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CA3 physiology

Mark John Hackett, Phyllis G Paterson, Ingrid J Pickering, Graham N George
A method to image taurine distributions within the central nervous system and other organs has long been sought. Since taurine is small and mobile, it cannot be chemically "tagged" and imaged using conventional immuno-histochemistry methods. Combining numerous indirect measurements, taurine is known to play critical roles in brain function during health and disease, and is proposed to act as a neuro-osmolyte, neuro-modulator and possibly a neuro-transmitter. Elucidation of taurine's neurochemical roles and importance would be substantially enhanced by a direct method to visualize alterations, due to physiological and pathological events in the brain, in the local concentration of taurine at or near cellular spatial resolution in vivo, or in situ in tissue sections...
October 4, 2016: Analytical Chemistry
J V Bukanova, I N Sharonova, V G Skrebitsky
Amyloid-β peptide (Aβ) is considered a key protein in the pathogenesis of Alzheimer's disease because of its neurotoxicity, resulting in impaired synaptic function and memory. On the other hand, it was demonstrated that low (picomolar) concentrations of Aβ enhance synaptic plasticity and memory, suggesting that in the healthy brain, physiological Aβ concentrations are necessary for normal cognitive functions. In the present study, we found that Aβ (1-42) in concentrations of 10 pМ - 100 nМ enhanced desensitization of the glycine-activated current in isolated CA3 pyramidal neurons and also reversibly suppressed its peak amplitude during short (600 ms) co-application with agonist...
September 20, 2016: Brain Research
Azahara Oliva, Antonio Fernández-Ruiz, György Buzsáki, Antal Berényi
It is well-established that the feed-forward connected main hippocampal areas, CA3, CA2 and CA1 work cooperatively during spatial navigation and memory. These areas are similar in terms of the prevalent types of neurons; however, they display different spatial coding and oscillatory dynamics. Understanding the temporal dynamics of these operations requires simultaneous recordings from these regions. However, simultaneous recordings from multiple regions and subregions in behaving animals have become possible only recently...
September 20, 2016: Hippocampus
Paloma Patiño, Esther Parada, Victor Farré-Alins, Simone Molz, Ramón Cacabelos, José Marco-Contelles, Manuela G López, Carla I Tasca, Eva Ramos, Alejandro Romero, Javier Egea
Therapeutic interventions on pathological processes involved in the ischemic cascade, such as oxidative stress, neuroinflammation, excitotoxicity and/or apoptosis, are of urgent need for stroke treatment. Melatonin regulates a large number of physiological actions and its beneficial properties have been reported. The aim of this study was to investigate whether melatonin mediates neuroprotection in rat hippocampal slices subjected to oxygen-glucose-deprivation (OGD) and glutamate excitotoxicity. Thus, we describe here that melatonin significantly reduced the amount of lactate dehydrogenase released in the OGD-treated slices, reverted neuronal injury caused by OGD-reoxygenation in CA1 and CA3 hippocampal regions, restored the reduction of GSH content of the hippocampal slices induced by OGD, and diminished the oxidative stress produced in the reoxygenation period...
September 9, 2016: Neurotoxicology
Eskedar Ayele Angamo, Joerg Roesner, Agustin Liotta, Richard Kovacs, Uwe Heinemann
Astrocyte derived lactate supports pathologically enhanced neuronal metabolism but its role under physiological conditions is still a matter of debate. Here, we determined the contribution of astrocytic neuronal lactate shuttle to maintenance of ion homeostasis and energy metabolism. We tested for the effects of α-cyano-4-hydroxycinnamic acid (4-CIN), which could interfere with energy metabolism by blocking monocarboxylate-transporter 2 (MCT2) mediated neuronal lactate uptake, on evoked potentials, stimulus induced changes in K(+), Na(+), Ca(2+) and oxygen concentrations as well as on changes in flavin adenine dinucleotide (FAD) autofluorescence in the hippocampal area CA3...
August 24, 2016: Journal of Neurophysiology
Bing-Huo Zhang, Nimaichand Salam, Juan Cheng, Han-Quan Li, Jian-Yuan Yang, Dai-Ming Zha, Yu-Qin Zhang, Meng-Jie Ai, Wael N Hozzein, Wen-Jun Li
A novel actinobacterium, designated strain JXJ CY 19T, was isolated from a culture mat of Microcystis aeruginosa FACHB-905 collected from Dianchi Lake, South-west China. 16S rRNA gene sequences comparison of strain JXJ CY 19T and the available sequences in the GenBank database showed that the strain was closely related to Modestobacter marinus 42H12-1T (99.1% similarity) and Modestobacter roseus KLBMP 1279T (99.0%). The isolate had meso-diaminopimelic in the cell wall with whole-cell sugars of mannose, rhamnose, ribose, glucose, galactose, and arabinose...
