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Musaeus CS, Kjaer TW, Lindberg U, Vestergaard MB, Bo H, Larsson W, Press DZ, Andersen BB, Høgh P, Kidmose P, Hemmsen MC, Rank ML, Hasselbalch SG, Waldemar G, Frederiksen KS. Subclinical epileptiform discharges in Alzheimer's disease are associated with increased hippocampal blood flow. Alzheimers Res Ther 2024; 16:80. [PMID: 38610005 PMCID: PMC11010418 DOI: 10.1186/s13195-024-01432-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 03/19/2024] [Indexed: 04/14/2024]
Abstract
BACKGROUND In epilepsy, the ictal phase leads to cerebral hyperperfusion while hypoperfusion is present in the interictal phases. Patients with Alzheimer's disease (AD) have an increased prevalence of epileptiform discharges and a study using intracranial electrodes have shown that these are very frequent in the hippocampus. However, it is not known whether there is an association between hippocampal hyperexcitability and regional cerebral blood flow (rCBF). The objective of the study was to investigate the association between rCBF in hippocampus and epileptiform discharges as measured with ear-EEG in patients with Alzheimer's disease. Our hypothesis was that increased spike frequency may be associated with increased rCBF in hippocampus. METHODS A total of 24 patients with AD, and 15 HC were included in the analysis. Using linear regression, we investigated the association between rCBF as measured with arterial spin-labelling MRI (ASL-MRI) in the hippocampus and the number of spikes/sharp waves per 24 h as assessed by ear-EEG. RESULTS No significant difference in hippocampal rCBF was found between AD and HC (p-value = 0.367). A significant linear association between spike frequency and normalized rCBF in the hippocampus was found for patients with AD (estimate: 0.109, t-value = 4.03, p-value < 0.001). Changes in areas that typically show group differences (temporal-parietal cortex) were found in patients with AD, compared to HC. CONCLUSIONS Increased spike frequency was accompanied by a hemodynamic response of increased blood flow in the hippocampus in patients with AD. This phenomenon has also been shown in patients with epilepsy and supports the hypothesis of hyperexcitability in patients with AD. The lack of a significant difference in hippocampal rCBF may be due to an increased frequency of epileptiform discharges in patients with AD. TRIAL REGISTRATION The study is registered at clinicaltrials.gov (NCT04436341).
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Affiliation(s)
- Christian Sandøe Musaeus
- Danish Dementia Research Centre (DDRC), Department of Neurology, Copenhagen University Hospital - Rigshospitalet, Inge Lehmanns vej 8, Copenhagen, 2100, Denmark.
| | - Troels Wesenberg Kjaer
- Danish Dementia Research Centre (DDRC), Department of Neurology, Copenhagen University Hospital - Rigshospitalet, Inge Lehmanns vej 8, Copenhagen, 2100, Denmark
| | - Ulrich Lindberg
- Functional Imaging Unit, Department of Clinical Physiology and Nuclear Medicine, University of Copenhagen, Valdemar Hansens Vej 13, Glostrup, 2600, Denmark
| | - Mark B Vestergaard
- Functional Imaging Unit, Department of Clinical Physiology and Nuclear Medicine, University of Copenhagen, Valdemar Hansens Vej 13, Glostrup, 2600, Denmark
| | - Henrik Bo
- Danish Dementia Research Centre (DDRC), Department of Neurology, Copenhagen University Hospital - Rigshospitalet, Inge Lehmanns vej 8, Copenhagen, 2100, Denmark
| | - Wiberg Larsson
- Functional Imaging Unit, Department of Clinical Physiology and Nuclear Medicine, University of Copenhagen, Valdemar Hansens Vej 13, Glostrup, 2600, Denmark
| | - Daniel Zvi Press
- Berenson-Allen Center for Non-invasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA, 02215, USA
| | - Birgitte Bo Andersen
- Danish Dementia Research Centre (DDRC), Department of Neurology, Copenhagen University Hospital - Rigshospitalet, Inge Lehmanns vej 8, Copenhagen, 2100, Denmark
| | - Peter Høgh
- Regional Dementia Research Centre, Department of Neurology, Zealand University Hospital, Vestermarksvej 11, Roskilde, 4000, Denmark
- Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 3B, Copenhagen, 2200, Denmark
| | - Preben Kidmose
- Department of Electrical and Computer Engineering, Aarhus University, Finlandsgade 22, Aarhus N, 8200, Denmark
| | | | | | - Steen Gregers Hasselbalch
- Danish Dementia Research Centre (DDRC), Department of Neurology, Copenhagen University Hospital - Rigshospitalet, Inge Lehmanns vej 8, Copenhagen, 2100, Denmark
- Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 3B, Copenhagen, 2200, Denmark
| | - Gunhild Waldemar
- Danish Dementia Research Centre (DDRC), Department of Neurology, Copenhagen University Hospital - Rigshospitalet, Inge Lehmanns vej 8, Copenhagen, 2100, Denmark
- Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 3B, Copenhagen, 2200, Denmark
| | - Kristian Steen Frederiksen
- Danish Dementia Research Centre (DDRC), Department of Neurology, Copenhagen University Hospital - Rigshospitalet, Inge Lehmanns vej 8, Copenhagen, 2100, Denmark
- Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 3B, Copenhagen, 2200, Denmark
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Musaeus CS, Kjaer TW, Cacic Hribljan M, Andersen BB, Høgh P, Kidmose P, Fabricius M, Hemmsen MC, Rank ML, Waldemar G, Frederiksen KS. Subclinical Epileptiform Activity in Dementia with Lewy Bodies. Mov Disord 2023; 38:1861-1870. [PMID: 37431847 DOI: 10.1002/mds.29531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 05/26/2023] [Accepted: 06/20/2023] [Indexed: 07/12/2023] Open
Abstract
BACKGROUND Patients with dementia with Lewy bodies (DLB) have a higher probability of seizures than in normal aging and in other types of neurodegenerative disorders. Depositions of α-synuclein, a pathological hallmark of DLB, can induce network excitability, which can escalate into seizure activity. Indicator of seizures are epileptiform discharges as observed using electroencephalography (EEG). However, no studies have so far investigated the occurrence of interictal epileptiform discharges (IED) in patients with DLB. OBJECTIVES To investigate if IED as measured with ear-EEG occurs with a higher frequency in patients with DLB compared to healthy controls (HC). METHODS In this longitudinal observational exploratory study, 10 patients with DLB and 15 HC were included in the analysis. Patients with DLB underwent up to three ear-EEG recordings, each lasting up to 2 days, over a period of 6 months. RESULTS At baseline, IED were detected in 80% of patients with DLB and in 46.7% of HC. The spike frequency (spikes or sharp waves/24 hours) was significantly higher in patients with DLB as compared to HC with a risk ratio of 2.52 (CI, 1.42-4.61; P-value = 0.001). Most IED occurred at night. CONCLUSIONS Long-term outpatient ear-EEG monitoring detects IED in most patients with DLB with an increased spike frequency compared to HC. This study extends the spectrum of neurodegenerative disorders in which epileptiform discharges occurs at an elevated frequency. It is possible that epileptiform discharges are, therefore, a consequence of neurodegeneration. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Christian Sandøe Musaeus
- Danish Dementia Research Centre (DDRC), Department of Neurology, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark
| | - Troels Wesenberg Kjaer
- Danish Dementia Research Centre (DDRC), Department of Neurology, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark
| | - Melita Cacic Hribljan
- Department of Clinical Neurophysiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Birgitte Bo Andersen
- Danish Dementia Research Centre (DDRC), Department of Neurology, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark
| | - Peter Høgh
- Regional Dementia Research Centre, Department of Neurology, Zealand University Hospital, Roskilde, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Preben Kidmose
- Department of Electrical and Computer Engineering, Aarhus University, Aarhus, Denmark
| | - Martin Fabricius
- Department of Clinical Neurophysiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | | | | | - Gunhild Waldemar
- Danish Dementia Research Centre (DDRC), Department of Neurology, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Kristian Steen Frederiksen
- Danish Dementia Research Centre (DDRC), Department of Neurology, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark
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Jørgensen SD, Kidmose P, Mikkelsen K, Blech M, Hemmsen MC, Rank ML, Kjaer TW. Long-term ear-EEG monitoring of sleep - A case study during shift work. J Sleep Res 2023; 32:e13853. [PMID: 36889935 DOI: 10.1111/jsr.13853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 01/26/2023] [Accepted: 01/26/2023] [Indexed: 03/10/2023]
Abstract
The interest in sleep as a potential clinical biomarker is growing, but the standard method of sleep assessment, polysomnography, is expensive, time consuming, and requires a lot of expert assistance for both set-up and interpretation. To make sleep analysis more available both in research and in the clinic, there is a need for a reliable wearable device for sleep staging. In this case study, we test ear-electroencephalography. A wearable, where electrodes are placed in the outer ear, as a platform for longitudinal at-home recording of sleep. We explore the usability of the ear-electroencephalography in a shift work case with alternating sleep conditions. We find the ear-electroencephalography platform to be reliable both in terms of showing substantial agreement to polysomnography after long-time use (with an overall agreement, using Cohen's kappa, of 0.72) and by being unobtrusive enough to wear during night shift conditions. We find that fractions of non-rapid eye movement sleep and transition probability between sleep stages show great potential as sleep metrics when exploring quantitative differences in sleep architecture between shifting sleep conditions. This study shows that the ear-electroencephalography platform holds great potential as a reliable wearable for quantifying sleep "in the wild", pushing this technology further towards clinical adaptation.
