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Witt, S. T., Drissi, N. M., Tapper, S., Wretman, A., Szakács, A., Hallböök, T., . . . Engström, M. (2018). Evidence for cognitive resource imbalance in adolescents with narcolepsy. Brain Imaging and Behavior, 12(2), 411-424
Open this publication in new window or tab >>Evidence for cognitive resource imbalance in adolescents with narcolepsy
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2018 (English)In: Brain Imaging and Behavior, ISSN 1931-7557, E-ISSN 1931-7565, Vol. 12, no 2, p. 411-424Article in journal (Refereed) Published
Abstract [en]

The study investigated brain activity changes during performance of a verbal working memory task in a population of adolescents with narcolepsy. Seventeen narcolepsy patients and twenty healthy controls performed a verbal working memory task during simultaneous fMRI and EEG acquisition. All subjects also underwent MRS to measure GABA and Glutamate concentrations in the medial prefrontal cortex. Activation levels in the default mode network and left middle frontal gyrus were examined to investigate whether narcolepsy is characterized by an imbalance in cognitive resources. Significantly increased deactivation within the default mode network during task performance was observed for the narcolepsy patients for both the encoding and recognition phases of the task. No evidence for task performance deficits or reduced activation within the left middle frontal gyrus was noted for the narcolepsy patients. Correlation analyses between the spectroscopy and fMRI data indicated that deactivation of the anterior aspect of the default mode in narcolepsy patients correlated more with increased concentrations of Glutamate and decreased concentrations of GABA. In contrast, deactivation in the default mode was correlated with increased concentrations of GABA and decreased concentrations of Glutamate in controls. The results suggested that narcolepsy is not characterized by a deficit in working memory but rather an imbalance of cognitive resources in favor of monitoring and maintaining attention over actual task performance. This points towards dysregulation within the sustained attention system being the origin behind self-reported cognitive difficulties in narcolepsy.

Place, publisher, year, edition, pages
Springer-Verlag New York, 2018
Keywords
EEG, GABA, MRS, Narcolepsy, Working memory, fMRI
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-145535 (URN)10.1007/s11682-017-9706-y (DOI)000429029000011 ()28321606 (PubMedID)2-s2.0-85015625386 (Scopus ID)
Available from: 2018-03-05 Created: 2018-03-05 Last updated: 2019-05-01Bibliographically approved
Simon, R., Pihlsgård, J., Berglind, U., Söderfeldt, B. & Engström, M. (2017). Mantra meditation suppression of default mode beyond an active task: a pilot study. Journal of Cognitive Enhancement, 1(2), 219-227
Open this publication in new window or tab >>Mantra meditation suppression of default mode beyond an active task: a pilot study
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2017 (English)In: Journal of Cognitive Enhancement, ISSN 2509-3290, Vol. 1, no 2, p. 219-227Article in journal (Refereed) Published
Abstract [en]

Within the field of neuroimaging, the discovery of a constellation of brain regions silently active when we are “resting” has provided a new view into the elusive effects of meditative practice. This network, called the default mode network (DMN), has been shown by functional neuroimaging to be active when an individual is at rest. Meta-analyses of the fMRI neurocorrelates of meditation have shown that across diverse practices, the most common general effect appears to be modulation of regions within the DMN. The specific ...

Place, publisher, year, edition, pages
Springer, 2017
Keywords
Meditation, Mantra, Attention, Default mode network, Anterior cingulate cortex, Posterior cingulate cortex, Precuneus, Functional magnetic resonance imaging (fMRI), Deactivation, Kundalini yoga
National Category
Neurosciences
Identifiers
urn:nbn:se:liu:diva-139581 (URN)10.1007/s41465-017-0028-1 (DOI)
Available from: 2017-08-09 Created: 2017-08-09 Last updated: 2018-01-13Bibliographically approved
Van Ettinger-Veenstra, H., Mcallister, A., Lundberg, P., Karlsson, T. & Engström, M. (2016). Higher Language Ability is Related to Angular Gyrus Activation Increase During Semantic Processing, Independent of Sentence Incongruency. Frontiers in Human Neuroscience, 10(110)
Open this publication in new window or tab >>Higher Language Ability is Related to Angular Gyrus Activation Increase During Semantic Processing, Independent of Sentence Incongruency
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2016 (English)In: Frontiers in Human Neuroscience, ISSN 1662-5161, E-ISSN 1662-5161, Vol. 10, no 110Article in journal (Refereed) Published
Abstract [en]

