Markus Handal Sneve

• Kransberg, Jonas Moe; Bråthen, Anne Cecilie Sjøli; Falch, Emilie Sogn; Øverbye, Knut Eiliv Ødegård; Garrido, Pablo F. & Fjell, Anders Martin [Vis alle 10 forfattere av denne artikkelen] (2026). Failure to detect entorhinal grid-like signals in a passive navigation human fMRI study. Imaging Neuroscience. 4. doi: 10.1162/imag.a.1196. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Grid cells in the human entorhinal cortex (EC) play a critical role in spatial navigation and memory. The EC is also one of the first regions affected by ageing and Alzheimer’s disease. This pre-registered functional magnetic resonance imaging (fMRI) study aimed to detect grid-cell-like signals (GLS) in a passive virtual navigation task. Contrary to our hypotheses and previous findings, we did not observe significant GLS at a population level, even in younger participants. Further exploratory analyses investigated the impact of task-engagement, as inferred from object-location memory performance, and showed no relationship with GLS magnitude. We also examined potential influences of a confounding one-fold directional signal and various data-processing choices but observed no consistent patterns. Our findings, consistent with recent null results from similar studies, suggest that passive navigation paradigms may be insufficient for reliably eliciting grid-like signals in human fMRI.

• Walhovd, Kristine B; Bråthen, Anne Cecilie Sjøli; Øverbye, Knut Eiliv Ødegård; Kransberg, Jonas Moe; Sørensen, Øystein & Garrido, Pablo F. [Vis alle 19 forfattere av denne artikkelen] (2026). Feature-specific environmental contributions to human cortical architecture revealed by twin brainprints. Communications Biology. doi: 10.1038/s42003-026-10707-w. Fulltekst i vitenarkiv Vis sammendrag

  Abstract How environmental variation shapes the human cerebral cortex remains incompletely understood. Here we compare cortical brainprints – individual profiles of regional cortical morphology – in 210 twins (age 16-78 years) to distinguish prenatal, adult naturalistic and experimentally induced environmental variation from genetic contributions. Monozygotic twins showed higher brainprint similarity than dizygotic twins, consistent with genetic effects. Lasting influences of early environment were evident in lower brainprint similarity in monozygotic twin-pairs with greater birthweight discordances, driven by surface area across the cortical ribbon. In contrast, within-pair differences in adult weight and lifestyle had minimal influence. Still, a 10-week virtual-reality navigation intervention revealed training-induced changes in the gray-white interface, with curvature and area changes supported by microstructural reconfigurations. Relative brainprint similarity increased in monozygotic but diverged in dizygotic pairs following training. These findings show that distinct environmental influences acting at prenatal and adult stages are reflected in different features of the human cerebral cortex.

• Padrela, Beatriz E.; Teceläo, Sandra Raquel Ramos; Kirsebom, Bjørn-Eivind; Geier, Oliver Marcel; Tranfa, Mario & Masserini, Federico [Vis alle 22 forfattere av denne artikkelen] (2025). Blood-brain barrier water exchange in relation to amyloid, cognition and cerebrovascular burden. NeuroImage: Clinical. 49. doi: 10.1016/j.nicl.2025.103926. Fulltekst i vitenarkiv Vis sammendrag

  Blood-brain barrier (BBB) water exchange may serve as a sensitive early biomarker for Alzheimer’s disease and age-related cognitive decline. This study applied a non-invasive multi-echo arterial spin labeling (ASL) technique to measure BBB water exchange time (Tex), cerebral blood flow (CBF), and arterial transit time (ATT) in 160 adults aged 50 years and older. Participants were classified as cognitively normal (CN), having subjective cognitive decline (SCD), or mild cognitive impairment (MCI). They were assessed for amyloid status and cerebrovascular burden. Compared to CN participants, Tex was significantly lower in both SCD (−9.5 %) and MCI (−14.5 %) groups, suggesting that reductions in BBB water exchange emerge early in the course of cognitive decline. In contrast, CBF was reduced only in MCI participants (−20.8 % compared to CN), and ATT was significantly increased only in individuals with severe cerebrovascular burden (Fazekas score 3). Notably, Tex showed a stepwise decrease with increasing Fazekas scores (1–2), supporting its sensitivity to moderate small vessel disease. No associations were found between Tex and amyloid positivity after adjusting for age and sex. These findings indicate that Tex alterations may precede changes in traditional perfusion markers and are more closely related to vascular and early cognitive changes than to amyloid pathology. BBB water exchange mapping may therefore provide a promising, non-invasive tool to detect early neurovascular dysfunction that contributes to cognitive decline in aging populations, potentially offering a useful biomarker for early intervention trials targeting vascular contributions to dementia.

• Fjell, Anders Martin; Røgeberg, Ole Jørgen; Sørensen, Øystein; Amlien, Inge; Bartrés-Faz, David & Brandmaier, Andreas M. [Vis alle 23 forfattere av denne artikkelen] (2025). Reevaluating the role of education on cognitive decline and brain aging in longitudinal cohorts across 33 Western countries. Nature Medicine. ISSN 1078-8956. 31, s. 2967–2976. doi: 10.1038/s41591-025-03828-y. Fulltekst i vitenarkiv Vis sammendrag

  Why education is linked to higher cognitive function in aging is fiercely debated. Leading theories propose that education reduces brain decline in aging and enhances tolerance to brain pathology or that it does not affect cognitive decline but, rather, reflects higher early-life cognitive function. To test these theories, we analyzed 407,356 episodic memory scores from 170,795 participants older than 50 years, alongside 15,157 brain magnetic resonance imaging scans from 6,472 participants across 33 Western countries. More education was associated with better memory, larger intracranial volume and slightly larger volume of memory-sensitive brain regions. However, education did not protect against age-related decline or weakened effects of brain decline on cognition. The most parsimonious explanation for the results is that the associations reflect factors present early in life, including propensity of individuals with certain traits to pursue more education. Although education has numerous benefits, the notion that it provides protection against cognitive or brain decline is not supported. In a large cross-national study, education was linked to better memory and larger brain volumes but not to slower cognitive or brain decline with age, suggesting that the association reflects early-life factors rather than neuroprotective effects in aging.

• Raud, Liisa; Smits, Martijn Johannes Bernardus; Sneve, Markus Handal; Ness, Hedda Tvedten; Folvik, Line & Rasch, Björn [Vis alle 7 forfattere av denne artikkelen] (2025). Differential expression of spatiotemporal sleep spindle clusters in aging. SLEEP Advances. 6(4). doi: 10.1093/sleepadvances/zpaf084. Fulltekst i vitenarkiv
• Ravndal, Anne; Fjell, Anders Martin; Vidal-Piñeiro, Didac; Sørensen, Øystein; Falch, Emilie Sogn & Kropiunig, Julia [Vis alle 21 forfattere av denne artikkelen] (2025). Sex differences in healthy brain aging are unlikely to explain higher Alzheimer’s disease prevalence in women. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 122(42). doi: 10.1073/pnas.2510486122. Fulltekst i vitenarkiv Vis sammendrag

  As Alzheimer’s disease (AD) is diagnosed more frequently in women, understanding the role of sex has become a key priority in AD research. However, despite aging being the primary risk factor for AD, it remains unclear whether men and women differ in the extent of brain decline with age. Using 12,638 longitudinal brain MRIs from 4,726 participants aged 17 to 95 y across 14 cohorts, we examined sex differences in structural brain changes over time, controlling for differences in head size. Men showed greater cortical thickness (CT) decline in the cuneus, lingual, parahippocampal, and pericalcarine regions; surface area decline in the fusiform and postcentral regions; and in older adults, greater subcortical decline in the caudate, nucleus accumbens, putamen, and pallidum. In contrast, women only showed greater surface area decline in the banks of the superior temporal sulcus and greater ventricular expansion in older adults. These results suggest that sex differences in age-related brain decline are unlikely to contribute to the higher AD diagnosis prevalence in women, necessitating research into alternative explanations.

