scholarly journals Disorganization of Oscillatory Activity in Animal Models of Schizophrenia

2021 ◽  
Vol 15 ◽  
Author(s):  
Lucinda J. Speers ◽  
David K. Bilkey
Keyword(s):  
Animal Models ◽  
Time Window ◽  
Research Effort ◽  
Brain Regions ◽  
Brain Dysfunction ◽  
Oscillatory Activity ◽  
Oscillation Phase ◽  
Phase Precession ◽  
Sequential Information

Schizophrenia is a chronic, debilitating disorder with diverse symptomatology, including disorganized cognition and behavior. Despite considerable research effort, we have only a limited understanding of the underlying brain dysfunction. In this article, we review the potential role of oscillatory circuits in the disorder with a particular focus on the hippocampus, a region that encodes sequential information across time and space, as well as the frontal cortex. Several mechanistic explanations of schizophrenia propose that a loss of oscillatory synchrony between and within these brain regions may underlie some of the symptoms of the disorder. We describe how these oscillations are affected in several animal models of schizophrenia, including models of genetic risk, maternal immune activation (MIA) models, and models of NMDA receptor hypofunction. We then critically discuss the evidence for disorganized oscillatory activity in these models, with a focus on gamma, sharp wave ripple, and theta activity, including the role of cross-frequency coupling as a synchronizing mechanism. Finally, we focus on phase precession, which is an oscillatory phenomenon whereby individual hippocampal place cells systematically advance their firing phase against the background theta oscillation. Phase precession is important because it allows sequential experience to be compressed into a single 120 ms theta cycle (known as a ‘theta sequence’). This time window is appropriate for the induction of synaptic plasticity. We describe how disruption of phase precession could disorganize sequential processing, and thereby disrupt the ordered storage of information. A similar dysfunction in schizophrenia may contribute to cognitive symptoms, including deficits in episodic memory, working memory, and future planning.

scholarly journals Synaptic Elimination in Neurological Disorders

2019 ◽  
Vol 17 (11) ◽  
pp. 1071-1095 ◽  
Author(s):  
Pablo L. Cardozo ◽  
Izabella B. Q. de Lima ◽  
Esther M.A. Maciel ◽  
Nathália C. Silva ◽  
Tomas Dobransky ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Animal Models ◽  
Neurological Disorders ◽  
Brain Regions ◽  
Complement Cascade ◽  
Complement Proteins ◽  
Complement Component 3 ◽  
Synaptic Pruning ◽  
Classical Complement

Synapses are well known as the main structures responsible for transmitting information through the release and recognition of neurotransmitters by pre- and post-synaptic neurons. These structures are widely formed and eliminated throughout the whole lifespan via processes termed synaptogenesis and synaptic pruning, respectively. Whilst the first process is needed for ensuring proper connectivity between brain regions and also with the periphery, the second phenomenon is important for their refinement by eliminating weaker and unnecessary synapses and, at the same time, maintaining and favoring the stronger ones, thus ensuring proper synaptic transmission. It is well-known that synaptic elimination is modulated by neuronal activity. However, only recently the role of the classical complement cascade in promoting this phenomenon has been demonstrated. Specifically, microglial cells recognize activated complement component 3 (C3) bound to synapses targeted for elimination, triggering their engulfment. As this is a highly relevant process for adequate neuronal functioning, disruptions or exacerbations in synaptic pruning could lead to severe circuitry alterations that could underlie neuropathological alterations typical of neurological and neuropsychiatric disorders. In this review, we focus on discussing the possible involvement of excessive synaptic elimination in Alzheimer’s disease, as it has already been reported dendritic spine loss in post-synaptic neurons, increased association of complement proteins with its synapses and, hence, augmented microglia-mediated pruning in animal models of this disorder. In addition, we briefly discuss how this phenomenon could be related to other neurological disorders, including multiple sclerosis and schizophrenia.

scholarly journals Probing the causal role of prestimulus interregional synchrony for perceptual integration via tACS

