scholarly journals Indication of Disrupted Temporal Structure in the Case of Thought Blocks in Schizophrenia: The Role of the Metastable Balance

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Elias Koutsoukos ◽  
Elias Angelopoulos
Keyword(s):  
Metastable State ◽  
Temporal Structure ◽  
Mental Processes ◽  
Brain Areas ◽  
Specific Symptom ◽  
Auditory Verbal Hallucinations ◽  
Cortical Areas ◽  
The Brain

This study is aimed at investigating probable disruption of the metastable balance relevant to a disruption of the mental processes observed in the neurophenomenal level. This disruption was found to occur under dense auditory verbal hallucinations (AVHs) which are accompanied by thought blocking (TB) phenomena. The entropy that quantifies the complexity of the spontaneous coupling has been used to describe the observed transitions. According to our findings, the high synchrony-derived entropy (SE) defines a metastable state, where formations of cortical areas are able to coordinate transiently under the demands of stimulus-oriented processes or other internal cognitive associations. It was also found that the disruption of the sensitive balance to the side of oversynergy (overconnectedness) rather than the side of independence (coincidental coupling) is relevant with functional fixations under the specific symptom of schizophrenia. An introduced measure relative to the persistence of coupling indicated that the overcoupled brain areas exhibit a kind of “stiffness” in processing incoherent phasic components. Our consideration enhances the understanding of the role the metastability plays in the interpretation of deeply subjective phenomena, such as AVHs and TBs that affect the normal information routing in the brain.

scholarly journals Neuronal spreading and plaque induction of intracellular Aβ and its disruption of Aβ homeostasis

2021 ◽  
Author(s):  
Tomas T. Roos ◽  
Megg G. Garcia ◽  
Isak Martinsson ◽  
Rana Mabrouk ◽  
Bodil Israelsson ◽  
...  
Keyword(s):  
Brain Homogenate ◽  
Fold Increase ◽  
Amyloid Beta Peptide ◽  
Intracellular Accumulation ◽  
Brain Areas ◽  
Cellular Models ◽  
Beta Peptide ◽  
The Brain

AbstractThe amyloid-beta peptide (Aβ) is thought to have prion-like properties promoting its spread throughout the brain in Alzheimer’s disease (AD). However, the cellular mechanism(s) of this spread remains unclear. Here, we show an important role of intracellular Aβ in its prion-like spread. We demonstrate that an intracellular source of Aβ can induce amyloid plaques in vivo via hippocampal injection. We show that hippocampal injection of mouse AD brain homogenate not only induces plaques, but also damages interneurons and affects intracellular Aβ levels in synaptically connected brain areas, paralleling cellular changes seen in AD. Furthermore, in a primary neuron AD model, exposure of picomolar amounts of brain-derived Aβ leads to an apparent redistribution of Aβ from soma to processes and dystrophic neurites. We also observe that such neuritic dystrophies associate with plaque formation in AD-transgenic mice. Finally, using cellular models, we propose a mechanism for how intracellular accumulation of Aβ disturbs homeostatic control of Aβ levels and can contribute to the up to 10,000-fold increase of Aβ in the AD brain. Our data indicate an essential role for intracellular prion-like Aβ and its synaptic spread in the pathogenesis of AD.

Complex auditory musical hallucinations with ambivalent feelings

2021 ◽  
Vol 14 (11) ◽  
pp. e245397
Author(s):  
Hugo Canas-Simião ◽  
Sandra Teles Nascimento ◽  
João Reis ◽  
Carina Freitas
Keyword(s):  
Cognitive Dysfunction ◽  
Diabetes Mellitus Type 2 ◽  
Clinical Case ◽  
Vascular Risk ◽  
Brain Areas ◽  
Auditory Verbal Hallucinations ◽  
Bilateral Sensorineural Hearing Loss ◽  
Musical Memory ◽  
The Brain