• Vidal-Piñeiro, Didac; Sørensen, Øystein; Strømstad, Marie Lorentsen; Amlien, Inge; Anderson, Micael & Baaré, William F.C. [Vis alle 25 forfattere av denne artikkelen] (2025). Reliability of structural brain change in cognitively healthy adult samples. Imaging Neuroscience. 3, s. 1–25. doi: 10.1162/imag_a_00547. Fulltekst i vitenarkiv Vis sammendrag

  In neuroimaging research, tracking individuals over time is key to understanding the interplay between brain changes and genetic, environmental, or cognitive factors across the lifespan. Yet, the extent to which we can estimate the individual trajectories of brain change over time with precision remains uncertain. In this study, we estimated the reliability of structural brain change in cognitively healthy adults from multiple samples and assessed the influence of follow-up time and number of observations. Estimates of cross-sectional measurement error and brain change variance were obtained using the longitudinal FreeSurfer processing stream. Our findings showed, on average, modest longitudinal reliability with 2 years of follow-up. Increasing the follow-up time was associated with a substantial increase in longitudinal reliability, while the impact of increasing the number of observations was comparatively minor. On average, 2-year follow-up studies require ≈2.7 and ≈4.0 times more individuals than designs with follow-ups of 4 and 6 years to achieve comparable statistical power. Subcortical volume exhibited higher longitudinal reliability than cortical area, thickness, and volume. The reliability estimates were comparable with those estimated from empirical data. The reliability estimates were affected by both the cohort’s age where younger adults had lower reliability of change and the preprocessing pipeline where the FreeSurfer’s longitudinal stream was notably superior than the cross-sectional stream. Suboptimal reliability inflated sample size requirements and compromised the ability to distinguish individual trajectories of brain aging. This study underscores the importance of long-term follow-ups and the need to consider reliability in longitudinal neuroimaging research.

• Grydeland, Håkon; Sneve, Markus Handal; Roe, James Michael; Raud, Liisa; Ness, Hedda Tvedten & Folvik, Line [Vis alle 12 forfattere av denne artikkelen] (2025). Network segregation during episodic memory shows age-invariant relations with memory performance from 7 to 82 years. Neurobiology of Aging. ISSN 0197-4580. 148, s. 1–15. doi: 10.1016/j.neurobiolaging.2025.01.004. Fulltekst i vitenarkiv Vis sammendrag

  Lower episodic memory capability, as seen in development and aging compared with younger adulthood, may partly depend on lower brain network segregation. Here, our objective was twofold: (1) test this hypothesis using within- and between-network functional connectivity (FC) during episodic memory encoding and retrieval, in two independent samples (n = 734, age 7–82 years). (2) Assess associations with age and the ability to predict memory comparing task-general FC and memory-modulated FC. In a multiverse-inspired approach, we performed tests across multiple analytic choices. Results showed that relationships differed based on these analytic choices and were mainly present in the largest dataset,. Significant relationships indicated that (i) memory-modulated FC predicted memory performance and associated with memory in an age-invariant manner. (ii) In line with the so-called neural dedifferentiation view, task-general FC showed lower segregation with higher age in adults which was associated with worse memory performance. In development, although there were only weak signs of a neural differentiation, that is, gradually higher segregation with higher age, we observed similar lower segregation-worse memory relationships. This age-invariant relationships between FC and episodic memory suggest that network segregation is pivotal for memory across the healthy lifespan.

• Padrela, Beatriz E.; Slivka, Maksim; Sneve, Markus Handal; Garrido, Pablo F.; Dijsselhof, Mathijs B.J. & Hageman, Tamara [Vis alle 18 forfattere av denne artikkelen] (2025). Blood-brain barrier water permeability across the adult lifespan: A multi-echo ASL study. Neurobiology of Aging. ISSN 0197-4580. 147, s. 176–186. doi: 10.1016/j.neurobiolaging.2024.12.012. Fulltekst i vitenarkiv
• Fjell, Anders Martin; Sneve, Markus Handal; Amlien, Inge; Grydeland, Håkon; Mowinckel, Athanasia Monika & Vidal-Piñeiro, Didac [Vis alle 8 forfattere av denne artikkelen] (2025). Stable hippocampal correlates of high episodic memory function across adulthood. Scientific Reports. 15(1). doi: 10.1038/s41598-025-92278-0. Fulltekst i vitenarkiv
• Etholm, Lars; Ivanovic, Jugoslav; Larsen, Vilde Stangebye; Sneve, Markus Handal; Lossius, Morten Ingvar & Alfstad, Kristin Åshild (2024). Localizing value of disturbances of self-integration, depersonalization, and forced thinking: A systematic review. Epileptic disorders. ISSN 1294-9361. s. 1–15. doi: 10.1002/epd2.20317. Fulltekst i vitenarkiv Vis sammendrag

  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. Studies published in peer-reviewed journals with an abstract available, limited to English, French, German, Spanish, or Italian were included for review. Abstracts from scientific meetings were included if precise data on semiology in addition to either localization or surgical outcome was presented. Cases were regarded as eligible if data informing on anatomo-clinical correlations were sufficient to allow determination of an epileptogenic zone and evaluate its level of confidence. For disturbances of self-integration, the search identified 18 publications containing 23 eligible cases, with 10 additional cases identified in the literature. For depersonalization, a single case from a two patient study fulfilled inclusion criteria. For forced thinking, the search identified two publications containing four eligible cases, with six additional cases identified through literature searches. The retrieved cases suggest that disturbances of self-integration often reflect an epileptogenic zone centered around the temporoparietal region, where neighboring areas in the parietal lobe, the posterior insula, and likely depending on the type of disturbance also the adjoining occipital lobe, the anterior and middle cingulum, premotor and supplementary motor in addition to medial temporal structures could be involved. When present, lateralized symptomatology reflects a contralateral focus. Depersonalization, as a localizing ictal phenomenon was quite elusive. Forced thinking either pointed to premotor frontal or temporal epileptogenic zones. Currently, outlined epileptogenic zones of ictal disturbances of self-integration and forced thinking are quite widespread and should be regarded with a low-to-moderate degree of reliability. A focus on such rarer ictal phenomena, in combination with improved imaging techniques and increased use of SEEG, will hopefully lead to an accumulation of cases with better defined epileptogenic zones.

• Ness, Hedda Tvedten; Folvik, Line; Sneve, Markus Handal; Grydeland, Håkon; Vidal-Piñeiro, Didac & Raud, Liisa [Vis alle 9 forfattere av denne artikkelen] (2024). Recalled through this day but forgotten next week?-retrieval activity predicts durability of partly consolidated memories. Cerebral Cortex. ISSN 1047-3211. 34(6), s. 1–15. doi: 10.1093/cercor/bhae233. Fulltekst i vitenarkiv
• Kransberg, Jonas; Sneve, Markus Handal; Falch, Emilie Sogn; Bråthen, Anne Cecilie Sjøli; Fjell, Anders Martin & Walhovd, Kristine B (2024). Failure to replicate detection of grid-cell like representations in human fMRI. Alzheimer's & Dementia. ISSN 1552-5260. 20, s. e086080–e086080. doi: 10.1002/alz.086080. Fulltekst i vitenarkiv
• Løchen, Aili Røtterud; Kolskår, Knut-Kristian; Lange, Ann-Marie Glasø de; Sneve, Markus Handal; Haatveit, Beathe & Lagerberg, Trine Vik [Vis alle 11 forfattere av denne artikkelen] (2023). Visual processing deficits in patients with schizophrenia spectrum and bipolar disorders and associations with psychotic symptoms, and intellectual abilities. Heliyon. 9(2). doi: 10.1016/j.heliyon.2023.e13354. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Objective Low-level sensory disruption is hypothesized as a precursor to clinical and cognitive symptoms in severe mental disorders. We compared visual discrimination performance in patients with schizophrenia spectrum disorder or bipolar disorder with healthy controls, and investigated associations with clinical symptoms and IQ. Methods Patients with schizophrenia spectrum disorder (n = 32), bipolar disorder (n = 55) and healthy controls (n = 152) completed a computerized visual discrimination task. Participants responded whether the latter of two consecutive grids had higher or lower spatial frequency, and discrimination thresholds were estimated using an adaptive maximum likelihood procedure. Case-control differences in threshold were assessed using linear regression, F-test and post-hoc pair-wise comparisons. Linear models were used to test for associations between visual discrimination threshold and psychotic symptoms derived from the PANSS and IQ assessed using the Matrix Reasoning and Vocabulary subtests from the Wechsler Abbreviated Scale of Intelligence (WASI). Results Robust regression revealed a significant main effect of diagnosis on discrimination threshold (robust F = 6.76, p = .001). Post-hoc comparisons revealed that patients with a schizophrenia spectrum disorder (mean = 14%, SD = 0.08) had higher thresholds compared to healthy controls (mean = 10.8%, SD = 0.07, β = 0.35, t = 3.4, p = .002), as did patients with bipolar disorder (12.23%, SD = 0.07, β = 0.21, t = 2.42, p = .04). There was no significant difference between bipolar disorder and schizophrenia (β = −0.14, t = −1.2, p = .45). Linear models revealed negative associations between IQ and threshold across all participants when controlling for diagnostic group (β = −0.3, t = −3.43, p = .0007). This association was found within healthy controls (t = −3.72, p = .0003) and patients with bipolar disorder (t = −2.53, p = .015), and no significant group by IQ interaction on threshold (F = 0.044, p = .97). There were no significant associations between PANSS domain scores and discrimination threshold. Conclusion Patients with schizophrenia spectrum or bipolar disorders exhibited higher visual discrimination thresholds than healthy controls, supporting early visual deficits among patients with severe mental illness. Discrimination threshold was negatively associated with IQ among healthy controls and bipolar disorder patients. These findings elucidate perception-related disease mechanisms in severe mental illness, which warrants replication in independent samples.