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Affiliation(s)
| | - Preben Kidmose
- Department of Electrical and Computer Engineering, Aarhus University, Aarhus, Denmark
| | - Kaare Mikkelsen
- Department of Electrical and Computer Engineering, Aarhus University, Aarhus, Denmark
| | | | | | | | - Troels Wesenberg Kjaer
- Department of Neurology, Zealand University Hospital, Roskilde, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
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Sandsten KE, Wainio-Theberge S, Nordgaard J, Kjaer TW, Northoff G, Parnas J. Relating self-disorders to neurocognitive and psychopathological measures in first-episode schizophrenia. Early Interv Psychiatry 2022; 16:1202-1210. [PMID: 35081668 PMCID: PMC9786869 DOI: 10.1111/eip.13269] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 09/27/2021] [Accepted: 01/18/2022] [Indexed: 12/30/2022]
Abstract
AIM The notion of a disturbed self as the core feature of schizophrenia dates back to the founding texts on the illness. Since the development of the psychometric tool for examination of anomalous self-experience (EASE), self-disorders have become accessible to empirical research. Empirical studies have shown that EASE measured self-disorders predict schizophrenia spectrum in prospective studies and consistently show a selective hyper aggregation of self-disorder in schizophrenia and schizotypal disorders. The aim of this study is to investigate the relationship between self-disorders cognitive deficits and symptoms in schizophrenia. METHODS Thirty-five non-acute first-episode patients with schizophrenia and 35 matched healthy controls were evaluated with EASE, cognitive deficits, and symptoms (PANSS positive, negative and general). [Correction added on 28 January 2022, after first online publication: the words, 'evaluated with' were missing and have now been added to the preceding sentence.] RESULTS: The results show that self-disorders and symptoms are correlated among patients with schizophrenia, but not with cognitive deficits. Moreover, with the exception of attentional deficits, neurocognitive impairment was not significantly higher among patients with schizophrenia compared to healthy controls. CONCLUSIONS We argue that this adds support to a view of schizophrenia as being characterized by specific traits of pre-reflective self-disturbance, which are related to the severity of symptoms, whereas neurocognitive impairment reflects a separate or distinct aspect of schizophrenia.
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Affiliation(s)
- Karl Erik Sandsten
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | | | - Julie Nordgaard
- Mental Health Center Amager, University Hospital of Copenhagen, Copenhagen, Denmark
| | | | - Georg Northoff
- University of Ottawa Institute of Mental Health Research, Ottawa, Ontario, Canada
| | - Josef Parnas
- Mental Health Center Glostrup, University Hospital of Copenhagen, Copenhagen, Denmark
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Kjaer TW, Rank ML, Hemmsen MC, Kidmose P, Mikkelsen K. Repeated automatic sleep scoring based on ear-EEG is a valuable alternative to manually scored polysomnography. PLOS Digit Health 2022; 1:e0000134. [PMID: 36812563 PMCID: PMC9931275 DOI: 10.1371/journal.pdig.0000134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 09/25/2022] [Indexed: 11/07/2022]
Abstract
While polysomnography (PSG) is the gold standard to quantify sleep, modern technology allows for new alternatives. PSG is obtrusive, affects the sleep it is set out to measure and requires technical assistance for mounting. A number of less obtrusive solutions based on alternative methods have been introduced, but few have been clinically validated. Here we validate one of these solutions, the ear-EEG method, against concurrently recorded PSG in twenty healthy subjects each measured for four nights. Two trained technicians scored the 80 nights of PSG independently, while an automatic algorithm scored the ear-EEG. The sleep stages and eight sleep metrics (Total Sleep Time (TST), Sleep Onset Latency, Sleep Efficiency, Wake After Sleep Onset, REM latency, REM fraction of TST, N2 fraction of TST, and N3 fraction of TST) were used in the further analysis. We found the sleep metrics: Total Sleep Time, Sleep Onset Latency, Sleep Efficiency, Wake After Sleep Onset were estimated with high accuracy and precision between automatic sleep scoring and manual sleep scoring. However, the REM latency and REM fraction of sleep showed high accuracy but low precision. Further, the automatic sleep scoring systematically overestimated the N2 fraction of sleep and slightly underestimated the N3 fraction of sleep. We demonstrate that sleep metrics estimated from automatic sleep scoring based on repeated ear-EEG in some cases are more reliably estimated with repeated nights of automatically scored ear-EEG than with a single night of manually scored PSG. Thus, given the obtrusiveness and cost of PSG, ear-EEG seems to be a useful alternative for sleep staging for the single night recording and an advantageous choice for several nights of sleep monitoring.
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Affiliation(s)
| | | | | | - Preben Kidmose
- Department of Electrical and Computer Engineering, University of Aarhus, Denmark
| | - Kaare Mikkelsen
- Department of Electrical and Computer Engineering, University of Aarhus, Denmark,* E-mail:
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Nielsen JM, Rades D, Kjaer TW. Wearable electroencephalography for ultra-long-term seizure monitoring: a systematic review and future prospects. Expert Rev Med Devices 2021; 18:57-67. [PMID: 34836477 DOI: 10.1080/17434440.2021.2012152] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
INTRODUCTION : Wearable electroencephalography (EEG) for objective seizure counting might transform the clinical management of epilepsy. Non-EEG modalities have been validated for the detection of convulsive seizures, but there is still an unmet need for the detection of non-convulsive seizures. AREAS COVERED : The main objective of this systematic review was to explore the current status on wearable surface- and subcutaneous EEG for long-term seizure monitoring in epilepsy. We included 17 studies and evaluated the progress on the field, including device specifications, intended populations, and main results on the published studies including diagnostic accuracy measures. Furthermore, we examine the hurdles for widespread clinical implementation. This systematic review and expert opinion both consults the PRISMA guidelines and reflects on the future perspectives of this emerging field. EXPERT OPINION : Wearable EEG for long-term seizure monitoring is an emerging field, with plenty of proposed devices and proof-of-concept clinical validation studies. The possible implications of these devices are immense including objective seizure counting and possibly forecasting. However, the true clinical value of the devices, including effects on patient important outcomes and clinical decision making is yet to be unveiled and large-scale clinical validation trials are called for.
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Affiliation(s)
- Jonas Munch Nielsen
- Department of Neurology, Zealand University Hospital, Region Sjælland. Vestermarksvej 11, 4000 Roskilde, Denmark.,Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
| | - Dirk Rades
- Department of Radiation Oncology, University of Lübeck, Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
| | - Troels Wesenberg Kjaer
- Department of Neurology, Zealand University Hospital, Region Sjælland. Vestermarksvej 11, 4000 Roskilde, Denmark.,Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
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Rønborg SN, Esteller R, Tcheng TK, Greene DA, Morrell MJ, Wesenberg Kjaer T, Arcot Desai S. Acute effects of brain-responsive neurostimulation in drug-resistant partial onset epilepsy. Clin Neurophysiol 2021; 132:1209-1220. [PMID: 33931295 DOI: 10.1016/j.clinph.2021.03.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 02/23/2021] [Accepted: 03/02/2021] [Indexed: 11/15/2022]
Abstract
OBJECTIVE Understanding the acute effects of responsive stimulation (AERS) based on intracranial EEG (iEEG) recordings in ambulatory patients with drug-resistant partial epilepsy, and correlating these with changes in clinical seizure frequency, may help clinicians more efficiently optimize responsive stimulation settings. METHODS In patients implanted with the NeuroPace® RNS® System, acute changes in iEEG spectral power following active and sham stimulation periods were quantified and compared within individual iEEG channels. Additionally, acute stimulation-induced acute iEEG changes were compared within iEEG channels before and after patients experienced substantial reductions in clinical seizure frequency. RESULTS Responsive stimulation resulted in a 20.7% relative decrease in spectral power in the 2-4 second window following active stimulation, compared to sham stimulation. On several detection channels, the AERS features changed when clinical outcomes improved but were relatively stable otherwise. AERS change direction associated with clinical improvement was generally consistent within detection channels. CONCLUSIONS In this retrospective analysis, patients with drug-resistant partial epilepsy treated with direct brain-responsive neurostimulation showed an acute stimulation related reduction in iEEG spectral power that was associated with reductions in clinical seizure frequency. SIGNIFICANCE Identifying favorable stimulation related changes in iEEG activity could help physicians to more rapidly optimize stimulation settings for each patient.
