scholarly journals Chronic Exposure to Hypoxia Inhibits Myelinogenesis and Causes Motor Coordination Deficits in Adult Mice

2021 ◽  
Author(s):  
Lin Chen ◽  
Shu-Yu Ren ◽  
Rui-Xue Li ◽  
Kun Liu ◽  
Jing-Fei Chen ◽  
...  
Keyword(s):  
Motor Coordination ◽  
Chronic Hypoxia ◽  
Brain Regions ◽  
Functional Deficits ◽  
Brain Functions ◽  
Highly Active ◽  
Adult Mice ◽  
Functional Consequences ◽  
Underlying Mechanisms ◽  
The Impact

AbstractExposure to chronic hypoxia is considered to be a risk factor for deficits in brain function in adults, but the underlying mechanisms remain largely unknown. Since active myelinogenesis persists in the adult central nervous system, here we aimed to investigate the impact of chronic hypoxia on myelination and the related functional consequences in adult mice. Using a transgenic approach to label newly-generated myelin sheaths (NG2-CreERTM; Tau-mGFP), we found that myelinogenesis was highly active in most brain regions, such as the motor cortex and corpus callosum. After exposure to hypoxia (10% oxygen) 12 h per day for 4 weeks, myelinogenesis was largely inhibited in the 4-month old brain and the mice displayed motor coordination deficits revealed by the beam-walking test. To determine the relationship between the inhibited myelination and functional impairment, we induced oligodendroglia-specific deletion of the transcription factor Olig2 by tamoxifen (NG2-CreERTM; Tau-mGFP; Olig2 fl/fl) in adult mice to mimic the decreased myelinogenesis caused by hypoxia. The deletion of Olig2 inhibited myelinogenesis and consequently impaired motor coordination, suggesting that myelinogenesis is required for motor function in adult mice. To understand whether enhancing myelination could protect brain functions against hypoxia, we treated hypoxic mice with the myelination-enhancing drug-clemastine, which resulted in enhanced myelogenesis and improved motor coordination. Taken together, our data indicate that chronic hypoxia inhibits myelinogenesis and causes functional deficits in the brain and that enhancing myelinogenesis protects brain functions against hypoxia-related deficits.

scholarly journals Sex in the brain: hormones and sex differences

2016 ◽  
Vol 18 (4) ◽  
pp. 373-383 ◽  
Keyword(s):  
Sex Differences ◽  
Sex Hormones ◽  
Genetic Factors ◽  
Motor Coordination ◽  
Brain Regions ◽  
New Era ◽  
Brain Functions ◽  
Opioid Sensitivity ◽  
Males And Females ◽  
The Brain

Contrary to popular belief, sex hormones act throughout the entire brain of both males and females via both genomic and nongenomic receptors. Many neural and behavioral functions are affected by estrogens, including mood, cognitive function, blood pressure regulation, motor coordination, pain, and opioid sensitivity. Subtle sex differences exist for many of these functions that are developmentally programmed by hormones and by not yet precisely defined genetic factors, including the mitochondrial genome. These sex differences, and responses to sex hormones in brain regions and upon functions not previously regarded as subject to such differences, indicate that we are entering a new era in our ability to understand and appreciate the diversity of gender-related behaviors and brain functions.

scholarly journals Assessing Lateral Interaction in the Synesthetic Visual Brain

Vision ◽  
2019 ◽  
Vol 3 (1) ◽  
pp. 7 ◽  
Author(s):  
Diana Jimena Arias ◽  
Anthony Hosein ◽  
Dave Saint-Amour
Keyword(s):  
Fundamental Frequency ◽  
Long Range ◽  
Visual Processing ◽  
Frequency Component ◽  
Brain Regions ◽  
Lateral Interaction ◽  
Lateral Interactions ◽  
Subjective Experiences ◽  
Underlying Mechanisms ◽  
The Impact