• Folvik, Line; Sneve, Markus Handal; Ness, Hedda Tvedten; Vidal-Piñeiro, Didac; Raud, Liisa & Geier, Oliver [Vis alle 8 forfattere av denne artikkelen] (2023). Sustained upregulation of widespread hippocampal-neocortical coupling following memory encoding. Cerebral Cortex. ISSN 1047-3211. 33(8), s. 4844–4858. doi: 10.1093/cercor/bhac384. Fulltekst i vitenarkiv
• Roe, James Michael; Vidal-Piñeiro, Didac; Amlien, Inge; Pan, Mengyu; Sneve, Markus Handal & Schotten, Michel Thiebaut de [Vis alle 14 forfattere av denne artikkelen] (2023). Tracing the development and lifespan change of population-level structural asymmetry in the cerebral cortex. eLIFE. 12, s. 1–32. doi: 10.7554/eLife.84685. Fulltekst i vitenarkiv
• Raud, Liisa; Sneve, Markus Handal; Vidal-Piñeiro, Didac; Sørensen, Øystein; Folvik, Line & Ness, Hedda Tvedten [Vis alle 10 forfattere av denne artikkelen] (2023). Hippocampal-cortical functional connectivity during memory encoding and retrieval. NeuroImage. ISSN 1053-8119. 279. doi: 10.1016/j.neuroimage.2023.120309. Fulltekst i vitenarkiv
• Capogna, Elettra; Sneve, Markus Handal; Raud, Liisa; Folvik, Line; Ness, Hedda Tvedten & Walhovd, Kristine B [Vis alle 8 forfattere av denne artikkelen] (2022). Whole-brain connectivity during encoding: age-related differences and associations with cognitive and brain structural decline. Cerebral Cortex. ISSN 1047-3211. 33(1), s. 68–82. doi: 10.1093/cercor/bhac053. Fulltekst i vitenarkiv
• Lengali, Lilly; Hippe, Johannes; Hatlestad-Hall, Christoffer; Rygvold, Trine Waage; Sneve, Markus Handal & Andersson, Stein (2021). Sensory-Induced Human LTP-Like Synaptic Plasticity – Using Visual Evoked Potentials to Explore the Relation Between LTP-Like Synaptic Plasticity and Visual Perceptual Learning. Frontiers in Human Neuroscience. 15. doi: 10.3389/fnhum.2021.684573. Fulltekst i vitenarkiv
• Ness, Hedda Tvedten; Folvik, Line; Sneve, Markus Handal; Pineiro, Didac Vidal; Raud, Liisa & Geier, Oliver [Vis alle 9 forfattere av denne artikkelen] (2021). Reduced Hippocampal-Striatal Interactions during Formation of Durable Episodic Memories in Aging. Cerebral Cortex. ISSN 1047-3211. 32(11), s. 2358–2372. doi: 10.1093/cercor/bhab331. Fulltekst i vitenarkiv
• Endestad, Tor; Godøy, Rolf Inge; Sneve, Markus Handal; Hagen, Thomas; Bochynska, Agata Elzbieta & Laeng, Bruno (2020). Mental Effort When Playing, Listening, and Imagining Music in One Pianist’s Eyes and Brain. Frontiers in Human Neuroscience. 14. doi: 10.3389/fnhum.2020.576888. Fulltekst i vitenarkiv Vis sammendrag

  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. This combined approach of psychophysiology and neuroimaging revealed the cognitive work during different musical activities. We found that pupil diameters were largest when “playing” (regardless of whether there was sound produced or not) compared to conditions with no movement (i.e., “listening” and “imagery”). We found positive correlations between pupil diameters of the professional pianist during different conditions with the same piano piece (i.e., normal playing, silenced playing, listen, imagining), which might indicate similar degrees of load on cognitive resources as well as an intimate link between the motor imagery of sound-producing body motions and gestures. We also confirmed that musical imagery had a strong commonality with music listening in both pianists and musically naïve individuals. Neuroimaging provided evidence for a relationship between noradrenergic (NE) activity and mental workload or attentional intensity within the domain of music cognition. We found effort related activity in the superior part of the locus coeruleus (LC) and, similarly to the pupil, the listening and imagery engaged less the LC–NE network than the motor condition. The pianists attended more intensively to the most difficult piece than the non-musicians since they showed larger pupils for the most difficult piece. Non-musicians were the most engaged by the music listening task, suggesting that the amount of attention allocated for the same task may follow a hierarchy of expertise demanding less attentional effort in expert or performers than in novices. In the professional pianist, we found only weak evidence for a commonality between subjective effort (as rated measure-by-measure) and the objective effort gauged with pupil diameter during listening. We suggest that psychophysiological methods like pupillometry can index mental effort in a manner that is not available to subjective awareness or introspection.

• Langnes, Espen; Sneve, Markus Handal; Sederevicius, Donatas; Amlien, Inge Kasbohm; Walhovd, Kristine B & Fjell, Anders Martin (2020). Anterior and posterior hippocampus macro‐ and microstructure across the lifespan in relation to memory—A longitudinal study. Hippocampus. ISSN 1050-9631. s. 1–15. doi: 10.1002/hipo.23189. Fulltekst i vitenarkiv Vis sammendrag

  There is evidence for a hippocampal long axis anterior–posterior (AP) differentiation in memory processing, which may have implications for the changes in episodic memory performance seen across development and aging. The hippocampus shows substantial structural changes with age, but the lifespan trajectories of hippocampal sub‐regions along the AP axis are not established. The aim of the present study was to test whether the micro‐ and macro‐structural age‐trajectories of the anterior (aHC) and posterior (pHC) hippocampus are different. In a single‐center longitudinal study, 1,790 cognitively healthy participants, 4.1–93.4 years of age, underwent a total of 3,367 MRI examinations and 3,033 memory tests sessions over 1–6 time points, spanning an interval up to 11.1 years. T1‐weighted scans were used to estimate the volume of aHC and pHC (macrostructure), and diffusion tensor imaging to measure mean diffusion (MD, microstructure) within each region. We found that the macro‐ and microstructural lifespan‐trajectories of aHC and pHC were clearly distinguishable, with partly common and partly unique variance shared with age. aHC showed a protracted period of microstructural development, while pHC microstructural development as indexed by MD was more or less completed in early childhood. In contrast, pHC showed larger unique aging‐related changes. An aHC–pHC difference was also observed for volume, with pHC changing relatively more with higher age. All regions showed age‐dependent relationships with episodic memory. aHC micro‐ and macrostructure was significantly related to verbal memory independently of age, but the relationships were still strongest among the older participants. We suggest that memory processes supported by each sub‐region improve or decline in concert with volumetric and microstructural changes in the same age‐period. Future research should disentangle the lifespan relationship between changes in these structural properties and different memory processes, encoding versus retrieval in particular, as well as other cognitive functions depending on the hippocampal long‐axis specialization.

