1
|
Vorobyov V, Deev A, Chaprov K, Ustyugov AA, Lysikova E. Age-Related Modifications of Electroencephalogram Coherence in Mice Models of Alzheimer's Disease and Amyotrophic Lateral Sclerosis. Biomedicines 2023; 11:biomedicines11041151. [PMID: 37189768 DOI: 10.3390/biomedicines11041151] [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] [Received: 02/21/2023] [Revised: 04/08/2023] [Accepted: 04/09/2023] [Indexed: 05/17/2023] Open
Abstract
Evident similarities in pathological features in aging and Alzheimer's disease (AD) raise the question of a role for natural age-related adaptive mechanisms in the prevention/elimination of disturbances in interrelations between different brain areas. In our previous electroencephalogram (EEG) studies on 5xFAD- and FUS-transgenic mice, as models of AD and amyotrophic lateral sclerosis (ALS), this suggestion was indirectly confirmed. In the current study, age-related changes in direct EEG synchrony/coherence between the brain structures were evaluated. METHODS In 5xFAD mice of 6-, 9-, 12-, and 18-month ages and their wild-type (WT5xFAD) littermates, we analyzed baseline EEG coherence between the cortex, hippocampus/putamen, ventral tegmental area, and substantia nigra. Additionally, EEG coherence between the cortex and putamen was analyzed in 2- and 5-month-old FUS mice. RESULTS In the 5xFAD mice, suppressed levels of inter-structural coherence vs. those in WT5xFAD littermates were observed at ages of 6, 9, and 12 months. In 18-month-old 5xFAD mice, only the hippocampus ventral tegmental area coherence was significantly reduced. In 2-month-old FUS vs. WTFUS mice, the cortex-putamen coherence suppression, dominated in the right hemisphere, was observed. In 5-month-old mice, EEG coherence was maximal in both groups. CONCLUSION Neurodegenerative pathologies are accompanied by the significant attenuation of intracerebral EEG coherence. Our data are supportive for the involvement of age-related adaptive mechanisms in intracerebral disturbances produced by neurodegeneration.
Collapse
Affiliation(s)
- Vasily Vorobyov
- School of Biosciences, Sir Martin Evans Building, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK
- Institute of Cell Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia
| | - Alexander Deev
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia
| | - Kirill Chaprov
- School of Biosciences, Sir Martin Evans Building, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK
- Institute of Physiologically Active Compounds, Russian Academy of Sciences, 142432 Chernogolovka, Russia
- Center of Pre-Clinical and Clinical Studies, Belgorod State National Research University, 308015 Belgorod, Russia
| | - Aleksey A Ustyugov
- Institute of Physiologically Active Compounds, Russian Academy of Sciences, 142432 Chernogolovka, Russia
| | - Ekaterina Lysikova
- School of Biosciences, Sir Martin Evans Building, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK
- Institute of Physiologically Active Compounds, Russian Academy of Sciences, 142432 Chernogolovka, Russia
| |
Collapse
|
2
|
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.
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
Aguerre NV, Gómez-Ariza CJ, Ibáñez-Molina AJ, Bajo MT. Electrophysiological correlates of dispositional mindfulness: A quantitative and complexity EEG study. Br J Psychol 2023. [PMID: 36748402 DOI: 10.1111/bjop.12636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 01/12/2023] [Accepted: 01/16/2023] [Indexed: 02/08/2023]
Abstract
While growing evidence supports that dispositional mindfulness relates to psychological health and cognitive enhancement, to date there have been only a few attempts to characterize its neural underpinnings. In the present study, we aimed at exploring the electrophysiological (EEG) signature of dispositional mindfulness using quantitative and complexity measures of EEG during resting state and while performing a learning task. Hundred twenty participants were assessed with the Five Facet Mindfulness Questionnaire and underwent 5 min eyes-closed resting state and 5 min at task EEG recording. We hypothesized that high mindfulness individuals would show patterns of brain activity related to (a) lower involvement of the default mode network (DMN) at rest (reduced frontal gamma power) and (b) a state of 'task readiness' reflected in a more similar pattern from rest to task (reduced overall q-EEG power at rest but not at task), as compared to their low mindfulness counterparts. Dispositional mindfulness was significantly linked to reduced frontal gamma power at rest and lower overall power during rest but not at task. In addition, we found a trend towards higher entropy during task performance in mindful individuals, which has recently been reported during mindfulness meditation. Altogether, our results add to those from expert meditators to show that high (dispositional) mindfulness seems to have a specific electrophysiological pattern characteristic of less involvement of the DMN and mind-wandering processes.
Collapse
Affiliation(s)
- Nuria Victoria Aguerre
- Department of Experimental Psychology - Mind, Brain and Behavior Research Center (CIMCYC), University of Granada, Granada, Spain
| | | | | | - María Teresa Bajo
- Department of Experimental Psychology - Mind, Brain and Behavior Research Center (CIMCYC), University of Granada, Granada, Spain
| |
Collapse
|
5
|
Mosbacher JA, Waser M, Garn H, Seiler S, Coronel C, Dal-Bianco P, Benke T, Deistler M, Ransmayr G, Mayer F, Sanin G, Lechner A, Lackner HK, Schwingenschuh P, Grossegger D, Schmidt R. Functional (un-)Coupling: Impairment, Compensation, and Future Progression in Alzheimer's Disease. Clin EEG Neurosci 2021; 54:316-326. [PMID: 34658289 DOI: 10.1177/15500594211052208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background: Functional (un-)coupling (task-related change of functional connectivity) between different sites of the brain is a mechanism of general importance for cognitive processes. In Alzheimer's disease (AD), prior research identified diminished cortical connectivity as a hallmark of the disease. However, little is known about the relation between the amount of functional (un-)coupling and cognitive performance and decline in AD. Method: Cognitive performance (based on CERAD-Plus scores) and electroencephalogram (EEG)-based functional (un-)coupling measures (connectivity changes from rest to a Face-Name-Encoding task) were assessed in 135 AD patients (age: M = 73.8 years; SD = 9.0). Of these, 68 patients (M = 73.9 years; SD = 8.9) participated in a follow-up assessment of their cognitive performance 1.5 years later. Results: The amounts of functional (un-)coupling in left anterior-posterior and homotopic interhemispheric connections in beta1-band were related to cognitive performance at baseline (β = .340; p < .001; β = .274; P = .001, respectively). For both markers, a higher amount of functional coupling was associated with better cognitive performance. Both markers also were significant predictors for cognitive decline. However, while patients with greater functional coupling in left anterior-posterior connections declined less in cognitive performance (β = .329; P = .035) those with greater functional coupling in interhemispheric connections declined more (β = -.402; P = .010). Conclusion: These findings suggest an important role of functional coupling mechanisms in left anterior-posterior and interhemispheric connections in AD. Especially the complex relationship with cognitive decline in AD patients might be an interesting aspect for future studies.
