scholarly journals The topology of higher-order complexes associated with brain hubs in human connectomes

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Miroslav Andjelković ◽  
Bosiljka Tadić ◽  
Roderick Melnik
Keyword(s):  
Complex Dynamics ◽  
Simplicial Complexes ◽  
Brain Regions ◽  
Higher Order ◽  
Core Networks ◽  
Right Cerebral Hemisphere ◽  
Left And Right ◽  
Order Complexes ◽  
The Brain

Abstract Higher-order connectivity in complex systems described by simplexes of different orders provides a geometry for simplex-based dynamical variables and interactions. Simplicial complexes that constitute a functional geometry of the human connectome can be crucial for the brain complex dynamics. In this context, the best-connected brain areas, designated as hub nodes, play a central role in supporting integrated brain function. Here, we study the structure of simplicial complexes attached to eight global hubs in the female and male connectomes and identify the core networks among the affected brain regions. These eight hubs (Putamen, Caudate, Hippocampus and Thalamus-Proper in the left and right cerebral hemisphere) are the highest-ranking according to their topological dimension, defined as the number of simplexes of all orders in which the node participates. Furthermore, we analyse the weight-dependent heterogeneity of simplexes. We demonstrate changes in the structure of identified core networks and topological entropy when the threshold weight is gradually increased. These results highlight the role of higher-order interactions in human brain networks and provide additional evidence for (dis)similarity between the female and male connectomes.

scholarly journals The role of thickness inhomogeneities in hierarchical cortical folding

2020 ◽  
Author(s):  
Lucas da Costa Campos ◽  
Raphael Hornung ◽  
Gerhard Gompper ◽  
Jens Elgeti ◽  
Svenja Caspers
Keyword(s):  
Fetal Brain ◽  
Epileptic Seizures ◽  
Quantitative Model ◽  
Higher Order ◽  
Mammalian Brain ◽  
Cortical Folding ◽  
Differential Growth ◽  
The Brain ◽  
Short Life Expectancy

AbstractThe morphology of the mammalian brain cortex is highly folded. For long it has been known that specific patterns of folding are necessary for an optimally functioning brain. On the extremes, lissencephaly, a lack of folds in humans, and polymicrogyria, an overly folded brain, can lead to severe mental retardation, short life expectancy, epileptic seizures, and tetraplegia. The construction of a quantitative model on how and why these folds appear during the development of the brain is the first step in understanding the cause of these conditions. In recent years, there have been various attempts to understand and model the mechanisms of brain folding. Previous works have shown that mechanical instabilities play a crucial role in the formation of brain folds, and that the geometry of the fetal brain is one of the main factors in dictating the folding characteristics. However, modeling higher-order folding, one of the main characteristics of the highly gyrencephalic brain, has not been fully tackled. The effects of thickness inhomogeneity in the gyrogenesis of the mammalian brain are studied in silico. Finite-element simulations of rectangular slabs are performed. The slabs are divided into two distinct regions, where the outer layer mimics the gray matter, and the inner layer the underlying white matter. Differential growth is introduced by growing the top layer tangentially, while keeping the underlying layer untouched. The brain tissue is modeled as a neo-Hookean hyperelastic material. Simulations are performed with both, homogeneous and inhomogeneous cortical thickness. The homogeneous cortex is shown to fold into a single wavelength, as is common for bilayered materials, while the inhomogeneous cortex folds into more complex conformations. In the early stages of development of the inhomogeneous cortex, structures reminiscent of the deep sulci in the brain are obtained. As the cortex continues to develop, secondary undulations, which are shallower and more variable than the structures obtained in earlier gyrification stage emerge, reproducing well-known characteristics of higher-order folding in the mammalian, and particularly the human, brain.

