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Pattern completion and hippocampus

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https://www.readbyqxmd.com/read/28213155/high-frequency-stimulation-of-afferent-fibers-generates-asynchronous-firing-in-the-downstream-neurons-in-hippocampus-through-partial-block-of-axonal-conduction
#1
Zhouyan Feng, Zhaoxiang Wang, Zheshan Guo, Wenjie Zhou, Ziyan Cai, Dominique M Durand
Deep brain stimulation (DBS) is effective for treating neurological disorders in clinic. However, the therapeutic mechanisms of high-frequency stimulation (HFS) of DBS have not yet been elucidated. Previous studies have suggested that HFS-induced changes in axon conduction could have important contributions to the DBS effects and desiderate further studies. To investigate the effects of prolonged HFS of afferent axons on the firing of downstream neurons, HFS trains of 100 and 200 Hz were applied on the Schaffer collaterals of the hippocampal CA1 region in anaesthetized rats...
February 14, 2017: Brain Research
https://www.readbyqxmd.com/read/28188304/-18-f-fdg-pet-patterns-of-surgical-success-and-failure-in-mesial-temporal-lobe-epilepsy
#2
Francine Chassoux, Eric Artiges, Franck Semah, Agathe Laurent, Elisabeth Landré, Baris Turak, Philippe Gervais, Badia-Ourkia Helal, Bertrand Devaux
OBJECTIVE: To search for [(18)F]-fluorodeoxyglucose (FDG)-PET patterns predictive of long-term prognosis in surgery for drug-resistant mesial temporal lobe epilepsy (MTLE) due to hippocampal sclerosis (HS). METHODS: We analyzed metabolic data with [(18)F]-FDG-PET in 97 patients with MTLE (53 female participants; age range 15-56 years) with unilateral HS (50 left) and compared the metabolic patterns, electroclinical features, and structural atrophy on MRI in patients with the best outcome after anteromesial temporal resection (Engel class IA, completely seizure-free) to those with a non-IA outcome, including suboptimal outcome and failure...
February 10, 2017: Neurology
https://www.readbyqxmd.com/read/28131561/-fragile-x-syndrome-and-white-matter-abnormalities-case-study-of-two-brothers
#3
E Wallach, E Bieth, A Sevely, C Cances
Fragile X syndrome is the most usual cause of hereditary intellectual deficiency. Typical symptoms combine intellectual deficiency, social anxiety, intense emotional vigilance, and a characteristic facial dysmorphy. This is subsequent to a complete mutation of the FMR1 gene, considering a semidominant transmission linked to the unstable X. The expansion of the CGG triplet greater than 200 units combined with a high methylation pattern lead to a transcriptional silence of the FMR1 gene, and the protein product, the FMRP, is not synthesized...
January 25, 2017: Archives de Pédiatrie: Organe Officiel de la Sociéte Française de Pédiatrie
https://www.readbyqxmd.com/read/28109667/aberrant-alpha-and-gamma-oscillations-ex-vivo-after-single-application-of-the-nmda-receptor-antagonist-mk-801
#4
Clément E Lemercier, Constance Holman, Zoltan Gerevich
Clinical symptoms of schizophrenia are associated with altered cortical neuronal oscillations in multiple frequency bands such as alpha (7-13Hz) and gamma (30-90Hz) rhythms. NMDA receptor antagonists induce psychotic symptoms in humans and a schizophrenia-like phenotype in animals, suggesting NMDA receptor dysfunction is involved in the generation of many symptoms of the disorder. We investigated the effects of a single intraperitoneal injection of the NMDA receptor antagonist MK-801 in rats, a model of first-episode schizophrenia, on network oscillations recorded ex vivo in the hippocampus and prefrontal cortex...
January 18, 2017: Schizophrenia Research
https://www.readbyqxmd.com/read/28072885/functional-role-of-intracellular-calcium-receptor-inositol-1-4-5-trisphosphate-type-1-in-rat-hippocampus-after-neonatal-anoxia
#5
Juliane Midori Ikebara, Silvia Honda Takada, Débora Sterzeck Cardoso, Natália Myuki Moralles Dias, Beatriz Crossiol Vicente de Campos, Talitha Amanda Sanches Bretherick, Guilherme Shigueto Vilar Higa, Mariana Sacrini Ayres Ferraz, Alexandre Hiroaki Kihara
Anoxia is one of the most prevalent causes of neonatal morbidity and mortality, especially in preterm neonates, constituting an important public health problem due to permanent neurological sequelae observed in patients. Oxygen deprivation triggers a series of simultaneous cascades, culminating in cell death mainly located in more vulnerable metabolic brain regions, such as the hippocampus. In the process of cell death by oxygen deprivation, cytosolic calcium plays crucial roles. Intracellular inositol 1,4,5-trisphosphate receptors (IP3Rs) are important regulators of cytosolic calcium levels, although the role of these receptors in neonatal anoxia is completely unknown...