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Affiliation(s)
- Søren N Rønborg
- University of Copenhagen, Clinical Medicine, Copenhagen, Denmark; Zealand University Hospital, Department of Neurology, Roskilde, Denmark; Stanford University, Department of Neurology, Palo Alto, CA USA.
| | | | | | | | - Martha J Morrell
- NeuroPace, Inc., Mountain View, CA, USA; Stanford University, Department of Neurology, Palo Alto, CA USA
| | - Troels Wesenberg Kjaer
- University of Copenhagen, Clinical Medicine, Copenhagen, Denmark; Zealand University Hospital, Department of Neurology, Roskilde, Denmark
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Tuckute G, Hansen ST, Kjaer TW, Hansen LK. Real-Time Decoding of Attentional States Using Closed-Loop EEG Neurofeedback. Neural Comput 2021; 33:967-1004. [PMID: 33513324 DOI: 10.1162/neco_a_01363] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 10/16/2020] [Indexed: 11/04/2022]
Abstract
Sustained attention is a cognitive ability to maintain task focus over extended periods of time (Mackworth, 1948; Chun, Golomb, & Turk-Browne, 2011). In this study, scalp electroencephalography (EEG) signals were processed in real time using a 32 dry-electrode system during a sustained visual attention task. An attention training paradigm was implemented, as designed in DeBettencourt, Cohen, Lee, Norman, and Turk-Browne (2015) in which the composition of a sequence of blended images is updated based on the participant's decoded attentional level to a primed image category. It was hypothesized that a single neurofeedback training session would improve sustained attention abilities. Twenty-two participants were trained on a single neurofeedback session with behavioral pretraining and posttraining sessions within three consecutive days. Half of the participants functioned as controls in a double-blinded design and received sham neurofeedback. During the neurofeedback session, attentional states to primed categories were decoded in real time and used to provide a continuous feedback signal customized to each participant in a closed-loop approach. We report a mean classifier decoding error rate of 34.3% (chance = 50%). Within the neurofeedback group, there was a greater level of task-relevant attentional information decoded in the participant's brain before making a correct behavioral response than before an incorrect response. This effect was not visible in the control group (interaction p=7.23e-4), which strongly indicates that we were able to achieve a meaningful measure of subjective attentional state in real time and control participants' behavior during the neurofeedback session. We do not provide conclusive evidence whether the single neurofeedback session per se provided lasting effects in sustained attention abilities. We developed a portable EEG neurofeedback system capable of decoding attentional states and predicting behavioral choices in the attention task at hand. The neurofeedback code framework is Python based and open source, and it allows users to actively engage in the development of neurofeedback tools for scientific and translational use.
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Affiliation(s)
- Greta Tuckute
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark, and Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, 02139, U.S.A.,
| | - Sofie Therese Hansen
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark,
| | - Troels Wesenberg Kjaer
- Department of Neurology, Zealand University Hospital, 4000 Roskilde, Denmark, and Department of Clinical Medicine, University of Copenhagen, 2200 Copenhagen, Denmark,
| | - Lars Kai Hansen
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark,
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Musaeus CS, Salem LC, Kjaer TW, Waldemar G. Electroencephalographic functional connectivity is altered in persons with Down syndrome and Alzheimer's disease. J Intellect Disabil Res 2021; 65:236-245. [PMID: 33336867 DOI: 10.1111/jir.12803] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 10/06/2020] [Accepted: 11/21/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND Persons with Down syndrome (DS) are at increased risk of developing Alzheimer's dementia (DS-AD). Due to heterogeneity in the functioning in persons with DS, it is difficult to use cognitive testing to assess whether a person with DS has developed dementia due to AD. Electroencephalography (EEG) functional connectivity has shown promising results as a diagnostic tool for AD in persons without DS. In the current exploratory study, we investigated whether EEG functional connectivity could be used as a diagnostic marker of AD in persons with DS and the association with symptoms. METHODS Electroencephalography from 12 persons with DS and 16 persons with DS-AD were analysed, and both coherence and weighted phase lag index were calculated. In addition, we calculated the average coherence for fronto-parietal and temporo-parietal connections. Lastly, we investigated the correlation between the informant-based Dementia Screening Questionnaire in Intellectual Disability (DSQIID) and total alpha coherence. RESULTS Decreased alpha and increased delta coherence and weighted phase lag index were observed in DS-AD as compared with DS. The decrease in alpha coherence was more marked in the fronto-parietal connections as compared with the temporo-parietal connections. No significant correlation was found between DSQIID and total alpha coherence (P value = 0.095, rho = -0.335). CONCLUSION The decreased alpha coherence and weighted phase lag index have previously been found in AD. The increased delta coherence and weighted phase lag index may indicate a different initial neurophysiological presentation as compared with patients with AD or may be a sign of more advanced disease. Larger studies are needed to confirm the current findings.
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Affiliation(s)
- C S Musaeus
- Department of Neurology, Danish Dementia Research Centre (DDRC), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - L C Salem
- Department of Neurology, Danish Dementia Research Centre (DDRC), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - T W Kjaer
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
- Neurophysiology Center, Zealand University Hospital, Roskilde, Denmark
| | - G Waldemar
- Department of Neurology, Danish Dementia Research Centre (DDRC), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
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Larsen LH, Lauritzen MH, Gangstad SW, Kjaer TW. The Use of Small Electronic Devices and Health: Feasibility of Interventions for a Forthcoming Crossover Design. JMIR Form Res 2021; 5:e20410. [PMID: 33393907 PMCID: PMC7813629 DOI: 10.2196/20410] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 10/15/2020] [Accepted: 10/28/2020] [Indexed: 12/16/2022] Open
Abstract
Background Modern lifestyle is heavily affected by technology such as smartphones, tablets, and other small computers; yet it remains unclear how our health and well-being are affected by the heavy use of these devices. Objective This feasibility study aims to test two different interventions of an experimental protocol for a forthcoming large-scale community-based study and get estimates of parameters for sample size calculation. The aim of the large-scale study is to investigate the effect of (1) a wearable tracking device on aerobic capacity (VO2max/kg) and the effect of (2) restricting media use on total sleep time. Methods Twenty healthy participants were included and equipped with a wrist-worn device tracking physical activity and sleep. Participants were allocated to either a physical activity group, which was instructed to use the wrist-worn device to support exercise, or a sleep silent group, which was instructed to remove or switch off all electronic devices in the bedroom (except the wrist-worn tracking device). The intervention lasted approximately 4 weeks. Data collected included blood pressure, submaximal cycle ergometer test, self-reported technology use, and compliance of using the wearable tracking device. Results All participants wore the wearable tracking device 95.8% (SD 4.4%) of the time. Participants in the physical activity group increased aerobic capacity from 30.38 (SD 8.98) to 32.1 (SD 8.71) mL/kg/min (t=–2.31, P=.046) and decreased their systolic blood pressure from 126.5 (SD 15.8) mm Hg to 121.8 (SD 11.7) mm Hg (t=2.72, P=.02). The sleep silent group prolonged their time offline before bedtime from 18.1 (SD 19.4) minutes to 27.2 (SD 17.3) minutes (t=–2.94, P=.02). Conclusions The two interventions are feasible to conduct. Participants were willing to wear the tracking device on their wrist and restrict all media use in their bedroom and thereby reduce bedtime technology use. Our results also suggest that tracking physical activity using a wearable device is accompanied by noteworthy health benefits. We outline necessary adjustments for a forthcoming large-scale study.
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Affiliation(s)
| | | | - Sirin Wilhelmsen Gangstad
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, Lyngby, Denmark.,Uneeg Medical, Lynge, Denmark
| | - Troels Wesenberg Kjaer
- Department of Neurology, Zealand University Hospital, Roskilde, Denmark.,Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Knudson M, Thomsen TH, Kjaer TW. Comparing Objective and Subjective Measures of Parkinson's Disease Using the Parkinson's KinetiGraph. Front Neurol 2020; 11:570833. [PMID: 33250843 PMCID: PMC7674832 DOI: 10.3389/fneur.2020.570833] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 10/01/2020] [Indexed: 11/25/2022] Open
Abstract
Background: Parkinson's disease (PD) is a neurodegenerative disease that can lead to impaired motor function and execution of activities of daily living (ADL). Since clinicians typically can only observe patients' symptoms during visits, prescribed medication schedules may not reflect the full range of symptoms experienced throughout the day. Therefore, objective tools are needed to provide comprehensive symptom data to optimize treatment. One such tool is the Parkinson's KinetiGraph® (PKG), a wearable sensor that measures motor symptoms of Parkinson's disease. Objective: To build a mathematical model to determine if PKG data measuring Parkinson's patients' motor symptoms can predict patients' ADL impairment. Methods: Thirty-four patients with PD wore the PKG device for 6 days while performing their ADL. Patients' PKG scores for bradykinesia and dyskinesia, as well as their responses to a questionnaire asking if their ADL-level had been impacted by various motor symptoms, were used to build a multiple regression model predicting the patients' Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part II scores. Results: Calculation of bradykinesia score response to medication showed that using a dosage response time of 30 min yielded a greater bradykinesia response than when the response time was set to 40, 50, 60, 70, 80, or 90 min. The overall multiple regression model predicting MDS-UPDRS part II score was significant (R2 = 0.546, p < 0.001). Conclusion: The PKG's ability to provide motor symptom data that correlates with clinical measures of ADL impairment suggests that it has strong potential as a tool for the assessment and management of Parkinson's disease motor symptoms.