This study investigates the relation between individual language ability and neural semantic processing abilities. Our aim was to explore whether high-level language ability would correlate to decreased activation in language-specific regions or rather increased activation in supporting language regions during processing of sentences. Moreover, we were interested if observed neural activation patterns are modulated by semantic incongruency similarly to previously observed changes upon syntactic congruency modulation. We investigated 27 healthy adults with a sentence reading task which tapped language comprehension and inference, and modulated sentence congruency employing functional magnetic resonance imaging (fMRI). We assessed the relation between neural activation, congruency modulation, and test performance on a high-level language ability assessment with multiple regression analysis. Our results showed increased activation in the left-hemispheric angular gyrus extending to the temporal lobe related to high language ability. This effect was independent of semantic congruency, and no significant relation between language ability and incongruency modulation was observed. Furthermore, there was a significant increase of activation in the inferior frontal gyrus (IFG) bilaterally when the sentences were incongruent, indicating that processing incongruent sentences was more demanding than processing congruent sentences and required increased activation in language regions. The correlation of high-level language ability with increased rather than decreased activation in the left angular gyrus, a region specific for language processing, is opposed to what the neural efficiency hypothesis would predict. We can conclude that no evidence is found for an interaction between semantic congruency related brain activation and highlevel language performance, even though the semantic incongruent condition shows to be more demanding and evoking more neural activation.

Place, publisher, year, edition, pages
FRONTIERS MEDIA SA, 2016
Keywords
fMRI; semantic processing; congruency; sentence reading; language ability; inferior frontal gyrus; angular gyrus
National Category
Clinical Medicine Basic Medicine
Identifiers
urn:nbn:se:liu:diva-126805 (URN)10.3389/fnhum.2016.00110 (DOI)000371873000001 ()27014040 (PubMedID)
Note

Funding Agencies|Linkoping University; Linkoping University Hospital local funds

Available from: 2016-04-07 Created: 2016-04-05 Last updated: 2018-01-10
Lundengård, K., Cedersund, G., Sten, S., Leong, F., Smedberg, A., Elinder, F. & Engström, M. (2016). Mechanistic Mathematical Modeling Tests Hypotheses of the Neurovascular Coupling in fMRI. PloS Computational Biology, 12(6), Article ID e1004971.
Open this publication in new window or tab >>Mechanistic Mathematical Modeling Tests Hypotheses of the Neurovascular Coupling in fMRI
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2016 (English)In: PloS Computational Biology, ISSN 1553-734X, E-ISSN 1553-7358, Vol. 12, no 6, article id e1004971Article in journal (Refereed) Published
Abstract [en]

Functional magnetic resonance imaging (fMRI) measures brain activity by detecting the blood-oxygen-level dependent (BOLD) response to neural activity. The BOLD response depends on the neurovascular coupling, which connects cerebral blood flow, cerebral blood volume, and deoxyhemoglobin level to neuronal activity. The exact mechanisms behind this neurovascular coupling are not yet fully investigated. There are at least three different ways in which these mechanisms are being discussed. Firstly, mathematical models involving the so-called Balloon model describes the relation between oxygen metabolism, cerebral blood volume, and cerebral blood flow. However, the Balloon model does not describe cellular and biochemical mechanisms. Secondly, the metabolic feedback hypothesis, which is based on experimental findings on metabolism associated with brain activation, and thirdly, the neurotransmitter feed-forward hypothesis which describes intracellular pathways leading to vasoactive substance release. Both the metabolic feedback and the neurotransmitter feed-forward hypotheses have been extensively studied, but only experimentally. These two hypotheses have never been implemented as mathematical models. Here we investigate these two hypotheses by mechanistic mathematical modeling using a systems biology approach; these methods have been used in biological research for many years but never been applied to the BOLD response in fMRI. In the current work, model structures describing the metabolic feedback and the neurotransmitter feed-forward hypotheses were applied to measured BOLD responses in the visual cortex of 12 healthy volunteers. Evaluating each hypothesis separately shows that neither hypothesis alone can describe the data in a biologically plausible way. However, by adding metabolism to the neurotransmitter feed-forward model structure, we obtained a new model structure which is able to fit the estimation data and successfully predict new, independent validation data. These results open the door to a new type of fMRI analysis that more accurately reflects the true neuronal activity.

