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Hippocampus

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https://www.readbyqxmd.com/read/27933676/white-matter-hyperintensities-are-associated-with-disproportionate-progressive-hippocampal-atrophy
#1
Cassidy M Fiford, Emily N Manning, Jonathan W Bartlett, David M Cash, Ian B Malone, Gerard R Ridgway, Manja Lehmann, Kelvin K Leung, Carole Sudre, Sebastien Ourselin, Geert Jan Biessels, Owen T Carmichael, Nick C Fox, M Jorge Cardoso, Josephine Barnes
This study investigates relationships between white matter hyperintensity (WMH) volume, cerebrospinal fluid (CSF) Alzheimer's disease (AD) pathology markers, and brain and hippocampal volume loss. Subjects included 198 controls, 345 Mild Cognitive Impairment (MCI) and 154 AD subjects with serial volumetric 1.5T MRI. CSF Aβ42 and total tau were measured (n=353). Brain and hippocampal loss were quantified from serial MRI using the Boundary Shift Integral (BSI). Multiple linear regression models assessed the relationships between WMHs and hippocampal and brain atrophy rates...
December 9, 2016: Hippocampus
https://www.readbyqxmd.com/read/27933672/single-neuron-activity-and-theta-modulation-in-the-posterior-parietal-cortex-in-a-visuospatial-attention-task
#2
Fang-Chi Yang, T K Jacobson, R D Burwell
The posterior parietal cortex (PPC) is implicated in directing and maintaining visual attention to locations in space. We hypothesized that the PPC also engages other cognitive processes in the transformation of behaviorally relevant visual inputs into appropriate actions, for example, monitoring of multiple locations, selection of responses to locations in space, and monitoring the outcome of response selections. We recorded single cells and local field potentials in the rat PPC during performance on a novel visuospatial attention (VSA) task that requires visually monitoring locations in space in order to make appropriate stimulus-guided locomotor responses...
December 9, 2016: Hippocampus
https://www.readbyqxmd.com/read/27933668/the-role-of-the-hippocampus-in-generalizing-configural-relationships
#3
Sam C Berens, Chris M Bird
The hippocampus has been implicated in integrating information across separate events in support of mnemonic generalizations. These generalizations may be underpinned by processes at both encoding (linking similar information across events) and retrieval ("on-the-fly" generalization). However, the relative contribution of the hippocampus to encoding- and retrieval-based generalizations is poorly understood. Using fMRI in humans, we investigated the hippocampal role in gradually learning a set of spatial discriminations and subsequently generalizing them in an acquired equivalence task...
December 9, 2016: Hippocampus
https://www.readbyqxmd.com/read/27874237/tactile-stimulation-during-different-developmental-periods-modifies-hippocampal-bdnf-and-gr-affecting-memory-and-behavior-in-adult-rats
#4
Caren T D Antoniazzi, Vinícia G Metz, Karine Roversi, Daniele L Freitas, Luciana T Vey, Verônica T Dias, Hecson J Segat, Marta M M F Duarte, Marilise Escobar Bürger
Recent studies have shown that tactile stimulation (TS) in pups is able to prevent and/or minimize fear, anxiety behaviors, and addiction to psychostimulant drugs in adult rats. In these studies, animals have been exposed to handling from postnatal day (PND) 1 to 21. The present study was designed to precisely establish which period of preweaning development has a greater influence of TS on neuronal development. After birth, male pups were exposed to TS from PND1 to 7, PND8 to 14, and PND15 to 21. In adulthood, the different periods of postnatal TS were assessed through behavioral, biochemical and molecular assessments...
November 22, 2016: Hippocampus
https://www.readbyqxmd.com/read/27863445/dissociable-profiles-of-generalization-discrimination-in-the-human-hippocampus-during-associative-retrieval
#5
Natalie G De Shetler, Jesse Rissman
When encountering stimuli that vary slightly from previous experiences, neural signals within the CA3 and dentate gyrus (CA3 DG) hippocampal subfields are thought to facilitate mnemonic discrimination, whereas CA1 may be less sensitive to minor stimulus changes, allowing for generalization across similar events. Studies have also posited a critical role for CA1 in the comparison of events to memory-derived expectations, but the degree to which these processes are impacted by explicit retrieval demands is yet unclear...