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Affiliation(s)
- Mei Knudson
- Department of Mathematics and Statistics, Carleton College, Northfield, MN, United States.,DIS Copenhagen, Copenhagen, Denmark.,Department of Clinical Neurophysiology and Neurology, Zealand University Hospital, Roskilde, Denmark
| | - Trine Hoermann Thomsen
- Department of Clinical Neurophysiology and Neurology, Zealand University Hospital, Roskilde, Denmark.,Department of Clinical Medicine, Faculty of Health, University of Copenhagen, Copenhagen, Denmark
| | - Troels Wesenberg Kjaer
- DIS Copenhagen, Copenhagen, Denmark.,Department of Clinical Neurophysiology and Neurology, Zealand University Hospital, Roskilde, Denmark.,Department of Clinical Medicine, Faculty of Health, University of Copenhagen, Copenhagen, Denmark
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12
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Abstract
Schizophrenia (SCZ) can be characterized as a basic self-disorder that is featured by abnormal temporal integration on phenomenological (experience) and psychological (information processing) levels. Temporal integration on the neuronal level can be measured by the brain's intrinsic neural timescale using the autocorrelation window (ACW) and power-law exponent (PLE). Our goal was to relate intrinsic neural timescales (ACW, PLE), as a proxy of temporal integration on the neuronal level, to temporal integration related to self-disorder on psychological (Enfacement illusion task in electroencephalography) and phenomenological (Examination of Anomalous Self-Experience [EASE]) levels. SCZ participants exhibited prolonged ACW and higher PLE during the self-referential task (Enfacement illusion), but not during the non-self-referential task (auditory oddball). The degree of ACW/PLE change during task relative to rest was significantly reduced in self-referential task in SCZ. A moderation model showed that low and high ACW/PLE exerted differential impact on the relationship of self-disorder (EASE) and negative symptoms (PANSS). In sum, we demonstrate abnormal prolongation in intrinsic neural timescale during self-reference in SCZ including its relation to basic self-disorder and negative symptoms. Our results point to abnormal relation of self and temporal integration at the core of SCZ constituting a "common currency" of neuronal, psychological, and phenomenological levels.
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Affiliation(s)
- Georg Northoff
- Mental Health Center, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China,Mind, Brain Imaging and Neuroethics, Institute of Mental Health Research, University of Ottawa, Ottawa, ON, Canada,To whom correspondence should be addressed; Mental Health Centre/7th Hospital, Zhejiang University School of Medicine, Hangzhou, Tianmu Road 305, Hangzhou, Zhejiang Province, 310013, China; Mind, Brain Imaging and Neuroethics, Institute of Mental Health Research, Royal Ottawa Healthcare Group and University of Ottawa, 1145 Carling Avenue, Room 6467, Ottawa, ON K1Z 7K4, Canada; tel: 613-722-6521 ex. 6959, fax: 613-798-2982, e-mail:
| | - Karl Erik Sandsten
- Early Psychosis Intervention Center, Region Zealand Psychiatry, Roskilde, Denmark
| | | | | | - Josef Parnas
- Center for Subjectivity Research, Copenhagen University, Copenhagen, Denmark,Mental Health Center Glostrup, Denmark
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13
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Affiliation(s)
| | - Troels Wesenberg Kjaer
- University of Copenhagen, Denmark
- Department of Neurology, Zealand University Hospital, Denmark
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14
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Musaeus CS, Engedal K, Høgh P, Jelic V, Khanna AR, Kjaer TW, Mørup M, Naik M, Oeksengaard AR, Santarnecchi E, Snaedal J, Wahlund LO, Waldemar G, Andersen BB. Changes in the left temporal microstate are a sign of cognitive decline in patients with Alzheimer's disease. Brain Behav 2020; 10:e01630. [PMID: 32338460 PMCID: PMC7303403 DOI: 10.1002/brb3.1630] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 03/05/2020] [Accepted: 03/20/2020] [Indexed: 01/01/2023] Open
Abstract
INTRODUCTION Large-scale brain networks are disrupted in the early stages of Alzheimer's disease (AD). Electroencephalography microstate analysis, a promising method for studying brain networks, parses EEG signals into topographies representing discrete, sequential network activations. Prior studies indicate that patients with AD show a pattern of global microstate disorganization. We investigated whether any specific microstate changes could be found in patients with AD and mild cognitive impairment (MCI) compared to healthy controls (HC). MATERIALS AND METHODS Standard EEGs were obtained from 135 HC, 117 patients with MCI, and 117 patients with AD from six Nordic memory clinics. We parsed the data into four archetypal microstates. RESULTS There was significantly increased duration, occurrence, and coverage of microstate A in patients with AD and MCI compared to HC. When looking at microstates in specific frequency bands, we found that microstate A was affected in delta (1-4 Hz), theta (4-8 Hz), and beta (13-30 Hz), while microstate D was affected only in the delta and theta bands. Microstate features were able to separate HC from AD with an accuracy of 69.8% and HC from MCI with an accuracy of 58.7%. CONCLUSIONS Further studies are needed to evaluate whether microstates represent a valuable disease classifier. Overall, patients with AD and MCI, as compared to HC, show specific microstate alterations, which are limited to specific frequency bands. These alterations suggest disruption of large-scale cortical networks in AD and MCI, which may be limited to specific frequency bands.
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Affiliation(s)
- Christian S Musaeus
- Department of Neurology, Danish Dementia Research Centre (DDRC), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Knut Engedal
- Norwegian National Advisory Unit on Ageing and Health (Ageing and Health), Vestfold Hospital Trust and Oslo University Hospital, Ullevaal, Oslo, Norway
| | - Peter Høgh
- Regional Dementia Research Center, Department of Neurology, Zealand University Hospital, Roskilde, Denmark.,Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Vesna Jelic
- Division of Clinical Geriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden.,Department of Geriatric Medicine, Memory Clinic, Karolinska University Hospital, Huddinge, Sweden
| | - Arjun R Khanna
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Troels Wesenberg Kjaer
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.,Neurophysiology Center, Zealand University Hospital, Roskilde, Denmark
| | - Morten Mørup
- Section for Cognitive Systems, DTU Compute, Technical University of Denmark, Lyngby, Denmark
| | - Mala Naik
- Department of Geriatric Medicine, Haraldsplass Deaconess Hospital, Bergen, Norway
| | - Anne-Rita Oeksengaard
- Division of Clinical Geriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Emiliano Santarnecchi
- Berenson-Allen Center for Non-invasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Jon Snaedal
- Department of Geriatric Medicine, Landspítali University Hospital, Reykjavik, Iceland
| | - Lars-Olof Wahlund
- Division of Clinical Geriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Gunhild Waldemar
- Department of Neurology, Danish Dementia Research Centre (DDRC), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Birgitte B Andersen
- Department of Neurology, Danish Dementia Research Centre (DDRC), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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15
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Jochumsen M, Knoche H, Kjaer TW, Dinesen B, Kidmose P. EEG Headset Evaluation for Detection of Single-Trial Movement Intention for Brain-Computer Interfaces. Sensors (Basel) 2020; 20:s20102804. [PMID: 32423133 PMCID: PMC7287803 DOI: 10.3390/s20102804] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/10/2020] [Accepted: 05/13/2020] [Indexed: 01/26/2023]
Abstract
Brain-computer interfaces (BCIs) can be used in neurorehabilitation; however, the literature about transferring the technology to rehabilitation clinics is limited. A key component of a BCI is the headset, for which several options are available. The aim of this study was to test four commercially available headsets' ability to record and classify movement intentions (movement-related cortical potentials-MRCPs). Twelve healthy participants performed 100 movements, while continuous EEG was recorded from the headsets on two different days to establish the reliability of the measures: classification accuracies of single-trials, number of rejected epochs, and signal-to-noise ratio. MRCPs could be recorded with the headsets covering the motor cortex, and they obtained the best classification accuracies (73%-77%). The reliability was moderate to good for the best headset (a gel-based headset covering the motor cortex). The results demonstrate that, among the evaluated headsets, reliable recordings of MRCPs require channels located close to the motor cortex and potentially a gel-based headset.
