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Hippocampus

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https://www.readbyqxmd.com/read/29116660/increased-hippocampus-to-ventromedial-prefrontal-connectivity-during-the-construction-of-episodic-future-events
#1
Karen L Campbell, Kevin P Madore, Roland G Benoit, Preston P Thakral, Daniel L Schacter
Both the hippocampus and ventromedial prefrontal cortex (vmPFC) appear to be critical for episodic future simulation. Damage to either structure affects one's ability to remember the past and imagine the future, and both structures are commonly activated as part of a wider core network during future simulation. However, the precise role played by each of these structures and, indeed, the direction of information flow between them during episodic simulation, is still not well understood. In this study, we scanned participants using functional magnetic resonance imaging (fMRI) while they imagined future events in response to object cues...
November 8, 2017: Hippocampus
https://www.readbyqxmd.com/read/29116659/type-1-astrocyte-like-stem-cells-harboring-cacna1d-gene-deletion-exhibit-reduced-proliferation-and-decreased-neuronal-fate-choice
#2
Bianca Völkening, Kai Schönig, Golo Kronenberg, Dusan Bartsch, Tillmann Weber
In the central nervous system, CaV 1.2 and CaV 1. 3 constitute the main L-type voltage-gated calcium channels (LTCCs) coupling membrane depolarization to gene transcription. We have previously demonstrated that inducible disruption of Cav1.2 in type-1 astrocyte-like stem cells of the adult dentate gyrus (DG) impairs hippocampal neurogenesis in a cell-autonomous fashion. To address the role of Cav1.3 channels (encoded by the Cacna1d gene), we here generated Tg(GLAST-CreERT2) /Cacna1d(fl/fl) /RCE:loxP mice which facilitate inducible deletion of Cacna1d in tandem with induction of EGFP expression in type-1 cells, allowing tracking of recombined cells and their descendants...
November 8, 2017: Hippocampus
https://www.readbyqxmd.com/read/29072798/characteristics-of-ca1-place-fields-in-a-complex-maze-with-multiple-choice-points
#3
H Tanila, S Ku, F Kloosterman, M A Wilson
For the sake of rigorous control of task variables, hippocampal place cells have been usually studied in relatively simple environments. To approach the situation of real-life navigation in an urban-like environment, we recorded CA1 place cells while rats performance a memory task in a 'Townmaze' with two start locations, three alternate paths in the maze mid-section, followed by a two-way choice that determined the trial outcome, access to a goal compartment. Further, to test the ability of place cells to update their spatial representation upon local changes in the environment while maintaining the integrity of the overall spatial map to allow effective navigation, we occasionally introduced barriers in the maze mid-section to force the rat to select a nonpreferred route...
October 26, 2017: Hippocampus
https://www.readbyqxmd.com/read/29072793/cytoarchitectonically-driven-mri-atlas-of-nonhuman-primate-hippocampus-preservation-of-subfield-volumes-in-aging
#4
Colin T Kyle, Jared Stokes, Jeffrey Bennett, Jeri Meltzer, Michele R Permenter, Julie A Vogt, Arne Ekstrom, Carol A Barnes
Identification of primate hippocampal subfields in vivo using structural MRI imaging relies on variable anatomical guidelines, signal intensity differences, and heuristics to differentiate between regions (Yushkevich et al., 2015a). Thus, a clear anatomically-driven basis for subfield demarcation is lacking. Recent work, however, has begun to develop methods to use ex vivo histology or ex vivo MRI (Adler et al., 2014; Iglesias et al., 2015) that have the potential to inform subfield demarcations of in vivo images...
October 26, 2017: Hippocampus
https://www.readbyqxmd.com/read/29034573/memory-encoding-related-anterior-hippocampal-potentials-are-modulated-by-deep-brain-stimulation-of-the-entorhinal-area
#5
Niels Hansen, Leila Chaieb, Marlene Derner, Kevin G Hampel, Christian E Elger, Rainer Surges, Bernhard Staresina, Nikolai Axmacher, Juergen Fell
BACKGROUND: Deep brain stimulation (DBS) of the human entorhinal area using 50 Hz pulses has revealed conflicting results regarding memory performance. Moreover, its impact on memory-related hippocampal potentials has not yet been investigated. METHODS: We recorded data from seven epilepsy patients implanted with depth electrodes in the entorhinal cortex, hippocampus, amygdala and parahippocampal cortex. Entorhinal DBS (bipolar, biphasic 50 Hz pulses, on- and off-cycles of 15 s) was applied with low amplitude (0...
