scholarly journals Multimodal Imaging of Alzheimer Pathophysiology in the Brain's Default Mode Network

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Jonghan Shin ◽  
Vladimir Kepe ◽  
Gary W. Small ◽  
Michael E. Phelps ◽  
Jorge R. Barrio
Keyword(s):  
Default Mode Network ◽  
Multimodal Imaging ◽  
Temporal Cortex ◽  
Brain Regions ◽  
Default Network ◽  
Spatial Correlations ◽  
Tau Pathology ◽  
Significant Discrepancy ◽  
Default Mode ◽  
The Brain

The spatial correlations between the brain's default mode network (DMN) and the brain regions known to develop pathophysiology in Alzheimer's disease (AD) have recently attracted much attention. In this paper, we compare results of different functional and structural imaging modalities, including MRI and PET, and highlight different patterns of anomalies observed within the DMN. Multitracer PET imaging in subjects with and without dementia has demonstrated that [C-11]PIB- and [F-18]FDDNP-binding patterns in patients with AD overlap within nodes of the brain's default network including the prefrontal, lateral parietal, lateral temporal, and posterior cingulate cortices, with the exception of the medial temporal cortex (especially, the hippocampus) where significant discrepancy between increased [F-18]FDDNP binding and negligible [C-11]PIB-binding was observed. [F-18]FDDNP binding in the medial temporal cortex—a key constituent of the DMN—coincides with both the presence of amyloid and tau pathology, and also with cortical areas with maximal atrophy as demonstrated by T1-weighted MR imaging of AD patients.

scholarly journals Topographic connectivity reveals task-dependent retinotopic processing throughout the human brain

2020 ◽  
Vol 118 (2) ◽  
pp. e2017032118
Author(s):  
Tomas Knapen
Keyword(s):  
Visual System ◽  
Default Mode Network ◽  
Spatial Organization ◽  
Brain Regions ◽  
Cognitive State ◽  
Default Mode ◽  
Visual Spatial ◽  
Retinotopic Maps ◽  
Visual Organization ◽  
The Brain

The human visual system is organized as a hierarchy of maps that share the topography of the retina. Known retinotopic maps have been identified using simple visual stimuli under strict fixation, conditions different from everyday vision which is active, dynamic, and complex. This means that it remains unknown how much of the brain is truly visually organized. Here I demonstrate widespread stable visual organization beyond the traditional visual system, in default-mode network and hippocampus. Detailed topographic connectivity with primary visual cortex during movie-watching, resting-state, and retinotopic-mapping experiments revealed that visual–spatial representations throughout the brain are warped by cognitive state. Specifically, traditionally visual regions alternate with default-mode network and hippocampus in preferentially representing the center of the visual field. This visual role of default-mode network and hippocampus would allow these regions to interface between abstract memories and concrete sensory impressions. Together, these results indicate that visual–spatial organization is a fundamental coding principle that structures the communication between distant brain regions.

scholarly journals A Suggestion for a New Interpretation of Dreams: Dreaming Is the Inverse of Anxious Mind-Wandering

2019 ◽  
Author(s):  
Joshua Eichler-Summers
Keyword(s):  
Rem Sleep ◽  
Default Mode Network ◽  
Mind Wandering ◽  
Brain Regions ◽  
Fear Response ◽  
Post Traumatic Stress ◽  
Default Mode ◽  
New Interpretation ◽  
Behaviour Changes ◽  
The Brain

Mind-wandering is associated with the simultaneous activation of a network of different brain regions known formally as the default mode network. Forward looking anxious mind-wandering (or worry) occurs when activity in this network is coupled with a biological fear response in the brain. The fear response constrains the con-tent of anxious mind-wandering, with imagined catastrophised scenarios pushing the mind-wanderer towards avoidant behaviours. There is an established relationship between dreaming and mind-wandering. During rapid eye moment (REM) sleep, where dreams most commonly occur, many of the brain regions within the default mode network are activated. This paper presents a novel argument that during REM sleep the brain is in a bio-logically relaxed state, and that this state acts as a constraint to the content of dreams, which in turn presents a possible function of dreaming. In direct contrast to anxious mind-wandering, dreams present imagined situations which demand confrontational, or un-avoidant, behaviours. Though the situations in dreams call for un-avoidant behaviour, dreamers act with avoidance. This difference between the in-dream behaviour (avoidant) and the behaviour the in-dream situation demands (un-avoidant) highlights an anxiety present in the dreamer which can then be used to direct the focus of therapeutic treatment. Fourteen examples of dreams are presented, including seven examples of interpretation, three examples of successful dream content prediction (a first for an interpretive theory of dreams), and four examples of dreams which demonstrate how in-dream behaviour changes during successful therapy, three of which are my own. Dreams focusing on anxieties developed during infancy as well as in adult moments of trauma (such as post-traumatic stress disorder) are discussed, with a focus on the former.

