Publications by authors named "Sneve M"

An emerging biomarker of blood-brain barrier (BBB) permeability is the time of exchange (Tex) of water from the blood to tissue, as measured by multi-echo arterial spin labeling (ASL) MRI. This new non-invasive sequence, already tested in mice, has recently been adapted to humans and optimized for clinical scanning time. In this study, we studied the normal variability of Tex over age and sex, which needs to be established as a reference for studying changes in neurological disease.

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We performed a systematic review of the localizational value of disturbances of self-integration, depersonalization and forced thinking in focal epilepsy with the aim to summarize the state-of-the-art anatomo-clinical correlations in the field and help guide interpretation of ictal semiology within the framework of pre-surgical evaluation. The review was performed using a PRISMA- and QUADAS2-based approach. Three separate PubMed and EMBASE searches were undertaken using the keywords self-integration, depersonalization and forced thinking, along with synonyms, in combination with terms to identify epileptogenic zone as defined by surgical outcome, MRI-findings or intracranially recorded EEG.

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Even partly consolidated memories can be forgotten given sufficient time, but the brain activity associated with durability of episodic memory at different time scales remains unclear. Here, we aimed to identify brain activity associated with retrieval of partly consolidated episodic memories that continued to be remembered in the future. Forty-nine younger (20 to 38 years; 25 females) and 43 older adults (60 to 80 years, 25 females) were scanned with functional magnetic resonance imaging during associative memory retrieval 12 h post-encoding.

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Introduction: Loss of blood-brain barrier (BBB) integrity is hypothesised to be one of the earliest microvascular signs of Alzheimer's disease (AD). Existing BBB integrity imaging methods involve contrast agents or ionising radiation, and pose limitations in terms of cost and logistics. Arterial spin labelling (ASL) perfusion MRI has been recently adapted to map the BBB permeability non-invasively.

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The glymphatic movement of fluid through the brain removes metabolic waste. Noninvasive 40 Hz stimulation promotes 40 Hz neural activity in multiple brain regions and attenuates pathology in mouse models of Alzheimer's disease. Here we show that multisensory gamma stimulation promotes the influx of cerebrospinal fluid and the efflux of interstitial fluid in the cortex of the 5XFAD mouse model of Alzheimer's disease.

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A method for reconstructing surface activity density (SAD) maps based on the solution of the Fredholm equation has been developed and applied. The construction of SAD maps was carried out for the site of the temporary storage (STS) of spent fuel and radioactive waste (RW) in Andreeva Bay using the results of measuring campaign in 2001-2002 and for the sheltering construction of the solid RW using the results of measurements in 2021. The Fredholm equation was solved in two versions: under conditions of a barrier-free environment and taking into account buildings and structures located on the industrial site of the STS Andreeva Bay.

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A method has been developed for solving the Fredholm equation in the barrier geometry for reconstructing the surface activity density (SAD) from the results of measuring the ambient dose equivalent rate (ADER). Inclusion of the barrier geometry means that the method takes into account the shielding effect of buildings and structures on the contaminated site. The method was based on the representation of the industrial site, buildings and radiation fields in the form of a raster and the use of the visibility matrix (VM) of raster cells to describe the barrier geometry.

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The full-scale invasion of Ukraine by Russian military forces on 24 February 2022 put the radiological well-being of the people in Ukraine under unprecedented threat. Apart from the risks linked to operating nuclear power plants, there was substantial evidence of looting of facilities of all kinds, including those holding radioactive materials, as well as the scope for physical disturbance of radioactively contaminated areas and waste storage facilities. The actions of Russian military personnel invading Ukraine through the territory of the Chornobyl Exclusion Zone (the ChEZ) were of serious concern.

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Memory encoding and retrieval are critical sub-processes of episodic memory. While the hippocampus is involved in both, less is known about its connectivity with the neocortex during memory processing in humans. This is partially due to variations in demands in common memory tasks, which inevitably recruit cognitive processes other than episodic memory.

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In the 1960s, a shore technical base (STB) was established at Andreeva Bay on the Kola Peninsula, in northwest Russia. The STB maintained nuclear submarines and the nuclear icebreaker fleet, receiving and storing fresh and spent nuclear fuel (SNF) as well as solid and liquid radioactive waste (RW). It was subsequently re-designated as a site for temporary storage (STS) for SNF and RW.

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Cortical asymmetry is a ubiquitous feature of brain organization that is subtly altered in some neurodevelopmental disorders, yet we lack knowledge of how its development proceeds across life in health. Achieving consensus on the precise cortical asymmetries in humans is necessary to uncover the developmental timing of asymmetry and the extent to which it arises through genetic and later influences in childhood. Here, we delineate population-level asymmetry in cortical thickness and surface area vertex-wise in seven datasets and chart asymmetry trajectories longitudinally across life (4-89 years; observations = 3937; 70% longitudinal).

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Article Synopsis
  • The study investigates how visual discrimination performance differs among patients with schizophrenia spectrum disorder, bipolar disorder, and healthy controls to understand sensory disruptions in severe mental disorders.
  • Results showed that patients with schizophrenia generally had higher discrimination thresholds compared to healthy controls, indicating greater difficulty in visual tasks; bipolar disorder patients' performance was also affected, but not as severely as those with schizophrenia.
  • In addition, a negative correlation was found between IQ and visual discrimination threshold across all groups, suggesting that lower IQ is associated with poorer visual performance regardless of the diagnosis.
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The Council Directive 2013/59/Euratom has introduced binding requirements for the management of radon in the workplace in Member States of the European Union. How does it work in practice? In 2021, the European ALARA Network created a working group on ALARA for Radon at Work with the objective of collecting and sharing experiences from the field. A survey was developed to detail each step of the national regulations for the control of radon and to describe case studies showing implementation.