2016: PloS One
Ralf-Peter Behrendt
If hallucinations are not fundamentally different from normal wakeful experiences, then the neural basis of hallucinations has to be essentially that of consciousness in general. The additional insight that consciousness reflects the formation (as opposed to consolidation) of event (episodic) memories links the pathophysiology of hallucinations to the hippocampus. Perceptions and misperceptions, insofar as they are consciously experienced, constitute contextualized and unitary phenomena (which are embedded as discrete events in the stream of consciousness); they are experiential manifestations of activity patters that recurrently emerge in the CA3 network of the hippocampus (and that are secondarily consolidated into retrievable and declarable memories)...
November 3, 2016: Progress in Neuro-psychopharmacology & Biological Psychiatry
Deebika Balu, John R Larson, Jennifer V Schmidt, David Wirtshafter, Aleksey Yevtodiyenko, John P Leonard
Activity-dependent plasticity in NMDA receptor-containing synapses can be regulated by phosphorylation of serines and tyrosines in the C-terminal domain of the receptor subunits by various kinases. We have previously identified S1291/S1312 as important sites for PKC phosphorylation; while Y1292/Y1312 are the sites indirectly phosphorylated by PKC via Src kinase. In the oocyte expression system, mutation of those Serine sites to Alanine (that cannot be phosphorylated) in the GluN2A subunit, resulted in a decreased PKC stimulated current enhancement through the receptors compared to wild-type NMDA receptors...
September 1, 2016: Brain Research
Jimmy George, Rodrigo A Cunha, Christophe Mulle, Thierry Amédée
Recent data have provided evidence that microglia, the brain-resident macrophage-like cells, modulate neuronal activity in both physiological and pathophysiological conditions, and microglia are therefore now recognized as synaptic partners. Among different neuromodulators, purines, which are produced and released by microglia, have emerged as promising candidates to mediate interactions between microglia and synapses. The cellular effects of purines are mediated through a large family of receptors for adenosine and for ATP (P2 receptors)...
May 2016: European Journal of Neuroscience
Kevin N Hascup, Erin R Hascup
Alzheimer's disease (AD) is an age-related neurodegenerative disorder characterized by progressive memory loss and hippocampal atrophy. Soluble amyloid-β (Aβ)42 and plaque accumulation is implicated as the neurotoxic species in this disorder; however, at physiological concentrations (pM-nM), Aβ42 contributes to neurogenesis, long-term potentiation, and neuromodulation. Because Aβ42 binds the α7 nicotinic acetylcholine receptors (α7nAChRs) located presynaptically on glutamatergic terminals, involved with hippocampal dependent learning and memory, we examined the effects of the human, monomeric isoform of Aβ42 on glutamate release in the dentate gyrus (DG), CA3, and CA1, of isoflurane anesthetized, 6-9 month old male C57BL/6J mice...
May 3, 2016: Journal of Alzheimer's Disease: JAD
Patrick Kaifosh, Attila Losonczy
We present a model for neural circuit mechanisms underlying hippocampal memory. Central to this model are nonlinear interactions between anatomically and functionally segregated inputs onto dendrites of pyramidal cells in hippocampal areas CA3 and CA1. We study the consequences of such interactions using model neurons in which somatic burst-firing and synaptic plasticity are controlled by conjunctive processing of these separately integrated input pathways. We find that nonlinear dendritic input processing enhances the model's capacity to store and retrieve large numbers of similar memories...
May 4, 2016: Neuron
Kerstin C Wagener, Benedikt Kolbrink, Katharina Dietrich, Kathrin M Kizina, Lukas S Terwitte, Belinda Kempkes, Guobin Bao, Michael Müller
AIMS: Reactive oxygen species (ROS) and downstream redox alterations not only mediate physiological signaling but also neuropathology. For long, ROS/redox imaging was hampered by a lack of reliable probes. Genetically encoded redox sensors overcame this gap and revolutionized (sub)cellular redox imaging. Yet, the successful delivery of sensor-coding DNA, which demands transfection/transduction of cultured preparations or stereotaxic microinjections of each subject, remains challenging...
July 1, 2016: Antioxidants & Redox Signaling
Z Kohus, S Káli, L Rovira-Esteban, D Schlingloff, O Papp, T F Freund, N Hájos, A I Gulyás
KEY POINTS: To understand how a network operates, its elements must be identified and characterized, and the interactions of the elements need to be studied in detail. In the present study, we describe quantitatively the connectivity of two classes of inhibitory neurons in the hippocampal CA3 area (parvalbumin-positive and cholecystokinin-positive interneurons), a key region for the generation of behaviourally relevant synchronous activity patterns. We describe how interactions among these inhibitory cells and their local excitatory target neurons evolve over the course of physiological and pathological activity patterns...
