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excitation/inhibition hippocampus

Yu-Jing Ding, Yu Song, Jun-Xiu Liu, Ya-Li Du, Li Zhu, Fu-Rong Ma
Background: Tinnitus is a common disorder that causes significant morbidity; however, the neurophysiological mechanism is not yet fully understood. A relationship between tinnitus and limbic system has been reported. As a significant component of the limbic system, the hippocampus plays an important role in various pathological processes, such as emotional disturbance, decreased learning ability, and deterioration of memory. This study was aimed to explore the role of the hippocampus in the generation of tinnitus by electrophysiological technology...
August 20, 2018: Chinese Medical Journal
Andrew L Eagle, Elizabeth S Williams, Joseph A Beatty, Charles L Cox, Alfred J Robison
Both the function of hippocampal neurons and hippocampus-dependent behaviors are dependent on changes in gene expression, but the specific mechanisms that regulate gene expression in hippocampus are not yet fully understood. The stable, activity-dependent transcription factor ΔFosB plays a role in various forms of hippocampal-dependent learning and in the structural plasticity of synapses onto CA1 neurons. The authors examined the consequences of viral-mediated overexpression or inhibition of ΔFosB on the function of adult mouse hippocampal CA1 neurons using ex vivo slice whole-cell physiology...
July 2018: ENeuro
Amir Segev, Masaya Yanagi, Daniel Scott, Sarah A Southcott, Jacob M Lister, Chunfeng Tan, Wei Li, Shari G Birnbaum, Saïd Kourrich, Carol A Tamminga
Recent findings from in vivo-imaging and human post-mortem tissue studies in schizophrenic psychosis (SzP), have demonstrated functional and molecular changes in hippocampal subfields that can be associated with hippocampal hyperexcitability. In this study, we used a subfield-specific GluN1 knockout mouse with a disease-like molecular perturbation expressed only in hippocampal dentate gyrus (DG) and assessed its association with hippocampal physiology and psychosis-like behaviors. First, we used whole-cell patch-clamp recordings to measure the physiological changes in hippocampal subfields and cFos immunohistochemistry to examine cellular excitability...
July 23, 2018: Molecular Psychiatry
Simone F Carron, Edwin B Yan, Benjamin J Allitt, Ramesh Rajan
Changes in inhibition following traumatic brain injury (TBI) appear to be one of the major factors that contribute to excitation:inhibition imbalance. Neuron pathology, interneurons in particular evolves from minutes to weeks post injury and follows a complex time course. Previously, we showed that in the long-term in diffuse TBI (dTBI), there was select reduction of specific dendrite-targeting neurons in sensory cortex and hippocampus while in motor cortex there was up-regulation of specific dendrite-targeting neurons...
July 21, 2018: Neuroscience
Alexandra Olimpio Siqueira Cunha, Cesar Celis Ceballos, Júnia Lara de Deus, Rodrigo Felipe de Oliveira Pena, José Antonio Cortes de Oliveira, Antonio Carlos Roque, Norberto Garcia-Cairasco, Ricardo Maurício Leão
Despite the many studies focusing on epilepsy, a lot of the basic mechanisms underlying seizure susceptibility are mainly unclear. Here, we studied cellular electrical excitability, as well as excitatory and inhibitory synaptic neurotransmission of CA1 pyramidal neurons from the dorsal hippocampus of a genetic model of epilepsy, the Wistar Audiogenic Rat (WARs) in which limbic seizures appear after repeated audiogenic stimulation. We examined intrinsic properties of neurons, as well as EPSCs evoked by Schaffer-collateral stimulation in slices from WARs and Wistar parental strain...
July 10, 2018: Scientific Reports
Christoph Anacker, Victor M Luna, Gregory S Stevens, Amira Millette, Ryan Shores, Jessica C Jimenez, Briana Chen, René Hen
Adult neurogenesis in the dentate gyrus of the hippocampus is highly regulated by environmental influences, and functionally implicated in behavioural responses to stress and antidepressants1-4 . However, how adult-born neurons regulate dentate gyrus information processing to protect from stress-induced anxiety-like behaviour is unknown. Here we show in mice that neurogenesis confers resilience to chronic stress by inhibiting the activity of mature granule cells in the ventral dentate gyrus (vDG), a subregion that is implicated in mood regulation...
July 2018: Nature
Naoki Yamawaki, Kevin A Corcoran, Anita L Guedea, Gordon M G Shepherd, Jelena Radulovic
Learning to associate stressful events with specific environmental contexts depends on excitatory transmission in the hippocampus, but how this information is transmitted to the neocortex for lasting memory storage is unclear. We identified dorsal hippocampal (DH) projections to the retrosplenial cortex (RSC), which arise mainly from the subiculum and contain either the vesicular glutamate transporter 1 (vGlut1) or vGlut2. Both vGlut1+ and vGlut2+ axons strongly excite and disynaptically inhibit RSC pyramidal neurons in superficial layers, but vGlut2+ axons trigger greater inhibition that spreads to deep layers, indicating that these pathways engage RSC circuits via partially redundant, partially differentiated cellular mechanisms...