October 16, 2017: Hippocampus
https://www.readbyqxmd.com/read/29028135/predicting-episodic-and-spatial-memory-performance-from-hippocampal-resting-state-functional-connectivity-evidence-for-an-anterior-posterior-division-of-function
#6
Jonas Persson, Eva Stening, Kristin Nordin, Hedvig Söderlund
fMRI studies have identified distinct resting-state functional connectivity (RSFC) networks associated with the anterior and posterior hippocampus. However, the functional relevance of these two networks is still largely unknown. Hippocampal lesion studies and task-related fMRI point to a role for the anterior hippocampus in non-spatial episodic memory and the posterior hippocampus in spatial memory. We used Relevance Vector Regression (RVR), a machine-learning method that enables predictions of continuous outcome measures from multivariate patterns of brain imaging data, to test the hypothesis that patterns of whole-brain RSFC associated with the anterior hippocampus predict episodic memory performance, while patterns of whole-brain RSFC associated with the posterior hippocampus predict spatial memory performance...
October 13, 2017: Hippocampus
https://www.readbyqxmd.com/read/29024221/dendrites-deep-learning-and-sequences-in-the-hippocampus
#7
Upinder S Bhalla
The hippocampus places us both in time and space. It does so over remarkably large spans: milliseconds to years, and centimeters to kilometers. This works for sensory representations, for memory, and for behavioral context. How does it fit in such wide ranges of time and space scales, and keep order among the many dimensions of stimulus context? A key organizing principle for a wide sweep of scales and stimulus dimensions is that of order in time, or sequences. Sequences of neuronal activity are ubiquitous in sensory processing, in motor control, in planning actions, and in memory...
October 12, 2017: Hippocampus
https://www.readbyqxmd.com/read/28972669/deletion-of-tlx-and-social-isolation-impairs-exercise-induced-neurogenesis-in-the-adolescent-hippocampus
#8
Danka A Kozareva, Olivia F O'Leary, John F Cryan, Yvonne M Nolan
Adolescence is a sensitive period of neurodevelopment during which life experiences and the surrounding environment can have profound effects on the brain. Neurogenesis is a neurodevelopmental process of generating functional neurons from neural stem cells. Hippocampal neurogenesis occurs throughout the lifespan and has been shown to play a role in learning, memory and in mood regulation. In adulthood it is influenced by extrinsic environmental factors such as exercise and stress. Intrinsic factors that regulate hippocampal neurogenesis include the orphan nuclear receptor TLX (Nr2e1) which is primarily expressed in the neurogenic niches of the brain...
October 3, 2017: Hippocampus
https://www.readbyqxmd.com/read/28921856/disruption-of-perineuronal-nets-increases-the-frequency-of-sharp-wave-ripple-events
#9
Zhi Yong Sun, P Lorenzo Bozzelli, Adam Caccavano, Megan Allen, Jason Balmuth, Stefano Vicini, Jian-Young Wu, Katherine Conant
Hippocampal sharp wave ripples (SWRs) represent irregularly occurring synchronous neuronal population events that are observed during phases of rest and slow wave sleep. SWR activity that follows learning involves sequential replay of training-associated neuronal assemblies and is critical for systems level memory consolidation. SWRs are initiated by CA2 or CA3 pyramidal cells (PCs) and require initial excitation of CA1 PCs as well as participation of parvalbumin (PV) expressing fast spiking (FS) inhibitory interneurons...
September 16, 2017: Hippocampus
https://www.readbyqxmd.com/read/28921762/inhibition-shapes-the-organization-of-hippocampal-representations
#10
Sam McKenzie
Hippocampal neurons become tuned to stimuli that predict behaviorally salient outcomes. This plasticity suggests that memory formation depends upon shifts in how different anatomical inputs can drive hippocampal activity. Here, I present evidence that inhibitory neurons can provide such a mechanism for learning-related changes in the tuning of pyramidal cells. Inhibitory currents arriving on the dendrites of pyramidal cells determine whether an excitatory input can drive action potential output. Specificity and plasticity of this dendritic modulation allows for precise, modifiable changes in how afferent inputs are integrated, a process that defines a neuron's receptive field...
