occurs in mild AD, both in a resting condition and during a working memory task. SIGNIFICANCE Decrease of beta band synchronization in mild AD is a robust finding. The present study confirms our findings in a different cohort of patients, using alternative frequency bands. The diagnostic value of the synchronization likelihood in AD and MCI needs to be further established.
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Affiliation(s)
- Y A L Pijnenburg
- Department of Neurology and Alzheimer Center, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands.
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Babiloni C, Miniussi C, Moretti DV, Vecchio F, Salinari S, Frisoni G, Rossini PM. Cortical Networks Generating Movement-Related EEG Rhythms in Alzheimer's Disease: An EEG Coherence Study. Behav Neurosci 2004; 118:698-706. [PMID: 15301597 DOI: 10.1037/0735-7044.118.4.698] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Patients with mild Alzheimer's disease (AD) present with abnormally strong values of frontal and ipsilateral central sensorimotor rhythms. The authors tested 2 working hypotheses of the related electroencephalographic (EEG) coherence: disconnection, defined as a sign of a reduced coordination within the frontoparietal and interhemispheric networks, and cooperation, defined as a reflection of the reorganization of the brain sensorimotor networks. Results showed that, compared with healthy controls, patients with mild AD had an unreactive and abnormally low interhemispheric EEG coherence and an unreactive and abnormally high frontoparietal EEG coherence. These findings support the hypothesis of an impaired mechanism of sensorimotor cortical coupling (disconnection) in mild AD.
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Affiliation(s)
- Claudio Babiloni
- Dipartimento Fisiologia Umana e Farmacologia, Università degli Studi di Roma "La Sapienza', Rome, Italy.
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Osipova D, Ahveninen J, Kaakkola S, Jääskeläinen IP, Huttunen J, Pekkonen E. Effects of scopolamine on MEG spectral power and coherence in elderly subjects. Clin Neurophysiol 2003; 114:1902-7. [PMID: 14499752 DOI: 10.1016/s1388-2457(03)00165-2] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Scopolamine, a muscarinic receptor antagonist, can produce temporary cognitive impairments as well as electroencephalographic changes that partially resemble those observed in Alzheimer's disease. In order to test the sensitivity of spectral power and hemispheric coherence to changes in cholinergic transmission, we evaluated quantitative magnetoencephalogram (MEG) after intravenous injection of scopolamine. METHODS MEG of 8 elderly healthy subjects (59-80 years) were measured with a whole-head magnetometer after intravenous injection of scopolamine. An injection of glycopyrrolate, a peripheral muscarinic antagonist, was used as the placebo in a double-blind, randomized, cross-over design. Spectral power and coherence were computed over 7 brain regions in 3 frequency bands. RESULTS Scopolamine administration increased theta activity (4-8 Hz) and resulted in the abnormal pattern of MEG desynchronization in eyes-open vs. eyes-closed conditions in the alpha band (8-13 Hz). These effects were most prominent over the posterior regions. Interhemispheric and left intrahemispheric coherence was significantly decreased in the theta band (4-8 Hz). CONCLUSIONS Spontaneous cortical activity at the theta and alpha range and functional coupling in the theta band are modulated by the cholinergic system. MEG may provide a tool for monitoring brain dynamics in neurological disorders associated with cholinergic abnormalities.
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Affiliation(s)
- Daria Osipova
- Cognitive Brain Research Unit, Department of Psychology, University of Helsinki, P.O. Box 9 00014, Helsinki, Finland.
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Abstract
This paper reviews the growing amount of evidence supporting the hypothesis that Alzheimer's disease includes a disconnection syndrome. This evidence came mainly from neuropathological, electrophysiological, and neuroimaging studies. Moreover, a few recent neuropsychological studies have also explored the effects of a disconnection between cerebral areas on cognitive functioning. Finally, and more generally, the contribution of this interpretation to the understanding of Alzheimer's disease cognitive deficits is considered.
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Affiliation(s)
- X Delbeuck
- Cognitive Psychopathology Unit, University of Geneva, Geneva, Switzerland.
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