In grapheme-color synesthesia, letters and numbers evoke abnormal colored perceptions. Although the underlying mechanisms are not known, it is largely thought that the synesthetic brain is characterized by atypical connectivity throughout various brain regions, including the visual areas. To study the putative impact of synesthesia on the visual brain, we assessed lateral interactions (i.e., local functional connectivity between neighboring neurons in the visual cortex) by recording steady-state visual evoked potentials (ssVEPs) over the occipital region in color-grapheme synesthetes (n = 6) and controls (n = 21) using the windmill/dartboard paradigm. Discrete Fourier Transform analysis was conducted to extract the fundamental frequency and the second harmonics of ssVEP responses from contrast-reversing stimuli presented at 4.27 Hz. Lateral interactions were assessed using two amplitude-based indices: Short-range and long-range lateral interactions. Results indicated that synesthetes had a statistically weaker signal coherence of the fundamental frequency component compared to the controls, but no group differences were observed on lateral interaction indices. However, a significant correlation was found between long-range lateral interactions and the type of synesthesia experience (projector versus associator). We conclude that the occipital activity related to lateral interactions in synesthetes does not substantially differ from that observed in controls. Further investigation is needed to understand the impact of synesthesia on visual processing, specifically in relation to subjective experiences of synesthete individuals.

scholarly journals Blue Light Stimulates Cognitive Brain Activity in Visually Blind Individuals

2013 ◽  
Vol 25 (12) ◽  
pp. 2072-2085 ◽  
Author(s):  
Gilles Vandewalle ◽  
Olivier Collignon ◽  
Joseph T. Hull ◽  
Véronique Daneault ◽  
Geneviève Albouy ◽  
...  
Keyword(s):  
Blue Light ◽  
Ganglion Cells ◽  
Brain Activity ◽  
Memory Task ◽  
Brain Regions ◽  
Human Cognition ◽  
Brain Functions ◽  
And Performance ◽  
Blind Individuals ◽  
The Impact

Light regulates multiple non-image-forming (or nonvisual) circadian, neuroendocrine, and neurobehavioral functions, via outputs from intrinsically photosensitive retinal ganglion cells (ipRGCs). Exposure to light directly enhances alertness and performance, so light is an important regulator of wakefulness and cognition. The roles of rods, cones, and ipRGCs in the impact of light on cognitive brain functions remain unclear, however. A small percentage of blind individuals retain non-image-forming photoreception and offer a unique opportunity to investigate light impacts in the absence of conscious vision, presumably through ipRGCs. Here, we show that three such patients were able to choose nonrandomly about the presence of light despite their complete lack of sight. Furthermore, 2 sec of blue light modified EEG activity when administered simultaneously to auditory stimulations. fMRI further showed that, during an auditory working memory task, less than a minute of blue light triggered the recruitment of supplemental prefrontal and thalamic brain regions involved in alertness and cognition regulation as well as key areas of the default mode network. These results, which have to be considered as a proof of concept, show that non-image-forming photoreception triggers some awareness for light and can have a more rapid impact on human cognition than previously understood, if brain processing is actively engaged. Furthermore, light stimulates higher cognitive brain activity, independently of vision, and engages supplemental brain areas to perform an ongoing cognitive process. To our knowledge, our results constitute the first indication that ipRGC signaling may rapidly affect fundamental cerebral organization, so that it could potentially participate to the regulation of numerous aspects of human brain function.

scholarly journals Rapid Reconfiguration of the Functional Connectome after Chemogenetic Locus Coeruleus Activation

2019 ◽  
Author(s):  
Valerio Zerbi ◽  
Amalia Floriou-Servou ◽  
Marija Markicevic ◽  
Yannick Vermeiren ◽  
Oliver Sturman ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Locus Coeruleus ◽  
Large Scale ◽  
Network Connectivity ◽  
Brain Regions ◽  
Causal Link ◽  
Receptor Expression ◽  
Brain Functions ◽  
Neuropsychiatric Diseases ◽  
The Impact

