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Pattern completion and hippocampus

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https://www.readbyqxmd.com/read/29670825/thalamic-functional-connectivity-and-its-association-with-behavioral-performance-in-older-age
#1
Aimée Goldstone, Stephen D Mayhew, Joanne R Hale, Rebecca S Wilson, Andrew P Bagshaw
Introduction: Despite the thalamus' dense connectivity with both cortical and subcortical structures, few studies have specifically investigated how thalamic connectivity changes with age and how such changes are associated with behavior. This study investigated the effect of age on thalamo-cortical and thalamo-hippocampal functional connectivity (FC) and the association between thalamic FC and visual-spatial memory and reaction time (RT) performance in older adults. Methods: Resting-state functional magnetic resonance images were obtained from younger ( n  = 20) and older ( n  = 20) adults...
April 2018: Brain and Behavior
https://www.readbyqxmd.com/read/29661379/isoflurane-disrupts-excitatory-neurotransmitter-dynamics-via-inhibition-of-mitochondrial-complex-i
#2
P I Zimin, C B Woods, E B Kayser, J M Ramirez, P G Morgan, M M Sedensky
BACKGROUND: The mechanisms of action of volatile anaesthetics are unclear. Volatile anaesthetics selectively inhibit complex I in the mitochondrial respiratory chain. Mice in which the mitochondrial complex I subunit NDUFS4 is knocked out [Ndufs4(KO)] either globally or in glutamatergic neurons are hypersensitive to volatile anaesthetics. The volatile anaesthetic isoflurane selectively decreases the frequency of spontaneous excitatory events in hippocampal slices from Ndufs4(KO) mice...
May 2018: British Journal of Anaesthesia
https://www.readbyqxmd.com/read/29541577/-18-f-fallypride-characterization-of-striatal-and-extrastriatal-d-2-3-receptors-in-parkinson-s-disease
#3
Adam J Stark, Christopher T Smith, Kalen J Petersen, Paula Trujillo, Nelleke C van Wouwe, Manus J Donahue, Robert M Kessler, Ariel Y Deutch, David H Zald, Daniel O Claassen
Parkinson's disease (PD) is characterized by widespread degeneration of monoaminergic (especially dopaminergic) networks, manifesting with a number of both motor and non-motor symptoms. Regional alterations to dopamine D2/3 receptors in PD patients are documented in striatal and some extrastriatal areas, and medications that target D2/3 receptors can improve motor and non-motor symptoms. However, data regarding the combined pattern of D2/3 receptor binding in both striatal and extrastriatal regions in PD are limited...
2018: NeuroImage: Clinical
https://www.readbyqxmd.com/read/29473984/dorsal-hippocampus-is-necessary-for-visual-categorization-in-rats
#4
Jangjin Kim, Leyre Castro, Edward A Wasserman, John H Freeman
The hippocampus may play a role in categorization because of the need to differentiate stimulus categories (pattern separation) and to recognize category membership of stimuli from partial information (pattern completion). We hypothesized that the hippocampus would be more crucial for categorization of low-density (few relevant features) stimuli-due to the higher demand on pattern separation and pattern completion-than for categorization of high-density (many relevant features) stimuli. Using a touchscreen apparatus, rats were trained to categorize multiple abstract stimuli into two different categories...
February 23, 2018: Hippocampus
https://www.readbyqxmd.com/read/29425692/a-rapidly-acquired-foraging-based-working-memory-task-sensitive-to-hippocampal-lesions-reveals-age-dependent-and-age-independent-behavioural-changes-in-a-mouse-model-of-amyloid-pathology
#5
Charles Evans, Martha Hvoslef-Eide, Rhian Thomas, Emma Kidd, Mark A Good
Three experiments examined the ability of mice to forage efficiently for liquid rewards in pots located in an open field arena. Search behaviour was unconstrained other than by the walls of the arena. All mice acquired the task within 4 days of training, with one trial per day. Experiment 1 tested the hypothesis that hippocampal lesions would disrupt foraging behaviour using extramaze cues. Mice with hippocampal lesions showed normal latency to initiate foraging and to complete the task relative to sham-operated mice...
