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Hippocampus

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https://www.readbyqxmd.com/read/28329909/testing-the-boundaries-of-boundary-extension-anticipatory-scene-representation-across-development-and-disorder
#1
G Spanò, H Intraub, J O Edgin
Recent studies have suggested that Boundary Extension (BE), a scene construction error, may be linked to the function of the hippocampus. In this study, we tested BE in two groups with variations in hippocampal development and disorder: a typically developing sample ranging from preschool to adolescence and individuals with Down syndrome. We assessed BE across three different test modalities: drawing, visual recognition, and a 3D scene boundary reconstruction task. Despite confirmed fluctuations in memory function measured through a neuropsychological assessment, the results showed consistent BE in all groups across test modalities, confirming the near universal nature of BE...
March 22, 2017: Hippocampus
https://www.readbyqxmd.com/read/28321961/aging-affects-spatial-reconstruction-more-than-spatial-pattern-separation-performance-even-after-extended-practice
#2
Rachel Clark, Asli C Tahan, Patrick D Watson, Joan Severson, Neal J Cohen, Michelle Voss
Although the hippocampus experiences age-related anatomical and functional deterioration, the effects of aging vary across hippocampal-dependent cognitive processes. In particular, whether or not the hippocampus is known to be required for a spatial memory process is not an accurate predictor on its own of whether aging will affect performance. Therefore, the primary objective of this study was to compare the effects of healthy aging on a test of spatial pattern separation and a test of spatial relational processing, which are two aspects of spatial memory that uniquely emphasize the use of multiple hippocampal-dependent processes...
March 21, 2017: Hippocampus
https://www.readbyqxmd.com/read/28281326/recollection-and-familiarity-in-aging-individuals-gaining-insight-into-relationships-with-medial-temporal-lobe-structural-integrity
#3
Dorothee Schoemaker, Charlotte Mascret, D Louis Collins, Elsa Yu, Serge Gauthier, Jens C Pruessner
No abstract text is available yet for this article.
March 9, 2017: Hippocampus
https://www.readbyqxmd.com/read/28281317/hippocampal-formation-alterations-differently-contribute-to-autobiographic-memory-deficits-in-mild-cognitive-impairment-and-alzheimer-s-disease
#4
Dusan Hirjak, Robert C Wolf, Barbara Pfeifer, Ulrich Seidl, Anne K Thomann, Katharina M Kubera, Johannes Schröder, Klaus H Maier-Hein, Philipp A Thomann
BACKGROUND: Autobiographical memory (AM) is part of declarative memory and includes both semantic and episodic aspects. AM deficits are among the major complaints of patients with Alzheimer's disease (AD) even in early or preclinical stages. OBJECTIVES: Previous MRI studies AD patients have showed that deficits in semantic and episodic AM are associated with hippocampal alterations. However, the question which specific hippocampal subfields and adjacent extrahippocampal structures contribute to deficits of AM in individuals with mild cognitive impairment (MCI) and AD patients has not been investigated so far...
March 9, 2017: Hippocampus
https://www.readbyqxmd.com/read/28244174/damage-to-right-medial-temporal-structures-disrupts-the-capacity-for-scene-construction-a-case-study
#5
Muireann Irish, Annu Mothakunnel, Nadene Dermody, Nikki-Anne Wilson, John R Hodges, Olivier Piguet
The medial temporal lobes (MTL) are widely held to support a range of constructive endeavors including remembering the past, envisaging the future, and imagining hypothetical scenarios. While right MTL structures have been ascribed a prominent role in the construction of spatial contexts, lesion evidence to directly test this hypothesis is lacking. To this end, we assessed scene construction performance in two cases, GC and DF, who presented with left- and right-lateralized presentations of semantic dementia, respectively...