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Affiliation(s)
- Mads Jochumsen
- Department of Health Science and Technology, Aalborg University, 9220 Aalborg, Denmark;
- Correspondence:
| | - Hendrik Knoche
- Department of Architecture, Design and Media Technology, Aalborg University, 9000 Aalborg, Denmark;
| | - Troels Wesenberg Kjaer
- Department of Neurology, Zealand University Hospital, Roskilde, Denmark. Department of Clinical Medicine, University of Copenhagen, 2200 Copenhagen, Denmark;
| | - Birthe Dinesen
- Department of Health Science and Technology, Aalborg University, 9220 Aalborg, Denmark;
| | - Preben Kidmose
- Department of Engineering—Electrical and Computer Engineering, Aarhus University, 8200 Aarhus, Denmark;
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16
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Sandsten KE, Nordgaard J, Kjaer TW, Gallese V, Ardizzi M, Ferroni F, Petersen J, Parnas J. Altered self-recognition in patients with schizophrenia. Schizophr Res 2020; 218:116-123. [PMID: 32007345 DOI: 10.1016/j.schres.2020.01.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 01/12/2020] [Accepted: 01/19/2020] [Indexed: 10/25/2022]
Abstract
Self-alienation is a common characterization of various disturbing experiences in patients with schizophrenia. A vivid example comes from patient reports of not recognizing themselves when inspecting their specular image in the mirror. By applying the multisensory paradigm of the Enfacement Illusion, this study empirically addresses the specular Self-Other discrimination in patients with schizophrenia. 35 patients diagnosed with schizophrenia and 35 healthy matched controls were enrolled in the study. Results found that the group of patients with schizophrenia had a significant skewed self-other discrimination towards the other at baseline. Furthermore, the effect of visuo-tactile stimulation on self-recognition in the schizophrenia patients was significantly altered after both synchronous and asynchronous stimulation compared to baseline. This contrasted with healthy controls which in line with earlier studies only had significantly different self-recognition after synchronous stimulation. The study thus suggests that patients with schizophrenia have deviations in their specular self-recognition compared to healthy controls. Moreover, that temporal factors in multisensory integration may contribute to alterations of self-related stimuli in patients with schizophrenia.
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Affiliation(s)
- Karl Erik Sandsten
- Early Psychosis Intervention Center, Region Zealand Psychiatry, Roskilde, Denmark.
| | | | | | - Vittorio Gallese
- Department of Medicine and Surgery, University of Parma, Parma, Italy; Institute of Philosophy, School of Advanced Study, University of London, London, UK
| | - Martina Ardizzi
- Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Francesca Ferroni
- Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Janne Petersen
- Center for Clinical Research and Prevention, Frederiksberg Hospital, Copenhagen, Denmark
| | - Josef Parnas
- Center for Subjectivity Research, Copenhagen University, Denmark; Mental Health Center Glostrup, Brondby, Denmark
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17
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Musaeus CS, Salem LC, Kjaer TW, Waldemar G. Microstate Changes Associated With Alzheimer's Disease in Persons With Down Syndrome. Front Neurosci 2019; 13:1251. [PMID: 31849579 PMCID: PMC6892825 DOI: 10.3389/fnins.2019.01251] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Accepted: 11/05/2019] [Indexed: 11/13/2022] Open
Abstract
Down syndrome (DS) is associated with development of dementia due to Alzheimer’s disease (AD). However, due to considerable heterogeneity in intellectual function among persons with DS, it is difficult to assess whether a person with DS has developed dementia due to AD (DS-AD). EEG spectral power has previously shown very promising results with increased slowing in DS-AD compared to DS. However, another technique called microstates may be used to assess whole-brain dynamics and has to our knowledge not previously been investigated in either DS or DS-AD. The aim of the current study was to assess whether microstates could be used to differentiate between adults with DS, and DS-AD. We included EEGs from 10 persons with DS and 15 persons with DS-AD in the analysis. For the microstate analyses, we calculated four global maps, which were then back-fitted to all the EEGs. Lastly, we extracted the duration, occurrence, and coverage for each of the microstates. Here, we found the four archetypical maps as has previously been reported in the literature. We did not find any significant difference between DS and DS-AD but the largest difference in microstate duration between DS and DS-AD was found in microstate A and D. These findings are in line with structural MR studies showing that both the frontal and temporal lobes are affected in persons with DS-AD. Microstates may potentially serve as a diagnostic marker, but larger studies are needed to confirm these findings.
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Affiliation(s)
- Christian Sandøe Musaeus
- Danish Dementia Research Centre, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Lise Cronberg Salem
- Danish Dementia Research Centre, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Troels Wesenberg Kjaer
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.,Neurophysiology Center, Zealand University Hospital, Roskilde, Denmark
| | - Gunhild Waldemar
- Danish Dementia Research Centre, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
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18
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Musaeus CS, Salem LC, Sabers A, Kjaer TW, Waldemar G. Associations between electroencephalography power and Alzheimer's disease in persons with Down syndrome. J Intellect Disabil Res 2019; 63:1151-1157. [PMID: 31025465 DOI: 10.1111/jir.12627] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/14/2019] [Accepted: 03/20/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND It is complicated to diagnose dementia in persons with Down syndrome (DS). Older studies have, however, demonstrated low-frequency activity in electroencephalography (EEG) in persons with concurrent DS and Alzheimer's disease (DS-AD). The aim of this study was to examine whether it was possible to identify AD-associated changes (increased high-frequency power and decreased low-frequency power) in persons with DS-AD compared with DS. METHODS We included 21 persons with DS-AD and 16 with DS without cognitive deterioration assessed by the informant-based Dementia Screening Questionnaire in Intellectual Disability. EEG was recorded for all participants. Absolute power for each electrode and global power were calculated for all frequency bands for both eyes open and eyes closed. RESULTS For global power in the eyes closed condition, we found an increased global slow-frequency activity and a decreased global high-frequency activity in DS-AD compared with DS. In addition, we found a significant difference in the global alpha/delta ratio with the largest difference found for global alpha power in DS-AD compared with DS. CONCLUSIONS In the current study, we found that changes known to be associated with AD could also be identified when comparing DS-AD with DS using quantitative EEG. In general, these findings suggest that EEG might be a useful tool in diagnosing AD in persons with DS, but larger studies are needed.
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Affiliation(s)
- C S Musaeus
- Department of Neurology, Danish Dementia Research Centre (DDRC), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - L C Salem
- Department of Neurology, Danish Dementia Research Centre (DDRC), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - A Sabers
- The Epilepsy Clinic, Department of Neurology, Rigshospitalet-Blegdamsvej, University Hospital, Copenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - T W Kjaer
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
- Neurophysiology Center, Zealand University Hospital, Roskilde, Denmark
| | - G Waldemar
- Department of Neurology, Danish Dementia Research Centre (DDRC), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
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19
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Kjaer TW, Hogenhaven H, Lee AP, Madsen FF, Jespersen B, Brennum J, Derm L, Moltke FB. Pharmacodynamics of remifentanil. Induced intracranial spike activity in mesial temporal lobe epilepsy. Epilepsy Res 2017; 133:41-45. [DOI: 10.1016/j.eplepsyres.2017.03.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 02/27/2017] [Accepted: 03/28/2017] [Indexed: 10/19/2022]
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20
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Olsen AS, Steensberg AT, la Cour M, Kjaer TW, Damato B, Pinborg LH, Kolko M. Can DMCO Detect Visual Field Loss in Neurological Patients? A Secondary Validation Study. Ophthalmic Res 2017; 58:85-93. [DOI: 10.1159/000468942] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 03/04/2017] [Indexed: 11/19/2022]
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21
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Andersen AD, Blaabjerg M, Binzer M, Kamal A, Thagesen H, Kjaer TW, Stenager E, Gramsbergen JBP. Cerebrospinal fluid levels of catecholamines and its metabolites in Parkinson's disease: effect of l-DOPA treatment and changes in levodopa-induced dyskinesia. J Neurochem 2017; 141:614-625. [PMID: 28244186 DOI: 10.1111/jnc.13997] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 02/09/2017] [Accepted: 02/15/2017] [Indexed: 11/28/2022]
Abstract
Levodopa (l-DOPA, l-3,4-dihydroxyphenylalanine) is the most effective drug in the symptomatic treatment of Parkinson's disease (PD), but chronic use initiates a maladaptive process leading to l-DOPA-induced dyskinesia (LID). Risk factors for early onset LID include younger age, more severe disease at baseline and higher daily l-DOPA dose, but biomarkers to predict the risk of motor complications are not yet available. Here, we investigated whether CSF levels of catecholamines and its metabolites are altered in PD patients with LID [PD-LID, n = 8)] as compared to non-dyskinetic PD patients receiving l-DOPA (PD-L, n = 6), or not receiving l-DOPA (PD-N, n = 7) as well as non-PD controls (n = 16). PD patients were clinically assessed using the Unified Parkinson's Disease Rating Scale and Unified Dyskinesia Rating Scale and CSF was collected after overnight fasting and 1-2 h after oral intake of l-DOPA or other anti-Parkinson medication. CSF catecholamines and its metabolites were analyzed by HPLC with electrochemical detection. We observed (i) decreased levels of dihydroxyphenylacetic acid (DOPAC) and homovanillic acid in PD patients not receiving l-DOPA (ii) higher dopamine (DA) levels in PD-LID as compared to controls (iii) higher DA/l-DOPA and lower DOPAC/DA ratio's in PD-LID as compared to PD-L and (iv) an age-dependent increase of DA and decrease of DOPAC/DA ratio in controls. These results suggest increased DA release from non-DA cells and deficient DA re-uptake in PD-LID. Monitoring DA and DOPAC in CSF of l-DOPA-treated PD patients may help identify patients at risk of developing LID.