March 2018: Neurobiology of Learning and Memory
https://www.readbyqxmd.com/read/29413716/proteomic-profiling-of-epileptogenesis-in-a-rat-model-focus-on-cell-stress-extracellular-matrix-and-angiogenesis
#6
Michael Keck, Roelof Maarten van Dijk, Cornelia A Deeg, Katharina Kistler, Andreas Walker, Eva-Lotta von Rüden, Vera Russmann, Stefanie M Hauck, Heidrun Potschka
Information about epileptogenesis-associated changes in protein expression patterns is of particular interest for future selection of target and biomarker candidates. Bioinformatic analysis of proteomic data sets can increase our knowledge about molecular alterations characterizing the different phases of epilepsy development following an initial epileptogenic insult. Here, we report findings from a focused analysis of proteomic data obtained for the hippocampus and parahippocampal cortex samples collected during the early post-insult phase, latency phase, and chronic phase of a rat model of epileptogenesis...
April 2018: Neurobiology of Disease
https://www.readbyqxmd.com/read/29339476/coding-of-episodic-memory-in-the-human-hippocampus
#7
John T Wixted, Stephen D Goldinger, Larry R Squire, Joel R Kuhn, Megan H Papesh, Kris A Smith, David M Treiman, Peter N Steinmetz
Neurocomputational models have long posited that episodic memories in the human hippocampus are represented by sparse, stimulus-specific neural codes. A concomitant proposal is that when sparse-distributed neural assemblies become active, they suppress the activity of competing neurons (neural sharpening). We investigated episodic memory coding in the hippocampus and amygdala by measuring single-neuron responses from 20 epilepsy patients (12 female) undergoing intracranial monitoring while they completed a continuous recognition memory task...
January 30, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29323700/heat-shock-protein-hsp-regulation-by-muscarinic-acetylcholine-receptor-machr-activation-in-the-rat-hippocampus
#8
Monica Frinchi, Pietro Scaduto, Francesco Cappello, Natale Belluardo, Giuseppa Mudò
The cholinergic system plays a crucial role in modulating in the central nervous system physiological responses such as neurogenesis, neuronal differentiation, synaptic plasticity, and neuroprotection. In a recent study, we showed that Oxotremorine-M, a non-selective muscarinic acetylcholine receptor agonist, is able to transactivate the fibroblast growth factor receptor and to produce a significant increase in the hippocampal primary neurite outgrowth. In the present study we aimed to explore in the rat hippocampus the possible effect of acute or chronic treatment with Oxotremorine-M on some heat shock proteins (Hsp60, Hsp70, Hsp90) and on activation of related transcription factor heat shock factor 1 (HSF1)...
August 2018: Journal of Cellular Physiology
https://www.readbyqxmd.com/read/29312826/heteroassociative-storage-of-hippocampal-pattern-sequences-in-the-ca3-subregion
#9
Raphael Y de Camargo, Renan S Recio, Marcelo B Reyes
Background: Recent research suggests that the CA3 subregion of the hippocampus has properties of both autoassociative network, due to its ability to complete partial cues, tolerate noise, and store associations between memories, and heteroassociative one, due to its ability to store and retrieve sequences of patterns. Although there are several computational models of the CA3 as an autoassociative network, more detailed evaluations of its heteroassociative properties are missing. Methods: We developed a model of the CA3 subregion containing 10,000 integrate-and-fire neurons with both recurrent excitatory and inhibitory connections, and which exhibits coupled oscillations in the gamma and theta ranges...
2018: PeerJ
https://www.readbyqxmd.com/read/29288866/altered-reward-learning-and-hippocampal-connectivity-following-psychosocial-stress
#10
Onno Kruse, Isabell Tapia León, Tobias Stalder, Rudolf Stark, Tim Klucken
Acute stress has a profound influence on learning, as has been demonstrated in verbal learning or fear conditioning. However, its effect on appetitive conditioning is still unclear. Fear conditioning research suggests the possibility of overgeneralization of conditioning to the CS- under acute stress due to its effect on prefrontal and hippocampal processing. In this study, participants (N = 56 males) were subjected to the Trier Social Stress Test or a placebo version. After that, all participants underwent an appetitive conditioning paradigm in the fMRI, in which one neutral cue (CS+) was repeatedly paired with reward, while another (CS-) was not...