February 28, 2017: Hippocampus
https://www.readbyqxmd.com/read/28244171/n-terminal-sap97-isoforms-differentially-regulate-synaptic-structure-and-postsynaptic-surface-pools-of-ampa-receptors
#6
Lucy Goodman, David Baddeley, Wojciech Ambroziak, Clarissa L Waites, Craig C Garner, Christian Soeller, Johanna M Montgomery
The location and density of postsynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors is controlled by scaffolding proteins within the postsynaptic density (PSD). SAP97 is a PSD protein with two N-terminal isoforms, α and β, that have opposing effects on synaptic strength thought to result from differential targeting of AMPA receptors into distinct synaptic versus extrasynaptic locations, respectively. In this study, we have applied dSTORM super resolution imaging in order to localize the synaptic and extrasynaptic pools of AMPA receptors in neurons expressing α or βSAP97...
February 28, 2017: Hippocampus
https://www.readbyqxmd.com/read/28241404/hippocampal-neural-activity-reflects-the-economy-of-choices-during-goal-directed-navigation
#7
Valerie L Tryon, Marsha R Penner, Shawn W Heide, Hunter O King, Joshua Larkin, Sheri J Y Mizumori
Distinguishing spatial contexts is likely essential for the well-known role of the hippocampus in episodic memory. We studied whether types of hippocampal neural organization thought to underlie context discrimination is impacted by learned economic considerations of choice behavior. Hippocampal place cells and theta activity were recorded as rats performed a maze-based probability discounting task that involved choosing between a small certain reward or a large probabilistic reward. Different spatial distributions of place fields were observed in response to changes in probability, the outcome of the rats' choice, and whether or not rats were free to make that choice...
February 27, 2017: Hippocampus
https://www.readbyqxmd.com/read/28241401/hippocampal-cortical-contributions-to-strategic-exploration-during-perceptual-discrimination
#8
Joel L Voss, Neal J Cohen
The hippocampus is crucial for long-term memory; its involvement in short-term or immediate expressions of memory is more controversial. Rodent hippocampus has been implicated in an expression of memory that occurs on-line during exploration termed "vicarious trial-and-error" (VTE) behavior. VTE occurs when rodents iteratively explore options during perceptual discrimination or at choice points. It is strategic in that it accelerates learning and improves later memory. VTE has been associated with activity of rodent hippocampal neurons, and lesions of hippocampus disrupt VTE and associated learning and memory advantages...
February 27, 2017: Hippocampus
https://www.readbyqxmd.com/read/28188665/memory-for-relations-in-the-short-term-and-the-long-term-after-medial-temporal-lobe-damage
#9
Larry R Squire
A central idea about the organization of declarative memory and the function of the hippocampus is that the hippocampus provides for the coding of relationships between items. A question arises whether this idea refers to the process of forming long-term memory or whether, as some studies have suggested, memory for relations might depend on the hippocampus even at short retention intervals and even when the task falls within the province of short-term (working) memory. The latter formulation appears to place the operation of relational memory into conflict with the idea that working memory is independent of medial temporal lobe (MTL) structures...
February 11, 2017: Hippocampus
https://www.readbyqxmd.com/read/28188663/histamine-facilitates-gabaergic-transmission-in-the-rat-entorhinal-cortex-roles-of-h1-and-h2-receptors-na-permeable-cation-channels-and-inward-rectifier-k-channels
#10
Nicholas I Cilz, Saobo Lei
In the brain, histamine (HA) serves as a neuromodulator and a neurotransmitter released from the tuberomammillary nucleus (TMN). HA is involved in wakefulness, thermoregulation, energy homeostasis, nociception and learning and memory. The medial entorhinal cortex (MEC) receives inputs from the TMN and expresses HA receptors (H1 , H2 , and H3 ). We investigated the effects of HA on GABAergic transmission in the MEC and found that HA significantly increased the frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) with an EC50 of 1...
February 11, 2017: Hippocampus
https://www.readbyqxmd.com/read/28188659/hippocampal-subfields-at-ultra-high-field-mri-an-overview-of-segmentation-and-measurement-methods
#11
Alessia Giuliano, Graziella Donatelli, Mirco Cosottini, Michela Tosetti, Alessandra Retico, Maria Evelina Fantacci
The hippocampus is one of the most interesting and studied brain regions because of its involvement in memory functions and its vulnerability in pathological conditions, such as neurodegenerative processes. In the recent years, the increasing availability of Magnetic Resonance Imaging (MRI) scanners that operate at ultra-high field (UHF), i.e. with static magnetic field strength ≥ 7T, has opened new research perspectives. Compared to conventional high-field scanners, these systems can provide new contrasts, increased signal-to-noise ratio and higher spatial resolution, thus they may improve the visualization of very small structures of the brain, such as the hippocampal subfields...