AbstractThe locus coeruleus (LC) supplies norepinephrine (NE) to the entire forebrain, regulates many fundamental brain functions, and is implicated in several neuropsychiatric diseases. Although selective manipulation of the LC is not possible in humans, studies have suggested that strong LC activation might shift network connectivity to favor salience processing. To test this hypothesis, we use a mouse model to study the impact of LC stimulation on large-scale functional connectivity by combining chemogenetic activation of the LC with resting-state fMRI, an approach we term “chemo-connectomics”. LC activation rapidly interrupts ongoing behavior and strongly increases brain-wide connectivity, with the most profound effects in the salience and amygdala networks. We reveal a direct correlation between functional connectivity changes and transcript levels of alpha-1, alpha-2, and beta-1 adrenoceptors across the brain, and a positive correlation between NE turnover and functional connectivity within select brain regions. These results represent the first brain-wide functional connectivity mapping in response to LC activation, and demonstrate a causal link between receptor expression, brain states and functionally connected large-scale networks at rest. We propose that these changes in large-scale network connectivity are critical for optimizing neural processing in the context of increased vigilance and threat detection.

scholarly journals Identification of amyloid beta oligomers in locus coeruleus (LC) neurons of Alzheimer’s patients and their impact on LC oxidative stress, inhibitory neurotransmitter receptors and neuronal excitability

2020 ◽  
Author(s):  
Louise Kelly ◽  
Mohsen Seifi ◽  
Ruolin Ma ◽  
Scott Mitchell ◽  
Uwe Rudolph ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Locus Coeruleus ◽  
Expression Profile ◽  
Neuronal Excitability ◽  
Psychiatric Symptoms ◽  
Amyloid Β ◽  
Wild Type Mouse ◽  
Brain Regions ◽  
Brain Functions ◽  
The Impact

AbstractAmyloid β oligomers (AβO) are potent modulators of two key Alzheimer’s pathological processes, namely synaptic dysfunction and tau tangle formation in various brain regions. Remarkably, the impact of AβO in one of the earliest brain regions to exhibit Alzheimer’s pathology, the locus coeruleus (LC), remains to be determined. Of particular importance is the effect of AβO on the excitability of individual LC neurons. This parameter determines brain-wide noradrenaline (NA) release, and thus NA-mediated brain functions, including cognition, emotion and immune function, which are all severely compromised in Alzheimer’s. Using a mouse model of increased Aβ production (APP-PSEN1), together with correlative histopathological analyses in post mortem Alzheimer’s patient samples, we determined the impact of Aβ pathology on various correlates of LC neuronal integrity. AβO immunoreactivity in the LC of APP-PSEN1 mice was replicated in patient samples, presenting as individual clusters located both intraneuronally, in mitochondrial compartments, as well as extracellularly in association with inhibitory synapses. No specific signal was detected in either patient control or wild type mouse samples. Accompanying this AβO expression profile was LC neuronal hyperexcitability and indicators of oxidative stress in APP-PSEN1 mice. LC hyperexcitability arose from a diminished inhibitory effect of GABA, due to impaired expression and function of the GABA-A receptor (GABAAR) α3 subunit. Importantly, this altered LC α3-GABAAR expression profile overlapped with AβO expression in both APP-PSEN1 mice and Alzheimer’s patient samples. Finally, strychnine-sensitive glycine receptors (GlyRs) remained resilient to AβO-induced changes and their activation reversed LC hyperexcitability. Alongside this first demonstration of AβO expression in the LC of Alzheimer’s patients, the study is also first to reveal a direct association between AβO and LC neuronal excitability. GlyR-α3-GABAAR modulation of AβO-dependent LC hyperexcitability could delay the onset of cognitive and psychiatric symptoms arising from LC-NA deficits, thereby significantly diminishing the disease burden for Alzheimer’s patients.

scholarly journals Modulatory Effects of Monoamines and Perineuronal Nets on Output of Cerebellar Purkinje Cells

2021 ◽  
Vol 15 ◽  
Author(s):  
Moritoshi Hirono ◽  
Fuyuki Karube ◽  
Yuchio Yanagawa
Keyword(s):  
Purkinje Cells ◽  
Motor Coordination ◽  
Gaba Release ◽  
Cerebellar Nuclei ◽  
Brain Regions ◽  
Perineuronal Nets ◽  
Gabaergic Transmission ◽  
Neural Connections ◽  
Brain Functions ◽  
Cerebellar Purkinje Cells