May 1, 2018: NeuroImage
https://www.readbyqxmd.com/read/29218403/the-storage-and-recall-of-memories-in-the-hippocampo-cortical-system
#11
REVIEW
Edmund T Rolls
A quantitative computational theory of the operation of the hippocampus as an episodic memory system is described. The CA3 system operates as a single attractor or autoassociation network (1) to enable rapid one-trial associations between any spatial location (place in rodents or spatial view in primates) and an object or reward and (2) to provide for completion of the whole memory during recall from any part. The theory is extended to associations between time and object or reward to implement temporal order memory, which is also important in episodic memory...
December 7, 2017: Cell and Tissue Research
https://www.readbyqxmd.com/read/29162816/impairments-of-spatial-memory-in-an-alzheimer-s-disease-model-via-degeneration-of-hippocampal-cholinergic-synapses
#12
Houze Zhu, Huanhuan Yan, Na Tang, Xinyan Li, Pei Pang, Hao Li, Wenting Chen, Yu Guo, Shu Shu, You Cai, Lei Pei, Dan Liu, Min-Hua Luo, Hengye Man, Qing Tian, Yangling Mu, Ling-Qiang Zhu, Youming Lu
Choline acetyltransferase neurons in the vertical diagonal band of Broca (vChATs) degenerate in the early stage of Alzheimer's disease (AD). Here, we report that vChATs directly innervate newly generated immature neurons (NGIs) in the dorsal hippocampus (dNGIs) of adult mice and regulate both the dNGIs survival and spatial pattern separation. In a mouse model that exhibits amyloid-β plaques similar to AD patients, cholinergic synaptic transmission, dNGI survival and spatial pattern separation are impaired...
November 22, 2017: Nature Communications
https://www.readbyqxmd.com/read/29149767/the-effects-of-sleep-on-the-neural-correlates-of-pattern-separation
#13
Christopher R Doxey, Cooper B Hodges, Ty A Bodily, Nathan M Muncy, C Brock Kirwan
Effective memory representations must be specific to prevent interference between episodes that may overlap in terms of place, time, or items present. Pattern separation, a computational process performed by the hippocampus, overcomes this interference by establishing nonoverlapping memory representations. Although it is widely accepted that declarative memories are consolidated during sleep, the effects of sleep on pattern separation have yet to be elucidated. We used whole-brain, high-resolution functional neuroimaging to investigate the effects of sleep on a task that places high demands on pattern separation...
February 2018: Hippocampus
https://www.readbyqxmd.com/read/29141678/novel-functions-of-lhx2-and-pax6-in-the-developing-telencephalon-revealed-upon-combined-loss-of-both-genes
#14
Geeta Godbole, Achira Roy, Ashwin S Shetty, Shubha Tole
Patterning of the telencephalic neuroepithelium is a tightly regulated process controlled by transcription factors and signalling molecules. The cortical primordium is flanked by two signalling centres, the hem medially, and the antihem laterally. The hem induces the formation of the hippocampus in adjacent neuroepithelium. Therefore, the position of the hem defines the position of the hippocampus in the brain. The antihem is positioned at the boundary between the dorsal and ventral telencephalon and proposed to provide patterning cues during development...
November 15, 2017: Neural Development
https://www.readbyqxmd.com/read/29118106/sleep-in-humans-stabilizes-pattern-separation-performance
#15
A Hanert, F D Weber, A Pedersen, J Born, T Bartsch
Replay of hippocampal neural representations during sleep is thought to promote systems consolidation of declarative memory. How this reprocessing of memory during sleep affects the hippocampal representation itself, is unclear. Here we tested hippocampal stimulus processing, i.e., pattern separation, before and after periods of sleep and wakefulness in humans (female and male participants). Pattern separation deteriorated across the wake period but remained stable across sleep (p = .013) with this sleep-wake difference being most pronounced for stimuli with low similarity to targets (p = ...