September 16, 2017: Hippocampus
https://www.readbyqxmd.com/read/28888073/selective-decline-of-neurotrophin-and-neurotrophin-receptor-genes-within-ca1-pyramidal-neurons-and-hippocampus-proper-correlation-with-cognitive-performance-and-neuropathology-in-mild-cognitive-impairment-and-alzheimer-s-disease
#11
Stephen D Ginsberg, Michael H Malek-Ahmadi, Melissa J Alldred, Shaoli Che, Irina Elarova, Yinghua Chen, Freddy Jeanneteau, Thorsten M Kranz, Moses V Chao, Scott E Counts, Elliott J Mufson
Hippocampal CA1 pyramidal neurons, a major component of the medial temporal lobe memory circuit, are selectively vulnerable during the progression of Alzheimer's disease (AD). The cellular mechanism(s) underlying degeneration of these neurons and the relationship to cognitive performance remains largely undefined. Here, we profiled neurotrophin and neurotrophin receptor gene expression within microdissected CA1 neurons along with regional hippocampal dissections from subjects who died with a clinical diagnosis of no cognitive impairment (NCI), mild cognitive impairment (MCI), or AD using laser capture microdissection (LCM), custom-designed microarray analysis, and qPCR of CA1 subregional dissections...
September 9, 2017: Hippocampus
https://www.readbyqxmd.com/read/28888032/close-but-no-cigar-spatial-precision-deficits-following-medial-temporal-lobe-lesions-provide-novel-insight-into-theoretical-models-of-navigation-and-memory
#12
Branden S Kolarik, Trevor Baer, Kiarash Shahlaie, Andrew P Yonelinas, Arne D Ekstrom
Increasing evidence suggests that the human hippocampus contributes to a range of different behaviors, including episodic memory, language, short-term memory, and navigation. A novel theoretical framework, the Precision and Binding Model, accounts for these phenomenon by describing a role for the hippocampus in high-resolution, complex binding. Other theories like Cognitive Map Theory, in contrast, predict a specific role for the hippocampus in allocentric navigation, while Declarative Memory Theory predicts a specific role in delay-dependent conscious memory...
September 9, 2017: Hippocampus
https://www.readbyqxmd.com/read/28888031/disconnection-of-hippocampal-networks-contributes-to-memory-dysfunction-in-individuals-with-temporal-lobe-epilepsy
#13
Travis R Stoub, Ada V Chicharro, Christopher L Grote, Andres M Kanner
A deficit in declarative memory function is common among individuals with temporal lobe epilepsy. The purpose of this study is to evaluate the relationship between the volume of the hippocampus, entorhinal cortex along with the surrounding parahippocampal white matter and memory performance in those with temporal lobe epilepsy. T1 weighted MRI scans were acquired using a 3-D pulse sequence in 50 individuals with temporal lobe epilepsy. Hippocampal and entorhinal cortex volumes were derived by manually tracing consecutive coronal slices aligned perpendicular to the long axis of the hippocampus...
September 9, 2017: Hippocampus
https://www.readbyqxmd.com/read/28881444/gabaergic-inhibition-gates-excitatory-ltp-in-perirhinal-cortex
#14
Vibhakar C Kotak, Ana Mirallave, Todd M Mowery, Dan H Sanes
The perirhinal cortex (PRh) is a key region downstream of auditory cortex (ACx) that processes familiarity linked mnemonic signaling. In gerbils, ACx-driven EPSPs recorded in PRh neurons are largely shunted by GABAergic inhibition (Kotak et al. 2015). To determine whether inhibitory shunting prevents the induction of excitatory long-term potentiation (e-LTP), we stimulated ACx-recipient PRh in a brain slice preparation using theta burst stimulation (TBS). Under control conditions, without GABA blockers, the majority of PRh neurons exhibited long-term depression...
September 7, 2017: Hippocampus
https://www.readbyqxmd.com/read/28843046/characterizing-the-role-of-the-hippocampus-during-episodic-simulation-and-encoding
#15
Preston P Thakral, Roland G Benoit, Daniel L Schacter
The hippocampus has been consistently associated with episodic simulation (i.e., the mental construction of a possible future episode). In a recent study, we identified an anterior-posterior temporal dissociation within the hippocampus during simulation. Specifically, transient simulation-related activity occurred in relatively posterior portions of the hippocampus and sustained activity occurred in anterior portions. In line with previous theoretical proposals of hippocampal function during simulation, the posterior hippocampal activity was interpreted as reflecting a transient retrieval process for the episodic details necessary to construct an episode...