• Fjell, Anders Martin; Sederevicius, Donatas; Sneve, Markus Handal; Lange, Ann-Marie Glasø de; Bråthen, Anne Cecilie Sjøli & Idland, Ane-Victoria [Vis alle 16 forfattere av denne artikkelen] (2020). Self-reported sleep problems are related to amyloid deposition in cortical regions with high HOMER1 gene expression. Cerebral Cortex. ISSN 1047-3211. 30(4), s. 2144–2156. doi: 10.1093/cercor/bhz228. Fulltekst i vitenarkiv Vis sammendrag

  Sleep problems are related to the elevated levels of the Alzheimer’s disease (AD) biomarker β-amyloid (Aβ). Hypotheses about the causes of this relationship can be generated from molecular markers of sleep problems identified in rodents. A major marker of sleep deprivation is Homer1a, a neural protein coded by the HOMER1 gene, which has also been implicated in brain Aβ accumulation. Here, we tested whether the relationship between cortical Aβ accumulation and self-reported sleep quality, as well as changes in sleep quality over 3 years, was stronger in cortical regions with high HOMER1 mRNA expression levels. In a sample of 154 cognitively healthy older adults, Aβ correlated with poorer sleep quality cross-sectionally and longitudinally (n = 62), but more strongly in the younger than in older individuals. Effects were mainly found in regions with high expression of HOMER1. The anatomical distribution of the sleep-Aβ relationship followed closely the Aβ accumulation pattern in 69 patients with mild cognitive impairment or AD. Thus, the results indicate that the relationship between sleep problems and Aβ accumulation may involve Homer1 activity in the cortical regions, where harbor Aβ deposits in AD. The findings may advance our understanding of the relationship between sleep problems and AD risk.

• Vidal-Piñeiro, Didac; Sneve, Markus Handal; Amlien, Inge Kasbohm; Grydeland, Håkon; Mowinckel, Athanasia Monika & Roe, James Michael [Vis alle 10 forfattere av denne artikkelen] (2020). The Functional Foundations of Episodic Memory Remain Stable Throughout the Lifespan. Cerebral Cortex. ISSN 1047-3211. doi: 10.1093/cercor/bhaa348. Fulltekst i vitenarkiv Vis sammendrag

  Abstract 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. The results revealed that lifespan trajectories of memory encoding function showed a continuity through life but no evidence of age-specific mechanisms such as compensatory patterns. Encoding activity was related to general cognitive abilities and variations of grey matter as captured by a multi-modal independent component analysis, variables reflecting core aspects of cognitive and structural change throughout the lifespan. Furthermore, memory encoding activity aligned to fundamental aspects of brain organization, such as large-scale connectivity and evolutionary cortical expansion gradients. Altogether, we provide novel support for a perspective on memory aging in which maintenance and decay of episodic memory in older age needs to be understood from a comprehensive life-long perspective rather than as a late-life phenomenon only.

• Vidal-Piñeiro, Didac; Sneve, Markus Handal; Nyberg, Lars; Mowinckel, Athanasia Monika; Sederevicius, Donatas & Walhovd, Kristine B [Vis alle 7 forfattere av denne artikkelen] (2019). Maintained Frontal Activity Underlies High Memory Function Over 8 Years in Aging. Cerebral Cortex. ISSN 1047-3211. 29(7), s. 3111–3123. doi: 10.1093/cercor/bhy177. Fulltekst i vitenarkiv
• Sneve, Markus Handal; Grydeland, Håkon; Rosa, Marcello G P; Paus, Tomáš; Chaplin, Tristan & Walhovd, Kristine B [Vis alle 7 forfattere av denne artikkelen] (2019). High-expanding regions in primate cortical brain evolution support supramodal cognitive flexibility. Cerebral Cortex. ISSN 1047-3211. 29(9), s. 3891–3901. doi: 10.1093/cercor/bhy268. Fulltekst i vitenarkiv
• Amlien, Inge Kasbohm; Sneve, Markus Handal; Vidal-Piñeiro, Didac; Walhovd, Kristine B & Fjell, Anders Martin (2019). Elaboration Benefits Source Memory Encoding Through Centrality Change. Scientific Reports. 9(1), s. 1–13. doi: 10.1038/s41598-019-39999-1. Fulltekst i vitenarkiv Vis sammendrag

  Variations in levels of processing affect memory encoding and subsequent retrieval performance, but it is unknown how processing depth affects communication patterns within the network of interconnected brain regions involved in episodic memory encoding. In 113 healthy adults scanned with functional MRI, we used graph theory to calculate centrality indices representing the brain regions’ relative importance in the memory network. We tested how communication patterns in 42 brain regions involved in episodic memory encoding changed as a function of processing depth, and how these changes were related to episodic memory ability. Centrality changes in right middle frontal gyrus, right inferior parietal lobule and left superior frontal gyrus were positively related to semantic elaboration during encoding. In the same regions, centrality during successful episodic memory encoding was related to performance on the episodic memory task, indicating that these centrality changes reflect processes that support memory encoding through deep elaborative processing. Similar analyses were performed for congruent trials, i.e. events that fit into existing knowledge structures, but no relationship between centrality changes and congruity were found. The results demonstrate that while elaboration and congruity have similar beneficial effects on source memory performance, the cortical signatures of these processes are probably not identical.

• Fjell, Anders Martin; Sneve, Markus Handal; Sederevicius, Donatas; Sørensen, Øystein; Krogsrud, Stine Kleppe & Mowinckel, Athanasia Monika [Vis alle 7 forfattere av denne artikkelen] (2019). Volumetric and microstructural regional changes of the hippocampus underlying development of recall performance after extended retention intervals. Developmental Cognitive Neuroscience. ISSN 1878-9293. 40:100723, s. 1–12. doi: 10.1016/j.dcn.2019.100723. Fulltekst i vitenarkiv Vis sammendrag

  Performance on recall tests improves through childhood and adolescence, in part due to structural maturation of the medial temporal cortex. Although partly different processes support successful recall over shorter vs. longer intervals, recall is usually tested after less than an hour. The aim of the present study was to test whether there are unique developmental changes in recall performance using extended retention intervals, and whether these are related to structural maturation of sub-regions of the hippocampus. 650 children and adolescents from 4.1 to 24.8 years were assessed in total 962 times (mean interval ≈ 1.8 years). The California Verbal Learning Test (CVLT) and the Rey Complex Figure Test (CFT) were used. Recall was tested 30 min and ≈ 10 days after encoding. We found unique developmental effects on recall in the extended retention interval condition independently of 30 min recall performance. For CVLT, major improvements happened between 10 and 15 years. For CFT, improvement was linear and was accounted for by visuo-constructive abilities. The relationships did not show anterior-posterior hippocampal axis differences. In conclusion, performance on recall tests using extended retention intervals shows unique development, likely due to changes in encoding depth or efficacy, or improvements of long-term consolidation processes.

• Fjell, Anders Martin; Chen, Chi-Hua Chen; Sederevicius, Donatas; Sneve, Markus Handal; Grydeland, Håkon & Krogsrud, Stine Kleppe [Vis alle 17 forfattere av denne artikkelen] (2019). Continuity and discontinuity in human cortical development and change from embryonic stages to old age. Cerebral Cortex. ISSN 1047-3211. 29(9), s. 3879–3890. doi: 10.1093/cercor/bhy266. Fulltekst i vitenarkiv Vis sammendrag

  The human cerebral cortex is highly regionalized, and this feature emerges from morphometric gradients in the cerebral vesicles during embryonic development. We tested if this principle of regionalization could be traced from the embryonic development to the human life span. Data-driven fuzzy clustering was used to identify regions of coordinated longitudinal development of cortical surface area (SA) and thickness (CT) (n = 301, 4–12 years). The principal divide for the developmental SA clusters extended from the inferior–posterior to the superior–anterior cortex, corresponding to the major embryonic morphometric anterior–posterior (AP) gradient. Embryonic factors showing a clear AP gradient were identified, and we found significant differences in gene expression of these factors between the anterior and posterior clusters. Further, each identified developmental SA and CT clusters showed distinguishable life span trajectories in a larger longitudinal dataset (4–88 years, 1633 observations), and the SA and CT clusters showed differential relationships to cognitive functions. This means that regions that developed together in childhood also changed together throughout life, demonstrating continuity in regionalization of cortical changes. The AP divide in SA development also characterized genetic patterning obtained in an adult twin sample. In conclusion, the development of cortical regionalization is a continuous process from the embryonic stage throughout life.