November 18, 2016: Hippocampus
https://www.readbyqxmd.com/read/27859925/material-specificity-drives-medial-temporal-lobe-familiarity-but-not-hippocampal-recollection
#6
Alex Kafkas, Ellen M Migo, Robin G Morris, Michael D Kopelman, Daniela Montaldi, Andrew R Mayes
The specific role of the perirhinal (PRC), entorhinal (ERC) and parahippocampal cortices (PHC) in supporting familiarity-based recognition remains unknown. An fMRI study explored whether these medial temporal lobe (MTL) structures responded in the same way or differentially to familiarity as a function of stimulus type at recognition. A secondary aim was to explore whether the hippocampus responds in the same way to equally strong familiarity and recollection and whether this is influenced by the kind of stimulus involved...
November 16, 2016: Hippocampus
https://www.readbyqxmd.com/read/27859914/visual-short-term-memory-for-high-resolution-associations-is-impaired-in-patients-with-medial-temporal-lobe-damage
#7
Joshua D Koen, Alyssa A Borders, Michael T Petzold, Andrew P Yonelinas
The medial temporal lobe (MTL) plays a critical role in episodic long-term memory, but whether the MTL is necessary for visual short-term memory is controversial. Some studies have indicated that MTL damage disrupts visual short-term memory performance whereas other studies have failed to find such evidence. To account for these mixed results, it has been proposed that the hippocampus is critical in supporting short-term memory for high resolution complex bindings, while the cortex is sufficient to support simple, low resolution bindings...
November 16, 2016: Hippocampus
https://www.readbyqxmd.com/read/27859884/repetition-reveals-ups-and-downs-of-hippocampal-thalamic-and-neocortical-engagement-during-mnemonic-decisions
#8
Zachariah M Reagh, Elizabeth A Murray, Michael A Yassa
The extent to which current information is consistent with past experiences and our capacity to recognize or discriminate accordingly are key factors in flexible memory-guided behavior. Despite a wealth of evidence linking hippocampal and neocortical computations to these phenomena, many important factors remain poorly understood. One such factor is repeated encoding of learned information. In this experiment, participants completed a task in which study stimuli were incidentally encoded either once or three separate times during high-resolution fMRI scanning...
November 16, 2016: Hippocampus
https://www.readbyqxmd.com/read/27860052/the-postrhinal-cortex-is-not-necessary-for-landmark-control-in-rat-head-direction-cells
#9
James R Peck, Jeffery S Taube
The rodent postrhinal cortex (POR), homologous to primate areas TH/TF and the human 'parahippocampal place area', has been implicated in processing visual landmark and contextual information about the environment. Head direction (HD) cells are neurons that encode allocentric head direction, independent of the animal's location or behavior, and are influenced by manipulations of visual landmarks. The present study determined whether the POR plays a role in processing environmental information within the HD circuit...
November 9, 2016: Hippocampus
https://www.readbyqxmd.com/read/27806441/acute-systemic-mk-801-induced-functional-uncoupling-between-hippocampal-areas-ca3-and-ca1-with-distant-effect-in-the-retrosplenial-cortex
#10
Helena Buchtová, Iveta Fajnerová, Aleš Stuchlík, Štěpán Kubík
The hippocampus and retrosplenial cortex are integrated within a higher-order cognitive circuit supporting relational (spatial, contextual, episodic) forms of learning and memory. Hippocampal place cells can coordinate multiple parallel representations in the same physical environment. Novel environment exploration triggers expression of immediate-early genes (IEGs) Arc and Homer1a in spatial context-specific ensembles of CA1 and CA3 neurons. Less is know about ensemble coding in the retrosplenial cortex (RSC), a region directly connected and functionally coupled to CA1...