June 6, 2018: Cerebral Cortex
Siddhartha Mondragón-Rodríguez, Ning Gu, Frederic Manseau, Sylvain Williams
Alzheimer's disease (AD) is defined by the presence of amyloid-β (Aβ) and tau protein aggregates. However, increasing data is suggesting that brain network alterations rather than protein deposition could account for the early pathogenesis of the disease. In the present study, we performed in vitro extracellular field recordings in the CA1/subiculum area of the hippocampus from 30 days old J20-TG-AD mice. Here, we found that theta oscillations were significantly less rhythmic than those recorded from control group...
2018: Frontiers in Cellular Neuroscience
Catia M Teixeira, Zev B Rosen, Deepika Suri, Qian Sun, Marc Hersh, Derya Sargin, Iva Dincheva, Ashlea A Morgan, Stephen Spivack, Anne C Krok, Tessa Hirschfeld-Stoler, Evelyn K Lambe, Steven A Siegelbaum, Mark S Ansorge
The efficacy and duration of memory storage is regulated by neuromodulatory transmitter actions. While the modulatory transmitter serotonin (5-HT) plays an important role in implicit forms of memory in the invertebrate Aplysia, its function in explicit memory mediated by the mammalian hippocampus is less clear. Specifically, the consequences elicited by the spatio-temporal gradient of endogenous 5-HT release are not known. Here we applied optogenetic techniques in mice to gain insight into this fundamental biological process...
June 6, 2018: Neuron
Qian Cao, Zhe-Man Xiao, Xi Wang, Chao Weng, Man Ding, Fan Zhu, Zu-Neng Lu
The existing data about whether acid sensing ion channels (ASICs) are proconvulsant or anticonvulsant are controversial. Particularly, acid sensing ion channel 3 (ASIC3) is the most sensitive to extracellular pH and has the characteristic ability to generate a biphasic current, but few studies have focused on the role of ASIC3 in seizure. Here we found ASIC3 expression was increased in the hippocampus of pilocarpine induced seizure rats, as well as in hippocampal neuronal cultures undergoing epileptiform discharge elicited by Mg2+ -free media...
May 7, 2018: Neurochemical Research
Paola Malerba, Maxim Bazhenov
The hippocampus is important for memory and learning, being a brain site where initial memories are formed and where sharp wave - ripples (SWR) are found, which are responsible for mapping recent memories to long-term storage during sleep-related memory replay. While this conceptual schema is well established, specific intrinsic and network-level mechanisms driving spatio-temporal patterns of hippocampal activity during sleep, and specifically controlling off-line memory reactivation are unknown. In this study, we discuss a model of hippocampal CA1-CA3 network generating spontaneous characteristic SWR activity...
May 1, 2018: Neurobiology of Learning and Memory
Rebecca A Piskorowski, Vivien Chevaleyre
The hippocampus is a central region in the coding of spatial, temporal and episodic memory. Recent discoveries have revealed surprising and complex roles of the small area CA2 in hippocampal function. Lesion studies have revealed that this region is required for social memory formation. Area CA2 is targeted by extra-hippocampal paraventricular inputs that release vasopressin and can act to enhance social memory performance. In vivo recordings have revealed nonconventional activity by neurons in this region that act to both initiate hippocampal sharp-wave ripple events as well as encode spatial information during immobility...
April 26, 2018: Current Opinion in Neurobiology
Jeehae Rhee, Kwanghoon Park, Ki Chan Kim, Chan Young Shin, ChiHye Chung
Recently, we have reported that animals with telomerase reverse transcriptase (TERT) overexpression exhibit reduced social interaction, decreased preference for novel social interaction and poor nest-building behaviors symptoms that mirror those observed in human autism spectrum disorders (ASD). Overexpression of TERT also alters the excitatory/inhibitory (E/I) ratio in the medial prefrontal cortex. However, the effects of TERT overexpression on hippocampal-dependent learning and synaptic efficacy have not been investigated...
May 31, 2018: Molecules and Cells
Peter Jedlicka, Julia Muellerleile, Stephan W Schwarzacher
The hippocampal dentate gyrus plays a role in spatial learning and memory and is thought to encode differences between similar environments. The integrity of excitatory and inhibitory transmission and a fine balance between them is essential for efficient processing of information. Therefore, identification and functional characterization of crucial molecular players at excitatory and inhibitory inputs is critical for understanding the dentate gyrus function. In this minireview, we discuss recent studies unraveling molecular mechanisms of excitatory/inhibitory synaptic transmission, long-term synaptic plasticity, and dentate granule cell excitability in the hippocampus of live animals...