Place, publisher, year, edition, pages
PUBLIC LIBRARY SCIENCE, 2016
National Category
Bioinformatics (Computational Biology)
Identifiers
urn:nbn:se:liu:diva-130437 (URN)10.1371/journal.pcbi.1004971 (DOI)000379349700045 ()27310017 (PubMedID)
Note

Funding Agencies|Swedish Research council [2014-6249]; Knut and Alice Wallenbergs foundation, KAW [2013.0076]; Research council of Southeast Sweden [FORSS-481691]; Linkoping University

Available from: 2016-08-06 Created: 2016-08-05 Last updated: 2018-03-19
Warntjes, M. J., Engström, M., Tisell, A. & Lundberg, P. (2016). Modeling the Presence of Myelin and Edema in the Brain Based on Multi-Parametric Quantitative MRI. Frontiers in Neurology, 7(16)
Open this publication in new window or tab >>Modeling the Presence of Myelin and Edema in the Brain Based on Multi-Parametric Quantitative MRI
2016 (English)In: Frontiers in Neurology, ISSN 1664-2295, E-ISSN 1664-2295, Vol. 7, no 16Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to present a model that uses multi-parametric quantitative MRI to estimate the presence of myelin and edema in the brain. The model relates simultaneous measurement of R-1 and R-2 relaxation rates and proton density to four partial volume compartments, consisting of myelin partial volume, cellular partial volume, free water partial volume, and excess parenchymal water partial volume. The model parameters were obtained using spatially normalized brain images of a group of 20 healthy controls. The pathological brain was modeled in terms of the reduction of myelin content and presence of excess parenchymal water, which indicates the degree of edema. The method was tested on spatially normalized brain images of a group of 20 age-matched multiple sclerosis (MS) patients. Clear differences were observed with respect to the healthy controls: the MS group had a 79 mL smaller brain volume (1069 vs. 1148 mL), a 38 mL smaller myelin volume (119 vs. 157 mL), and a 21 mL larger excess parenchymal water volume (78 vs. 57 mL). Template regions of interest of various brain structures indicated that the myelin partial volume in the MS group was 1.6 +/- 1.5% lower for gray matter (GM) structures and 2.8 +/- 1.0% lower for white matter (WM) structures. The excess parenchymal water partial volume was 9 +/- 10% larger for GM and 5 +/- 2% larger for WM. Manually placed ROls indicated that the results using the template ROls may have suffered from loss of anatomical detail due to the spatial normalization process. Examples of the application of the method on high-resolution images are provided for three individual subjects: a 45-year-old healthy subject, a 72-year-old healthy subject, and a 45-year-old MS patient. The observed results agreed with the expected behavior considering both age and disease. In conclusion, the proposed model may provide clinically important parameters, such as the total brain volume, degree of myelination, and degree of edema, based on a single qMRI acquisition with a clinically acceptable scan time.

Place, publisher, year, edition, pages
FRONTIERS MEDIA SA, 2016
Keywords
quantitative magnetic resonance imaging; brain tissue modeling; myelin; edema; T-1 relaxation; T-2 relaxation; proton density
National Category
Clinical Medicine
Identifiers
urn:nbn:se:liu:diva-126132 (URN)10.3389/fneur.2016.00016 (DOI)000370433200002 ()26925030 (PubMedID)
Note

Funding Agencies|Linkoping University; County Council Ostergotland

Available from: 2016-03-15 Created: 2016-03-15 Last updated: 2017-11-30
Källman, U., Bergstrand, S., Ek, A.-C., Engström, M. & Lindgren, M. (2016). Nursing staff induced repositionings and immobile patients' spontaneous movements in nursing care.. International Wound Journal, 13(6), 1168-1175
Open this publication in new window or tab >>Nursing staff induced repositionings and immobile patients' spontaneous movements in nursing care.
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2016 (English)In: International Wound Journal, ISSN 1742-4801, E-ISSN 1742-481X, Vol. 13, no 6, p. 1168-1175Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to investigate nursing staff induced repositionings and the patients' spontaneous movements during the day and night among older immobile patients in nursing care. Furthermore, the aim was to identify factors associated with the nursing staff induced repositionings and the patients' spontaneous movement frequency. An observational cross-sectional design was used. Spontaneous movements among patients (n = 52) were registered continuously using the MovinSense monitoring system. The nursing staff documented each time they repositioned the patient. Patients spontaneous movements were compared with nursing staff induced repositionings. There were large variations in the patients' spontaneous repositioning frequency during both days and nights, which shows that, although immobilised, some patients frequently reposition themselves. Analgesics were positively related to the movement frequency and psycholeptics were negatively related. The nursing staff more often repositioned the patients who were assessed as high risk than those assessed as low risk, but the patients' spontaneous movement frequency was not correlated to the risk score. This may be important when planning repositioning schedules. A monitoring system may be useful in decision making with regard to planning repositioning and positions used in the prevention of pressure ulcers among elderly immobile patients.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2016
Keywords
Nursing home residents, patient repositioning, pressure ulcer, interface pressure, skin temperature, tissue blood flow
National Category
Nursing
Identifiers
urn:nbn:se:liu:diva-117445 (URN)10.1111/iwj.12435 (DOI)000387664400011 ()25779932 (PubMedID)
Note