A Classification Mechanism of Brain Functional fMRI in Resting State

2014 ◽  
Vol 687-691 ◽  
pp. 1087-1090
Author(s):  
Hui Zhou ◽  
Zhen Cheng Chen ◽  
Jian Ming Zhu ◽  
Dong Cui Wang ◽  
Biao Xu
Keyword(s):  
Hierarchical Clustering ◽  
Default Mode Network ◽  
Resting State ◽  
Low Frequency ◽  
Brain Regions ◽  
Default Mode ◽  
Complex Network Theory ◽  
Healthy Young People ◽  
Comparative Results ◽  
The Brain

To investigate the brain default mode network (DMN) of healthy young people, a novel hierarchical clustering method was proposed to detect similarities of low-frequency fluctuations between any two out of 160 regions of interest (ROI) all over the brain. Feature of these ROIs were firstextractedand analyzed the feature using hierarchical clustering approach.Combining with the strongest connected network node identified by network centric criterion, the default mode network which presented the strongest connectivity in resting state was then determined. The results demonstrated that cingulate had the highest value of average degree, making it the most suspectof where the centrality indices of DMN lay.The comparative results between nodes included by DMN returned by our method and these given by Dosenbach’s research showed quite high coincidence rates,indicating the proposed method of combining complex network theory and hierarchical clustering analysis feasible method to parse brain regions.

scholarly journals A Suggestion for a New Interpretation of Dreams: Dreaming Is the Inverse of Anxious Mind-Wandering.

2019 ◽  
Author(s):  
Joshua Eichler-Summers
Keyword(s):  
Rem Sleep ◽  
Default Mode Network ◽  
Mind Wandering ◽  
Brain Regions ◽  
Fear Response ◽  
Post Traumatic Stress ◽  
Default Mode ◽  
New Interpretation ◽  
Behaviour Changes ◽  
The Brain

Mind-wandering is associated with the simultaneous activation of a network of different brain regions known formally as the default mode network. Forward looking anxious mind-wandering (or worry) occurs when activity in this network is coupled with a biological fear response in the brain. The fear response constrains the con-tent of anxious mind-wandering, with imagined catastrophised scenarios pushing the mind-wanderer towards avoidant behaviours. There is an established relationship between dreaming and mind-wandering. During rapid eye moment (REM) sleep, where dreams most commonly occur, many of the brain regions within the default mode network are activated. This paper presents a novel argument that during REM sleep the brain is in a bio-logically relaxed state, and that this state acts as a constraint to the content of dreams, which in turn presents a possible function of dreaming. In direct contrast to anxious mind-wandering, dreams present imagined situations which demand confrontational, or un-avoidant, behaviours. Though the situations in dreams call for un-avoidant behaviour, dreamers act with avoidance. This difference between the in-dream behaviour (avoidant) and the behaviour the in-dream situation demands (un-avoidant) highlights an anxiety present in the dreamer which can then be used to direct the focus of therapeutic treatment. Fourteen examples of dreams are presented, including seven examples of interpretation, three examples of successful dream content prediction (a first for an interpretive theory of dreams), and four examples of dreams which demonstrate how in-dream behaviour changes during successful therapy, three of which are my own. Dreams focusing on anxieties developed during infancy as well as in adult moments of trauma (such as post-traumatic stress disorder) are discussed, with a focus on the former.

scholarly journals Cerebral Blood Flow in Posterior Cortical Nodes of the Default Mode Network Decreases with Task Engagement but Remains Higher than in Most Brain Regions

2010 ◽  
Vol 21 (1) ◽  
pp. 233-244 ◽  
Author(s):  
A. Pfefferbaum ◽  
S. Chanraud ◽  
A.-L. Pitel ◽  
E. Muller-Oehring ◽  
A. Shankaranarayanan ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Default Mode Network ◽  
Brain Regions ◽  
Task Engagement ◽  
Default Mode

scholarly journals Maturation of Brain Regions Related to the Default Mode Network during Adolescence Facilitates Narrative Comprehension