Collapse
Affiliation(s)
| | - Markus Waser
- Center for Digital Safety and Security, AIT Austrian Institute of Technology, Vienna, Austria
| | - Heinrich Garn
- Center for Digital Safety and Security, AIT Austrian Institute of Technology, Vienna, Austria
| | - Stephan Seiler
- Department of Neurology, 31475Medical University of Graz, Graz, Austria
| | - Carmina Coronel
- Center for Digital Safety and Security, AIT Austrian Institute of Technology, Vienna, Austria
| | - Peter Dal-Bianco
- Department of Neurology, 27271Medical University of Vienna, Vienna, Austria
| | - Thomas Benke
- Department of Neurology, 27280Medical University of Innsbruck, Innsbruck, Austria
| | - Manfred Deistler
- Institute of Statistics and Mathematical Methods in Economics, 27259Vienna University of Technology, Vienna, Austria
| | - Gerhard Ransmayr
- Department of Neurology 2, 31197Kepler University Hospital Linz, Med Campus III, Linz, Austria
| | - Florian Mayer
- Department of Neurology, 27271Medical University of Vienna, Vienna, Austria
| | - Guenter Sanin
- Department of Neurology, 27280Medical University of Innsbruck, Innsbruck, Austria
| | - Anita Lechner
- Department of Neurology, 31475Medical University of Graz, Graz, Austria
| | - Helmut K Lackner
- Division of Physiology, Otto Loewi Research Center, Medical University of Graz, Graz, Austria
| | | | | | - Reinhold Schmidt
- Department of Neurology, 31475Medical University of Graz, Graz, Austria
| |
Collapse
|
6
|
Laptinskaya D, Küster OC, Fissler P, Thurm F, Von Arnim CAF, Kolassa IT. No Evidence That Cognitive and Physical Activities Are Related to Changes in EEG Markers of Cognition in Older Adults at Risk of Dementia. Front Aging Neurosci 2021; 13:610839. [PMID: 33815087 PMCID: PMC8017171 DOI: 10.3389/fnagi.2021.610839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 01/27/2021] [Indexed: 11/13/2022] Open
Abstract
An active lifestyle as well as cognitive and physical training (PT) may benefit cognition by increasing cognitive reserve, but the underlying neurobiological mechanisms of this reserve capacity are not well understood. To investigate these mechanisms of cognitive reserve, we focused on electrophysiological correlates of cognitive performance, namely on an event-related measure of auditory memory and on a measure of global coherence. Both measures have shown to be sensitive markers for cognition and might therefore be suitable to investigate potential training- and lifestyle-related changes. Here, we report on the results of an electrophysiological sub-study that correspond to previously published behavioral findings. Altogether, 65 older adults with subjective or objective cognitive impairment and aged 60-88 years were assigned to a 10-week cognitive (n = 19) or a 10-week PT (n = 21) or to a passive control group (n = 25). In addition, self-reported lifestyle was assessed at baseline. We did not find an effect of both training groups on electroencephalography (EEG) measures of auditory memory decay or global coherence (ps ≥ 0.29) and a more active lifestyle was not associated with improved global coherence (p = 0.38). Results suggest that a 10-week unimodal cognitive or PT and an active lifestyle in older adults at risk for dementia are not strongly related to improvements in electrophysiological correlates of cognition.
Collapse
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
| | - Olivia Caroline Küster
- Department of Neurology, Ulm University, Ulm, Germany
- Clinic for Neurogeriatrics and Neurological Rehabilitation, University- and Rehabilitation Hospital Ulm, Ulm, Germany
| | - Patrick Fissler
- Clinical and Biological Psychology, Institute of Psychology and Education, Ulm University, Ulm, Germany
- Department of Neurology, Ulm University, Ulm, Germany
- Psychiatric Services of Thurgovia, Academic Teaching Hospital of Paracelsus Medical University Salzburg, Muensterlingen, Switzerland
| | - Franka Thurm
- Department of Psychology, University of Konstanz, Konstanz, Germany
- Faculty of Psychology, TU Dresden, Dresden, Germany
| | - Christine A. F. Von Arnim
- Department of Neurology, Ulm University, Ulm, Germany
- Division 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
| |
Collapse
|
7
|
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.
Collapse
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
| |
Collapse
|
8
|
Han Y, Wang K, Jia J, Wu W. Changes of EEG Spectra and Functional Connectivity during an Object-Location Memory Task in Alzheimer's Disease. Front Behav Neurosci 2017; 11:107. [PMID: 28620287 PMCID: PMC5449767 DOI: 10.3389/fnbeh.2017.00107] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 05/18/2017] [Indexed: 12/19/2022] Open
Abstract
Object-location memory is particularly fragile and specifically impaired in Alzheimer’s disease (AD) patients. Electroencephalogram (EEG) was utilized to objectively measure memory impairment for memory formation correlates of EEG oscillatory activities. We aimed to construct an object-location memory paradigm and explore EEG signs of it. Two groups of 20 probable mild AD patients and 19 healthy older adults were included in a cross-sectional analysis. All subjects took an object-location memory task. EEG recordings performed during object-location memory tasks were compared between the two groups in the two EEG parameters (spectral parameters and phase synchronization). The memory performance of AD patients was worse than that of healthy elderly adults The power of object-location memory of the AD group was significantly higher than the NC group (healthy elderly adults) in the alpha band in the encoding session, and alpha and theta bands in the retrieval session. The channels-pairs the phase lag index value of object-location memory in the AD group was clearly higher than the NC group in the delta, theta, and alpha bands in encoding sessions and delta and theta bands in retrieval sessions. The results provide support for the hypothesis that the AD patients may use compensation mechanisms to remember the items and episode.