2017: PloS One
https://www.readbyqxmd.com/read/28059792/quantitative-comparison-of-dense-core-amyloid-plaque-accumulation-in-amyloid-%C3%AE-protein-precursor-transgenic-mice
#6
Peng Liu, John H Reichl, Eshaan R Rao, Brittany M McNellis, Eric S Huang, Laura S Hemmy, Colleen L Forster, Michael A Kuskowski, David R Borchelt, Robert Vassar, Karen H Ashe, Kathleen R Zahs
There exist several dozen lines of transgenic mice that express human amyloid-β protein precursor (AβPP) with Alzheimer's disease (AD)-linked mutations. AβPP transgenic mouse lines differ in the types and amounts of Aβ that they generate and in their spatiotemporal patterns of expression of Aβ assemblies, providing a toolkit to study Aβ amyloidosis and the influence of Aβ aggregation on brain function. More complete quantitative descriptions of the types of Aβ assemblies present in transgenic mice and in humans during disease progression should add to our understanding of how Aβ toxicity in mice relates to the pathogenesis of AD...
2017: Journal of Alzheimer's Disease: JAD
https://www.readbyqxmd.com/read/28057726/reduced-hippocampal-functional-connectivity-during-episodic-memory-retrieval-in-autism
#7
Rose A Cooper, Franziska R Richter, Paul M Bays, Kate C Plaisted-Grant, Simon Baron-Cohen, Jon S Simons
Increasing recent research has sought to understand the recollection impairments experienced by individuals with autism spectrum disorder (ASD). Here, we tested whether these memory deficits reflect a reduction in the probability of retrieval success or in the precision of memory representations. We also used functional magnetic resonance imaging (fMRI) to study the neural mechanisms underlying memory encoding and retrieval in ASD, focusing particularly on the functional connectivity of core episodic memory networks...
January 4, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28011437/childhood-poverty-is-associated-with-altered-hippocampal-function-and-visuospatial-memory-in-adulthood
#8
Elizabeth R Duval, Sarah N Garfinkel, James E Swain, Gary W Evans, Erika K Blackburn, Mike Angstadt, Chandra S Sripada, Israel Liberzon
Childhood poverty is a risk factor for poorer cognitive performance during childhood and adulthood. While evidence linking childhood poverty and memory deficits in adulthood has been accumulating, underlying neural mechanisms are unknown. To investigate neurobiological links between childhood poverty and adult memory performance, we used functional magnetic resonance imaging (fMRI) during a visuospatial memory task in healthy young adults with varying income levels during childhood. Participants were assessed at age 9 and followed through young adulthood to assess income and related factors...
February 2017: Developmental Cognitive Neuroscience
https://www.readbyqxmd.com/read/27920723/sex-dependent-anti-stress-effect-of-an-%C3%AE-5-subunit-containing-gabaa-receptor-positive-allosteric-modulator
#9
Sean C Piantadosi, Beverly J French, Michael M Poe, Tamara Timić, Bojan D Marković, Mohan Pabba, Marianne L Seney, Hyunjung Oh, Beverley A Orser, Miroslav M Savić, James M Cook, Etienne Sibille
Rationale: Current first-line treatments for stress-related disorders such as major depressive disorder (MDD) act on monoaminergic systems and take weeks to achieve a therapeutic effect with poor response and low remission rates. Recent research has implicated the GABAergic system in the pathophysiology of depression, including deficits in interneurons targeting the dendritic compartment of cortical pyramidal cells. Objectives: The present study evaluates whether SH-053-2'F-R-CH3 (denoted "α5-PAM"), a positive allosteric modulator selective for α5-subunit containing GABAA receptors found predominantly on cortical pyramidal cell dendrites, has anti-stress effects...
2016: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/27903335/patterns-of-cortical-and-subcortical-amyloid-burden-across-stages-of-preclinical-alzheimer-s-disease
#10
Emily C Edmonds, Katherine J Bangen, Lisa Delano-Wood, Daniel A Nation, Ansgar J Furst, David P Salmon, Mark W Bondi
OBJECTIVES: We examined florbetapir positron emission tomography (PET) amyloid scans across stages of preclinical Alzheimer's disease (AD) in cortical, allocortical, and subcortical regions. Stages were characterized using empirically defined methods. METHODS: A total of 312 cognitively normal Alzheimer's Disease Neuroimaging Initiative participants completed a neuropsychological assessment and florbetapir PET scan. Participants were classified into stages of preclinical AD using (1) a novel approach based on the number of abnormal biomarkers/cognitive markers each individual possessed, and (2) National Institute on Aging and the Alzheimer's Association (NIA-AA) criteria...