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Affiliation(s)
- Andreas Dammann Andersen
- Department of Neurology, Hospital of Southern Jutland, Sønderborg, Denmark.,Institute of Regional Health Research, Center of Southern Jutland, University of Southern Denmark, Aabenraa, Denmark.,Focused Research Group in Neurology, Hospital of Southern Jutland, Aabenraa, Denmark.,Odense Patient data Exploratory Network, Odense University Hospital, Odense, Denmark
| | - Morten Blaabjerg
- Department of Neurology, Odense University Hospital, Odense, Denmark.,Department of Neurology, Zealand University Hospital, Roskilde, Denmark.,Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Michael Binzer
- Institute of Regional Health Research, Center of Southern Jutland, University of Southern Denmark, Aabenraa, Denmark.,Focused Research Group in Neurology, Hospital of Southern Jutland, Aabenraa, Denmark
| | - Akram Kamal
- Department of Neurology, Zealand University Hospital, Roskilde, Denmark
| | - Helle Thagesen
- Department of Neurology, Zealand University Hospital, Roskilde, Denmark
| | | | - Egon Stenager
- Department of Neurology, Hospital of Southern Jutland, Sønderborg, Denmark.,Institute of Regional Health Research, Center of Southern Jutland, University of Southern Denmark, Aabenraa, Denmark.,Focused Research Group in Neurology, Hospital of Southern Jutland, Aabenraa, Denmark.,The Multiple Sclerosis Clinic of Southern Jutland, Vejle, Sonderborg, Esbjerg, Denmark
| | - Jan Bert Paul Gramsbergen
- Institute of Molecular Medicine, Neurobiological Research, University of Southern Denmark, Odense, Denmark
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22
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Zibrandtsen I, Kidmose P, Otto M, Ibsen J, Kjaer TW. Case comparison of sleep features from ear-EEG and scalp-EEG. ACTA ACUST UNITED AC 2016; 9:69-72. [PMID: 27656268 PMCID: PMC5021956 DOI: 10.1016/j.slsci.2016.05.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 05/18/2016] [Accepted: 05/25/2016] [Indexed: 11/30/2022]
Abstract
Background We investigate the potential usability of a novel in-the-ear electroencephalography recording device for sleep staging. Methods In one healthy subject we compare simultaneous earelectroencephalography to standard scalp EEG visually and using power spectrograms. Hypnograms independently derived from the records are compared. Results We find that alpha activity, K complexes, sleep spindles and slow wave sleep can be visually distinguished using earelectroencephalography. Spectral peaks are shared between the two records. Hypnograms are 90.9% similar. Conclusion The results indicate that ear-electroencephalography can be used for sleep staging.
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Affiliation(s)
- I Zibrandtsen
- Neurophysiology Center, Dept. of Neurology, Zealand University Hospital, Roskilde, Denmark
| | - P Kidmose
- Dept. of Eng., Aarhus University, Aarhus, Denmark
| | - M Otto
- Dept. of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark
| | - J Ibsen
- Neurophysiology Center, Dept. of Neurology, Zealand University Hospital, Roskilde, Denmark
| | - T W Kjaer
- Neurophysiology Center, Dept. of Neurology, Zealand University Hospital, Roskilde, Denmark
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23
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Westhall E, Rossetti AO, van Rootselaar AF, Wesenberg Kjaer T, Horn J, Ullén S, Friberg H, Nielsen N, Rosén I, Åneman A, Erlinge D, Gasche Y, Hassager C, Hovdenes J, Kjaergaard J, Kuiper M, Pellis T, Stammet P, Wanscher M, Wetterslev J, Wise MP, Cronberg T. Standardized EEG interpretation accurately predicts prognosis after cardiac arrest. Neurology 2016; 86:1482-90. [PMID: 26865516 PMCID: PMC4836886 DOI: 10.1212/wnl.0000000000002462] [Citation(s) in RCA: 247] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 12/01/2015] [Indexed: 01/17/2023] Open
Abstract
Objective: To identify reliable predictors of outcome in comatose patients after cardiac arrest using a single routine EEG and standardized interpretation according to the terminology proposed by the American Clinical Neurophysiology Society. Methods: In this cohort study, 4 EEG specialists, blinded to outcome, evaluated prospectively recorded EEGs in the Target Temperature Management trial (TTM trial) that randomized patients to 33°C vs 36°C. Routine EEG was performed in patients still comatose after rewarming. EEGs were classified into highly malignant (suppression, suppression with periodic discharges, burst-suppression), malignant (periodic or rhythmic patterns, pathological or nonreactive background), and benign EEG (absence of malignant features). Poor outcome was defined as best Cerebral Performance Category score 3–5 until 180 days. Results: Eight TTM sites randomized 202 patients. EEGs were recorded in 103 patients at a median 77 hours after cardiac arrest; 37% had a highly malignant EEG and all had a poor outcome (specificity 100%, sensitivity 50%). Any malignant EEG feature had a low specificity to predict poor prognosis (48%) but if 2 malignant EEG features were present specificity increased to 96% (p < 0.001). Specificity and sensitivity were not significantly affected by targeted temperature or sedation. A benign EEG was found in 1% of the patients with a poor outcome. Conclusions: Highly malignant EEG after rewarming reliably predicted poor outcome in half of patients without false predictions. An isolated finding of a single malignant feature did not predict poor outcome whereas a benign EEG was highly predictive of a good outcome.
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Affiliation(s)
- Erik Westhall
- Authors' affiliations are listed at the end of the article.
| | | | | | | | - Janneke Horn
- Authors' affiliations are listed at the end of the article
| | - Susann Ullén
- Authors' affiliations are listed at the end of the article
| | - Hans Friberg
- Authors' affiliations are listed at the end of the article
| | - Niklas Nielsen
- Authors' affiliations are listed at the end of the article
| | - Ingmar Rosén
- Authors' affiliations are listed at the end of the article
| | - Anders Åneman
- Authors' affiliations are listed at the end of the article
| | - David Erlinge
- Authors' affiliations are listed at the end of the article
| | - Yvan Gasche
- Authors' affiliations are listed at the end of the article
| | | | - Jan Hovdenes
- Authors' affiliations are listed at the end of the article
| | | | - Michael Kuiper
- Authors' affiliations are listed at the end of the article
| | - Tommaso Pellis
- Authors' affiliations are listed at the end of the article
| | - Pascal Stammet
- Authors' affiliations are listed at the end of the article
| | | | | | - Matt P Wise
- Authors' affiliations are listed at the end of the article
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Westhall E, Rosén I, Rossetti AO, van Rootselaar AF, Kjaer TW, Horn J, Ullén S, Friberg H, Nielsen N, Cronberg T. Electroencephalography (EEG) for neurological prognostication after cardiac arrest and targeted temperature management; rationale and study design. BMC Neurol 2014; 14:159. [PMID: 25267568 PMCID: PMC4440598 DOI: 10.1186/s12883-014-0159-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 07/29/2014] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Electroencephalography (EEG) is widely used to assess neurological prognosis in patients who are comatose after cardiac arrest, but its value is limited by varying definitions of pathological patterns and by inter-rater variability. The American Clinical Neurophysiology Society (ACNS) has recently proposed a standardized EEG-terminology for critical care to address these limitations. METHODS/DESIGN In the TTM-trial, 399 post cardiac arrest patients who remained comatose after rewarming underwent a routine EEG. The presence of clinical seizures, use of sedatives and antiepileptic drugs during the EEG-registration were prospectively documented. DISCUSSION A well-defined terminology for interpreting post cardiac arrest EEGs is critical for the use of EEG as a prognostic tool. TRIAL REGISTRATION The TTM-trial is registered at ClinicalTrials.gov (NCT01020916).