Collapse
Affiliation(s)
- Yuliang Han
- Department of Neurology, Chinese PLA General HospitalBeijing, China.,Department of Neurology, Chinese PLA 305 HospitalBeijing, China
| | - Kai Wang
- Department of Neurology, Chinese PLA 305 HospitalBeijing, China
| | - Jianjun Jia
- Department of Neurology, Chinese PLA General HospitalBeijing, China
| | - Weiping Wu
- Department of Neurology, Chinese PLA General HospitalBeijing, China
| |
Collapse
|
9
|
Marceglia S, Mrakic-Sposta S, Rosa M, Ferrucci R, Mameli F, Vergari M, Arlotti M, Ruggiero F, Scarpini E, Galimberti D, Barbieri S, Priori A. Transcranial Direct Current Stimulation Modulates Cortical Neuronal Activity in Alzheimer's Disease. Front Neurosci 2016; 10:134. [PMID: 27065792 PMCID: PMC4814712 DOI: 10.3389/fnins.2016.00134] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 03/16/2016] [Indexed: 02/02/2023] Open
Abstract
Quantitative electroencephalography (qEEG) showed that Alzheimer's disease (AD) is characterized by increased theta power, decreased alpha and beta power, and decreased coherence in the alpha and theta band in posterior regions. These abnormalities are thought to be associated with functional disconnections among cortical areas, death of cortical neurons, axonal pathology, and cholinergic deficits. Since transcranial Direct Current Stimulation (tDCS) over the temporo-parietal area is thought to have beneficial effects in patients with AD, in this study we aimed to investigate whether tDCS benefits are related to tDCS-induced changes in cortical activity, as represented by qEEG. A weak anodal current (1.5 mA, 15 min) was delivered bilaterally over the temporal-parietal lobe to seven subjects with probable AD (Mini-Mental State Examination, MMSE score >20). EEG (21 electrodes, 10–20 international system) was recorded for 5 min with eyes closed before (baseline, t0) and 30 min after anodal and cathodal tDCS ended (t1). At the same time points, patients performed a Word Recognition Task (WRT) to assess working memory functions. The spectral power and the inter- and intra-hemispheric EEG coherence in different frequency bands (e.g., low frequencies, including delta and theta; high frequencies, including alpha and beta) were calculated for each subject at t0 and t1. tDCS-induced changes in EEG neurophysiological markers were correlated with the performance of patients at the WRT. At baseline, qEEG features in AD patients confirmed that the decreased high frequency power was correlated with lower MMSE. After anodal tDCS, we observed an increase in the high-frequency power in the temporo-parietal area and an increase in the temporo-parieto-occipital coherence that correlated with the improvement at the WRT. In addition, cathodal tDCS produced a non-specific effect of decreased theta power all over the scalp that was not correlated with the clinical observation at the WRT. Our findings disclosed that tDCS induces significant modulations in the cortical EEG activity in AD patients. The abnormal pattern of EEG activity observed in AD during memory processing is partially reversed by applying anodal tDCS, suggesting that anodal tDCS benefits in AD patients during working memory tasks are supported by the modulation of cortical activity.
Collapse
Affiliation(s)
- Sara Marceglia
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Clinical Center for Neurostimulation, Neurotechnology, and Movement DisordersMilano, Italia; Dipartimento di Ingegneria e Architettura, Università degli Studi di TriesteTrieste, Italia
| | - Simona Mrakic-Sposta
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Clinical Center for Neurostimulation, Neurotechnology, and Movement DisordersMilano, Italia; Istituto di Bioimmagini e di Fisiologia Molecolare, Consiglio Nazionale delle RicercheSegrate, Italia
| | - Manuela Rosa
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Clinical Center for Neurostimulation, Neurotechnology, and Movement Disorders Milano, Italia
| | - Roberta Ferrucci
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Clinical Center for Neurostimulation, Neurotechnology, and Movement Disorders Milano, Italia
| | - Francesca Mameli
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Clinical Center for Neurostimulation, Neurotechnology, and Movement Disorders Milano, Italia
| | - Maurizio Vergari
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Clinical Center for Neurostimulation, Neurotechnology, and Movement Disorders Milano, Italia
| | - Mattia Arlotti
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Clinical Center for Neurostimulation, Neurotechnology, and Movement DisordersMilano, Italia; Dipartimento di Ingegneria Elettrica e dell'Informazione "Guglielmo Marconi," Università di BolognaCesena, Italia
| | - Fabiana Ruggiero
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Clinical Center for Neurostimulation, Neurotechnology, and Movement Disorders Milano, Italia
| | - Elio Scarpini
- Unità di Neurologia, Dipartimento di Fisiologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Italia
| | - Daniela Galimberti
- Unità di Neurologia, Dipartimento di Fisiologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milano, Italia
| | - Sergio Barbieri
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Clinical Center for Neurostimulation, Neurotechnology, and Movement Disorders Milano, Italia
| | - Alberto Priori
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Clinical Center for Neurostimulation, Neurotechnology, and Movement DisordersMilano, Italia; Dipartimento di Scienze della Salute, Università degli Studi di Milano, Polo Ospedaliero San PaoloMilano, Italia
| |
Collapse
|
10
|
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.
Collapse
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
| |
Collapse
|
11
|
Bian Z, Li Q, Wang L, Lu C, Yin S, Li X. Relative power and coherence of EEG series are related to amnestic mild cognitive impairment in diabetes. Front Aging Neurosci 2014. [PMID: 24550827 DOI: 10.3389/fnagi.2014.00011/bibtex] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
OBJECTIVE Diabetes is a risk factor for dementia and mild cognitive impairment. The aim of this study was to investigate whether some features of resting-state EEG (rsEEG) could be applied as a biomarker to distinguish the subjects with amnestic mild cognitive impairment (aMCI) from normal cognitive function in type 2 diabetes. MATERIALS AND METHODS In this study, 28 patients with type 2 diabetes (16 aMCI patients and 12 controls) were investigated. Recording of the rsEEG series and neuropsychological assessments were performed. The rsEEG signal was first decomposed into delta, theta, alpha, beta, gamma frequency bands. The relative power of each given band/sum of power and the coherence of waves from different brain areas were calculated. The extracted features from rsEEG and neuropsychological assessments were analyzed as well. RESULTS The main findings of this study were that: (1) compared with the control group, the ratios of power in theta band [P(theta)] vs. power in alpha band [P(alpha)] [P(theta)/P(alpha)] in the frontal region and left temporal region were significantly higher for aMCI, and (2) for aMCI, the alpha coherences in posterior, fronto-right temporal, fronto-posterior, right temporo-posterior were decreased; the theta coherences in left central-right central (LC-RC) and left posterior-right posterior (LP-RP) regions were also decreased; but the delta coherences in left temporal-right temporal (LT-RT) region were increased. CONCLUSION The proposed indexes from rsEEG recordings could be employed to track cognitive function of diabetic patients and also to help in the diagnosis of those who develop aMCI.