Role of adrenal catecholamines in cerebrovasodilation evoked from brain stem

1987 ◽  
Vol 252 (6) ◽  
pp. H1183-H1191
Author(s):  
C. Iadecola ◽  
P. M. Lacombe ◽  
M. D. Underwood ◽  
T. Ishitsuka ◽  
D. J. Reis
Keyword(s):  
Brain Function ◽  
Blood Gases ◽  
Brain Regions ◽  
Elevated Plasma ◽  
Regional Cerebral Blood ◽  
Medullary Reticular Formation ◽  
Alpha Chloralose ◽  
The Brain ◽  
Stimulation Of

We studied whether adrenal medullary catecholamines (CAs) contribute to the metabolically linked increase in regional cerebral blood flow (rCBF) elicited by electrical stimulation of the dorsal medullary reticular formation (DMRF). Rats were anesthetized (alpha-chloralose, 30 mg/kg), paralyzed, and artificially ventilated. The DMRF was electrically stimulated with intermittent trains of pulses through microelectrodes stereotaxically implanted. Blood gases were controlled and, during stimulation, arterial pressure was maintained within the autoregulated range for rCBF. rCBF and blood-brain barrier (BBB) permeability were determined in homogenates of brain regions by using [14C]iodoantipyrine and alpha-aminoisobutyric acid (AIB), respectively, as tracers. Plasma CAs (epinephrine and norepinephrine) were measured radioenzymatically. DMRF stimulation increased rCBF throughout the brain (n = 5; P less than 0.01, analysis of variance) and elevated plasma CAs substantially (n = 4). Acute bilateral adrenalectomy abolished the increase in plasma epinephrine (n = 4), reduced the increases in flow (n = 6) in cerebral cortex (P less than 0.05), and abolished them elsewhere in brain (P greater than 0.05). Comparable effects on rCBF were obtained by selective adrenal demedullation (n = 7) or pretreatment with propranolol (1.5 mg/kg iv) (n = 5). DMRF stimulation did not increase the permeability of the BBB to AIB (n = 5). We conclude that the increases in rCBF elicited from the DMRF has two components, one dependent on, and the other independent of CAs. Since the BBB is impermeable to CAs and DMRF stimulation fails to open the BBB, the results suggest that DMRF stimulation allows, through a mechanism not yet determined, circulating CAs to act on brain and affect brain function.

scholarly journals Neural Substrates of Social Status Inference: Roles of Medial Prefrontal Cortex and Superior Temporal Sulcus

2014 ◽  
Vol 26 (5) ◽  
pp. 1131-1140 ◽  
Author(s):  
Malia Mason ◽  
Joe C. Magee ◽  
Susan T. Fiske
Keyword(s):  
Social Order ◽  
Neural Substrates ◽  
Brain Regions ◽  
Third Party ◽  
Social Interdependence ◽  
Medial Pfc ◽  
State Inference ◽  
The Brain ◽  
Track Status

The negotiation of social order is intimately connected to the capacity to infer and track status relationships. Despite the foundational role of status in social cognition, we know little about how the brain constructs status from social interactions that display it. Although emerging cognitive neuroscience reveals that status judgments depend on the intraparietal sulcus, a brain region that supports the comparison of targets along a quantitative continuum, we present evidence that status judgments do not necessarily reduce to ranking targets along a quantitative continuum. The process of judging status also fits a social interdependence analysis. Consistent with third-party perceivers judging status by inferring whose goals are dictating the terms of the interaction and who is subordinating their desires to whom, status judgments were associated with increased recruitment of medial pFC and STS, brain regions implicated in mental state inference.

scholarly journals The NCX3 Isoform of the Na+/Ca2+ Exchanger Contributes to Neuroprotection Elicited by Ischemic Postconditioning

2010 ◽  
Vol 31 (1) ◽  
pp. 362-370 ◽  
Author(s):  
Giuseppe Pignataro ◽  
Elga Esposito ◽  
Ornella Cuomo ◽  
Rossana Sirabella ◽  
Francesca Boscia ◽  
...  
Keyword(s):  
Brain Regions ◽  
Ischemic Postconditioning ◽  
Intracerebroventricular Infusion ◽  
Ionic Transporters ◽  
Relevant Role ◽  
Ischemic Episode ◽  
Study Support ◽  
Interfering Rna ◽  
The Brain