A 78-year-old woman with hypertension, diabetes mellitus type 2 and bilateral sensorineural hearing loss was referenced to geriatric psychiatry consultation. She presented cognitive dysfunction, erotomanic delusion and complex musical hallucinations (MH), described as hearing her neighbour singing a familiar church song along with bells in the background, making comments and talking to her. A computed tomography (CT) of the brain detected small right nucleocapsular and bilateral external capsules hypodensities of presumed vascular aetiology during hospitalisation. MH are a rare phenomenon with heterogeneous aetiology. Most frequently, the cause is hearing impairment; other causes include social isolation, cognitive dysfunction, vascular risk factors and medication. Studies suggest that some brain areas related to musical memory circuitry might be related and not fully mapped. Auditory verbal hallucinations with a voice that either comments, talks or sings to the patient have never been described in the literature, making this clinical case attractive.

scholarly journals Inflammation and Cognition in Depression: A Narrative Review

2021 ◽  
Vol 10 (24) ◽  
pp. 5859
Author(s):  
Katarzyna Wachowska ◽  
Piotr Gałecki
Keyword(s):  
Inflammatory Markers ◽  
Health Condition ◽  
Narrative Review ◽  
Brain Areas ◽  
Mediating Factors ◽  
Hormonal Imbalance ◽  
The World ◽  
Depressive Patients ◽  
The Brain

The authors aim to present a narrative review of research on the inflammatory aetiology of depression. Depression is a psychiatric disorder, constituting the most common reason of disability due to a health condition. It has been estimated that at least one in six people suffer from depression at some point of their lives. The aetiology of depression, although researched extensively all around the world, still remains unclear. Authors discuss the possible role of inflammation in depression, the neurodevelopmental theory of depression as well as associations between cognition and depression. Possible associations between memory dysfunction among depressive patients and inflammatory markers are included. The associations between the immune system, depression and cognition are observed. Possible mediating factors between these areas include personality traits, hormonal imbalance and functioning of the brain areas. The question as to what mediating factors are involved is still open to research.

scholarly journals Synchronization in the connectome: Metastable oscillatory modes emerge from interactions in the brain spacetime network

2022 ◽  
Author(s):  
Joana Cabral ◽  
Francesca Castaldo ◽  
Jakub Vohryzek ◽  
Vladimir Litvak ◽  
Christian Bick ◽  
...  
Keyword(s):  
Coupled Oscillators ◽  
Brain Activity ◽  
Power Spectra ◽  
Brain Areas ◽  
Neural Mass ◽  
Spatially Distributed ◽  
Weakly Stable ◽  
Human Brains ◽  
The Brain

A rich repertoire of oscillatory signals is detected from human brains with electro- and magnetoencephalography (EEG/MEG). However, the principles underwriting coherent oscillations and their link with neural activity remain unclear. Here, we hypothesise that the emergence of transient brain rhythms is a signature of weakly stable synchronization between spatially distributed brain areas, occurring at network-specific collective frequencies due to non-negligible conduction times. We test this hypothesis using a phenomenological network model to simulate interactions between neural mass potentials (resonating at 40Hz) in the structural connectome. Crucially, we identify a critical regime where metastable oscillatory modes emerge spontaneously in the delta (0.5-4Hz), theta (4-8Hz), alpha (8-13Hz) and beta (13-30Hz) frequency bands from weak synchronization of subsystems, closely approximating the MEG power spectra from 89 healthy individuals. Grounded in the physics of delay-coupled oscillators, these numerical analyses demonstrate the role of the spatiotemporal connectome in structuring brain activity in the frequency domain.

Regulation of metallothionein concentrations in rat brain: effect of glucocorticoids, zinc, copper, and endotoxin

1994 ◽  
Vol 266 (5) ◽  
pp. E760-E767 ◽  
Author(s):  
T. Gasull ◽  
M. Giralt ◽  
J. Hernandez ◽  
P. Martinez ◽  
I. Bremner ◽  
...  
Keyword(s):  
Frontal Cortex ◽  
Rat Brain ◽  
Medulla Oblongata ◽  
Adrenocorticotropic Hormone ◽  
Brain Areas ◽  
Deficient Diet ◽  
Zinc Deficient Diet ◽  
The Brain