Collapse
Affiliation(s)
- Zhijie Bian
- Institute of Electrical Engineering, Yanshan University Qinhuangdao, China
| | - Qiuli Li
- Department of Neurology, The Second Artillery General Hospital of PLA Beijing, China
| | - Lei Wang
- Department of Neurology, The Second Artillery General Hospital of PLA Beijing, China
| | - Chengbiao Lu
- Institute of Electrical Engineering, Yanshan University Qinhuangdao, China
| | - Shimin Yin
- Department of Neurology, The Second Artillery General Hospital of PLA Beijing, China
| | - Xiaoli Li
- State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, Beijing Normal University Beijing, China ; Center for Collaboration and Innovation in Brain and Learning Sciences, Beijing Normal University Beijing, China
| |
Collapse
|
12
|
Bian Z, Li Q, Wang L, Lu C, Yin S, Li X. Relative power and coherence of EEG series are related to amnestic mild cognitive impairment in diabetes. Front Aging Neurosci 2014; 6:11. [PMID: 24550827 PMCID: PMC3912457 DOI: 10.3389/fnagi.2014.00011] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Accepted: 01/19/2014] [Indexed: 12/25/2022] Open
Abstract
Objective: Diabetes is a risk factor for dementia and mild cognitive impairment. The aim of this study was to investigate whether some features of resting-state EEG (rsEEG) could be applied as a biomarker to distinguish the subjects with amnestic mild cognitive impairment (aMCI) from normal cognitive function in type 2 diabetes. Materials and Methods: In this study, 28 patients with type 2 diabetes (16 aMCI patients and 12 controls) were investigated. Recording of the rsEEG series and neuropsychological assessments were performed. The rsEEG signal was first decomposed into delta, theta, alpha, beta, gamma frequency bands. The relative power of each given band/sum of power and the coherence of waves from different brain areas were calculated. The extracted features from rsEEG and neuropsychological assessments were analyzed as well. Results: The main findings of this study were that: (1) compared with the control group, the ratios of power in theta band [P(theta)] vs. power in alpha band [P(alpha)] [P(theta)/P(alpha)] in the frontal region and left temporal region were significantly higher for aMCI, and (2) for aMCI, the alpha coherences in posterior, fronto-right temporal, fronto-posterior, right temporo-posterior were decreased; the theta coherences in left central-right central (LC-RC) and left posterior-right posterior (LP-RP) regions were also decreased; but the delta coherences in left temporal-right temporal (LT-RT) region were increased. Conclusion: The proposed indexes from rsEEG recordings could be employed to track cognitive function of diabetic patients and also to help in the diagnosis of those who develop aMCI.
Collapse
Affiliation(s)
- Zhijie Bian
- Institute of Electrical Engineering, Yanshan University Qinhuangdao, China
| | - Qiuli Li
- Department of Neurology, The Second Artillery General Hospital of PLA Beijing, China
| | - Lei Wang
- Department of Neurology, The Second Artillery General Hospital of PLA Beijing, China
| | - Chengbiao Lu
- Institute of Electrical Engineering, Yanshan University Qinhuangdao, China
| | - Shimin Yin
- Department of Neurology, The Second Artillery General Hospital of PLA Beijing, China
| | - Xiaoli Li
- State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, Beijing Normal University Beijing, China ; Center for Collaboration and Innovation in Brain and Learning Sciences, Beijing Normal University Beijing, China
| |
Collapse
|
13
|
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]
|
14
|
Kulandaivel K, Holmes GL. Power spectral analysis in infants with seizures: relationship to development. Epilepsy Behav 2011; 20:700-5. [PMID: 21439912 DOI: 10.1016/j.yebeh.2011.02.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Revised: 02/12/2011] [Accepted: 02/15/2011] [Indexed: 11/26/2022]
Abstract
There is increasing evidence that there is a strong relationship between brain oscillations and neurocognitive function. We used EEG power spectral analysis to determine if frequency and power provide an independent measure of developmental impairment in infants. We examined the spectral power of EEGs in 200 infants between 6 and 24 months of age who were evaluated for seizures. Infants were stratified into three age groups 6-12, 12-18, and 18-24 months, and development assessments were coded as normal, moderately delayed, and severely delayed. Compared with the normal infants, children with developmental delay had lower mean frequencies and greater delta and less theta and alpha power. Delta/theta and theta/alpha ratios were highly significant indicators of developmental status. This study demonstrates that frequency and power of brain oscillations during wakefulness is a strong predictor of development in infants. The findings support the concept that normal oscillatory activity is critical for normal cognitive function during development.
Collapse
Affiliation(s)
- Kandan Kulandaivel
- Department of Neurology, Neuroscience Center at Dartmouth, Dartmouth Medical School, Hanover, NH 03756, USA
| | | |
Collapse
|
15
|
van der Hiele K, Reijntjes RHAM, Vein AA, Westendorp RGJ, van Buchem MA, Bollen ELEM, Middelkoop HAM, van Dijk JG. Electromyographic activity in the EEG in Alzheimer's disease: noise or signal? Int J Alzheimers Dis 2011; 2011:547024. [PMID: 21559240 PMCID: PMC3089836 DOI: 10.4061/2011/547024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Accepted: 01/26/2011] [Indexed: 11/20/2022] Open
Abstract
Many efforts have been directed at negating the influence of electromyographic (EMG) activity on the EEG, especially in elderly demented patients. We wondered whether these “artifacts” might reflect cognitive and behavioural aspects of dementia. In this pilot study, 11 patients with probable Alzheimer's disease (AD), 13 with amnestic mild cognitive impairment (MCI) and 13 controls underwent EEG registration. As EMG measures, we used frontal and temporal 50–70 Hz activity. We found that the EEGs of AD patients displayed more theta activity, less alpha reactivity, and more frontal EMG than controls. Interestingly, increased EMG activity indicated more cognitive impairment and more depressive complaints. EEG variables on the whole distinguished better between groups than EMG variables, but an EMG variable was best for the distinction between MCI and controls. Our results suggest that EMG activity in the EEG could be more than noise; it differs systematically between groups and may reflect different cerebral functions than the EEG.