November 2016: Journal of the International Neuropsychological Society: JINS
https://www.readbyqxmd.com/read/27896314/graph-theoretic-and-motif-analyses-of-the-hippocampal-neuron-type-potential-connectome
#11
Christopher L Rees, Diek W Wheeler, David J Hamilton, Charise M White, Alexander O Komendantov, Giorgio A Ascoli
We computed the potential connectivity map of all known neuron types in the rodent hippocampal formation by supplementing scantly available synaptic data with spatial distributions of axons and dendrites from the open-access knowledge base Hippocampome.org. The network that results from this endeavor, the broadest and most complete for a mammalian cortical region at the neuron-type level to date, contains more than 3200 connections among 122 neuron types across six subregions. Analyses of these data using graph theory metrics unveil the fundamental architectural principles of the hippocampal circuit...
November 2016: ENeuro
https://www.readbyqxmd.com/read/27816769/in-vivocharacterization-of-the-aspartyl-trna-synthetase-dars-homing-in-on-the-leukodystrophy-hbsl
#12
Dominik Fröhlich, Alexandra K Suchowerska, Ziggy H T Spencer, Georg von Jonquieres, Claudia B Klugmann, Andre Bongers, Fabien Delerue, Holly Stefen, Lars M Ittner, Thomas Fath, Gary D Housley, Matthias Klugmann
BACKGROUND: The recently diagnosed leukodystrophy Hypomyelination with Brain stem and Spinal cord involvement and Leg spasticity (HBSL) is caused by mutations of the cytoplasmic aspartyl-tRNA synthetase geneDARS. The physiological role of DARS in translation is to accurately pair aspartate with its cognate tRNA. Clinically, HBSL subjects show a distinct pattern of hypomyelination and develop progressive leg spasticity, variable cognitive impairment and epilepsy. To elucidate the underlying pathomechanism, we comprehensively assessed endogenous DARS expression in mice...
January 2017: Neurobiology of Disease
https://www.readbyqxmd.com/read/27806432/the-hippocampus-integrates-context-and-shock-into-a-configural-memory-in-contextual-fear-conditioning
#13
Shih-Dar Chang, K C Liang
Contextual fear conditioning involves forming a representation for the context and associating it with a shock, which were attributed by the prevailing view to functions of the hippocampus and amygdala, respectively. Yet our recent evidence suggested that both processes require integrity of the dorsal hippocampus (DH). In view of the DH involvement in uniting multiple stimuli into a configuration, this study examined whether the DH would integrate context and shock into a shocked-context representation. Male Wistar rats were trained on a two-phase training paradigm of contextual fear conditioning...
November 2, 2016: Hippocampus
https://www.readbyqxmd.com/read/27801892/bifidobacterium-longum-1714-as-a-translational-psychobiotic-modulation-of-stress-electrophysiology-and-neurocognition-in-healthy-volunteers
#14
A P Allen, W Hutch, Y E Borre, P J Kennedy, A Temko, G Boylan, E Murphy, J F Cryan, T G Dinan, G Clarke
The emerging concept of psychobiotics-live microorganisms with a potential mental health benefit-represents a novel approach for the management of stress-related conditions. The majority of studies have focused on animal models. Recent preclinical studies have identified the B. longum 1714 strain as a putative psychobiotic with an impact on stress-related behaviors, physiology and cognitive performance. Whether such preclinical effects could be translated to healthy human volunteers remains unknown. We tested whether psychobiotic consumption could affect the stress response, cognition and brain activity patterns...
November 1, 2016: Translational Psychiatry
https://www.readbyqxmd.com/read/27666968/the-human-dentate-gyrus-plays-a-necessary-role-in-discriminating-new-memories
#15
Stevenson Baker, Paula Vieweg, Fuqiang Gao, Asaf Gilboa, Thomas Wolbers, Sandra E Black, R Shayna Rosenbaum
Our day-to-day experiences are often similar to one another, occurring in the same place at the same time of day, with common people and objects, and with a shared purpose. Humans have an episodic memory to represent unique, personal events that are rich in detail [1]. For this to occur, at least two basic neural mechanisms are required: one to orthogonalize or "separate" overlapping input patterns at encoding and another to reinstate or "complete" memories from partial cues at retrieval [2-6]. To what extent do these purported "pattern separation" and "pattern completion" mechanisms rely on distinct subfields of the hippocampus [6]? Computational models [4-6] and lesion and genetic studies in rodents [7-12] largely point to the dentate gyrus as responsible for pattern separation and the CA3 and CA1 subfields for pattern completion (but see [13-16])...