• Roe, James Michael; Vidal-Piñeiro, Didac; Sneve, Markus Handal; Kompus, Kristiina; Greve, Douglas N. & Walhovd, Kristine B [Vis alle 8 forfattere av denne artikkelen] (2019). Age-Related Differences in Functional AsymmetryDuring Memory Retrieval Revisited: No Evidence forContralateral Overactivation or Compensation. Cerebral Cortex. ISSN 1047-3211. 0(0), s. 1–19. doi: 10.1093/cercor/bhz153. Fulltekst i vitenarkiv Vis sammendrag

  Brain asymmetry is inherent to cognitive processing and seems to reflect processing efficiency. Lower frontal asymmetry is often observed in older adults during memory retrieval, yet it is unclear whether lower asymmetry implies an age-related increase in contralateral recruitment, whether less asymmetry reflects compensation, is limited to frontal regions, or predicts neurocognitive stability or decline. We assessed age-related differences in asymmetry across the entire cerebral cortex, using functional magnetic resonance imaging data from 89 young and 76 older adults during successful retrieval, and surface-based methods allowing direct homotopic comparison of activity between cortical hemispheres . An extensive left-asymmetric network facilitated retrieval in both young and older adults, whereas diverse frontal and parietal regions exhibited lower asymmetry in older adults. However, lower asymmetry was not associated with age-related increases in contralateral recruitment but primarily reflected either less deactivation in contralateral regions reliably signaling retrieval failure in the young or lower recruitment of the dominant hemisphere—suggesting that functional deficits may drive lower asymmetry in older brains, not compensatory activity. Lower asymmetry predicted neither current memory performance nor the extent of memory change across the preceding ~ 8 years in older adults. Together, these findings are inconsistent with a compensation account for lower asymmetry during retrieval and aging.

• Walle, Kjersti Mæhlum; Nordvik, Jan Egil; Becker, Frank; Espeseth, Thomas; Sneve, Markus Handal & Laeng, Bruno (2019). Unilateral neglect post stroke: Eye movement frequencies indicate directional hypokinesia while fixation distributions suggest compensational mechanism. Brain and Behavior. 9:e01170(1). doi: 10.1002/brb3.1170. Fulltekst i vitenarkiv Vis sammendrag

  Introduction: Eye movements and spatial attention are closely related, and eye‐tracking can provide valuable information in research on visual attention. We investigated the pathology of overt attention in right hemisphere (RH) stroke patients differing in their severity of neglect symptoms by using eye‐tracking during a dynamic attention task. Methods: Eye movements were recorded in 26 RH stroke patients (13 with and 13 without unilateral spatial neglect, and a matched group of 26 healthy controls during a Multiple Object Tracking task. We assessed the frequency and spatial distributions of fixations, as well as frequencies of eye movements to the left and to the right side of visual space so as to investigate individuals’ efficiency of visual processing, distribution of attentional processing resources, and oculomotoric orienting mechanisms. Results: Both patient groups showed increased fixation frequencies compared to controls. A spatial bias was found in neglect patients’ fixation distribution, depending on neglect severity (indexed by scores on the Behavioral Inattention Test). Patients with more severe neglect had more fixations within the right field, while patients with less severe neglect had more fixations within their left field. Eye movement frequencies were dependent on direction in the neglect patient group, as they made more eye movements toward the right than toward the left. Conclusion: The patient groups’ higher fixation rates suggest that patients are generally less efficient in visual processing. The spatial bias in fixation distribution, dependent on neglect severity, suggested that patients with less severe neglect were able to use compensational mechanisms in their contralesional space. The observed relation between eye movement rates and directions observed in neglect patients provides a measure of the degree of difficulty these patients may encounter during dynamic situations in daily life and supports the idea that directional oculomotor hypokinesia may be a relevant component in this syndrome.

• Bråthen, Anne Cecilie Sjøli; Lange, Ann-Marie Glasø de; Rohani, Darius; Sneve, Markus Handal; Fjell, Anders Martin & Walhovd, Kristine B (2018). Multimodal cortical and hippocampal prediction of episodic‐memory plasticity in young and older adults. Human Brain Mapping. ISSN 1065-9471. 39(11), s. 4480–4492. doi: 10.1002/hbm.24287. Fulltekst i vitenarkiv Vis sammendrag

  Episodic memory can be trained in both early and late adulthood, but there is considerable variation in cognitive improvement across individuals. Which brain characteristics make some individuals benefit more than others? We used a multimodal approach to investigate whether volumetric magnetic resonance imaging (MRI) and resting‐state functional MRI characteristics of the cortex and hippocampus, brain regions involved in episodic‐memory function, were predictive of cognitive improvement after memory training. We hypothesized that these brain characteristics would differentially predict memory improvement in young and older adults, given the vulnerability of cortical regions as well as the hippocampus to healthy aging. Following structural and resting‐state activity magnetic resonance scans, 50 young and 76 older participants completed 10 weeks of strategic episodic‐memory training. Both age groups improved their memory performance, but the young adults more so than the older. Vertex‐wise analyses of cortical volume showed no significant relation to memory benefit. When analyzing the two age groups separately, hippocampal volume was predictive of memory improvement in the group of older participants only. In this age group, the lower resting‐state activity of the hippocampus was also predictive of memory improvement. Both volumetric and resting‐state characteristics of the hippocampus explained unique variance of the improvement in the older participants suggesting that a multimodal imaging approach is valuable for the understanding of mechanisms underlying memory plasticity in aging.

• Amlien, Inge Kasbohm; Sneve, Markus Handal; Vidal-Piñeiro, Didac; Walhovd, Kristine B & Fjell, Anders Martin (2018). The lifespan trajectory of the encoding-retrieval flip: A multimodal examination of medial parietal cortex contributions to episodic memory. Journal of Neuroscience. ISSN 0270-6474. 38(40), s. 8666–8679. doi: 10.1523/JNEUROSCI.1702-17.2018. Fulltekst i vitenarkiv Vis sammendrag

  The formation of episodic memories is associated with deactivation during encoding and activation during retrieval in the posteromedial cortex (PMC). We hypothesized that the encoding/retrieval (E/R) flip is a critical component of episodic memory across the lifespan because structural and metabolic changes in thePMCcoincide with the fine tuning of the episodicmemorysystem in development and the reductions of memory performance in aging. The aims of the present study were, first, to describe lifespan trajectories of PMC encoding and retrieval activity in 270 human participants (167 females) from 6 to 80 years of age. Our second goal was to construct a model for episodic memory development in which contributions from brain activity, cortical thickness (CT), and structural connectivity are accounted for. We found that modulation of neural activity in response to memory encoding and retrieval demands was not fully developed until adolescence and decreased from adulthood through old age. The magnitude of the E/R flip was related to source memory and 55% of the age-related variance in source memory performance during childhood and adolescence could be accounted for by the E/R flip, CT, and mean diffusivity together. However, only CT and the E/R flip provided unique contributions with which to explain memory performance. The results suggest that neural dynamics in the PMC is related to the development of episodic memory during childhood and adolescence. The similar trajectories of the E/R flip and episodic memory emergence and decline through development and aging further suggests that a lifelong relationship exists.