Collapse
Affiliation(s)
- Karin van der Hiele
- Neuropsychology, Department of Neurology, Leiden University Medical Centre, P.O. Box 9600, 2300 RC Leiden, The Netherlands
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Fonseca LC, Tedrus GMAS, Prandi LR, Andrade ACA. Quantitative electroencephalography power and coherence measurements in the diagnosis of mild and moderate Alzheimer's disease. ARQUIVOS DE NEURO-PSIQUIATRIA 2011; 69:297-303. [DOI: 10.1590/s0004-282x2011000300006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 12/16/2010] [Indexed: 11/21/2022]
Abstract
OBJECTIVE: To evaluate the contribution of quantitative electroencephalographic (qEEG) analyses in the diagnosis of Alzheimer's disease (AD). METHOD: Thirty-five patients from the Neurology Outpatients Clinic of PUC-Campinas, diagnosed with AD according to the NINCDS/ADRDA were evaluated, and compared with a control group consisting of 30 individuals with no cognitive deficit. The procedures consisted of clinical-neurological, cognitive and behavioral analyses and the qEEG (absolute power and coherence). RESULTS: The AD group presented greater absolute power values in the delta and theta bands, greater theta/alpha indices and less frontal alpha and beta coherence. Logistic multiple regression models were constructed and those only showing variations in the qEEG (frontal alpha coherence and left frontal absolute theta power) showed an accuracy classification (72.3%) below that obtained in the mini-mental state examination (93%). CONCLUSION: The study of coherence and power in the qEEG showed a relatively limited accuracy with respect to its application in routine clinical practice.
Collapse
|
17
|
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.
| | | | | | | |
Collapse
|
18
|
Jelic V, Kowalski J. Evidence-based evaluation of diagnostic accuracy of resting EEG in dementia and mild cognitive impairment. Clin EEG Neurosci 2009; 40:129-42. [PMID: 19534305 DOI: 10.1177/155005940904000211] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Cognitive impairment is the most frequent chronic condition in the elderly, and dementia is the most disabling form of cognitive impairment in elderly. In the absence of specific and reliable markers of etiologically different dementia syndromes and their preclinical stages, diagnosis in living patients is probabilistic and based on standardized clinical diagnostic criteria. There is still not enough information on the validity of the EEG method in dementia work-up, and an updated evidence-based consensus on appropriateness of this method in the initial evaluation of patients with suspected cognitive disorder and dementia is missing. Using an evidence-based technique we searched for articles on diagnostic accuracy of spontaneous EEG in dementia disorders published from 1980 until June 2008. Inclusion criteria were: original article published in English with 10 or more subjects per diagnostic group, diagnosed according to the established consensus clinical diagnostic criteria used as a "gold standard." In addition, it should have been possible to calculate from the reported results indexes of diagnostic test accuracy: sensitivity, specificity, likelihood ratios and diagnostic odds ratios. Forty-six articles were retrieved that satisfied eligibility criteria. Thirty-four (74%) studies employed case-control design where study population was recruited from consecutive patients at specialist clinic settings, 12 (26%) were prospective in terms of reported clinical followup of study population. Four (9%) studies used population-based samples and 5 (11%) studies stated in methods the recruitment procedures for patients and healthy subjects. Number of patients included in diagnostic groups and healthy subjects varied in included studies between 10 and 180 and 10 and 171, respectively. Figures on sensitivity and specificity across the studies varied widely. Positive likelihood ratio in studies reporting classification accuracies between Alzheimer's disease and controls ranged between 2.3 and 38.5, and diagnostic odds ratios consequently showed large variations between 7 and 219. In conclusion, despite the wealth of published research and reported high indexes of diagnostic accuracy of EEG, and qEEG in particular, in individual studies, evidence of diagnostic utility of resting EEG in dementia and mild cognitive impairment (MCI) is still not sufficient to establish this method for the initial evaluation of subjects with cognitive impairment in the routine clinical practice. Joint effort of preferably multicenter studies using uniform standards should develop optimized methods, investigate added diagnostic value of EEG in clinically established dementia diagnosis and predictive utility of EEG in MCI and questionable dementia.
Collapse
Affiliation(s)
- Vesna Jelic
- Karolinska Institute, Department of NVS, Alzheimer's Disease Research Centre, Stockholm, Sweden.
| | | |
Collapse
|
19
|
Abstract
Neuropsychological studies show that cognitive deficits associated with Alzheimer's disease (AD) are distinct from age-associated cognitive decline. Quantitative and qualitative differences are apparent across many cognitive domains, but are especially obvious in episodic memory (particularly delayed recall), semantic knowledge, and some aspects of executive functions. The qualitatively distinct pattern of deficits is less salient in very old AD patients than in younger AD patients. Although decline in episodic memory is usually the earliest cognitive change that occurs prior to the development of the AD dementia syndrome, asymmetry in cognitive abilities may also occur in this "preclinical" phase of the disease and predict imminent dementia. Discrete patterns of cognitive deficits occur in AD and several neuropathologically distinct age-associated neurodegenerative disorders. Knowledge of these differences helps to clinically distinguish among various causes of dementia and provides useful models for understanding brain-behavior relationships that mediate cognitive abilities affected in various neurodegenerative diseases.
Collapse
Affiliation(s)
- David P Salmon
- Department of Neurosciences, University of California, San Diego, California 92093, USA.
| | | |
Collapse
|
20
|
Stam CJ, de Haan W, Daffertshofer A, Jones BF, Manshanden I, van Cappellen van Walsum AM, Montez T, Verbunt JPA, de Munck JC, van Dijk BW, Berendse HW, Scheltens P. Graph theoretical analysis of magnetoencephalographic functional connectivity in Alzheimer's disease. Brain 2008; 132:213-24. [PMID: 18952674 DOI: 10.1093/brain/awn262] [Citation(s) in RCA: 611] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- C J Stam
- Department of Clinical Neurophysiology and MEG, Amsterdam, The Netherlands
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Adeli H, Ghosh-Dastidar S, Dadmehr N. A spatio-temporal wavelet-chaos methodology for EEG-based diagnosis of Alzheimer's disease. Neurosci Lett 2008; 444:190-4. [DOI: 10.1016/j.neulet.2008.08.008] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2008] [Revised: 08/01/2008] [Accepted: 08/02/2008] [Indexed: 11/16/2022]
|
22
|
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.