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Affiliation(s)
- Erik Westhall
- />Department of Clinical Sciences, Division of Clinical Neurophysiology, Lund University, Lund, Sweden
| | - Ingmar Rosén
- />Department of Clinical Sciences, Division of Clinical Neurophysiology, Lund University, Lund, Sweden
| | - Andrea O Rossetti
- />Department of Neurology, CHUV and University of Lausanne, Lausanne, Switzerland
| | - Anne-Fleur van Rootselaar
- />Department of Neurology/Clinical Neurophysiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Troels Wesenberg Kjaer
- />Department of Clinical Neurophysiology, Rigshospitalet University Hospital, Copenhagen, Denmark
| | - Janneke Horn
- />Department of Intensive Care Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Susann Ullén
- />R&D Centre Skane, Skane University Hospital, Lund, Sweden
| | - Hans Friberg
- />Department of Clinical Sciences, Division of Intensive and Perioperative Care, Lund University, Lund, Sweden
| | - Niklas Nielsen
- />Department of Anaesthesia and Intensive Care, Intensive Care Unit, Helsingborg Hospital, Helsingborg, Sweden
| | - Tobias Cronberg
- />Department of Clinical Sciences, Division of Neurology, Lund University, Lund, Sweden
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25
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Lou AR, Kjaer TW. [How does it affect the brain when the vision is changed?]. Ugeskr Laeger 2010; 172:1751-1755. [PMID: 20534203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Until quite recently, only the young brain was thought to be capable of adaptation. It is now known that also the aging brain is plastic and may be influenced by stimulation and pharmacological intervention. Future demographic changes will bring an increase in the incidence of age-related diseases. To optimize treatment of reduced vision, more detailed knowledge of the plasticity in the aging brain is necessary.
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Kjaer TW, Gyllenborg J. [Diagnosis and monitoring of status epilepticus]. Ugeskr Laeger 2010; 172:940. [PMID: 20334774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Affiliation(s)
- Troels Wesenberg Kjaer
- Neurofysiologisk Klinik NF, 3063, Neurocentret, Rigshospitalet, DK-2100 København Ø, Denmark.
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Abstract
OBJECTIVES To assess the value of remifentanil in intraoperative evaluation of spike activity in patients undergoing surgery for mesial temporal lobe epilepsy (MTLE). MATERIALS AND METHODS Twenty-five patients undergoing temporal lobectomy for medically intractable MTLE were enrolled in the study. Electrocorticography (ECoG) recordings were performed on the intraventricular hippocampus and from the anterior inferior temporal and lateral neocortex before and after a 300 microg intravenous bolus of remifentanil. Spike activity was quantified as spike-count per minute. RESULTS A significant increase (P < 0.005) in spike activity was observed after administration of remifentanil in 23 of 25 patients (92%). Furthermore, two patients who did not have any spike activity on the baseline ECoG developed spikes after administration of remifentanil. CONCLUSIONS The results suggest that remifentanil can enhance spike activity in the epileptogenic zone and reveal otherwise concealed epileptogenic tissue in patients with MTLE. Thus, remifentanil may prove to be an important diagnostic tool during surgical treatment for intractable focal epilepsy.
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Affiliation(s)
- L Grønlykke
- Deaprtment of Clinical Neurophysiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
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28
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Johnsen B, Kjaer TW, Fabricius ME. [Neurophysiologic monitoring. The Danish Society of Clinical Neurophysiology]. Ugeskr Laeger 2007; 169:1116. [PMID: 17394827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Affiliation(s)
- Birger Johnsen
- Neurofysiologisk Afdeling, Arhus Sygehus, Arhus Universitetshospital, DK-8000 Arhus C.
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29
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Kjaer TW, Christensen T. [Diagnostic imaging in epilepsy]. Ugeskr Laeger 2004; 166:3912-5. [PMID: 15554199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
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Abstract
Awareness is a personal experience, which is only accessible to the rest of world through interpretation. We set out to identify a neural correlate of visual awareness, using brief subliminal and supraliminal verbal stimuli while measuring cerebral blood flow distribution with H(2)(15)O PET. Awareness of visual verbal stimuli differentially activated medial parietal association cortex (precuneus), which is a polymodal sensory cortex, and dorsolateral prefrontal cortex, which is thought to be primarily executive. Our results suggest participation of these higher order perceptual and executive cortical structures in visual verbal awareness.
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Affiliation(s)
- T W Kjaer
- John F. Kennedy Institute, DK-2600 Glostrup, Denmark
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Buschard K, Bock T, Pedersen CR, Hansen SV, Aaen K, Jørgensen M, Hansen MW, Kjaer TW, Hageman I, Josefsen K. Neonatal treatment with beta-cell stimulatory agents reduces the incidence of diabetes in BB rats. Int J Exp Diabetes Res 2000; 1:1-8. [PMID: 11469386 PMCID: PMC2477749 DOI: 10.1155/edr.2000.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The aim of the study was to investigate whether various beta-cell stimulatory drugs, given neonatally, influence the incidence of diabetes in BB rats. Newborn BB rats were treated twice daily for 6 days and diabetes development was observed during the following 200-day study period. Compared to a diabetes incidence of 63.8% in 163 control BB rats which received saline or were untreated, the percentage of experimental BB rats that developed diabetes was as follows in the different subgroups: arginine-glucose: 47% (n = 73, p < 0.02); glucagon: 37% (n = 93, p < 0.0001); tolbutamide-glucose: 36% (n = 58, p < 0.0005); and theophylline-glucose: 39% (n = 41, p < 0.005). A long-term arginine-glucose treatment was not superior to the shorter neonatal treatment. Histological examination revealed a higher degree of insulitis in diabetic than in non-diabetic animals but no difference according to the kind of treatment was observed. Finally, we found that the diabetes incidence in BB rats was higher in the first litter compared to subsequent litters (p = 0.04). Thus, neonatal treatment with various beta-cell stimulatory agents reduces diabetes incidence in BB rats. The theory behind the study, that the treatment accelerates beta-cell maturation leading to increased immunological tolerance towards beta cells, is discussed.
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Affiliation(s)
- K Buschard
- Bartholin Institutet, Kommunehospitalet, Copenhagen, Denmark.
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Lou HC, Kjaer TW, Friberg L, Wildschiodtz G, Holm S, Nowak M. A 15O-H2O PET study of meditation and the resting state of normal consciousness. Hum Brain Mapp 1999; 7:98-105. [PMID: 9950067 PMCID: PMC6873339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
The aim of the present study was to examine whether the neural structures subserving meditation can be reproducibly measured, and, if so, whether they are different from those supporting the resting state of normal consciousness. Cerebral blood flow distribution was investigated with the 15O-H20 PET technique in nine young adults, who were highly experienced yoga teachers, during the relaxation meditation (Yoga Nidra), and during the resting state of normal consciousness. In addition, global CBF was measured in two of the subjects. Spectral EEG analysis was performed throughout the investigations. In meditation, differential activity was seen, with the noticeable exception of V1, in the posterior sensory and associative cortices known to participate in imagery tasks. In the resting state of normal consciousness (compared with meditation as a baseline), differential activity was found in dorso-lateral and orbital frontal cortex, anterior cingulate gyri, left temporal gyri, left inferior parietal lobule, striatal and thalamic regions, pons and cerebellar vermis and hemispheres, structures thought to support an executive attentional network. The mean global flow remained unchanged for both subjects throughout the investigation (39+/-5 and 38+/-4 ml/100 g/min, uncorrected for partial volume effects). It is concluded that the (H2)15O PET method may measure CBF distribution in the meditative state as well as during the resting state of normal consciousness, and that characteristic patterns of neural activity support each state. These findings enhance our understanding of the neural basis of different aspects of consciousness.
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Affiliation(s)
- H C Lou
- Kennedy Institute, Glostrup, Denmark.
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Kjaer TW, Gawne TJ, Hertz JA, Richmond BJ. Insensitivity of V1 complex cell responses to small shifts in the retinal image of complex patterns. J Neurophysiol 1997; 78:3187-97. [PMID: 9405538 DOI: 10.1152/jn.1997.78.6.3187] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
An important role for neurons in the early visual system is to convey information about the structure of visual stimuli. However, neuronal responses show substantial variation across presentations of the same stimulus. In awake monkeys, it has been assumed that a great deal of this variation is related to the scatter in eye position (inducing scatter in the retinal position of the stimulus). Here we investigate the implied consequence of this assumption, i.e., that the scatter variation in eye position degrades the decodability of the neural response. We recorded from 50 complex cells in primary visual cortex of fixating monkeys while different complex stimuli were presented. Three types of retinal shifts were considered: natural scatter in the fixation, systematic fixation point shift, and systematic stimulus position shift. The stimulus pattern accounts for >50% of the response variance, always six times that accounted for by the scatter in eye position during fixation. The retinal location of a stimulus had to be shifted by 10-12 min of arc, an amount almost two times larger than the smallest picture element, before the responses changed systematically. Nonetheless, changes of the stimulus at the single pixel level often gave rise to discriminable responses. Thus complex cells convey information about the spatial structure of a stimulus, independent of rigid stimulus displacements on the order of the receptive field size or smaller.