November 2, 2016: Hippocampus
https://www.readbyqxmd.com/read/27806432/the-hippocampus-integrates-context-and-shock-into-a-configural-memory-in-contextual-fear-conditioning
#11
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/27784133/a-novel-antibody-targeting-sequence-31-35-in-amyloid-%C3%AE-protein-attenuates-alzheimer-s-disease-related-neuronal-damage
#12
Li Cheng, Jun Zhang, Xin-Yi Li, Li Yuan, Yan-Fang Pan, Xiao-Rong Chen, Tian-Ming Gao, Jian-Tian Qiao, Jin-Shun Qi
Amyloid β protein (Aβ) plays a critical role in pathogenesis of Alzheimer's disease (AD). Our previous studies indicated that the sequence 31-35 in Aβ molecule is an effective active center responsible for Aβ neurotoxicity in vivo and in vitro. In the present study, we prepared a novel antibody specifically targeting the sequence 31-35 of amyloid β protein, and investigated the neuroprotection of the anti-Aβ31-35 antibody against Aβ1-42 -induced impairments in neuronal viability, spatial memory, and hippocampal synaptic plasticity in rats...
October 26, 2016: Hippocampus
https://www.readbyqxmd.com/read/27784124/dendrites-of-dentate-gyrus-granule-cells-contribute-to-pattern-separation-by-controlling-sparsity
#13
Spyridon Chavlis, Panagiotis C Petrantonakis, Panayiota Poirazi
The hippocampus plays a key role in pattern separation, the process of transforming similar incoming information to highly dissimilar, nonverlapping representations. Sparse firing granule cells (GCs) in the dentate gyrus (DG) have been proposed to undertake this computation, but little is known about which of their properties influence pattern separation. Dendritic atrophy has been reported in diseases associated with pattern separation deficits, suggesting a possible role for dendrites in this phenomenon. To investigate whether and how the dendrites of GCs contribute to pattern separation, we build a simplified, biologically relevant, computational model of the DG...
October 26, 2016: Hippocampus
https://www.readbyqxmd.com/read/27862600/a-harmonized-segmentation-protocol-for-hippocampal-and-parahippocampal-subregions-why-do-we-need-one-and-what-are-the-key-goals
#14
Laura E M Wisse, Ana M Daugherty, Rosanna K Olsen, David Berron, Valerie A Carr, Craig E L Stark, Robert S C Amaral, Katrin Amunts, Jean C Augustinack, Andrew R Bender, Jeffrey D Bernstein, Marina Boccardi, Martina Bocchetta, Alison Burggren, M Mallar Chakravarty, Marie Chupin, Arne Ekstrom, Robin de Flores, Ricardo Insausti, Prabesh Kanel, Olga Kedo, Kristen M Kennedy, Geoffrey A Kerchner, Karen F LaRocque, Xiuwen Liu, Anne Maass, Nicolai Malykhin, Susanne G Mueller, Noa Ofen, Daniela J Palombo, Mansi B Parekh, John B Pluta, Jens C Pruessner, Naftali Raz, Karen M Rodrigue, Dorothee Schoemaker, Andrea T Shafer, Trevor A Steve, Nanthia Suthana, Lei Wang, Julie L Winterburn, Michael A Yassa, Paul A Yushkevich, Renaud la Joie
The advent of high-resolution magnetic resonance imaging (MRI) has enabled in vivo research in a variety of populations and diseases on the structure and function of hippocampal subfields and subdivisions of the parahippocampal gyrus. Because of the many extant and highly discrepant segmentation protocols, comparing results across studies is difficult. To overcome this barrier, the Hippocampal Subfields Group was formed as an international collaboration with the aim of developing a harmonized protocol for manual segmentation of hippocampal and parahippocampal subregions on high-resolution MRI...
October 24, 2016: Hippocampus
https://www.readbyqxmd.com/read/27774683/stress-as-a-mnemonic-filter-interactions-between-medial-temporal-lobe-encoding-processes-and-post-encoding-stress
#15
Maureen Ritchey, Andrew M McCullough, Charan Ranganath, Andrew P Yonelinas
Acute stress has been shown to modulate memory for recently learned information, an effect attributed to the influence of stress hormones on medial temporal lobe (MTL) consolidation processes. However, little is known about which memories will be affected when stress follows encoding. One possibility is that stress interacts with encoding processes to selectively protect memories that had elicited responses in the hippocampus and amygdala, two MTL structures important for memory formation. There is limited evidence for interactions between encoding processes and consolidation effects in humans, but recent studies of consolidation in rodents have emphasized the importance of encoding "tags" for determining the impact of consolidation manipulations on memory...