October 10, 2016: Current Biology: CB
https://www.readbyqxmd.com/read/27573200/uncovering-representations-of-sleep-associated-hippocampal-ensemble-spike-activity
#16
Zhe Chen, Andres D Grosmark, Hector Penagos, Matthew A Wilson
Pyramidal neurons in the rodent hippocampus exhibit spatial tuning during spatial navigation, and they are reactivated in specific temporal order during sharp-wave ripples observed in quiet wakefulness or slow wave sleep. However, analyzing representations of sleep-associated hippocampal ensemble spike activity remains a great challenge. In contrast to wake, during sleep there is a complete absence of animal behavior, and the ensemble spike activity is sparse (low occurrence) and fragmental in time. To examine important issues encountered in sleep data analysis, we constructed synthetic sleep-like hippocampal spike data (short epochs, sparse and sporadic firing, compressed timescale) for detailed investigations...
2016: Scientific Reports
https://www.readbyqxmd.com/read/27571506/anxiolytic-actions-of-exercise-in-absence-of-new-neurons
#17
Timothy J Schoenfeld, Hayley C McCausland, Anup N Sonti, Heather A Cameron
Physical exercise reduces anxiety-like behavior in adult mice. The specific mechanisms that mediate this anxiolytic effect are unclear, but adult neurogenesis in the dentate gyrus has been implicated because it is robustly increased by running and has been linked to anxiodepressive-like behavior. We therefore tested the effects of long-term wheel running on anxiety-like behavior in GFAP-TK (TK) mice, a transgenic strain with complete ablation of adult neurogenesis. Five weeks of running reduced anxiety-like behavior equally in both TK mice and wild type (WT) control mice on two tests, elevated plus-maze and novelty-suppressed feeding...
November 2016: Hippocampus
https://www.readbyqxmd.com/read/27508355/hippocampal-pattern-completion-is-linked-to-gamma-power-increases-and-alpha-power-decreases-during-recollection
#18
Bernhard P Staresina, Sebastian Michelmann, Mathilde Bonnefond, Ole Jensen, Nikolai Axmacher, Juergen Fell
How do we retrieve vivid memories upon encountering a simple cue? Computational models suggest that this feat is accomplished by pattern completion processes involving the hippocampus. However, empirical evidence for hippocampal pattern completion and its underlying mechanisms has remained elusive. Here, we recorded direct intracranial EEG as human participants performed an associative memory task. For each study (encoding) and test (retrieval) event, we derived time-frequency resolved representational patterns in the hippocampus and compared the extent of pattern reinstatement for different mnemonic outcomes...
2016: ELife
https://www.readbyqxmd.com/read/27479868/ca-2-transients-in-astrocyte-fine-processes-occur-via-ca-2-influx-in-the-adult-mouse-hippocampus
#19
Ravi L Rungta, Louis-Philippe Bernier, Lasse Dissing-Olesen, Christopher J Groten, Jeffrey M LeDue, Rebecca Ko, Sibyl Drissler, Brian A MacVicar
Astrocytes display complex morphologies with an array of fine extensions extending from the soma and the primary thick processes. Until the use of genetically encoded calcium indicators (GECIs) selectively expressed in astrocytes, Ca(2+) signaling was only examined in soma and thick primary processes of astrocytes where Ca(2+) -sensitive fluorescent dyes could be imaged. GECI imaging in astrocytes revealed a previously unsuspected pattern of spontaneous Ca(2+) transients in fine processes that has not been observed without chronic expression of GECIs, raising potential concerns about the effects of GECI expression...
August 1, 2016: Glia
https://www.readbyqxmd.com/read/27469909/expressions-of-ccaat-enhancer-binding-protein-homologous-protein-and-calnexin-in-the-hippocampus-of-a-mouse-model-of-mesial-temporal-lobe-epilepsy
#20
(no author information available yet)
<strong>Objective </strong>To explore the temporal and spatial distribution of CCAAT/enhancer-binding protein homologous protein (CHOP) and calnexin (CNX) in the dentate gyrus of mesial temporal lobe epilepsy (mTLE) mouse model. <strong>Methods </strong>We used kainic acid (KA) to induce acute phase (12 h and 24 h) mTLE mouse models and performed Western blotting and immunofluorescence to detect the different expressions and distribution pattern of CHOP and CNX in CA3 of the hippocampus...
June 10, 2016: Zhongguo Yi Xue Ke Xue Yuan Xue Bao. Acta Academiae Medicinae Sinicae
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