Collapse
Affiliation(s)
- Natalia Bobkova
- Institute of Cell Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
| | | | | | | | | |
Collapse
|
23
|
Kurimoto R, Ishii R, Canuet L, Ikezawa K, Azechi M, Iwase M, Yoshida T, Kazui H, Yoshimine T, Takeda M. Event-related synchronization of alpha activity in early Alzheimer's disease and mild cognitive impairment: an MEG study combining beamformer and group comparison. Neurosci Lett 2008; 443:86-9. [PMID: 18634854 DOI: 10.1016/j.neulet.2008.07.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 06/25/2008] [Accepted: 07/04/2008] [Indexed: 10/21/2022]
Abstract
In patients with Alzheimer's disease (AD), it is sometimes challenging to identify typical findings in electroencephalography (EEG) or magnetoencephalography (MEG) such as a slowing of the posterior dominant activity or an increase in slow activity. In this MEG study, we evaluated the event-related synchronization (ERS) of alpha activity after eye closing in patients with early AD and mild cognitive impairment (MCI) who presented no slow MEG pattern. Thirteen patients with probable AD and thirteen patients with MCI, who met NINCDS-ADRDA and Petersen's diagnostic criteria, respectively, were enrolled. We also selected fourteen age-matched normal control subjects. MEG activity was acquired during eye-open and eye-closed states. The ERS after eye closing within 8-15Hz frequency band was calculated and its cortical source was superimposed on the individual's MRI by using the beamformer implemented in Brain Electrical Source Analysis (BESA). The Source image was converted into a standardized image, and group comparisons across patients with AD, MCI and controls were performed using BrainVoyager QX. The averaged ERS was observed dominantly in posterior regions in all three groups. Significant difference in ERS was observed only for the comparison between AD patients and controls, with AD patients showing increased ERS in frontal regions. Frontal shift of posterior alpha activity was observed clearly in AD patients using the combination of beamformer and group comparison.
Collapse
Affiliation(s)
- Ryu Kurimoto
- Department of Psychiatry, Osaka University Graduate School of Medicine, Osaka, Japan.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Jackson CE, Snyder PJ. Electroencephalography and event‐related potentials as biomarkers of mild cognitive impairment and mild Alzheimer's disease. Alzheimers Dement 2007; 4:S137-43. [DOI: 10.1016/j.jalz.2007.10.008] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2007] [Accepted: 10/24/2007] [Indexed: 11/29/2022]
Affiliation(s)
| | - Peter J. Snyder
- Department of PsychologyUniversity of ConnecticutStorrsCTUSA
- Department of NeurologyUniversity of Connecticut School of MedicineFarmingtonCTUSA
- Child Study CenterYale University School of MedicineNew HavenCTUSA
| |
Collapse
|
25
|
van der Hiele K, Vein AA, Reijntjes RHAM, Westendorp RGJ, Bollen ELEM, van Buchem MA, van Dijk JG, Middelkoop HAM. EEG correlates in the spectrum of cognitive decline. Clin Neurophysiol 2007; 118:1931-9. [PMID: 17604688 DOI: 10.1016/j.clinph.2007.05.070] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 05/14/2007] [Accepted: 05/22/2007] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To investigate relations between EEG measures and performance on tests of global cognition, memory, language and executive functioning. METHODS Twenty-two controls, 18 patients with mild cognitive impairment (MCI) and 16 with probable Alzheimer's disease (AD) underwent neuropsychological and EEG investigations. We used the following EEG measures: theta relative power during eyes closed, alpha reactivity during memory activation (i.e. the percentual decrease in alpha power as compared to eyes closed) and alpha coherence during eyes closed and memory activation. RESULTS Theta relative power was increased in AD patients as compared with controls (p<0.001) and MCI patients (p<0.01) and related to decreased performance in all cognitive domains. Alpha reactivity was decreased in AD patients as compared with controls (p<0.005) and related to decreased performance on tests of global cognition, memory and executive functioning. Alpha coherence did not differ between groups and was unrelated to cognition. CONCLUSIONS EEG power measures were associated with decreased performance on tests of global cognition, memory, language and executive functioning, while coherence measures were not. SIGNIFICANCE The EEG yielded several power measures related to cognitive functions. These EEG power measures might prove useful in prospective studies aimed at predicting longitudinal cognitive decline and dementia.
Collapse
Affiliation(s)
- K van der Hiele
- Department of Neurology, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands.
| | | | | | | | | | | | | | | |
Collapse
|
26
|
Hidasi Z, Czigler B, Salacz P, Csibri E, Molnár M. Changes of EEG spectra and coherence following performance in a cognitive task in Alzheimer's disease. Int J Psychophysiol 2007; 65:252-60. [PMID: 17586077 DOI: 10.1016/j.ijpsycho.2007.05.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Revised: 03/02/2007] [Accepted: 05/03/2007] [Indexed: 10/23/2022]
Abstract
Electroencephalographic measures combined with cognitive tasks are widely used for the assessment of cognitive and pathophysiological changes in Alzheimer's disease (AD). Instead of the analysis of EEG data obtained during the performance of the task, in this study data recorded in the immediate after-task period were analyzed. It was expected that this period would correspond to the electrophysiological consequences of the cognitive effort. Data of 14 patients with AD (MMS score: 16-24) were compared to that of 10 healthy control subjects. Reverse counting of a fix duration was used as a cognitive task. Changes of relative frequency spectra, and those of inter-and intrahemispheric coherence were analyzed. Relative theta power was significantly higher in AD patients compared to the controls both before and after the task. The performance of the task resulted in an increase of the relative alpha2 band in the AD group, whereas it slightly decreased in the control group. The most prominent coherence differences between AD and controls were found in the alpha1 band, especially for long-range coherence values. Coherence in this frequency band increased in the control group following the task, not seen in the AD group. We conclude that EEG parameters calculated from epochs following the completion of a cognitive task clearly differentiates patients with AD from normal controls. The electrophysiological changes found in AD may correspond to the decrease of functional connectivity of cortical areas and to the malfunctioning of the networks engaged in the cognitive task investigated.