November 8, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29116882/lingering-cognitive-states-shape-fundamental-mnemonic-abilities
#16
Anuya Patil, Katherine Duncan
Why are people sometimes able to recall associations in exquisite detail while at other times left frustrated by the deficiencies of memory? Although this apparent fickleness of memory has been extensively studied by investigating factors that build strong memory traces, researchers know less about whether memory success also depends on cognitive states that are in place when a cue is encountered. Motivating this possibility, neurocomputational models propose that the hippocampus's capacity to support associative recollection (pattern completion) is biased by persistent neurochemical states, which can be elicited by exposure to familiarity and novelty...
January 2018: Psychological Science
https://www.readbyqxmd.com/read/28988234/dynamics-of-goldfish-subregional-hippocampal-pallium-activity-throughout-spatial-memory-formation
#17
Francisco M Ocaña, Sara Uceda, Jorge L Arias, Cosme Salas, Fernando Rodríguez
The teleost fish hippocampal pallium, like the hippocampus of tetrapods, is essential for relational map-like spatial memories. In mammals, these relational memories involve the dynamic interactions among different hippocampal subregions and between the hippocampus-neocortex network, which performs specialized operations such as memory encoding and retrieval. However, how the teleost hippocampal homologue operates to achieve comparably sophisticated spatial cognition capabilities is largely unknown. In the present study, the progressive changes in the metabolic activity of the pallial regions that have been proposed as possible homologues of the mammalian hippocampus were monitored in goldfish...
2017: Brain, Behavior and Evolution
https://www.readbyqxmd.com/read/28923531/hippocampal-infarction-identification-of-three-new-types
#18
A Förster, M Al-Zghloul, P Eisele, H Wenz, J Böhme, C Groden, E Neumaier-Probst
BACKGROUND AND PURPOSE: Hippocampal infarction (HI) is common but yet still not comprehensively studied. In the present study, we aimed to identify novel HI patterns and to describe additional ischemic lesions outside the hippocampus to draw conclusions regarding the underlying vessel occlusion. METHODS: In 222 patients (mean age 69.9 (±13.6) years; 129 (58.1%) male, 93 (41.9%) female) with HI, diffusion-weighted images were analyzed with emphasis on HI patterns and associated ischemic lesions outside the hippocampus...
February 2018: Journal of Neuroradiology. Journal de Neuroradiologie
https://www.readbyqxmd.com/read/28923275/in-vivo-magnetic-resonance-images-reveal-neuroanatomical-sex-differences-through-the-application-of-voxel-based-morphometry-in-c57bl-6-mice
#19
Cassandra E Meyer, Florian Kurth, Stefano Lepore, Josephine L Gao, Hadley Johnsonbaugh, Mandavi R Oberoi, Stephen J Sawiak, Allan MacKenzie-Graham
Behaviorally relevant sex differences are often associated with structural differences in the brain and many diseases are sexually dimorphic in prevalence and progression. Characterizing sex differences is imperative to gaining a complete understanding of behavior and disease which will, in turn, allow for a balanced approach to scientific research and the development of therapies. In this study, we generated novel tissue probability maps (TPMs) based on 30 male and 30 female in vivo C57BL/6 mouse brain magnetic resonance images and used voxel-based morphometry (VBM) to analyze sex differences...
December 2017: NeuroImage
https://www.readbyqxmd.com/read/28912681/divergence-in-morris-water-maze-based-cognitive-performance-under-chronic-stress-is-associated-with-the-hippocampal-whole-transcriptomic-modification-in-mice
#20
Seung H Jung, Milene L Brownlow, Matteo Pellegrini, Ryan Jankord
Individual susceptibility determines the magnitude of stress effects on cognitive function. The hippocampus, a brain region of memory consolidation, is vulnerable to stressful environments, and the impact of stress on hippocampus may determine individual variability in cognitive performance. Therefore, the purpose of this study was to define the relationship between the divergence in spatial memory performance under chronically unpredictable stress and an associated transcriptomic alternation in hippocampus, the brain region of spatial memory consolidation...
2017: Frontiers in Molecular Neuroscience
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