The effects of known inducers of liver metallothionein (MT) synthesis on MT concentrations in the rat brain have been determined using antibodies that are specific for MT I and II and do not cross-react with MT III. There were substantial differences in the MT concentrations in different areas of the brain. Dexamethasone increased MT levels after 24 h in the frontal cortex, cortex, medulla oblongata plus pons, midbrain, striatum, hippocampus, and cerebellum but not in the hypothalamus. Corticosterone produced similar results except in the hippocampus. Long-lasting adrenocorticotropic hormone increased MT concentrations after 12 h in midbrain and striatum but not in the liver. Adrenalectomy decreased MT concentrations after 6 days in the medulla oblongata plus pons, striatum, hippocampus, and hypothalamus but increased concentrations in the liver and kidneys; these effects were reversed by corticosterone. The role of glucocorticoids in the regulation of MT levels therefore differs between tissues and within specific areas of the brain. Injection of zinc or copper intracerebroventricularly and the use of a zinc-deficient diet increased and decreased MT levels, respectively, in some but not all brain areas. Endotoxin increased liver MT but not brain MT I levels after 8 h.

scholarly journals Loss of cerebellar function selectively affects intrinsic rhythmicity of eupneic breathing

2019 ◽  
Author(s):  
Yu Liu ◽  
Shuhua Qi ◽  
Fridtjof Thomas ◽  
Brittany L. Correia ◽  
Angela P. Taylor ◽  
...  
Keyword(s):  
Mouse Model ◽  
Respiratory Rate ◽  
Coefficient Of Variation ◽  
Brain Areas ◽  
Neuronal Circuitry ◽  
Cerebellar Function ◽  
Orofacial Movements ◽  
Average Coefficient ◽  
The Brain

ABSTRACTRespiration is controlled by central pattern generating circuits in the brain stem, whose activity can be modulated by inputs from other brain areas to adapt respiration to autonomic and behavioral demands. The cerebellum is known to be part of the neuronal circuitry activated during respiratory challenges, such as hunger for air, but has not been found to be involved in the control of unobstructed breathing at rest (eupnea). Here we applied a measure of intrinsic rhythmicity, the CV2, which evaluates the similarity of subsequent intervals and is thus sensitive to changes in rhythmicity at the temporal resolution of individual respiratory intervals. The variability of intrinsic respiratory rhythmicity was reduced in a mouse model of cerebellar ataxia compared to their healthy littermates. Irrespective of that difference, the average respiratory rate and the average coefficient of variation (CV) were comparable between healthy and ataxic mice. We argue that these findings are consistent with a proposed role of the cerebellum in the coordination of respiration with other rhythmic orofacial movements, such as fluid licking and swallowing.

scholarly journals Estimating null and potent modes of feedforward communication in a computational model of cortical activity

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Jean-Philippe Thivierge ◽  
Artem Pilzak
Keyword(s):  
Visual Processing ◽  
Null Space ◽  
Motor Processes ◽  
Cortical Areas ◽  
Pairwise Correlations ◽  
Neural Interactions ◽  
Modes Of Interaction ◽  
Systematic Control ◽  
The Brain

AbstractCommunication across anatomical areas of the brain is key to both sensory and motor processes. Dimensionality reduction approaches have shown that the covariation of activity across cortical areas follows well-delimited patterns. Some of these patterns fall within the "potent space" of neural interactions and generate downstream responses; other patterns fall within the "null space" and prevent the feedforward propagation of synaptic inputs. Despite growing evidence for the role of null space activity in visual processing as well as preparatory motor control, a mechanistic understanding of its neural origins is lacking. Here, we developed a mean-rate model that allowed for the systematic control of feedforward propagation by potent and null modes of interaction. In this model, altering the number of null modes led to no systematic changes in firing rates, pairwise correlations, or mean synaptic strengths across areas, making it difficult to characterize feedforward communication with common measures of functional connectivity. A novel measure termed the null ratio captured the proportion of null modes relayed from one area to another. Applied to simultaneous recordings of primate cortical areas V1 and V2 during image viewing, the null ratio revealed that feedforward interactions have a broad null space that may reflect properties of visual stimuli.

scholarly journals Learning Naturalistic Temporal Structure in the Posterior Medial Network

