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

2020 ◽  
Author(s):  
Tomas Knapen
Keyword(s):  
Visual System ◽  
Spatial Organization ◽  
Brain Regions ◽  
Retinotopic Mapping ◽  
Visual Spatial ◽  
Retinotopic Maps ◽  
Sensory Predictions ◽  
Visual Organization ◽  
The Brain

The human visual system is organized as a hierarchy of maps that share the retina's topography. Although retinotopic maps have been identified throughout the brain, how much of the brain is visually organized remains unknown. Here we demonstrate widespread stable visual organization beyond the traditional visual system by analyzing topographic connectivity with primary visual cortex during moviewatching, rest, and retinotopic mapping. Detailed visual-spatial organization derived from retinotopic connectivity is modulated by experimental condition. Specifically, traditionally visual regions alternate with default mode network and hippocampus in preferentially representing the center of the visual field. This visual role of hippocampus would allow it to implement sensory predictions by interfacing between abstract memories and concrete perceptions. These results indicate that pervasive sensory coding facilitates the communication between far-flung brain regions.

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 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 I know that I don’t know: Structural and functional connectivity underlying meta-ignorance in pre-schoolers

2018 ◽  
Author(s):  
Elisa Filevich ◽  
Caroline Garcia Forlim ◽  
Carmen Fehrman ◽  
Carina Forster ◽  
Markus Paulus ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Default Mode Network ◽  
Orbitofrontal Cortex ◽  
Cingulate Gyrus ◽  
Partial Knowledge ◽  
Metacognitive Monitoring ◽  
Default Mode ◽  
Posterior Cingulate Gyrus ◽  
Knowledge Condition ◽  
The Brain

Research Highlights[1] Children develop the ability to report that they do not know something at around five years of age.[2] Children who could correctly report their own ignorance in a partial-knowledge task showed thicker cortices within medial orbitofrontal cortex.[3] This region was functionally connected to parts of the default-mode network.[4] The default-mode network might support the development of correct metacognitive monitoring.AbstractMetacognition plays a pivotal role in human development. The ability to realize that we do not know something, or meta-ignorance, emerges after approximately five years of age. We aimed at identifying the brain systems that underlie the developmental emergence of this ability in a preschool sample.Twenty-four children aged between five and six years answered questions under three conditions of a meta-ignorance task twice. In the critical partial knowledge condition, an experimenter first showed two toys to a child, then announced that she would place one of them in a box behind a screen, out of sight from the child. The experimenter then asked the child whether or not she knew which toy was in the box.Children who answered correctly both times to the metacognitive question in the partial knowledge condition (n=9) showed greater cortical thickness in a cluster within left medial orbitofrontal cortex than children who did not (n=15). Further, seed-based functional connectivity analyses of the brain during resting state revealed that this region is functionally connected to the medial orbitofrontal gyrus, posterior cingulate gyrus and precuneus, and mid- and inferior temporal gyri.This finding suggests that the default mode network, critically through its prefrontal regions, supports introspective processing. It leads to the emergence of metacognitive monitoring allowing children to explicitly report their own ignorance.

Assessment of Graph Metrics and Lateralization of Brain Connectivity in Progression of Alzheimer's Disease Using fMRI

2017 ◽  
Vol 9 (4) ◽  
pp. 46-66 ◽  
Author(s):  
Bhuvaneshwari Bhaskaran ◽  
Kavitha Anandan
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Default Mode Network ◽  
Brain Connectivity ◽  
Brain Network ◽  
Brain Disorder ◽  
Default Mode ◽  
Graph Metrics ◽  
Functional Topology ◽  
The Brain

Alzheimer's disease (AD) is a progressive brain disorder which has a long preclinical phase. The beta-amyloid plaques and tangles in the brain are considered as the main pathological causes. Functional connectivity is typically examined in capturing brain network dynamics in AD. A definitive underconnectivity is observed in patients through the progressive stages of AD. Graph theoretic modeling approaches have been effective in understanding the brain dynamics. In this article, the brain connectivity patterns and the functional topology through the progression of Alzheimer's disease are analysed using resting state fMRI. The altered network topology is analysed by graphed theoretical measures and explains cognitive deficits caused by the progression of this disease. Results show that the functional topology is disrupted in the default mode network regions as the disease progresses in patients. Further, it is observed that there is a lack of left lateralization involving default mode network regions as the severity in AD increases.

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