October 24, 2016: Hippocampus
https://www.readbyqxmd.com/read/27770476/familiarity-expands-space-and-contracts-time
#16
Anna Jafarpour, Hugo Spiers
When humans draw maps, or make judgments about travel-time, their responses are rarely accurate and are often systematically distorted. Distortion effects on estimating time to arrival and the scale of sketch-maps reveal the nature of mental representation of time and space. Inspired by data from rodent entorhinal grid cells, we predicted that familiarity to an environment would distort representations of the space by expanding the size of it. We also hypothesized that travel-time estimation would be distorted in the same direction as space-size, if time and space rely on the same cognitive map...
October 22, 2016: Hippocampus
https://www.readbyqxmd.com/read/27770465/perception-of-impossible-scenes-reveals-differential-hippocampal-and-parahippocampal-place-area-contributions-to-spatial-coherency
#17
Danielle Douglas, Sathesan Thavabalasingam, Zahraa Chorghay, Edward B O'Neil, Morgan D Barense, Andy C H Lee
Surprisingly little is known about how the brain combines spatial elements to form a coherent percept. Regions that may underlie this process include the hippocampus (HC) and parahippocampal place area (PPA), regions central to spatial perception but whose role in spatial coherency has not been explored. Participants were scanned with functional MRI while they judged whether Escher-like scenes were possible or impossible. Univariate analyses revealed differential HC and PPA involvement, with greater HC activity during spatial incoherency detection and more PPA activity during spatial coherency detection...
October 22, 2016: Hippocampus
https://www.readbyqxmd.com/read/27756104/electroconvulsive-stimulation-results-in-long-term-survival-of-newly-generated-hippocampal-neurons-in-rats
#18
Mikkel Vestergaard Olesen, Gitta Wörtwein, Jonas Folke, Bente Pakkenberg
Electroconvulsive stimulation (ECS) is one of the strongest stimulators of hippocampal neurogenesis in rodents that represents a plausible mechanism for the efficacy of electroconvulsive therapy (ECT) in major depressive disorder. Using design-based stereological cell counting, we recently documented an initial 2.6-fold increase in neurogenesis following a clinical relevant schedule of ECS, a treatment also rescuing depression-like behavior in rats. However, these results gave no demonstration of the longevity of newly generated neurons...
October 18, 2016: Hippocampus
https://www.readbyqxmd.com/read/27701786/environmental-enrichment-and-physical-exercise-revert-behavioral-and-electrophysiological-impairments-caused-by-reduced-adult-neurogenesis
#19
Marna Eliana Sakalem, Thomas Seidenbecher, Mingyue Zhang, Roja Saffari, Mykola Kravchenko, Stephanie Wördemann, Kai Diederich, Jens C Schwamborn, Weiqi Zhang, Oliver Ambrée
It is well known that adult neurogenesis occurs in two distinct regions, the subgranular zone of the dentate gyrus and the subventricular zone along the walls of the lateral ventricles. Until now, the contribution of these newly born neurons to behavior and cognition is still uncertain. The current study tested the functional impacts of diminished hippocampal neurogenesis on emotional and cognitive functions in transgenic Gfap-tk mice. Our results showed that anxiety-related behavior evaluated both in the elevated plus maze as well as in the open field, social interaction in the sociability test, and spatial working memory in the spontaneous alternation test were not affected...
October 4, 2016: Hippocampus
https://www.readbyqxmd.com/read/27699923/age-related-cognitive-decline-coincides-with-accelerated-volume-loss-of-the-dorsal-but-not-ventral-hippocampus-in-mice
#20
J M Reichel, B T Bedenk, M Czisch, C T Wotjak
Even in the absence of neurodegenerative diseases, progressing age often coincides with cognitive decline and morphological changes. However, longitudinal studies that directly link these two processes are missing. In this proof-of-concept study we therefore performed repeated within-subject testing of healthy male R26R mice in a spatial learning task in combination with manganese-enhanced volumetric MRI analyses at the ages of 8, 16, and 24 months. We grouped the mice into good and poor performers (n = 6, each), based on their spatial learning abilities at the age of 24 months...
October 4, 2016: Hippocampus
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