July 1, 2016: Journal of Physiology
Jennifer A Honeycutt, Kevin M Keary Iii, Vanessa M Kania, James J Chrobak
Local circuit GABAergic neurons, including parvalbumin (PV)-containing basket cells, likely play a key role in the development, physiology, and pathology of neocortical circuits. Regionally selective and well-defined decreases in PV have been described in human postmortem schizophrenic brain tissue in both the hippocampus and prefrontal cortex. Animal models of schizophreniform dysfunction following acute and/or chronic ketamine treatment have also demonstrated decreases in PV expression. Conflicting reports with respect to PV immunoreactivity following acute and chronic ketamine treatments in rodents question the utility of using PV as a biological marker of pathology-related dysfunction...
2016: Developmental Neuroscience
Yudong Gao, Scott A Heldt
Although it is generally recognized that certain α-subunits of γ-aminobutyric acid type A receptors (GABAARs) form enriched clusters on the axonal initial segment (AIS), the degree to which these clusters vary in different brain areas is not well known. In the current study, we quantified the density, size, and enrichment ratio of fluorescently labeled α1-, α2-, or α3-subunits aggregates co-localized with the AIS-marker ankyrin G and compared them to aggregates in non-AIS locations among different brain areas including hippocampal subfields, basal lateral amygdala (BLA), prefrontal cortex (PFC), and sensory cortex (CTX)...
2016: Frontiers in Cellular Neuroscience
Amelia Toesca, Maria Concetta Geloso, Adriana Maria Mongiovì, Alfredo Furno, Arcangelo Schiattarella, Fabrizio Michetti, Valentina Corvino
Reelin is an extracellular matrix glycoprotein involved in the modulation of synaptic plasticity and essential for the proper radial migration of cortical neurons during development and for the integration and positioning of dentate granular cell progenitors; its expression is down-regulated as brain maturation is completed. Trimethyltin (TMT) is a potent neurotoxicant which causes selective neuronal death mainly localised in the CA1-CA3/hilus hippocampal regions. In the present study we analysed the expression of reelin and the modulation of endogenous neurogenesis in the postnatal rat hippocampus during TMT-induced neurodegeneration (TMT 6 mg/kg)...
July 2016: Neurochemical Research
Gürsel Çalışkan, Iris Müller, Marcus Semtner, Aline Winkelmann, Ahsan S Raza, Jan O Hollnagel, Anton Rösler, Uwe Heinemann, Oliver Stork, Jochen C Meier
Parvalbumin-positive (PV) basket cells provide perisomatic inhibition in the cortex and hippocampus and control generation of memory-related network activity patterns, such as sharp wave ripples (SPW-R). Deterioration of this class of fast-spiking interneurons has been observed in neuropsychiatric disorders and evidence from animal models suggests their involvement in the acquisition and extinction of fear memories. Here, we used mice with neuron type-targeted expression of the presynaptic gain-of-function glycine receptor RNA variant GlyR α3L(185L)to genetically enhance the network activity of PV interneurons...
May 2016: Cerebral Cortex
Jossina Gonzalez, Desiree M Villarreal, Isaiah S Morales, Brian E Derrick
Hippocampal area CA1 receives direct entorhinal layer III input via the temporoammonic path (TAP) and recent studies implicate TAP-CA1 synapses are important for some aspects of hippocampal memory function. Nonetheless, as few studies have examined TAP-CA1 synaptic plasticity in vivo, the induction and longevity of TAP-CA1 long-term potentiation (LTP) has not been fully characterized. We analyzed CA1 responses following stimulation of the medial aspect of the angular bundle and investigated LTP at medial temporoammonic path (mTAP)-CA1 synapses in freely moving rats...
2016: Frontiers in Neural Circuits
Vivek Mahadevan, Melanie A Woodin
KCC2 is the central regulator of neuronal Cl(-) homeostasis, and is critical for enabling strong hyperpolarizing synaptic inhibition in the mature brain. KCC2 hypofunction results in decreased inhibition and increased network hyperexcitability that underlies numerous disease states including epilepsy, neuropathic pain and neuropsychiatric disorders. The current holy grail of KCC2 biology is to identify how we can rescue KCC2 hypofunction in order to restore physiological levels of synaptic inhibition and neuronal network activity...
May 15, 2016: Journal of Physiology
Vincent Villette, Philippe Guigue, Michel Aimé Picardo, Vitor Hugo Sousa, Erwan Leprince, Philippe Lachamp, Arnaud Malvache, Thomas Tressard, Rosa Cossart, Agnès Baude
Early-born γ-aminobutyric acid (GABA) neurons (EBGNs) are major components of the hippocampal circuit because at early postnatal stages they form a subpopulation of "hub cells" transiently supporting CA3 network synchronization (Picardo et al. [2011] Neuron 71:695-709). It is therefore essential to determine when these cells acquire the remarkable morphofunctional attributes supporting their network function and whether they develop into a specific subtype of interneuron into adulthood. Inducible genetic fate mapping conveniently allows for the labeling of EBGNs throughout their life...
August 15, 2016: Journal of Comparative Neurology
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