2018 ◽  
Vol 30 (9) ◽  
pp. 1345-1365 ◽  
Author(s):  
Mariam Aly ◽  
Janice Chen ◽  
Nicholas B. Turk-Browne ◽  
Uri Hasson
Keyword(s):  
De Novo ◽  
Temporal Structure ◽  
Temporal Integration ◽  
Functional Coupling ◽  
Relative Role ◽  
Dynamics And Function ◽  
And Function ◽  
The Brain ◽  
Event Schemas

The posterior medial network is at the apex of a temporal integration hierarchy in the brain, integrating information over many seconds of viewing intact, but not scrambled, movies. This has been interpreted as an effect of temporal structure. Such structure in movies depends on preexisting event schemas, but temporal structure can also arise de novo from learning. Here, we examined the relative role of schema-consistent temporal structure and arbitrary but consistent temporal structure on the human posterior medial network. We tested whether, with repeated viewing, the network becomes engaged by scrambled movies with temporal structure. Replicating prior studies, activity in posterior medial regions was immediately locked to stimulus structure upon exposure to intact, but not scrambled, movies. However, for temporally structured scrambled movies, functional coupling within the network increased across stimulus repetitions, rising to the level of intact movies. Thus, temporal structure is a key determinant of network dynamics and function in the posterior medial network.

scholarly journals Histone Deacetylases and Their Isoform-Specific Inhibitors in Ischemic Stroke

Biomedicines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1445
Author(s):  
Svetlana Demyanenko ◽  
Valentina Dzreyan ◽  
Svetlana Sharifulina
Keyword(s):  
Ischemic Stroke ◽  
Cerebral Ischemia ◽  
Histone Deacetylases ◽  
Histone Deacetylase Inhibitors ◽  
Neuroprotective Activity ◽  
Stroke Therapy ◽  
Brain Areas ◽  
Histone Deacetylases Inhibitors ◽  
The Brain

Cerebral ischemia is the second leading cause of death in the world and multimodal stroke therapy is needed. The ischemic stroke generally reduces the gene expression due to suppression of acetylation of histones H3 and H4. Histone deacetylases inhibitors have been shown to be effective in protecting the brain from ischemic damage. Histone deacetylases inhibitors induce neurogenesis and angiogenesis in damaged brain areas promoting functional recovery after cerebral ischemia. However, the role of different histone deacetylases isoforms in the survival and death of brain cells after stroke is still controversial. This review aims to analyze the data on the neuroprotective activity of nonspecific and selective histone deacetylase inhibitors in ischemic stroke.

scholarly journals C/EBPβIsoforms Expression in the Rat Brain during the Estrous Cycle

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Valeria Hansberg-Pastor ◽  
Ana Gabriela Piña-Medina ◽  
Aliesha González-Arenas ◽  
Ignacio Camacho-Arroyo
Keyword(s):  
Rat Brain ◽  
Estrous Cycle ◽  
Brain Areas ◽  
Tissue Specific ◽  
Sex Steroid Hormone ◽  
Female Sex Hormones ◽  
Enhancer Binding Protein ◽  
Differentiation And Proliferation ◽  
The Brain

The CCAAT/enhancer-binding protein beta (C/EBPβ) is a transcription factor expressed in different areas of the brain that regulates the expression of several genes involved in cell differentiation and proliferation. This protein has three isoforms (LAP1, LAP2, and LIP) with different transcription activation potential. The role of female sex hormones in the expression pattern of C/EBPβisoforms in the rat brain has not yet been described. In this study we demonstrate by western blot that the expression of the three C/EBPβisoforms changes in different brain areas during the estrous cycle. In the cerebellum, LAP2 content diminished on diestrus and proestrus and LIP content diminished on proestrus and estrus days. In the prefrontal cortex, LIP content was higher on proestrus and estrus days. In the hippocampus, LAP isoforms presented a switch on diestrus day, since LAP1 content was the highest while that of LAP2 was the lowest. The LAP2 isoform was the most abundant one in all the three brain areas. The LAP/LIP ratio changed throughout the cycle and was tissue specific. These results suggest that C/EBPβisoforms expression changes in a tissue-specific manner in the rat brain due to the changes in sex steroid hormone levels presented during the estrous cycle.

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