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Systems consolidation of new experiences into lasting episodic memories involves hippocampal-neocortical interactions. Evidence of this process is already observed during early post-encoding rest periods, both as increased hippocampal coupling with task-relevant perceptual regions and reactivation of stimulus-specific patterns following intensive encoding tasks. We investigate the spatial and temporal characteristics of these hippocampally anchored post-encoding neocortical modulations.

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Article Synopsis
  • The study aimed to explore how cardiovascular risk factors like age, BMI, and blood pressure relate to the thickness of various retinal layers, like the ganglion cell-inner plexiform layer (GCIPL).
  • The research included data from two rounds of the Tromsø Study, measuring retinal thickness and excluding individuals with diabetes or glaucoma, ultimately analyzing 8,288 participants cross-sectionally and 2,595 longitudinally.
  • The findings revealed that GCIPL thickness was notably impacted by age and BMI, with significant relationships identified for blood pressure, emphasizing that weight and blood pressure are important factors for modifying retinal health.
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There is a limited understanding of age differences in functional connectivity during memory encoding. In the present study, a sample of cognitively healthy adult participants (n = 488, 18-81 years), a subsample of whom had longitudinal cognitive and brain structural data spanning on average 8 years back, underwent functional magnetic resonance imaging while performing an associative memory encoding task. We investigated (1) age-related differences in whole-brain connectivity during memory encoding; (2) whether encoding connectivity patterns overlapped with the activity signatures of specific cognitive processes, and (3) whether connectivity associated with memory encoding related to longitudinal brain structural and cognitive changes.

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Mapping and determining the molecular identity of individual synapses is a crucial step towards the comprehensive reconstruction of neuronal circuits. Throughout the history of neuroscience, microscopy has been a key technology for mapping brain circuits. However, subdiffraction size and high density of synapses in brain tissue make this process extremely challenging.

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Encoding of durable episodic memories requires cross-talk between the hippocampus and multiple brain regions. Changes in these hippocampal interactions could contribute to age-related declines in the ability to form memories that can be retrieved after extended time intervals. Here we tested whether hippocampal-neocortical- and subcortical functional connectivity (FC) observed during encoding of durable episodic memories differed between younger and older adults.

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The site of temporary storage for spent fuel and radioactive waste at Andreeva Bay is a largest nuclear legacy site in the Russian Northwest. The radiation situation within the industrial site and in the surrounding health protection zone (HPZ) is characterised by significant local contamination of the topsoil, which is a source of environmental contamination and potential spread of radioactivity within and outside the HPZ, including the adjacent marine environment. The highest levels of radioactive contamination of soil due to manmade radionuclides have been registered around the spent nuclear fuel storage facilities, where the specific activity of Cs-137 reaches 5 × 10Bq kg, and that of Sr-90, 5.

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The safe management and disposal of radioactive waste (RW) arising from the nuclear legacy, as well as newly generated RW, are key problems. Their solution will have important implications for nuclear energy development, the introduction of other radiation technologies, and their public perception. In the framework of the cooperation between the Committee of Atomic and Energy Supervision and Control (CAESC) of the Ministry of Energy of the Republic of Kazakhstan and the Norwegian Radiation and Nuclear Safety Authority (DSA), work has been carried out to analyse the current state of nuclear and radiation safety in the Republic of Kazakhstan.

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Objective: Stimulus-selective response modulation (SRM) of sensory evoked potentials represents a well-established non-invasive index of long-term potentiation-like (LTP-like) synaptic plasticity in the human sensory cortices. Although our understanding of the mechanisms underlying stimulus-SRM has increased over the past two decades, it remains unclear how this form of LTP-like synaptic plasticity is related to other basic learning mechanisms, such as perceptual learning. The aim of the current study was twofold; firstly, we aimed to corroborate former stimulus-SRM studies, demonstrating modulation of visual evoked potential (VEP) components following high-frequency visual stimulation.

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The coordinated organisation of decommissioning, remediation of legacy sites and facilities and management of the resultant waste materials has long been recognized as complex, involving technical challenges, safety and security issues, and a wide range of stakeholder interests. To help address these matters, an international workshop was held in November 2019 in Tromsø, jointly organized by the Norwegian Radiation and Nuclear Safety Authority and the Nuclear Energy Agency, in cooperation with the International Commission on Radiological Protection and the International Atomic Energy Agency. The workshop was the third in series hosted by DSA.

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It has been suggested that specific forms of cognition in older age rely largely on late-life specific mechanisms. Here instead, we tested using task-fMRI (n = 540, age 6-82 years) whether the functional foundations of successful episodic memory encoding adhere to a principle of lifespan continuity, shaped by developmental, structural, and evolutionary influences. We clustered regions of the cerebral cortex according to the shape of the lifespan trajectory of memory activity in each region so that regions showing the same pattern were clustered together.

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We investigated "musical effort" with an internationally renowned, classical, pianist while playing, listening, and imagining music. We used pupillometry as an objective measure of mental effort and fMRI as an exploratory method of effort with the same musical pieces. We also compared a group of non-professional pianists and non-musicians by the use of pupillometry and a small group of non-musicians with fMRI.

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