August 26, 2017: Hippocampus
https://www.readbyqxmd.com/read/28843045/hippocampal-mechanisms-in-impaired-spatial-learning-and-memory-in-male-offspring-of-rats-fed-a-low-protein-isocaloric-diet-in-pregnancy-and-or-lactation
#16
L A Reyes-Castro, E Padilla-Gómez, N J Parga-Martínez, D C Castro-Rodríguez, G L Quirarte, S Díaz-Cintra, P W Nathanielsz, E Zambrano
Maternal nutritional challenges during fetal and neonatal development result in developmental programming of multiple offspring organ systems including brain maturation and function. A maternal low-protein diet during pregnancy and lactation impairs associative learning and motivation. We evaluated effects of a maternal low-protein diet during gestation and/or lactation on male offspring spatial learning and hippocampal neural structure. Control mothers (C) ate 20% casein and restricted mothers (R) 10% casein, providing four groups: CC, RR, CR, and RC (first letter pregnancy, second lactation diet)...
August 26, 2017: Hippocampus
https://www.readbyqxmd.com/read/28843041/the-social-hippocampus
#17
Alison Montagrin, Catarina Saiote, Daniela Schiller
The concept of cognitive map has been proposed as a way to organize our experiences and guide behavior across all domains of cognition. The hippocampus has been identified as the neural substrate supporting cognitive maps for navigating physical space. Recent evidence is broadening the role of the hippocampus into mapping other manner of spaces. Here we focus on the case of social space as a candidate for hippocampal representation because it combines multiple continuous dimensions and requires dynamic navigation through social contexts...
August 26, 2017: Hippocampus
https://www.readbyqxmd.com/read/28768062/selforganization-of-modular-activity-of-grid-cells
#18
Eugenio Urdapilleta, Bailu Si, Alessandro Treves
A unique topographical representation of space is found in the concerted activity of grid cells in the rodent medial entorhinal cortex. Many among the principal cells in this region exhibit a hexagonal firing pattern, in which each cell expresses its own set of place fields (spatial phases) at the vertices of a triangular grid, the spacing and orientation of which are typically shared with neighboring cells. Grid spacing, in particular, has been found to increase along the dorso-ventral axis of the entorhinal cortex but in discrete steps, that is, with a modular structure...
November 2017: Hippocampus
https://www.readbyqxmd.com/read/28710800/dissociation-of-spatial-memory-systems-in-williams-syndrome
#19
Mathilde Bostelmann, Emilie Fragnière, Floriana Costanzo, Silvia Di Vara, Deny Menghini, Stefano Vicari, Pierre Lavenex, Pamela Banta Lavenex
Williams syndrome (WS), a genetic deletion syndrome, is characterized by severe visuospatial deficits affecting performance on both tabletop spatial tasks and on tasks which assess orientation and navigation. Nevertheless, previous studies of WS spatial capacities have ignored the fact that two different spatial memory systems are believed to contribute parallel spatial representations supporting navigation. The place learning system depends on the hippocampal formation and creates flexible relational representations of the environment, also known as cognitive maps...
November 2017: Hippocampus
https://www.readbyqxmd.com/read/28686814/early-survival-and-delayed-death-of-developmentally-born-dentate-gyrus-neurons
#20
Shaina P Cahill, Ru Qi Yu, Dylan Green, Evgenia V Todorova, Jason S Snyder
The storage and persistence of memories depends on plasticity in the hippocampus. Adult neurogenesis produces new neurons that mature through critical periods for plasticity and cellular survival, which determine their contributions to learning and memory. However, most granule neurons are generated prior to adulthood; the maturational timecourse of these neurons is poorly understood compared to adult-born neurons but is essential to identify how the dentate gyrus (DG), as a whole, contributes to behavior. To characterize neurons born in the early postnatal period, we labeled DG neurons born on postnatal day 6 (P6) with BrdU and quantified maturation and survival across early (1 hr to 8 weeks old) and late (2-6 months old) cell ages...
November 2017: Hippocampus
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