Collapse
Affiliation(s)
- Zoltán Hidasi
- Department of Psychiatry and Psychotherapy, General Medical Faculty, Semmelweis University, Budapest, Hungary
| | | | | | | | | |
Collapse
|
27
|
Ponomareva NV, Korovaitseva GI, Rogaev EI. EEG alterations in non-demented individuals related to apolipoprotein E genotype and to risk of Alzheimer disease. Neurobiol Aging 2007; 29:819-27. [PMID: 17293007 DOI: 10.1016/j.neurobiolaging.2006.12.019] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2006] [Revised: 12/06/2006] [Accepted: 12/29/2006] [Indexed: 11/25/2022]
Abstract
Identification of preclinical markers is required for early diagnosis of Alzheimer's disease (AD) and cognitive dysfunction in advancing age. Quantitative EEG was examined in 145 individuals with AD, their unaffected relatives and unrelated individuals. The AD patients and their relatives were stratified by ApoE genotype. The resting EEG parameters were severely changed in AD patients, and in patients carrying the ApoE epsilon4 allele the decrease in alpha power was higher than in epsilon4 non-carriers. The resting EEG parameters were indistinguishable in AD relatives with different ApoE genotypes and similar to EEG pattern in common population. Under hyperventilation the presence of the epsilon4 allele in AD relatives was associated with the manifestation of synchronous high-voltage delta-, theta-activity and sharp-waves, pronounced decrease in alpha and increase in delta and theta relative powers. The data suggest that neurophysiological endophenotype of non-demented individuals at genetic risk for AD, characterized by increased excitability and dysfunction of deep brain and alpha rhythm-generating structures, may be revealed decades before the first clinical symptoms of presumable dementia.
Collapse
Affiliation(s)
- N V Ponomareva
- Institute of Neurology, Brain Research Department, Russian Academy of Medical Sciences, Moscow, Russia.
| | | | | |
Collapse
|
28
|
Stam CJ, Jones BF, Manshanden I, van Cappellen van Walsum AM, Montez T, Verbunt JPA, de Munck JC, van Dijk BW, Berendse HW, Scheltens P. Magnetoencephalographic evaluation of resting-state functional connectivity in Alzheimer's disease. Neuroimage 2006; 32:1335-44. [PMID: 16815039 DOI: 10.1016/j.neuroimage.2006.05.033] [Citation(s) in RCA: 202] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Revised: 05/11/2006] [Accepted: 05/15/2006] [Indexed: 10/24/2022] Open
Abstract
Statistical interdependencies between magnetoencephalographic signals recorded over different brain regions may reflect the functional connectivity of the resting-state networks. We investigated topographic characteristics of disturbed resting-state networks in Alzheimer's disease patients in different frequency bands. Whole-head 151-channel MEG was recorded in 18 Alzheimer patients (mean age 72.1 years, SD 5.6; 11 males) and 18 healthy controls (mean age 69.1 years, SD 6.8; 7 males) during a no-task eyes-closed resting state. Pair-wise interdependencies of MEG signals were computed in six frequency bands (delta, theta, alpha1, alpha2, beta and gamma) with the synchronization likelihood (a nonlinear measure) and coherence and grouped into long distance (intra- and interhemispheric) and short distance interactions. In the alpha1 and beta band, Alzheimer patients showed a loss of long distance intrahemispheric interactions, with a focus on left fronto-temporal/parietal connections. Functional connectivity was increased in Alzheimer patients locally in the theta band (centro-parietal regions) and the beta and gamma band (occipito-parietal regions). In the Alzheimer group, positive correlations were found between alpha1, alpha2 and beta band synchronization likelihood and MMSE score. Resting-state functional connectivity in Alzheimer's disease is characterized by specific changes of long and short distance interactions in the theta, alpha1, beta and gamma bands. These changes may reflect loss of anatomical connections and/or reduced central cholinergic activity and could underlie part of the cognitive impairment.
Collapse
Affiliation(s)
- C J Stam
- Department of Clinical Neurophysiology and MEG, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Festa EK, Insler RZ, Salmon DP, Paxton J, Hamilton JM, Heindel WC. Neocortical disconnectivity disrupts sensory integration in Alzheimer's disease. Neuropsychology 2006; 19:728-38. [PMID: 16351348 DOI: 10.1037/0894-4105.19.6.728] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The cortical pathology in Alzheimer's disease (AD) should lead to the loss of effective interaction between distinct neocortical areas. This study compared 2 conditions within a single sensory integration task that differed in the demands placed on effective cross-cortical interaction. AD patients were impaired in their ability to bind distinct visual features of a stimulus when this binding placed greater demands on cross-cortical interaction (i.e., motion and color) but were not impaired when this binding placed lesser demands on such interaction (i.e., motion and luminance). In contrast, neurologically intact individuals and patients with Huntington's disease were able to effectively bind features under both conditions. These results provide psychophysical support for the presence of functional disconnectivity in AD and demonstrate the utility of AD for investigating the neurocognitive substrates of sensory integration.
Collapse
Affiliation(s)
- Elena K Festa
- Department of Psychology, Brown University, Providence, RI 02912, USA.
| | | | | | | | | | | |
Collapse
|
30
|
Spiegel A, Tonner PH, Renna M. Altered states of consciousness: Processed EEG in mental disease. Best Pract Res Clin Anaesthesiol 2006; 20:57-67. [PMID: 16634414 DOI: 10.1016/j.bpa.2005.07.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Due to increasing life expectancy and a rising elderly population in Europe, the incidence of mild cognitive impairment which may predict diseases like Alzheimer's Disease or Vascular Dementia, is rising. Neurophysiological techniques are simple and inexpensive tools for early diagnosis and provide useful and objective correlates of cognitive activity both in normal subjects and patients suffering from the above conditions. Cognitive impairment due to different mental disease is characterized by decreased power and coherence in the alpha/beta band, which suggests functional disconnection among cortical areas, whereas both power and coherence in the delta and theta bands increase as a sign of cortical deafferentation from subcortical structures. Quantification of power and phase relationship by bispectral analysis suggests the Bispectral Index could be a useful but simple tool for early diagnosis of mental disease.