Funding agencies: Research Council Sodra Alvsborg Boras Sweden; Research Council ostergotland Linkoping Sweden; SwedBank Sjuharad foundation for research at the Sodra Alvsborg Hospital Boras Sweden; Sodra Alvsborgs Hospital Boras Sweden; King Gustaf V and Queen Victorias F

Available from: 2015-04-27 Created: 2015-04-27 Last updated: 2017-12-04Bibliographically approved
Walter, S. A., Forsgren, M., Lundengård, K., Simon, R., Torkildsen Nilsson, M., Söderfeldt, B., . . . Engström, M. (2016). Positive Allosteric Modulator of GABA Lowers BOLD Responses in the Cingulate Cortex. PLoS ONE, 11(3)
Open this publication in new window or tab >>Positive Allosteric Modulator of GABA Lowers BOLD Responses in the Cingulate Cortex
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2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 3Article in journal (Refereed) Published
Abstract [en]

Knowledge about the neural underpinnings of the negative blood oxygen level dependent (BOLD) responses in functional magnetic resonance imaging (fMRI) is still limited. We hypothesized that pharmacological GABAergic modulation attenuates BOLD responses, and that blood concentrations of a positive allosteric modulator of GABA correlate inversely with BOLD responses in the cingulate cortex. We investigated whether or not pure task-related negative BOLD responses were co-localized with pharmacologically modulated BOLD responses. Twenty healthy adults received either 5 mg diazepam or placebo in a double blind, randomized design. During fMRI the subjects performed a working memory task. Results showed that BOLD responses in the cingulate cortex were inversely correlated with diazepam blood concentrations; that is, the higher the blood diazepam concentration, the lower the BOLD response. This inverse correlation was most pronounced in the pregenual anterior cingulate cortex and the anterior mid-cingulate cortex. For subjects with diazepam plasma concentration > 0.1 mg/L we observed negative BOLD responses with respect to fixation baseline. There was minor overlap between cingulate regions with task-related negative BOLD responses and regions where the BOLD responses were inversely correlated with diazepam concentration. We interpret that the inverse correlation between the BOLD response and diazepam was caused by GABA-related neural inhibition. Thus, this study supports the hypothesis that GABA attenuates BOLD responses in fMRI. The minimal overlap between task-related negative BOLD responses and responses attenuated by diazepam suggests that these responses might be caused by different mechanisms.

Place, publisher, year, edition, pages
San Francisco, CA, United States: Public Library of Science, 2016
Keywords
quantitative magnetic resonance imaging; brain tissue modeling; myelin; edema; T-1 relaxation; T-2 relaxation; proton density
National Category
Neurosciences
Identifiers
urn:nbn:se:liu:diva-126192 (URN)10.1371/journal.pone.0148737 (DOI)000371434500011 ()26930498 (PubMedID)
Note

Funding agencies: Linkoping University; County Council of Ostergotland

Available from: 2016-03-18 Created: 2016-03-18 Last updated: 2018-01-10Bibliographically approved
Landtblom, A.-M. & Engström, M. (2015). Brain circuitries involved in sleep disorders. Frontiers in Neurology, 6(UNSP 66)
Open this publication in new window or tab >>Brain circuitries involved in sleep disorders
2015 (English)In: Frontiers in Neurology, ISSN 1664-2295, E-ISSN 1664-2295, Vol. 6, no UNSP 66Article in journal, Editorial material (Refereed) Published
Abstract [en]

n/a

Place, publisher, year, edition, pages
FRONTIERS MEDIA SA, 2015
Keywords
imaging; neuronal; narcolepsy; Kleine-Levin syndrome; hypersomnia; obstructive sleep apnea; pharmacotherapy; side effects
National Category
Basic Medicine
Identifiers
urn:nbn:se:liu:diva-122790 (URN)10.3389/fneur.2015.00066 (DOI)000363777300001 ()25926812 (PubMedID)
Available from: 2015-11-23 Created: 2015-11-23 Last updated: 2018-01-10
Lowén, M. B. O., Mayer, E., Tillisch, K., Labus, J., Naliboff, B., Lundberg, P., . . . Walter, S. (2015). Deficient habituation to repeated rectal distensions in irritable bowel syndrome patients with visceral hypersensitivity. Neurogastroenterology and Motility, 27(5), 646-655
Open this publication in new window or tab >>Deficient habituation to repeated rectal distensions in irritable bowel syndrome patients with visceral hypersensitivity
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2015 (English)In: Neurogastroenterology and Motility, ISSN 1350-1925, E-ISSN 1365-2982, Vol. 27, no 5, p. 646-655Article in journal (Refereed) Published
Abstract [en]