It has been recently shown that a short sublethal brain ischemia subsequent to a prolonged harmful ischemic episode may confer ischemic neuroprotection, a phenomenon termed ischemic postconditioning. Na+/Ca2+ exchanger (NCX) isoforms, NCX1, NCX2, and NCX3, are plasma membrane ionic transporters widely distributed in the brain and involved in the control of Na+ and Ca2+ homeostasis and in the progression of stroke damage. The objective of this study was to evaluate the role of these three proteins in the postconditioning-induced neuroprotection. The NCX protein and mRNA expression was evaluated at different time points in the ischemic temporoparietal cortex of rats subjected to tMCAO alone or to tMCAO plus ischemic postconditioning. The results of this study showed that NCX3 protein and ncx3 mRNA were upregulated in those brain regions protected by postconditioning treatment. These changes in NCX3 expression were mediated by the phosphorylated form of the ubiquitously expressed serine/threonine protein kinase p-AKT, as the p-AKT inhibition prevented NCX3 upregulation. The relevant role of NCX3 during postconditioning was further confirmed by results showing that NCX3 silencing, induced by intracerebroventricular infusion of small interfering RNA (siRNA), partially reverted the postconditioning-induced neuroprotection. The results of this study support the idea that the enhancement of NCX3 expression and activity might represent a reasonable strategy to reduce the infarct extension after stroke.

scholarly journals Neural Underpinnings of Obesity: The Role of Oxidative Stress and Inflammation in the Brain

Antioxidants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1018
Author(s):  
Caitlyn A. Mullins ◽  
Ritchel B. Gannaban ◽  
Md Shahjalal Khan ◽  
Harsh Shah ◽  
Md Abu B. Siddik ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Energy Homeostasis ◽  
Dorsal Striatum ◽  
Brain Regions ◽  
Therapeutic Interventions ◽  
Low Grade ◽  
Obesity Prevalence ◽  
Beneficial Effects ◽  
The Brain

Obesity prevalence is increasing at an unprecedented rate throughout the world, and is a strong risk factor for metabolic, cardiovascular, and neurological/neurodegenerative disorders. While low-grade systemic inflammation triggered primarily by adipose tissue dysfunction is closely linked to obesity, inflammation is also observed in the brain or the central nervous system (CNS). Considering that the hypothalamus, a classical homeostatic center, and other higher cortical areas (e.g. prefrontal cortex, dorsal striatum, hippocampus, etc.) also actively participate in regulating energy homeostasis by engaging in inhibitory control, reward calculation, and memory retrieval, understanding the role of CNS oxidative stress and inflammation in obesity and their underlying mechanisms would greatly help develop novel therapeutic interventions to correct obesity and related comorbidities. Here we review accumulating evidence for the association between ER stress and mitochondrial dysfunction, the main culprits responsible for oxidative stress and inflammation in various brain regions, and energy imbalance that leads to the development of obesity. Potential beneficial effects of natural antioxidant and anti-inflammatory compounds on CNS health and obesity are also discussed.

GLOBAL EFFECTS OF FLUCTUATIONS IN NEURAL INFORMATION PROCESSING

1996 ◽  
Vol 07 (04) ◽  
pp. 497-505 ◽  
Author(s):  
HANS LILJENSTRÖM
Keyword(s):  
Information Processing ◽  
Neuronal Excitability ◽  
Complex Dynamics ◽  
Memory State ◽  
Cortical Dynamics ◽  
Neural Information ◽  
Neural Information Processing ◽  
Correct Pattern ◽  
The Brain

We are interested in how the complex dynamics of the brain, which may include oscillations, chaos and noise, can affect the efficiency of neural information processing. Here, we consider the amplification and functional role of fluctuations, expressed as chaos or noise in the system. Using computer simulations of a neural network model of the olfactory cortex, we demonstrate how microscopic fluctuations can result in global effects at the network level. In particular, we show that the rate of information processing in associative memory tasks can be maximized for optimal noise levels. Noise can also induce transitions between different dynamical states, related to learning and memory. A chaotic-like behavior, induced by noise or by an increase in neuronal excitability, can enhance system performance if it is transient and converges to a limit cycle memory state. The level of accuracy required for correct pattern association further affects the rate of information processing. We discuss how neuromodulatory control of the cortical dynamics can shift the balance between rate and accuracy optimization, as well as between sensitivity and stability.