• Langnes, Espen; Vidal-Piñeiro, Didac; Sneve, Markus Handal; Amlien, Inge Kasbohm; Walhovd, Kristine B & Fjell, Anders Martin (2018). Development and decline of the hippocampal long-axis specialization and differentiation during encoding and retrieval of episodic memories. Cerebral Cortex. ISSN 1047-3211. s. 1–17. doi: 10.1093/cercor/bhy209. Fulltekst i vitenarkiv
• Fjell, Anders Martin; Sneve, Markus Handal; Grydeland, Håkon; Storsve, Andreas Berg; Amlien, Inge Kasbohm & Yendiki, Anastasia [Vis alle 7 forfattere av denne artikkelen] (2017). Relationship between structural and functional connectivity change across the lifespan – a longitudinal investigation. Human Brain Mapping. ISSN 1065-9471. 38(1), s. 561–573. doi: 10.1002/hbm.23403. Fulltekst i vitenarkiv Vis sammendrag

  Extensive efforts are devoted to understand the functional (FC) and structural connections (SC) of the brain. FC is usually measured by functional magnetic resonance imaging (fMRI), and conceptualized as degree of synchronicity in brain activity between different regions. SC is typically indexed by measures of white matter (WM) properties, for example, by diffusion weighted imaging (DWI). FC and SC are intrinsically related, in that coordination of activity across regions ultimately depends on fast and efficient transfer of information made possible by structural connections. Convergence between FC and SC has been shown for specific networks, especially the default mode network (DMN). However, it is not known to what degree FC is constrained by major WM tracts and whether FC and SC change together over time. Here, 120 participants (20–85 years) were tested at two time points, separated by 3.3 years. Resting-state fMRI was used to measure FC, and DWI to measure WM microstructure as an index of SC. TRACULA, part of FreeSurfer, was used for automated tractography of 18 major WM tracts. Cortical regions with tight structural couplings defined by tractography were only weakly related at the functional level. Certain regions of the DMN showed a modest relationship between change in FC and SC, but for the most part, the two measures changed independently. The main conclusions are that anatomical alignment of SC and FC seems restricted to specific networks and tracts, and that changes in SC and FC are not necessarily strongly correlated. This is the peer reviewed version of the following article: Relationship between structural and functional connectivity change across the adult lifespan: A longitudinal investigation, which has been published in final form at Hum Brain Mapp. 2016 Sep 22. doi: 10.1002/hbm.23403. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

• Vidal-Piñeiro, Didac; Sneve, Markus Handal; Storsve, Andreas Berg; Roe, James Michael; Walhovd, Kristine B & Fjell, Anders Martin (2017). Neural correlates of durable memories across the adult lifespan: brain activity at encoding and retrieval. Neurobiology of Aging. ISSN 0197-4580. 60, s. 20–33. doi: 10.1016/j.neurobiolaging.2017.08.017. Fulltekst i vitenarkiv
• Sneve, Markus Handal; Grydeland, Håkon; Amlien, Inge Kasbohm; Langnes, Espen; Walhovd, Kristine B & Fjell, Anders Martin (2017). Decoupling of large-scale brain networks supports the consolidation of durable episodic memories. NeuroImage. ISSN 1053-8119. 153, s. 336–345. doi: 10.1016/j.neuroimage.2016.05.048. Fulltekst i vitenarkiv Vis sammendrag

  At a large scale, the human brain is organized into modules of interconnected regions, some of which play opposing roles in supporting cognition. In particular, the Default-Mode Network (DMN) has been linked to operations on internal representations, while task-positive networks are recruited during interactions with the external world. Here, we test the hypothesis that the generation of durable long-term memories depends on optimal recruitment of such antagonistic large-scale networks. As long-term memory consolidation is a process ongoing for days and weeks after an experience, we propose that individuals characterized by strong decoupling of the DMN and task-positive networks at rest operate in a mode beneficial for the long-term stabilization of episodic memories. To capture network connectivity unaffected by transient task demands and representative of brain behavior outside an experimental setting, 87 participants were scanned during rest before performing an associative encoding task. To link individual resting-state functional connectivity patterns to time-dependent memory consolidation processes, participants were given an unannounced memory test, either after a brief interval or after a retention period of ~6 weeks. We found that participants with a resting state characterized by high synchronicity in a DMN-centered network system and low synchronicity between task-positive networks showed superior recollection weeks after encoding. These relationships were not observed for information probed only hours after encoding. Furthermore, the two network systems were found to be anticorrelated. Our results suggest that this memory-relevant antagonism between DMN and task-positive networks is maintained through complex regulatory interactions between the systems.

• Fjell, Anders Martin; Sneve, Markus Handal; Grydeland, Håkon; Storsve, Andreas Berg & Walhovd, Kristine B (2016). The Disconnected Brain and Executive Function Decline in Aging. Cerebral Cortex. ISSN 1047-3211. doi: 10.1093/cercor/bhw082. Fulltekst i vitenarkiv Vis sammendrag

  Higher order speeded cognitive abilities depend on efficient coordination of activity across the brain, rendering them vulnerable to age reductions in structural and functional brain connectivity. The concept of “disconnected aging” has been invoked, suggesting that degeneration of connections between distant brain regions cause cognitive reductions. However, it has not been shown that changes in cognitive functions over time can be explained by simultaneous changes in brain connectivity. We followed 119 young and middle-aged (23–52 years) and older (63–86 years) adults for 3.3 years with repeated assessments of structural and functional brain connectivity and executive functions. We found unique age-related longitudinal reductions in executive function over and above changes in more basic cognitive processes. Intriguingly, 82.5% of the age-related decline in executive function could be explained by changes in connectivity over time. While both structural and functional connectivity changes were related to longitudinal reductions in executive function, only structural connectivity change could explain the age-specific decline. This suggests that the major part of the age-related reductions in executive function can be attributed to micro- and macrostructural alterations in brain connectivity. Although correlational in nature, we believe the present results constitute evidence for a “disconnected brain” view on cognitive aging. This is a pre-copyedited, author-produced PDF of an article accepted for publication in Cerebral Cortex following peer review. The version of record is available online at: http://dx.doi.org/10.1093/cercor/bhw082.

• Dørum, Erlend Solberg; Alnæs, Dag; Kaufmann, Tobias; Richard, Geneviéve´; Lund, Martina Jonette & Tønnesen, Siren [Vis alle 15 forfattere av denne artikkelen] (2016). Age-related differences in brain network activation and co-activation during multiple object tracking. Brain and Behavior. 6(11). doi: 10.1002/brb3.533. Fulltekst i vitenarkiv Vis sammendrag

  Introduction: Multiple object tracking (MOT) is a powerful paradigm for measuring sustained attention. Although previous fMRI studies have delineated the brain activation patterns associated with tracking and documented reduced tracking performance in aging, age-related effects on brain activation during MOT have not been characterized. In particular, it is unclear if the task-related activation of different brain networks is correlated, and also if this coordination between activations within brain networks shows differential effects of age. Methods: We obtained fMRI data during MOT at two load conditions from a group of younger (n = 25, mean age = 24.4 ± 5.1 years) and older (n = 21, mean age = 64.7 ± 7.4 years) healthy adults. Using a combination of voxel-wise and independent component analysis, we investigated age-related differences in the brain network activation. In order to explore to which degree activation of the various brain networks reflect unique and common mechanisms, we assessed the correlations between the brain networks’ activations. Results: Behavioral performance revealed an age-related reduction in MOT accuracy. Voxel and brain network level analyses converged on decreased load-dependent activations of the dorsal attention network (DAN) and decreased load-dependent deactivations of the default mode networks (DMN) in the old group. Lastly, we found stronger correlations in the task-related activations within DAN and within DMN components for younger adults, and stronger correlations between DAN and DMN components for older adults. Conclusion: Using MOT as means for measuring attentional performance, we have demonstrated an age-related attentional decline. Network-level analysis revealed age-related alterations in network recruitment consisting of diminished activations of DAN and diminished deactivations of DMN in older relative to younger adults. We found stronger correlations within DMN and within DAN components for younger adults and stronger correlations between DAN and DMN components for older adults, indicating age-related alterations in the coordinated network-level activation during attentional processing.