Classically, the cerebellum has been thought to play a significant role in motor coordination. However, a growing body of evidence for novel neural connections between the cerebellum and various brain regions indicates that the cerebellum also contributes to other brain functions implicated in reward, language, and social behavior. Cerebellar Purkinje cells (PCs) make inhibitory GABAergic synapses with their target neurons: other PCs and Lugaro/globular cells via PC axon collaterals, and neurons in the deep cerebellar nuclei (DCN) via PC primary axons. PC-Lugaro/globular cell connections form a cerebellar cortical microcircuit, which is driven by serotonin and noradrenaline. PCs’ primary outputs control not only firing but also synaptic plasticity of DCN neurons following the integration of excitatory and inhibitory inputs in the cerebellar cortex. Thus, strong PC-mediated inhibition is involved in cerebellar functions as a key regulator of cerebellar neural networks. In this review, we focus on physiological characteristics of GABAergic transmission from PCs. First, we introduce monoaminergic modulation of GABAergic transmission at synapses of PC-Lugaro/globular cell as well as PC-large glutamatergic DCN neuron, and a Lugaro/globular cell-incorporated microcircuit. Second, we review the physiological roles of perineuronal nets (PNNs), which are organized components of the extracellular matrix and enwrap the cell bodies and proximal processes, in GABA release from PCs to large glutamatergic DCN neurons and in cerebellar motor learning. Recent evidence suggests that alterations in PNN density in the DCN can regulate cerebellar functions.

Asymmetrical Attribution of Performance in China

Asian Survey ◽  
2020 ◽  
Vol 60 (5) ◽  
pp. 978-1003
Author(s):  
Jacqueline Chen Chen ◽  
Jun Xiang
Keyword(s):  
Economic Development ◽  
Local Governments ◽  
Central Government ◽  
Cultural Theory ◽  
Political Trust ◽  
Mediation Model ◽  
Multilevel Mediation ◽  
Dual Pathway ◽  
Underlying Mechanisms ◽  
The Impact

Existing studies of the impact of economic development on political trust in China have two major gaps: they fail to explain how economic development contributes to the hierarchical trust pattern, and they do not pay enough attention to the underlying mechanisms. In light of cultural theory and political control theory, we propose adapting performance theory into a theory of “asymmetrical attribution of performance” to better illuminate the case of China. This adapted theory leads to dual pathway theses: expectation fulfillment and local blaming. Using a multilevel mediation model, we show that expectation fulfillment mainly upholds trust in the central government, whereas local blaming undermines trust in local governments. We also uncover a rural–urban distinction in the dual pathway, revealing that both theses are more salient among rural Chinese.

scholarly journals Conscious perception and perceptual echoes: a binocular rivalry study

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Canhuang Luo ◽  
Rufin VanRullen ◽  
Andrea Alamia
Keyword(s):  
Binocular Rivalry ◽  
Visual Information ◽  
Visual Stimulation ◽  
Brain Regions ◽  
Travelling Wave ◽  
Alpha Power ◽  
Conscious Perception ◽  
Impulse Response Functions ◽  
Band Frequency ◽  
Underlying Mechanisms

Abstract Alpha rhythms (∼10Hz) in the human brain are classically associated with idling activities, being predominantly observed during quiet restfulness with closed eyes. However, recent studies demonstrated that alpha (∼10Hz) rhythms can directly relate to visual stimulation, resulting in oscillations, which can last for as long as one second. This alpha reverberation, dubbed perceptual echoes (PE), suggests that the visual system actively samples and processes visual information within the alpha-band frequency. Although PE have been linked to various visual functions, their underlying mechanisms and functional role are not completely understood. In this study, we investigated the relationship between conscious perception and the generation and the amplitude of PE. Specifically, we displayed two coloured Gabor patches with different orientations on opposite sides of the screen, and using a set of dichoptic mirrors, we induced a binocular rivalry between the two stimuli. We asked participants to continuously report which one of two Gabor patches they consciously perceived, while recording their EEG signals. Importantly, the luminance of each patch fluctuated randomly over time, generating random sequences from which we estimated two impulse-response functions (IRFs) reflecting the PE generated by the perceived (dominant) and non-perceived (suppressed) stimulus, respectively. We found that the alpha power of the PE generated by the consciously perceived stimulus was comparable with that of the PE generated during monocular vision (control condition) and higher than the PE induced by the suppressed stimulus. Moreover, confirming previous findings, we found that all PEs propagated as a travelling wave from posterior to frontal brain regions, irrespective of conscious perception. All in all our results demonstrate a correlation between conscious perception and PE, suggesting that the synchronization of neural activity plays an important role in visual sampling and conscious perception.