Anxiety-related behavior in hyperhomocysteinemia induced by methionine nutritional overload in rats: role of the brain oxidative stress

2016 ◽  
Vol 94 (10) ◽  
pp. 1074-1082 ◽  
Author(s):  
Dragan Hrncic ◽  
Jelena Mikić ◽  
Aleksandra Rasic-Markovic ◽  
Milica Velimirović ◽  
Tihomir Stojković ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Open Field ◽  
Wistar Rats ◽  
Brain Regions ◽  
Oxidative Status ◽  
Standard Diet ◽  
Male Wistar Rats ◽  
Brain Oxidative Stress ◽  
The Brain

The aim of this study was to examine the effects of a methionine-enriched diet on anxiety-related behavior in rats and to determine the role of the brain oxidative status in these alterations. Adult male Wistar rats were fed from the 30th to 60th postnatal day with standard or methionine-enriched diet (double content comparing with standard diet: 7.7 g/kg). Rats were tested in open field and light–dark tests and afterwards oxidative status in the different brain regions were determined. Hyperhomocysteinemia induced by methionine-enriched diet in this study decreased the number of rearings, as well as the time that these animals spent in the center of the open field, but increased index of thigmotaxy. Oxidative status was selectively altered in the examined regions. Lipid peroxidation was significantly increased in the cortex and nc. caudatus of rats developing hyperhomocysteinemia, but unaltered in the hippocampus and thalamus. Based on the results of this research, it could be concluded that hyperhomocysteinemia induced by methionine nutritional overload increased anxiety-related behavior in rats. These proanxiogenic effects could be, at least in part, a consequence of oxidative stress in the rat brain.

scholarly journals Rewiring of the Serotonin System in Major Depression

2021 ◽  
Vol 12 ◽  
Author(s):  
Faranak Vahid-Ansari ◽  
Paul R. Albert
Keyword(s):  
Mental Illness ◽  
Cognitive Impairment ◽  
Major Depression ◽  
Selective Serotonin Reuptake Inhibitors ◽  
Chronic Treatment ◽  
Brain Regions ◽  
Synaptic Organization ◽  
Serotonin System ◽  
The Brain

Serotonin is a key neurotransmitter that is implicated in a wide variety of behavioral and cognitive phenotypes. Originating in the raphe nuclei, 5-HT neurons project widely to innervate many brain regions implicated in the functions. During the development of the brain, as serotonin axons project and innervate brain regions, there is evidence that 5-HT plays key roles in wiring the developing brain, both by modulating 5-HT innervation and by influencing synaptic organization within corticolimbic structures. These actions are mediated by 14 different 5-HT receptors, with region- and cell-specific patterns of expression. More recently, the role of the 5-HT system in synaptic re-organization during adulthood has been suggested. The 5-HT neurons have the unusual capacity to regrow and reinnervate brain regions following insults such as brain injury, chronic stress, or altered development that result in disconnection of the 5-HT system and often cause depression, anxiety, and cognitive impairment. Chronic treatment with antidepressants that amplify 5-HT action, such as selective serotonin reuptake inhibitors (SSRIs), appears to accelerate the rewiring of the 5-HT system by mechanisms that may be critical to the behavioral and cognitive improvements induced in these models. In this review, we survey the possible 5-HT receptor mechanisms that could mediate 5-HT rewiring and assess the evidence that 5-HT-mediated brain rewiring is impacting recovery from mental illness. By amplifying 5-HT-induced rewiring processes using SSRIs and selective 5-HT agonists, more rapid and effective treatments for injury-induced mental illness or cognitive impairment may be achieved.

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.

The Brain in a Physician’s Life

2017 ◽  
Author(s):  
Peggy Mason
Keyword(s):  
Nervous System ◽  
Brain Regions ◽  
Altered State ◽  
Compassionate Care ◽  
Clinical Impairment ◽  
Altered State Of Consciousness ◽  
Individual Nature ◽  
The Impact ◽  
The Brain

With the knowledge acquired from this book, the brain regions responsible for each of the symptoms suffered by Jean-Dominique Bauby can be identified. It is also possible to understand why thought, language, and memory were unaffected in Bauby. Bauby’s narrative is used to launch a consideration of the role of embodiment in affective experience. The experience of Clive Wearing who, after a bout of encephalitis, was left without the ability to make new declarative memories is introduced to illustrate the highly personal and individual nature of people’s reactions to disease or clinical impairment. The impact of disease does not stop with the patient but extends to the patient’s loved ones and caregivers. This is particularly true of patients with dementia or those in an altered state of consciousness. Finally the reader is encouraged to use their understanding of the nervous system to provide compassionate care for patients.

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