• Fjell, Anders Martin; Sneve, Markus Handal; Storsve, Andreas Berg; Grydeland, Håkon; Yendiki, Anastasia & Walhovd, Kristine B (2016). Brain Events Underlying Episodic Memory Changes in Aging: A Longitudinal Investigation of Structural and Functional Connectivity. Cerebral Cortex. ISSN 1047-3211. 26(3), s. 1272–1286. doi: 10.1093/cercor/bhv102. Fulltekst i vitenarkiv Vis sammendrag

  Episodic memories are established and maintained by close interplay between hippocampus and other cortical regions, but degradation of a fronto-striatal network has been suggested to be a driving force of memory decline in aging. We wanted to directly address how changes in hippocampal-cortical versus striatal-cortical networks over time impact episodic memory with age. We followed 119 healthy participants (20–83 years) for 3.5 years with repeated tests of episodic verbal memory and magnetic resonance imaging for quantification of functional and structural connectivity and regional brain atrophy. While hippocampal-cortical functional connectivity predicted memory change in young, changes in cortico-striatal functional connectivity were related to change in recall in older adults. Within each age group, effects of functional and structural connectivity were anatomically closely aligned. Interestingly, the relationship between functional connectivity and memory was strongest in the age ranges where the rate of reduction of the relevant brain structure was lowest, implying selective impacts of the different brain events on memory. Together, these findings suggest a partly sequential and partly simultaneous model of brain events underlying cognitive changes in aging, where different functional and structural events are more or less important in various time windows, dismissing a simple uni-factorial view on neurocognitive aging. This is a pre-copyedited, author-produced PDF of an article accepted for publication in Cerebral Cortex following peer review. The version of record [insert complete citation information here] is available online at: http://dx.doi.org/10.1093/cercor/bhv102

• Roe, James; Nesheim, Mathias; Mathiesen, Nina Chung; Moberget, Torgeir; Alnæs, Dag & Sneve, Markus Handal (2016). The effects of tDCS upon sustained visual attention are dependent on cognitive load. Neuropsychologia. ISSN 0028-3932. 80, s. 1–8. doi: 10.1016/j.neuropsychologia.2015.11.005. Fulltekst i vitenarkiv
• Sneve, Markus Handal; Grydeland, Håkon; Nyberg, Lars; Bowles, Ben; Amlien, Inge Kasbohm & Langnes, Espen [Vis alle 8 forfattere av denne artikkelen] (2015). Mechanisms underlying encoding of short-lived versus durable episodic memories. Journal of Neuroscience. ISSN 0270-6474. 35(13), s. 5202–5212. doi: 10.1523/JNEUROSCI.4434-14.2015. Fulltekst i vitenarkiv Vis sammendrag

  We continuously encounter and process novel events in the surrounding world, but only some episodes will leave detailed memory traces that can be recollected after weeks and months. Here, our aim was to monitor brain activity during encoding of events that eventually transforms into long-term stable memories. Previous functional magnetic resonance imaging (fMRI) studies have shown that the degree of activation of different brain regions during encoding is predictive of later recollection success. However, most of these studies tested participants' memories the same day as encoding occurred, whereas several lines of research suggest that extended post-encoding processing is of crucial importance for long-term consolidation. Using fMRI, we tested whether the same encoding mechanisms are predictive of recollection success after hours as after a retention interval of several weeks. Seventy-eight participants were scanned during an associative encoding task and given a source memory test the same day or after ∼6 weeks. We found a strong link between regional activity levels during encoding and recollection success over short time intervals. However, results further showed that durable source memories, i.e., events recollected after several weeks, were not simply the events associated with the highest activity levels at encoding. Rather, strong levels of connectivity between the right hippocampus and perceptual areas, as well as with parts of the self-referential default-mode network, seemed instrumental in establishing durable source memories. Thus, we argue that an initial intensity-based encoding is necessary for short-term encoding of events, whereas additional processes involving hippocampal–cortical communication aid transformation into stable long-term memories.

• Fjell, Anders Martin; Sneve, Markus Handal; Grydeland, Håkon; Storsve, Andreas Berg; Lange, Ann-Marie Glasø de & Amlien, Inge Kasbohm [Vis alle 8 forfattere av denne artikkelen] (2015). Functional connectivity change across multiple cortical networks relates to episodic memory changes in aging. Neurobiology of Aging. ISSN 0197-4580. 36(12), s. 3255–3268. doi: 10.1016/j.neurobiolaging.2015.08.020. Fulltekst i vitenarkiv Vis sammendrag

  A major task of contemporary cognitive neuroscience of aging is to explain why episodic memory declines. Change in resting-state functional connectivity (rsFC) could be a mechanism accounting for reduced function. We addressed this through 3 studies. In study 1, 119 healthy participants (20–83 years) were followed for 3.5 years with verbal recall testing and magnetic resonance imaging. Independent of atrophy, recall change was related to change in rsFC in anatomically widespread areas. Striking age-effects were observed in that a positive relationship between rsFC and memory characterized older participants while a negative relationship was seen among the younger and middle-aged. This suggests that cognitive consequences of rsFC change are not stable across age. In study 2 and 3, the age-dependent differences in rsFC-memory relationship were replicated by use of a simulation model (study 2) and by a cross-sectional experimental recognition memory task (study 3). In conclusion, memory changes were related to altered rsFC in an age-dependent manner, and future research needs to detail the mechanisms behind age-varying relationships.

• Alnæs, Dag; Sneve, Markus Handal; Richard, Geneviéve´; Skåtun, Kristina Cecilie; Kaufmann, Tobias & Nordvik, Jan Egil [Vis alle 10 forfattere av denne artikkelen] (2015). Functional connectivity indicates differential roles for the intraparietal sulcus and the superior parietal lobule in multiple object tracking. NeuroImage. ISSN 1053-8119. 123, s. 129–137. doi: 10.1016/j.neuroimage.2015.08.029. Fulltekst i vitenarkiv
• Alnæs, Dag; Kaufmann, Tobias; Richard, Geneviéve´; Duff, Eugene; Sneve, Markus Handal & Endestad, Tor [Vis alle 10 forfattere av denne artikkelen] (2015). Attentional load modulates large-scale functional brain connectivity beyond the core attention networks. NeuroImage. ISSN 1053-8119. 109, s. 260–272. doi: 10.1016/j.neuroimage.2015.01.026. Fulltekst i vitenarkiv Vis sammendrag

  In line with the notion of a continuously active and dynamic brain, functional networks identified during rest correspond with those revealed by task-fMRI. Characterizing the dynamic cross-talk between these network nodes is key to understanding the successful implementation of effortful cognitive processing in healthy individuals and its breakdown in a variety of conditions involving aberrant brain biology and cognitive dysfunction. We employed advanced network modeling on fMRI data collected during a task involving sustained attentive tracking of objects at two load levels and during rest. Using multivariate techniques, we demonstrate that attentional load levels can be significantly discriminated, and from a resting-state condition, the accuracy approaches 100%, by means of estimates of between-node functional connectivity. Several network edges were modulated during task engagement: The dorsal attention network increased connectivity with a visual node, while decreasing connectivity with motor and sensory nodes. Also, we observed a decoupling between left and right hemisphere dorsal visual streams. These results support the notion of dynamic network reconfigurations based on attentional effort. No simple correspondence between node signal amplitude change and node connectivity modulations was found, thus network modeling provides novel information beyond what is revealed by conventional task-fMRI analysis. The current decoding of attentional states confirms that edge connectivity contains highly predictive information about the mental state of the individual, and the approach shows promise for the utilization in clinical contexts.

• Sneve, Markus Handal; Sreenivasan, Kartik K; Alnæs, Dag; Endestad, Tor & Magnussen, Svein (2015). Short-term retention of visual information: Evidence in support of feature-based attention as an underlying mechanism. Neuropsychologia. ISSN 0028-3932. 66, s. 1–9. doi: 10.1016/j.neuropsychologia.2014.11.004. Fulltekst i vitenarkiv
• Fjell, Anders Martin; Amlien, Inge; Sneve, Markus Handal; Grydeland, Håkon; Tamnes, Christian Krog & Chaplin, Tristan [Vis alle 8 forfattere av denne artikkelen] (2015). The roots of Alzheimer's disease: Are high-expanding cortical areas preferentially targeted? Cerebral Cortex. ISSN 1047-3211. 25(9), s. 2556–2565. doi: 10.1093/cercor/bhu055. Fulltekst i vitenarkiv Vis sammendrag

  Alzheimer's disease (AD) is regarded a human-specific condition, and it has been suggested that brain regions highly expanded in humans compared with other primates are selectively targeted. We calculated shared and unique variance in the distribution of AD atrophy accounted for by cortical expansion between macaque and human, affiliation to the default mode network (DMN), ontogenetic development and normal aging. Cortical expansion was moderately related to atrophy, but a critical discrepancy was seen in the medial temporo-parietal episodic memory network. Identification of “hotspots” and “coldspots” of expansion across several primate species did not yield compelling evidence for the hypothesis that highly expanded regions are specifically targeted. Controlling for distribution of atrophy in aging substantially attenuated the expansion–AD relationship. A path model showed that all variables explained unique variance in AD atrophy but were generally mediated through aging. This supports a systems-vulnerability model, where critical networks are subject to various negative impacts, aging in particular, rather than being selectively targeted in AD. An alternative approach is suggested, focused on the interplay of the phylogenetically old and preserved medial temporal lobe areas with more highly expanded association cortices governed by different principles of plasticity and stability. This is a pre-copyedited, author-produced PDF of an article accepted for publication in Cerebral Cortex following peer review. The version of record is available online at: http://dx.doi.org/10.1093/cercor/bhu055