2018: Neural Plasticity
Kingsley P Storer, George N Reeke
BACKGROUND: Propofol produces memory impairment at concentrations well below those abolishing consciousness. Episodic memory, mediated by the hippocampus, is most sensitive. Two potentially overlapping scenarios may explain how γ-aminobutyric acid receptor type A (GABAA) potentiation by propofol disrupts episodic memory-the first mediated by shifting the balance from excitation to inhibition while the second involves disruption of rhythmic oscillations. We use a hippocampal network model to explore these scenarios...
July 2018: Anesthesiology
Vassilios Papaleonidopoulos, Costas Papatheodoropoulos
The hippocampus is a functionally heterogeneous structure with the cognitive and emotional signal processing ascribed to the dorsal (DH) and the ventral hippocampus (VH) respectively. However, the underlying mechanisms are poorly understood. Noradrenaline is released in hippocampus during emotional arousal modulating synaptic plasticity and memory consolidation through activation of β adrenergic receptors (β-ARs). Using recordings of field excitatory postsynaptic potentials from the CA1 field of adult rat hippocampal slices we demonstrate that long-term potentiation (LTP) induced either by theta-burst stimulation (TBS) that mimics a physiological firing pattern of hippocampal neurons or by high-frequency stimulation is remarkably more sensitive to β-AR activation in VH than in DH...
May 2018: Neurobiology of Learning and Memory
Juan Gu, Xin Tian, Wei Wang, Qin Yang, Peijia Lin, Yuanlin Ma, Yan Xiong, Demei Xu, Yanke Zhang, Yong Yang, Shanshan Lu, Zijun Lin, Jing Luo, Fei Xiao, Xuefeng Wang
BACKGROUND/AIMS: The imbalance between excitation and inhibition is a defining feature of epilepsy. GluA1 is an AMPA receptor subunit that can strengthen excitatory synaptic transmission when upregulated in the postsynaptic membrane, which has been implicated in the pathogenesis of epilepsy. cGKII, a cGMP-dependent protein kinase, regulates the GluA1 levels at the plasma membrane. METHODS: To explore the role of cGKII in epilepsy, we investigated the expression of cGKII in patients with temporal lobe epilepsy (TLE) and in a pilocarpine-induced rat model and then performed behavioral, histological, and electrophysiological analyses by applying either a cGKII agonist or inhibitor in the hippocampus of the animal model...
2018: Cellular Physiology and Biochemistry
Misato Yoshikawa, Yoshiyuki Soeda, Makoto Michikawa, Osborne F X Almeida, Akihiko Takashima
Hippocampal hyperactivity, ascribed to amyloid β (Aβ)-induced imbalances in neural excitation and inhibition, is found in patients with mild cognitive impairment, a prodromal stage of Alzheimer's disease (AD). To better understand the relationship between hippocampal hyperactivity and the molecular triggers of behavioral impairments in AD, we used Mn-enhanced MRI (MEMRI) to assess neuronal activity after subjecting mice to a task requiring spatial learning and memory. Depletion of endogenous tau in an amyloid precursor protein (APP) transgenic (J20) mouse line was shown to ameliorate hippocampal hyperactivity in J20 animals, tau depletion failed to reverse memory deficits associated with APP/Aβ overproduction...
2018: Frontiers in Neuroscience
Allie J Widman, Lori L McMahon
Low-dose ketamine, an open-channel N -methyl d-aspartate receptor (NMDAR) antagonist, mediates rapid antidepressant effects in humans that are mimicked in preclinical rodent models. Disinhibition of pyramidal cells via decreased output of fast-spiking GABAergic interneurons has been proposed as a key mechanism that triggers the antidepressant response. Unfortunately, to date, disinhibition has not been directly demonstrated. Furthermore, whether disinhibition is a common mechanism shared among other antagonists with rapid antidepressant properties in humans has not been investigated...
March 27, 2018: Proceedings of the National Academy of Sciences of the United States of America
Lin Zhou, Liang Zhou, Li-da Su, Sheng-Long Cao, Ya-Jun Xie, Na Wang, Chong-Yu Shao, Ya-Nan Wang, Jia-Huan Zhou, John K Cowell, Ying Shen
Autosomal dominant lateral temporal epilepsy (ADLTE) is an inherited syndrome caused by mutations in the leucine-rich glioma inactivated 1 (LGI1) gene. It is known that glutamatergic transmission is altered in LGI1 mutant mice, and seizures can be reduced by restoring LGI1 function. Yet, the mechanism underlying ADLTE is unclear. Here, we propose that seizures in male LGI1 -/- mice are due to nonsynaptic epileptiform activity in cortical neurons. We examined the intrinsic excitability of pyramidal neurons in the temporal cortex of male LGI1 -/- mice and found that the voltage-gated K+ channel Kv1...
March 28, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
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