February 11, 2017: Hippocampus
https://www.readbyqxmd.com/read/28186683/corrigendum-dendrites-of-dentate-gyrus-granule-cells-contribute-to-pattern-separation-by-controlling-sparsity
#12
(no author information available yet)
No abstract text is available yet for this article.
February 10, 2017: Hippocampus
https://www.readbyqxmd.com/read/28177571/optimizing-for-generalization-in-the-decoding-of-internally-generated-activity-in-the-hippocampus
#13
Matthijs A A van der Meer, Alyssa A Carey, Youki Tanaka
The decoding of a sensory or motor variable from neural activity benefits from a known ground truth against which decoding performance can be compared. In contrast, the decoding of covert, cognitive neural activity, such as occurs in memory recall or planning, typically cannot be compared to a known ground truth. As a result, it is unclear how decoders of such internally generated activity should be configured in practice. We suggest that if the true code for covert activity is unknown, decoders should be optimized for generalization performance using cross-validation...
February 8, 2017: Hippocampus
https://www.readbyqxmd.com/read/28176459/reconsolidation-induced-rescue-of-a-remote-fear-memory-blocked-by-an-early-cortical-inhibition-involvement-of-the-anterior-cingulate-cortex-and-the-mediation-by-the-thalamic-nucleus-reuniens
#14
Rodrigo O Sierra, Lizeth K Pedraza, Querusche K Zanona, Fabiana Santana, Flávia Z Boos, Ana P Crestani, Josué Haubrich, Lucas de Oliveira Alvares, Maria Elisa Calcagnotto, Jorge A Quillfeldt
Systems consolidation is a time-dependent reorganization process involving neocortical and hippocampal networks underlying memory storage and retrieval. The involvement of the hippocampus during acquisition is well described, however we know much less about the concomitant contribution of cortical activity levels to the formation of stable remote memories. Here, after a reversible pharmacological inhibition of the anterior cingulate cortex (ACC) during the acquisition of a contextual fear conditioning, retrieval of both recent and remote memories were impaired, an effect that was reverted by a single memory reactivation session 48h after training, through a destabilization-dependent mechanism interpreted as reconsolidation, that restored the normal course of systems consolidation in order to rescue a remote memory...
February 8, 2017: Hippocampus
https://www.readbyqxmd.com/read/28176408/hippocampal-release-of-dopamine-and-norepinephrine-encodes-novel-contextual-information
#15
Perla Moreno-Castilla, Rodrigo Pérez-Ortega, Valeria Violante-Soria, Israela Balderas, Federico Bermúdez-Rattoni
The detection and processing of novel information encountered in our environment is crucial for proper adaptive behavior and learning. Hippocampus is a prime structure for novelty detection that receives high-level inputs including context information. It is of our interest to understand the mechanisms by which the hippocampus processes contextual information. For this, we performed in vivo microdyalisis in order to monitor extracellular changes in neurotransmitter levels during Object Location Memory (OLM), a behavioral protocol developed to evaluate contextual information processing in recognition memory...
February 8, 2017: Hippocampus
https://www.readbyqxmd.com/read/28176400/effect-of-a-hallucinogenic-serotonin-5-ht2a-receptor-agonist-on-visually-guided-hippocampal-dependent-spatial-cognition-in-c57bl-6j-mice
#16
Gongliang Zhang, David Cinalli, Robert W Stackman
By acting on serotonin 5-HT2A receptors (5-HT2A Rs), serotonergic psychedelic drugs induce perceptual and visual hallucinations by increasing neuronal excitability and altering visual-evoked neuronal responses. The present study was designed to examine whether the perceptual alterations induced by a serotonergic psychedelic drug would affect the integrity of hippocampal-dependent, visually guided spatial cognition. phenylalkylamine hallucinogen TCB-2 is a selective agonist of 5-HT2A Rs. Mice received TCB-2 (1...