• Alnæs, Dag; Sneve, Markus Handal; Espeseth, Thomas; Endestad, Tor; Pavert, Steven van de & Laeng, Bruno (2014). Pupil size signals mental effort deployed during multiple object tracking and predicts brain activity in the dorsal attention network and the locus coeruleus. Journal of Vision. 14(4), s. 1–20. doi: 10.1167/14.4.1. Fulltekst i vitenarkiv
• Sneve, Markus Handal; Magnussen, Svein; Alnæs, Dag; Endestad, Tor & D'Esposito, Mark (2013). Top–Down Modulation from Inferior Frontal Junction to FEFs and Intraparietal Sulcus during Short-term Memory for Visual Features. Journal of Cognitive Neuroscience. ISSN 0898-929X. 25, s. 1944–1956. doi: 10.1162/jocn_a_00426. Fulltekst i vitenarkiv
• Sneve, Markus Handal; Alnæs, Dag; Endestad, Tor; Greenlee, Mark W. & Magnussen, Svein (2012). Visual short-term memory: Activity supporting encoding and maintenance in retinotopic visual cortex. NeuroImage. ISSN 1053-8119. 63(1), s. 166–178. doi: 10.1016/j.neuroimage.2012.06.053. Fulltekst i vitenarkiv Vis sammendrag

  Recent studies have demonstrated that retinotopic cortex maintains information about visual stimuli during retention intervals. However, the process by which transient stimulus-evoked sensory responses are transformed into enduring memory representations is unknown. Here, using fMRI and short-term visual memory tasks optimized for univariate and multivariate analysis approaches, we report differential involvement of human retinotopic areas during memory encoding of the low-level visual feature orientation. All visual areas show weaker responses when memory encoding processes are interrupted, possibly due to effects in orientation-sensitive primary visual cortex (V1) propagating across extrastriate areas. Furthermore, intermediate areas in both dorsal (V3a/b) and ventral (LO1/2) streams are significantly more active during memory encoding compared with non-memory (active and passive) processing of the same stimulus material. These effects in intermediate visual cortex are also observed during memory encoding of a different stimulus feature (spatial frequency), suggesting that these areas are involved in encoding processes on a higher level of representation. Using pattern-classification techniques to probe the representational content in visual cortex during delay periods, we further demonstrate that simply initiating memory encoding is not sufficient to produce long-lasting memory traces. Rather, active maintenance appears to underlie the observed memory-specific patterns of information in retinotopic cortex.

• Sneve, Markus Handal; Alnæs, Dag; Endestad, Tor; Greenlee, Mark W. & Magnussen, Svein (2011). Modulation of activity in human visual area V1 during memory masking. PLOS ONE. 6(4). doi: 10.1371/journal.pone.0018651. Fulltekst i vitenarkiv
• Espeseth, Thomas; Sneve, Markus Handal; Rootwelt, Helge & Laeng, Bruno (2010). Nicotinic Receptor Gene CHRNA4 Interacts with Processing Load in Attention. PLOS ONE. 5(12). doi: 10.1371/journal.pone.0014407. Fulltekst i vitenarkiv

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• Sneve, Markus Handal (2026). Movies as memory probes: a low-demand fMRI paradigm designed for lifespan samples and clinical populations. doi: https:/www.siemens-healthineers.com/no/news-and-events/siemens-academy-no/userforum-imaging/magnetomforum. Fulltekst i vitenarkiv
• Walhovd, Kristine B; Sneve, Markus Handal; Garrido, Pablo F.; Kransberg, Jonas Moe & Fjell, Anders Martin (2026). Navigation training alters twin cortical similarity at the gray-white matter boundary. doi: https:/www.humanbrainmapping.org/aperture-neuro/. Fulltekst i vitenarkiv Vis sammendrag

  Talk at OHBM 2026

• Warren, José Luis Alatorre & Sneve, Markus Handal (2026). Navigation training alters twin cortical similarity at the gray–white matter boundary. Fulltekst i vitenarkiv
• Padrela, Beatriz; Mahroo, Amnah; Tee, Mervin; Sneve, Markus Handal; Moyaert, Paulien & Geier, Oliver [Vis alle 43 forfattere av denne artikkelen] (2024). Developing blood-brain barrier arterial spin labelling as a non-invasive early biomarker of Alzheimer's disease (DEBBIE-AD): a prospective observational multicohort study protocol. BMJ Open. 14(3). doi: 10.1136/bmjopen-2023-081635. Fulltekst i vitenarkiv Vis sammendrag

  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. The DEveloping BBB-ASL as a non-Invasive Early biomarker (DEBBIE) consortium aims to develop this modified ASL-MRI technique for patient-specific and robust BBB permeability assessments. This article outlines the study design of the DEBBIE cohorts focused on investigating the potential of BBB-ASL as an early biomarker for AD (DEBBIE-AD). Methods and analysis DEBBIE-AD consists of a multicohort study enrolling participants with subjective cognitive decline, mild cognitive impairment and AD, as well as age-matched healthy controls, from 13 cohorts. The precision and accuracy of BBB-ASL will be evaluated in healthy participants. The clinical value of BBB-ASL will be evaluated by comparing results with both established and novel AD biomarkers. The DEBBIE-AD study aims to provide evidence of the ability of BBB-ASL to measure BBB permeability and demonstrate its utility in AD and AD-related pathologies. Ethics and dissemination Ethics approval was obtained for 10 cohorts, and is pending for 3 cohorts. The results of the main trial and each of the secondary endpoints will be submitted for publication in a peer-reviewed journal.

• Sneve, Markus Handal (2021). fMRI ved LCBC, en oversikt. Fulltekst i vitenarkiv
• Sneve, Markus Handal (2021). Hvorfor glemmer vi. Fulltekst i vitenarkiv
• Sneve, Markus Handal (2021). fMRI som verktøy i pre-operativ kartlegging. En case-study. Fulltekst i vitenarkiv
• Storsve, Andreas Berg; Walhovd, Kristine B; Sneve, Markus Handal; Tamnes, Christian Krog; Krogsrud, Stine Kleppe & Fjell, Anders Martin (2013). Hukommelse gjennom livet - Nevrovitenskapelige perspektiver. Fulltekst i vitenarkiv
• Alnæs, Dag; Endestad, Tor; Magnussen, Svein; Sneve, Markus Handal; Spillmann, Lothar & Werner, John S. (2010). Perceptual filling-in of the blind spot: an fMRI study. Perception. ISSN 0301-0066. 39, s. 175–175. Fulltekst i vitenarkiv
• Sneve, Markus Handal; Alnæs, Dag; Endestad, Tor; Greenlee, Mark W. & Magnussen, Svein (2010). Retrieval-related activity in early visual areas. Perception. ISSN 0301-0066. 39, s. 38–38. Fulltekst i vitenarkiv
• Espeseth, Thomas; Pavert, Steven van de; Jynge, Slije; Sneve, Markus Handal & Laeng, Bruno (2010). The pupil dilates as a function of attentional effort in multiple object tracking. Fulltekst i vitenarkiv
• Emaus, Nina; Omsland, Tone Kristin; Ahmed, Luai Awad; Grimnes, Guri; Sneve, Markus Handal & Berntsen, Gro (2009). BONE MINERAL DENSITY AND PREVALENCE OF OSTEOPOROSIS AT THE HIP IN WOMEN AND MEN AGED 30-85 YEARS - THE TROMSO STUDY. Osteoporosis International. ISSN 0937-941X. 20, s. 64–65. Fulltekst i vitenarkiv
• Sneve, Markus Handal; Magnussen, Svein; Endestad, Tor & Greenlee, Mark W. (2009). Memory modulation of area V1. Perception. ISSN 0301-0066. 38, s. 178–178. Fulltekst i vitenarkiv

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