2016 ◽  
Author(s):  
Rolandas Stonkus ◽  
Verena Braun ◽  
Jess Kerlin ◽  
Gregor Volberg ◽  
Simon Hanslmayr
Keyword(s):  
Specific Activity ◽  
Brain Regions ◽  
Causal Role ◽  
Oscillatory Activity ◽  
Perceptual Integration ◽  
After Effects ◽  
Activity Phase ◽  
Fmri Study ◽  
Transcranial Alternating Current Stimulation

The phase of prestimulus oscillations at 7-10 Hz has been shown to modulate perception of briefly presented visual stimuli. Specifically, a recent combined EEG-fMRI study suggested that a prestimulus oscillation at around 7 Hz represents open and closed windows for perceptual integration by modulating connectivity between lower order occipital and higher order parietal brain regions. We here utilized brief event-related transcranial alternating current stimulation (tACS) to specifically modulate this prestimulus 7 Hz oscillation, and the synchrony between parietal and occipital brain regions. To this end we tested for a causal role of this particular prestimulus oscillation for perceptual integration. The EEG was acquired at the same time allowing us to investigate frequency specific after effects phase-locked to stimulation offset. On a behavioural level our results suggest that the tACS did modulate perceptual integration, however, in an unexpected manner. On an electrophysiological level our results suggest that brief tACS does induce oscillatory entrainment, as visible in frequency specific activity phase-locked to stimulation offset. Together, our results do not strongly support a causal role of prestimulus 7 Hz oscillations for perceptual integration. However, our results suggest that brief tACS is capable of modulating oscillatory activity in a temporally sensitive manner.

scholarly journals The Role of Stress Regulation on Neural Plasticity in Pain Chronification

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Xiaoyun Li ◽  
Li Hu
Keyword(s):  
Chronic Pain ◽  
Animal Models ◽  
Neural Plasticity ◽  
Clinical Symptoms ◽  
Brain Plasticity ◽  
Brain Regions ◽  
Stress Regulation ◽  
Pain Chronification ◽  
A Chain

Pain, especially chronic pain, is one of the most common clinical symptoms and has been considered as a worldwide healthcare problem. The transition from acute to chronic pain is accompanied by a chain of alterations in physiology, pathology, and psychology. Increasing clinical studies and complementary animal models have elucidated effects of stress regulation on the pain chronification via investigating activations of the hypothalamic-pituitary-adrenal (HPA) axis and changes in some crucial brain regions, including the amygdala, prefrontal cortex, and hippocampus. Although individuals suffer from acute pain benefit from such physiological alterations, chronic pain is commonly associated with maladaptive responses, like the HPA dysfunction and abnormal brain plasticity. However, the causal relationship among pain chronification, stress regulation, and brain alterations is rarely discussed. To call for more attention on this issue, we review recent findings obtained from clinical populations and animal models, propose an integrated stress model of pain chronification based on the existing models in perspectives of environmental influences and genetic predispositions, and discuss the significance of investigating the role of stress regulation on brain alteration in pain chronification for various clinical applications.

Neural Oscillations: Understanding a Neural Code of Pain

2020 ◽  
pp. 107385842095862
Author(s):  
Junseok A. Kim ◽  
Karen D. Davis
Keyword(s):  
Chronic Pain ◽  
Brain Regions ◽  
Oscillatory Activity ◽  
Neural Oscillations ◽  
Brain Functions ◽  
Disease States ◽  
Efficient Communication ◽  
Nociceptive Processing ◽  
The Brain

Neural oscillations play an important role in the integration and segregation of brain regions that are important for brain functions, including pain. Disturbances in oscillatory activity are associated with several disease states, including chronic pain. Studies of neural oscillations related to pain have identified several functional bands, especially alpha, beta, and gamma bands, implicated in nociceptive processing. In this review, we introduce several properties of neural oscillations that are important to understand the role of brain oscillations in nociceptive processing. We also discuss the role of neural oscillations in the maintenance of efficient communication in the brain. Finally, we discuss the role of neural oscillations in healthy and chronic pain nociceptive processing. These data and concepts illustrate the key role of regional and interregional neural oscillations in nociceptive processing underlying acute and chronic pains.

scholarly journals What’s in Your Gamma? Activation of The Ventral Fronto-Parietal Attentional Network in Response to Distracting Sounds