February 8, 2017: Hippocampus
https://www.readbyqxmd.com/read/28176397/a-scientific-theory-of-ars-memoriae-spatial-view-cells-in-a-continuous-attractor-network-with-linked-items
#17
Edmund T Rolls
The art of memory (ars memoriae) used since classical times includes using a well-known scene to associate each view or part of the scene with a different item in a speech. This memory technique is also known as the 'method of loci'. The new theory is proposed that this type of memory is implemented in the CA3 region of the hippocampus where there are spatial view cells in primates that allow a particular view to be associated with a particular object in an event or episodic memory. Given that the CA3 cells with their extensive recurrent collateral system connecting different CA3 cells, and associative synaptic modifiability, form an autoassociation or attractor network, the spatial view cells with their approximately Gaussian view fields become linked in a continuous attractor network...
February 8, 2017: Hippocampus
https://www.readbyqxmd.com/read/28100033/relaxin-3-inputs-target-hippocampal-interneurons-and-deletion-of-hilar-relaxin-3-receptors-in-floxed-rxfp3-mice-impairs-spatial-memory
#18
M Haidar, G Guèvremont, C Zhang, Rad Bathgate, E Timofeeva, C M Smith, A L Gundlach
Hippocampus is innervated by γ-aminobutyric acid (GABA) 'projection' neurons of the nucleus incertus (NI), including a population expressing the neuropeptide, relaxin-3 (RLN3). In studies aimed at gaining an understanding of the role of RLN3 signaling in hippocampus via its Gi/o -protein-coupled receptor, RXFP3, we examined the distribution of RLN3-immunoreactive nerve fibres and RXFP3 mRNA-positive neurons in relation to hippocampal GABA neuron populations. RLN3-positive elements were detected in close-apposition with a substantial population of somatostatin (SST)- and GABA-immunoreactive neurons, and a smaller population of parvalbumin- and calretinin-immunoreactive neurons in different hippocampal areas, consistent with the relative distribution patterns of RXFP3 mRNA and these marker transcripts...
January 18, 2017: Hippocampus
https://www.readbyqxmd.com/read/28100032/sequential-learning-during-contextual-fear-conditioning-guides-the-rate-of-systems-consolidation-implications-for-consolidation-of-multiple-memory-traces
#19
Lizeth K Pedraza, Rodrigo O Sierra, Ana P Crestani, Jorge A Quillfeldt, Lucas de Oliveira Alvares
Systems consolidation has been described as a time-dependent reorganization process involving the neocortical and hippocampal networks underlying memory storage and retrieval. Previous studies of our lab were able to demonstrate that systems consolidation is a dynamic process, rather than a merely passive, time-dependent phenomenon. Here, we studied the influence of sequential learning in contextual fear conditioning (CFC) with different training intensities in the time-course of hippocampal dependency and contextual specificity...
January 18, 2017: Hippocampus
https://www.readbyqxmd.com/read/28100031/impact-of-melatonin-receptor-signaling-on-zeitgeber-time-dependent-changes-in-cell-proliferation-and-apoptosis-in-the-adult-murine-hippocampus
#20
Michaela Fredrich, Mareike Hampel, Kay Seidel, Elmar Christ, Horst-Werner Korf
The hippocampus is subjected to diurnal/circadian rhythms on both the morphological and molecular levels. Certain aspects of cell proliferation in the adult hippocampus are regulated by melatonin and accompanied by apoptosis to ensure proper tissue maintenance and function. The present study investigated Zeitgeber time (ZT)-dependent changes in cell proliferation and apoptosis in the adult murine hippocampus and their regulation by melatonin receptor type1 and type2 (MT1/2)-mediated signaling. Adult melatonin-proficient C3H/HeN mice and melatonin-proficient (C3H/HeN) mice with targeted deletion of MT1/2 were adapted to a 12-hours light, 12-hours dark photoperiod and were sacrificed at ZT00, ZT06, ZT12, and ZT18...
January 18, 2017: Hippocampus
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