scholarly journals Aerobic Exercise Induces Alternative Splicing of Neurexins in Frontal Cortex

2021 ◽  
Vol 6 (2) ◽  
pp. 48
Author(s):  
Elisa Innocenzi ◽  
Ida Cariati ◽  
Emanuela De Domenico ◽  
Erika Tiberi ◽  
Giovanna D’Arcangelo ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Aerobic Exercise ◽  
Frontal Cortex ◽  
Molecular Mechanisms ◽  
Splice Variants ◽  
Brain Regions ◽  
Synaptic Function ◽  
Molecular Changes ◽  
Beneficial Effects ◽  
The Impact

Aerobic exercise (AE) is known to produce beneficial effects on brain health by improving plasticity, connectivity, and cognitive functions, but the underlying molecular mechanisms are still limited. Neurexins (Nrxns) are a family of presynaptic cell adhesion molecules that are important in synapsis formation and maturation. In vertebrates, three-neurexin genes (NRXN1, NRXN2, and NRXN3) have been identified, each encoding for α and β neurexins, from two independent promoters. Moreover, each Nrxns gene (1–3) has several alternative exons and produces many splice variants that bind to a large variety of postsynaptic ligands, playing a role in trans-synaptic specification, strength, and plasticity. In this study, we investigated the impact of a continuous progressive (CP) AE program on alternative splicing (AS) of Nrxns on two brain regions: frontal cortex (FC) and hippocampus. We showed that exercise promoted Nrxns1–3 AS at splice site 4 (SS4) both in α and β isoforms, inducing a switch from exon-excluded isoforms (SS4−) to exon-included isoforms (SS4+) in FC but not in hippocampus. Additionally, we showed that the same AE program enhanced the expression level of other genes correlated with synaptic function and plasticity only in FC. Altogether, our findings demonstrated the positive effect of CP AE on FC in inducing molecular changes underlying synaptic plasticity and suggested that FC is possibly a more sensitive structure than hippocampus to show molecular changes.

scholarly journals Retrospective analysis of hemispheric structural network change as a function of location and size of glioma

2020 ◽  
Author(s):  
Shawn D’Souza ◽  
Lisa Hirt ◽  
David R Ormond ◽  
John A Thompson
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Temporal Lobe ◽  
Diffusion Tensor ◽  
Brain Regions ◽  
Structural Network ◽  
Tumour Location ◽  
The Impact ◽  
Tractography Data ◽  
Diffusion Tensor Imaging Tractography

Abstract Gliomas are neoplasms that arise from glial cell origin and represent the largest fraction of primary malignant brain tumours (77%). These highly infiltrative malignant cell clusters modify brain structure and function through expansion, invasion and intratumoral modification. Depending on the growth rate of the tumour, location and degree of expansion, functional reorganization may not lead to overt changes in behaviour despite significant cerebral adaptation. Studies in simulated lesion models and in patients with stroke reveal both local and distal functional disturbances, using measures of anatomical brain networks. Investigations over the last two decades have sought to use diffusion tensor imaging tractography data in the context of intracranial tumours to improve surgical planning, intraoperative functional localization, and post-operative interpretation of functional change. In this study, we used diffusion tensor imaging tractography to assess the impact of tumour location on the white matter structural network. To better understand how various lobe localized gliomas impact the topology underlying efficiency of information transfer between brain regions, we identified the major alterations in brain network connectivity patterns between the ipsilesional versus contralesional hemispheres in patients with gliomas localized to the frontal, parietal or temporal lobe. Results were indicative of altered network efficiency and the role of specific brain regions unique to different lobe localized gliomas. This work draws attention to connections and brain regions which have shared structural susceptibility in frontal, parietal and temporal lobe glioma cases. This study also provides a preliminary anatomical basis for understanding which affected white matter pathways may contribute to preoperative patient symptomology.

Sign in / Sign up

Export Citation Format

Share Document