2018 ◽  
Author(s):  
Hesham A. ElShafei ◽  
Lesly Fornoni ◽  
Rémy Masson ◽  
Olivier Bertrand ◽  
Aurélie Bidet-Caulet
Keyword(s):  
Prefrontal Cortex ◽  
Brain Regions ◽  
Anterior Cingulate ◽  
Gamma Activity ◽  
Oscillatory Activity ◽  
Attention Task ◽  
Novel Method ◽  
Auditory Cortices ◽  
Insight Into

ABSTRACTAuditory attention operates through top-down (TD) and bottom-up (BU) mechanisms that are supported by dorsal and ventral brain networks, respectively, with the main overlap in the lateral prefrontal cortex (lPFC). A good TD/BU balance is essential to be both task-efficient and aware of our environment, yet it is rarely investigated. Oscillatory activity is a novel method to probe the attentional dynamics with evidence that gamma activity (>30Hz) could signal BU processing and thus would be a good candidate to support the activation of the ventral BU network. MEG data were collected from 21 young adults performing the Competitive Attention Task which enables simultaneous investigation of BU and TD attentional mechanisms. Distracting sounds elicited an increase in gamma activity in regions of the BU ventral network. TD attention modulated these gamma responses in regions of the inhibitory cognitive control system: the medial prefrontal and anterior cingulate cortices. Finally, distracting-sound-induced gamma activity was synchronous between the auditory cortices and several distant brain regions, notably the lPFC. We provide novel insight into the role of gamma activity (1) in supporting the activation of the BU ventral network, and (2) in subtending the TD/BU attention balance in the prefrontal cortex.

scholarly journals Is There Any Evidence of Monocytes Involvement in Alzheimer’s Disease? A Pilot Study on Human Postmortem Brain

2021 ◽  
pp. 1-11
Author(s):  
Camelia-Maria Monoranu ◽  
Tim Hartmann ◽  
Sabrina Strobel ◽  
Helmut Heinsen ◽  
Peter Riederer ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Animal Models ◽  
Human Brain ◽  
Amyloid Β ◽  
Occipital Lobe ◽  
Inflammatory Cells ◽  
Brain Regions ◽  
Postmortem Brain

Background: The role of neuroinflammation has become more evident in the pathogenesis of neurodegenerative diseases. Increased expression of microglial markers is widely reported in Alzheimer’s disease (AD), but much less is known about the role of monocytes in AD pathogenesis. In AD animal models, bone marrow-derived monocytes appear to infiltrate the parenchyma and contribute to the phagocytosis of amyloid-β depositions, but this infiltration has not been established in systematic studies of the human brain postmortem. Objective: In addition to assessing the distribution of different subtypes of microglia by immunostaining for CD68, HLA-DR, CD163, and CD206, we focused on the involvement of C-chemokine receptor type2 (CCR2) positive monocytes during the AD course. Methods: We used formalin-fixed and paraffin-embedded tissue from four vulnerable brain regions (hippocampus, occipital lobe, brainstem, and cerebellum) from neuropathologically characterized AD cases at different Braak stages and age-matched controls. Results: Only singular migrated CCR2-positive cells were found in all brain regions and stages. The brainstem showed the highest number of positive cells overall, followed by the hippocampus. This mechanism of recruitment seems to work less efficiently in the human brain at an advanced age, and the ingress of monocytes obviously takes place in much reduced numbers or not at all. Conclusion: In contrast to studies on animal models, we observed only a quite low level of myeloid monocytes associated with AD pathology. Furthermore, we provide evidence associating early microglial reactions carried out in particular by pro-inflammatory cells with early effects on tangle- and plaque-positive vulnerable brain regions.