Collapse
Affiliation(s)
- Andreas Spiegel
- Department of Anaesthesiology and Intensive Care Medicine, University Hospital Schleswig-Holstein, Campus Kiel, Schwanenweg 21, D-24105 Kiel, Germany.
| | | | | |
Collapse
|
31
|
Kai T, Asai Y, Sakuma K, Koeda T, Nakashima K. Quantitative electroencephalogram analysis in dementia with Lewy bodies and Alzheimer's disease. J Neurol Sci 2005; 237:89-95. [PMID: 16019033 DOI: 10.1016/j.jns.2005.05.017] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2005] [Accepted: 05/28/2005] [Indexed: 11/18/2022]
Abstract
Clinicopathophysiological differences between dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) remain obscure. Our goals were to determine whether characteristic findings of electroencephalogram (EEG) power and coherence in DLB and a differential pathophysiological mechanism of quantitative EEG existed between DLB and AD. The group consisted of 15 patients with AD or DLB and 12 age-matched controls. Original EEG signals were recorded from 14 scalp electrodes positioned according to the International 10-20 System, using digitally linked earlobes as a reference. Although EEG power spectral analysis showed increasing EEG power density in patients with DLB in the delta and theta bands, such a difference did not exist in patients with AD. Compared with AD, the delta and theta band intrahemispheric coherence values in the fronto-temporo-central regions were higher in DLB. In the beta band, AD was lower than DLB in almost all temporo-centro-parieto-occipital regions. Comparing the mean power value between patients with/without donepezil treatment, there was a significantly lower EEG power density in the delta and theta bands in DLB subjects taking donepezil than in subjects not taking donepezil, whereas there was no significant difference in AD patients. These results suggest that cholinergic dysfunction is stronger in DLB than AD.
Collapse
Affiliation(s)
- Toru Kai
- Division of Neurology, Institute of Neurological Sciences, Faculty of Medicine, Tottori University, 36-1 Nishimachi, Yonago 683-8504, Japan
| | | | | | | | | |
Collapse
|
32
|
Abstract
In a recent article the authors presented a comprehensive review of research performed on computational modeling of Alzheimer's disease (AD) and its markers with a focus on computer imaging, classification models, connectionist neural models, and biophysical neural models. The popularity of imaging techniques for detection and diagnosis of possible AD stems from the relative ease with which neurological markers can be converted to visual markers. However, due to the expense of specialized experts and equipment involved in the use of imaging techniques, a subject of significant research interest is detecting markers in EEGs obtained from AD patients. In this article, the authors present a state-of-the-art review of models of computation and analysis of EEGs for diagnosis and detection of AD. This review covers three areas: time-frequency analysis, wavelet analysis, and chaos analysis. The vast number of physiological parameters involved in the poorly understood processes responsible for AD yields a large combination of parameters that can be manipulated and studied. A combination of parameters from different investigation modalities seems to be more effective in increasing the accuracy of detection-and diagnosis.
Collapse
Affiliation(s)
- Hojjat Adeli
- Department of Biomedical Informatics, The Ohio State University, 470 Hitchcock Hall, 2070 Neil Avenue, Columbus, OH 43210, USA.
| | | | | |
Collapse
|
33
|
Brassen S, Braus DF, Weber-Fahr W, Tost H, Moritz S, Adler G. Late-onset depression with mild cognitive deficits: electrophysiological evidences for a preclinical dementia syndrome. Dement Geriatr Cogn Disord 2005; 18:271-7. [PMID: 15286459 DOI: 10.1159/000080028] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/04/2004] [Indexed: 12/22/2022] Open
Abstract
Mild cognitive impairment (MCI) is present in up to 60% of patients with late-onset depression and constitutes a major diagnostic problem in geriatric psychiatry. Searching for sensitive markers for the detection of early brain changes suggestive of dementia, we compared this depressive risk population with mildly to moderately demented patients and cognitively unimpaired depressed patients using EEG power and coherence. We found a considerable similarity between Alzheimer's disease patients and cognitively impaired depressed patients regarding the cognitive profile and EEG pattern. Changes in EEG power and coherence at frontotemporal leads in depressive patients with MCI thereby allowed discrimination from cognitively unimpaired patients with a sensitivity of 88% and a specifity of 81%.
Collapse
Affiliation(s)
- Stefanie Brassen
- NeuroImage Nord, Department of Psychiatry, University of Hamburg, Hamburg, Germany.
| | | | | | | | | | | |
Collapse
|
34
|
Franken IHA, Stam CJ, Hendriks VM, van den Brink W. Electroencephalographic power and coherence analyses suggest altered brain function in abstinent male heroin-dependent patients. Neuropsychobiology 2004; 49:105-10. [PMID: 14981343 DOI: 10.1159/000076419] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Previous studies have shown that drug abuse is associated with altered brain function. However, studies of heroin abuse-related brain dysfunctions are scarce. Electroencephalographic (EEG) power and coherence analyses are two important tools for examining the effects of drugs on brain function. In the present study, we compared EEG power and coherence measures of 18 abstinent heroin-dependent subjects with those of 12 healthy control subjects. Furthermore, within the heroin group, associations between heroin use in the past, heroin craving and these EEG measures were studied. The results show that heroin-dependent subjects have increased relative beta-2 power and increased left intrahemispheric gamma coherence compared with control subjects. Furthermore, coherence measures showed correlations with clinical variables. These EEG abnormalities may reflect underlying changes in brain function due to long-term drug abuse and premorbid characteristics.
Collapse
Affiliation(s)
- Ingmar H A Franken
- Parnassia Addiction Research Center, Den Haag, Rotterdam, The Netherlands.
| | | | | | | |
Collapse
|
35
|
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.
Collapse
Affiliation(s)
- Claudio Babiloni
- Dipartimento Fisiologia Umana e Farmacologia, Università degli Studi di Roma "La Sapienza', Rome, Italy.
| | | | | | | | | | | | | |
Collapse
|
36
|
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.
Collapse
Affiliation(s)
- Daria Osipova
- Cognitive Brain Research Unit, Department of Psychology, University of Helsinki, P.O. Box 9 00014, Helsinki, Finland.
| | | | | | | | | | | |
Collapse
|