Background Irritable bowel syndrome (IBS) patients show evidence of altered central processing of visceral signals. One of the proposed alterations in sensory processing is an altered engagement of endogenous pain modulation mechanisms. The aim was to test the hypothesis that IBS patients with (IBS-S) and without visceral hypersensitivity (IBS-N) differ in their ability to engage endogenous pain modulation mechanism during habituation to repeated visceral stimuli.

Methods Brain blood oxygen level dependent (BOLD) response was measured during repeated rectal distension and its anticipation in 33 IBS patients with and without visceral hypersensitivity and 18 healthy controls (HCs). BOLD response to early and late phase of the distension series was compared within and between groups.

Key Results While BOLD response was similar during the early phase of the experiment, IBS-S showed greater BOLD response than IBS-N and HCs during the late phase of the distension series. IBS-S showed increasing BOLD response both to the anticipation and delivery of low intensity rectal distensions in brain regions including insula, anterior and mid cingulate cortex. IBS-N showed decreasing BOLD response to repeated rectal distensions in brain regions including insula, prefrontal cortex and amygdala.

Conclusions & Inferences These findings are consistent with compromised ability of IBS-S to respond to repeated delivery of rectal stimuli, both in terms of sensitization of sensory pathways and habituation of emotional arousal. The fact that both IBS subgroups met Rome criteria, and did not differ in terms of reported symptom severity demonstrates that similar symptom patterns can result from different underlying neurobiological mechanisms.

Keywords
irritable bowel syndrome, brain-gut interaction, fMRI, visceral sensitivity
National Category
Gastroenterology and Hepatology Neurosciences
Identifiers
urn:nbn:se:liu:diva-122143 (URN)10.1111/nmo.12537 (DOI)000364742000007 ()25777251 (PubMedID)
Note

Funding agencies: County Council of Ostergotland, Sweden; National Institute of Health [DK 64531]

Available from: 2015-10-20 Created: 2015-10-20 Last updated: 2018-01-11Bibliographically approved
Engström, M., Karlsson, T., Landtblom, A.-M. & Craig, A. (2015). Evidence of conjoint activation of the anterior insular and cingulate cortices during effortful tasks. Frontiers in Human Neuroscience, 8(1071)
Open this publication in new window or tab >>Evidence of conjoint activation of the anterior insular and cingulate cortices during effortful tasks
2015 (English)In: Frontiers in Human Neuroscience, ISSN 1662-5161, E-ISSN 1662-5161, Vol. 8, no 1071Article in journal (Refereed) Published
Abstract [en]

The ability to perform effortful tasks is a topic that has received considerable interest in the research of higher functions of the human brain. Neuroimaging studies show that the anterior insular and the anterior cingulate cortices are involved in a multitude of cognitive tasks that require mental effort. In this study, we investigated brain responses to effort using cognitive tasks with task-difficulty modulations and functional magnetic resonance imaging (fMRI). We hypothesized that effortful performance involves modulation of activation in the anterior insular and the anterior cingulate cortices, and that the modulation correlates with individual performance levels. Healthy participants performed tasks probing verbal working memory capacity using the reading span task, and visual perception speed using the inspection time task. In the fMRI analysis, we focused on identifying effort-related brain activation. The results showed that working memory and inspection time performances were directly related. The bilateral anterior insular and anterior cingulate cortices showed significantly increased activation during each task with common portions that were active across both tasks. We observed increased brain activation in the right anterior insula and the anterior cingulate cortex in participants with low working memory performance. In line with the reported results, we suggest that activation in the anterior insular and cingulate cortices is consistent with the neural efficiency hypothesis (Neubauer).

Place, publisher, year, edition, pages
Frontiers, 2015
Keywords
functional magnetic resonance imaging; working memory; visual perception; forebrain asymmetry
National Category
Clinical Medicine Basic Medicine
Identifiers
urn:nbn:se:liu:diva-114419 (URN)10.3389/fnhum.2014.01071 (DOI)000348354700001 ()25674057 (PubMedID)
Note

Funding Agencies|County Council of Ostergotland; Linkoping University

Available from: 2015-03-02 Created: 2015-02-20 Last updated: 2018-01-11
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ORCID iD: ORCID iD iconorcid.org/0000-0002-2167-2450

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