2017 ◽  
Vol 05 (01) ◽  
Author(s):  
Tzipi Horowitz Kraus ◽  
Rola Farah ◽  
Ardag Hajinazarian ◽  
Kenneth Eaton ◽  
Akila Rajagopal ◽  
...  
Keyword(s):  
Default Mode Network ◽  
Brain Regions ◽  
Narrative Comprehension ◽  
Default Mode

scholarly journals Transcriptomic analysis of frontotemporal lobar degeneration with TDP-43 pathology reveals cellular alterations across multiple brain regions

2021 ◽  
Author(s):  
Rahat Hasan ◽  
Jack Humphrey ◽  
Conceicao Bettencourt ◽  
Tammaryn Lashley ◽  
Pietro Fratta ◽  
...  
Keyword(s):  
Gene Expression ◽  
Frontotemporal Lobar Degeneration ◽  
Molecular Mechanisms ◽  
Rna Binding ◽  
Temporal Cortex ◽  
Neuronal Loss ◽  
Underlying Disease ◽  
Brain Regions ◽  
Neuronal Markers ◽  
The Brain

Frontotemporal lobar degeneration (FTLD) is a group of heterogeneous neurodegenerative disorders affecting the frontal and temporal lobes of the brain. Nuclear loss and cytoplasmic aggregation of the RNA-binding protein TDP-43 represents the major FTLD pathology, known as FTLD-TDP. To date, there is no effective treatment for FTLD-TDP due to an incomplete understanding of the molecular mechanisms underlying disease development. Here we compared post-mortem tissue RNA-seq transcriptomes from the frontal cortex, temporal cortex and cerebellum between 28 controls and 30 FTLD-TDP patients to profile changes in cell-type composition, gene expression and transcript usage. We observed downregulation of neuronal markers in all three regions of the brain, accompanied by upregulation of microglia, astrocytes, and oligodendrocytes, as well as endothelial cells and pericytes, suggesting shifts in both immune activation and within the vasculature. We validate our estimates of neuronal loss using neuropathological atrophy scores and show that neuronal loss in the cortex can be mainly attributed to excitatory neurons, and that increases in microglial and endothelial cell expression are highly correlated with neuronal loss. All our analyses identified a strong involvement of the cerebellum in the neurodegenerative process of FTLD-TDP. Altogether, our data provides a detailed landscape of gene expression alterations to help unravel relevant disease mechanisms in FTLD.

scholarly journals Neurotoxic astrocytic glypican-4 drives APOE4-dependent tau pathology

2021 ◽  
Author(s):  
Sivaprakasam Ramamoorthy ◽  
Kirill Gorbachev ◽  
Ana Pereira
Keyword(s):  
Late Onset ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Brain Regions ◽  
Tau Proteins ◽  
Tau Pathology ◽  
Density Lipoprotein Receptor ◽  
Apoe Receptor ◽  
The Brain

Apolipoprotein E4 (APOE4) is the crucial genetic risk factor of late-onset Alzheimer disease (AD). Aggregation of tau proteins into insoluble filaments and their spreading across the brain regions are major drivers of neurodegeneration in tauopathies, including in AD. However, the exact mechanisms through which APOE4 induces tau pathology remains unknown. Here, we report that the astrocyte-secreted protein glypican-4 (GPC-4), a novel binding partner of APOE4, drives tau pathology. GPC-4 preferentially interacts with APOE4 in comparison to other APOE isoforms and post-mortem APOE4-carrying AD brains highly express GPC-4 in neurotoxic astrocytes. The astrocyte-secreted GPC-4 induced both tau accumulation and propagation in vitro. CRISPR/dCas9 mediated activation of GPC-4 in a tauopathy animal model robustly induced tau pathology. Further, APOE4-induced tau pathology was greatly diminished in the absence of GPC-4. We found that GPC-4 promoted the stabilization of the APOE receptor low-density lipoprotein receptor-related protein 1 (LRP1) on the cellular surface, which effectively facilitates endocytosis of tau protein. Together, our data comprehensively demonstrate that one of the key APOE4-induced tau pathologies is directly mediated by GPC-4.

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