Amodal Atypical Neural Oscillatory Activity in Dyslexia

2016 ◽  
Vol 5 (2) ◽  
pp. 379-401 ◽  
Author(s):  
Marie Lallier ◽  
Nicola Molinaro ◽  
Mikel Lizarazu ◽  
Mathieu Bourguignon ◽  
Manuel Carreiras
Keyword(s):  
Developmental Dyslexia ◽  
Brain Dysfunction ◽  
Oscillatory Activity ◽  
Neural Oscillations ◽  
Future Research ◽  
Orthographic Depth ◽  
Oscillatory Mechanisms ◽  
Linguistic Approach ◽  
Shed Light

It has been proposed that atypical neural oscillations in both the auditory and the visual modalities could explain why some individuals fail to learn to read and suffer from developmental dyslexia. However, the role of specific oscillatory mechanisms in reading acquisition is still under debate. In this article, we take a cross-linguistic approach and argue that both the phonological and orthographic specifics of a language (e.g., linguistic rhythm, orthographic depth) shape the oscillatory activity thought to contribute to reading development. The proposed theoretical framework should allow future research to test cross-linguistic hypotheses that will shed light on the heterogeneity of auditory and visual disorders and their underlying brain dysfunction(s) in developmental dyslexia, and inform clinical practice by helping us to diagnose dyslexia across languages.

Inflammational Animal Models for Schizophrenia

2015 ◽  
Vol 223 (3) ◽  
pp. 157-164 ◽  
Author(s):  
Georg Juckel
Keyword(s):  
Animal Model ◽  
Animal Models ◽  
Immune Activation ◽  
Microglial Activation ◽  
Treatment Options ◽  
Early Adulthood ◽  
Brain Regions ◽  
Synaptic Connections ◽  
Preventive Interventions ◽  
Immunological System

Abstract. Inflammational-immunological processes within the pathophysiology of schizophrenia seem to play an important role. Early signals of neurobiological changes in the embryonal phase of brain in later patients with schizophrenia might lead to activation of the immunological system, for example, of cytokines and microglial cells. Microglia then induces – via the neurotoxic activities of these cells as an overreaction – a rarification of synaptic connections in frontal and temporal brain regions, that is, reduction of the neuropil. Promising inflammational animal models for schizophrenia with high validity can be used today to mimic behavioral as well as neurobiological findings in patients, for example, the well-known neurochemical alterations of dopaminergic, glutamatergic, serotonergic, and other neurotransmitter systems. Also the microglial activation can be modeled well within one of this models, that is, the inflammational PolyI:C animal model of schizophrenia, showing a time peak in late adolescence/early adulthood. The exact mechanism, by which activated microglia cells then triggers further neurodegeneration, must now be investigated in broader detail. Thus, these animal models can be used to understand the pathophysiology of schizophrenia better especially concerning the interaction of immune activation, inflammation, and neurodegeneration. This could also lead to the development of anti-inflammational treatment options and of preventive interventions.

Cellular and animal models in pheochromocytoma/paragangliomas research: role of microenvironment

2016 ◽  
Author(s):  
M Mannelli ◽  
E Rapizzi ◽  
L Canu ◽  
T Ercolino ◽  
V Giache
Keyword(s):  
Animal Models

Bioengineered in vitro Vascular Models for Applications in Interventional Radiology

2019 ◽  
Vol 24 (45) ◽  
pp. 5367-5374 ◽  
Author(s):  
Xiaoyun Li ◽  
Seyed M. Moosavi-Basri ◽  
Rahul Sheth ◽  
Xiaoying Wang ◽  
Yu S. Zhang
Keyword(s):  
Interventional Radiology ◽  
Animal Models ◽  
Blood Vessels ◽  
In Vitro Models ◽  
The Past ◽  
Endovascular Interventions ◽  
Conventional Animal ◽  
Vascular Structures

The role of endovascular interventions has progressed rapidly over the past several decades. While animal models have long-served as the mainstay for the advancement of this field, the use of in vitro models has become increasingly widely adopted with recent advances in engineering technologies. Here, we review the strategies, mainly including bioprinting and microfabrication, which allow for fabrication of biomimetic vascular models that will potentially serve to supplement the conventional animal models for convenient investigations of endovascular interventions. Besides normal blood vessels, those in diseased states, such as thrombosis, may also be modeled by integrating cues that simulate the microenvironment of vascular disorders. These novel engineering strategies for the development of biomimetic in vitro vascular structures will possibly enable unconventional means of studying complex endovascular intervention problems that are otherwise hard to address using existing models.

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