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Affiliation(s)
- T W Kjaer
- Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, Maryland 20892-4415, USA
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Abstract
1. We recorded the responses of 37 striate cortical complex cells in fixating monkeys while presenting a set of oriented stimuli that varied in contrast. 2. The two response parameters of strength and latency can be interpreted as a code: the strength defines the stimulus form (here the orientation), and the latency is more a function of the stimulus contrast. 3. Synchronization based on latency could make a strong contribution to the process of organizing the neural responses to different objects, i.e., binding.
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Affiliation(s)
- T J Gawne
- Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, Maryland 20892-4415, USA
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Abstract
The responses of adjacent neurons in inferior temporal (IT) cortex carry signals that are to a large degree independent (Gawne and Richmond, 1993). Adjacent primary visual cortical neurons have similar orientation tuning (Hubel and Wiesel, 1962, 1968), suggesting that their responses might be more redundant than those in IT. We recorded the responses of 26 pairs of adjacent complex cells in the primary visual cortex of two awake monkeys while using both a set of 16 bar-like stimuli, and a more complex set of 128 two-dimensional patterns. Linear regression showed that 40% of the signal variance of one neuron was related to that of the other when the responses to the bar-like stimuli were considered. However, when the responses to the two-dimensional stimuli were included in the analysis, only 19% of the signal variance of one neuron was related to that of the adjacent one, almost exactly the same results as found in IT. An information theoretic analysis gave similar results. We hypothesize that this trend toward independence of information processing by adjacent cortical neurons is a general organizational strategy used to maximize the amount of information carried in local groups.
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Affiliation(s)
- T J Gawne
- Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, MD, USA
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Abstract
We perform time-resolved calculations of the information transmitted about visual patterns by neurons in primary visual and inferior temporal cortices. All measurable information is carried in an effective time-varying firing rate, obtained by averaging the neuronal response with a resolution no finer than about 25 ms in primary visual cortex and around twice that in inferior temporal cortex. We found no better way for a neuron receiving these messages to decode them than simply to count spikes for this long. Most of the information tends to be concentrated in one or, more often, two brief packets, one at the very beginning of the response and the other typically 100 ms later. The first packet is the most informative part of the message, but the second one generally contains new information. A small but significant part of the total information in the message accumulates gradually over the entire course of the response. These findings impose strong constraints on the codes used by these neurons.
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Affiliation(s)
- J Heller
- Division of Applied Sciences, Harvard University, Cambridge, MA, USA
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Abstract
We have studied the encoding of spatial pattern information by complex cells in the primary visual cortex of awake monkeys. Three models for the conditional probabilities of different stimuli, given the neuronal response, were fit and compared using cross-validation. For our data, a feed-forward neural network proved to be the best of these models. The information carried by a cell about a stimulus set can be calculated from the estimated conditional probabilities. We performed a spatial spectroscopy of the encoding, examining how the transmitted information varies with both the average coarseness of the stimulus set and the coarseness differences within it. We find that each neuron encodes information about many features at multiple scales. Our data do not appear to allow a characterization of these variations in terms of the detection of simple single features such as oriented bars.
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Affiliation(s)
- T W Kjaer
- Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, MD 20892, USA
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Kjaer I, Kjaer TW, Graem N. Ossification sequence of occipital bone and vertebrae in human fetuses. J Craniofac Genet Dev Biol 1993; 13:83-8. [PMID: 8325971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The aim of this radiographic study of human fetuses was to examine the pattern and sequence of ossification in the occipital bone and the spinal vertebrae. Together with previous studies of ossification of the human fetal basal cranium, this study can serve as a reference for normalcy in future studies of fetuses with neural tube defects and associated pathological development of the axial skeleton. Thirty-nine normal fetuses aborted between 9 and 14 weeks of gestation were examined. Based on the appearance of ossification centers in the bones under study, the fetuses could be grouped in four well-defined developmental stages, which were named occipito-spinal stages I-IV (OS I-IV). The OS stage was closely related to gestational age, crown-rump length, foot length, and degree of ossification in the hands and feet.
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Affiliation(s)
- I Kjaer
- Department of Orthodontics, School of Dentistry, University of Copenhagen, Denmark
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Abstract
This experiment was conducted in order to investigate whether expression of gangliosides on islet cell surface in vitro is influenced by cytokines, especially interleukin 1. Islets from adult Lewis rats were incubated with different concentrations of recombinant-derived human cytokines. Following dispase treatment, the single cells were labeled with monoclonal antiganglioside antibodies A2B5 or R2D6, and conjugate. Both are directed against beta cells; A2B5 is recognized to bind specifically to pancreatic islet cells, while R2D6 is shown to bind no other pancreatic cells than beta cells. Surface labeling was evaluated in blind trials using a fluorescence microscope and a fluorescence-activated cell sorter (FACS). A2B5 staining demonstrated a significantly higher number of labeled cells after incubation with interleukin 1 alpha (14.9% +/- 2.8; p less than 0.005), interleukin 1 beta (23.2% +/- 4.2; p less than 0.0005) or TNF alpha (16.1% +/- 4.0; p = 0.005) compared to endotoxin controls (4.1% +/- 1.1). Interleukin 1 beta (9.5% +/- 1.5; p less than 0.005) showed a significantly increased number of R2D6-stained cells (control: 2.3% +/- 1.3). A similar but not significant effect was seen with interleukin 1 alpha and TNF alpha. Interleukin 6 had no effect on the antigen expression. The intensity of labeling was elevated among interleukin 1 beta-incubated cells compared to control samples. Thus, treatment of islets with different cytokines, especially interleukin 1 beta, increases surface antigen expression. We suggest that this mechanism of action in vitro may be of importance for the putative diabetogenic effect of interleukin 1.
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Affiliation(s)
- T W Kjaer
- Bartholin Instituttet, Kommunehospitalet, Copenhagen, Denmark
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van den Eynde B, Kjaer I, Solow B, Graem N, Kjaer TW, Mathiesen M. Cranial base angulation and prognathism related to cranial and general skeletal maturation in human fetuses. J Craniofac Genet Dev Biol 1992; 12:22-32. [PMID: 1572937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The purpose of the present study was to describe normal midsagittal craniofacial morphology in second trimester human fetuses. Measurements of the cranial base angle and the prognathism of the maxilla and the mandible were performed on radiographs of cranial midsagittal tissue blocks of 52 fetuses with a gestational age from 13 to 27 weeks. Special procedures were developed for the definitions of the nasion and sella reference points on the radiographs in the early stages of fetal development. Mean data were reported for stages of crown rump length (CRL) and maturation of the fetal cranial base (MSS), usable as reference in assessment of pathological fetal crania in reports and autopsy procedures. Regression equations were determined for the regression of the angular values on CRL, MSS, and general skeletal maturation (TNO). The cranial base angle was found to decrease significantly, and the angles of prognathism to increase significantly with increasing CRL, TNO, and MSS values. It was suggested that these simultaneous and similar changes in the three angles could be accounted for by the upwards movement of the sella point produced by a cranial displacement of the pituitary fossa caused by local cartilagenous growth and bony remodelling during the period of study. The study thus reflects the influence of cranial skeletal maturation on the early development in shape of the craniofacial complex.
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Affiliation(s)
- B van den Eynde
- Institute of Orthodontics, Royal Dental College Copenhagen, Denmark
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Abstract
The aim of this study was to investigate whether neonatal glucose treatment influences the incidence of diabetes in NOD mice. Thirty-nine NOD mice (19 males, 20 females) were treated with 8 g glucose/kg BW/day administered by subcutaneous injections twice a day for the first six days of life. Thirty-six untreated NOD mice (20 males, 16 females) served as a control group. In the glucose-treated group, 33% became diabetic compared with 58% in the control group (X2 = 5.3, p = 0.021). Among the glucose-treated males, 16% became diabetic compared with 50% of the untreated males (X2 = 5.5, p = 0.019), whereas 50% of the glucose-treated females became diabetic compared with 69% of the untreated females (X2 = 1.1, NS). We conclude that neonatal glucose treatment can reduce the diabetes incidence in NOD mice. These results could have implications for the prevention of type 1 diabetes mellitus in humans.
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Affiliation(s)
- T Bock
- Bartholin Instituttet, Kommunehospitalet, Copenhagen, Denmark
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