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Hippocampus

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https://www.readbyqxmd.com/read/28628945/precise-spike-timing-dynamics-of-hippocampal-place-cell-activity-sensitive-to-cholinergic-disruption
#1
Ehren L Newman, Sarah Jo C Venditto, Jason R Climer, Elijah A Petter, Shea N Gillet, Sam Levy
New memory formation depends upon both the hippocampus and modulatory effects of acetylcholine. The mechanism by which acetylcholine levels in the hippocampus enable new encoding remains poorly understood. Here, we tested the hypothesis that cholinergic modulation supports memory formation by leading to structured spike timing in the hippocampus. Specifically, we tested if phase precession in dorsal CA1 was reduced under the influence of a systemic cholinergic antagonist. Unit and field potential was recorded from the dorsal CA1 of rats as they completed laps on a circular track for food rewards before and during the influence of the systemically administered acetylcholine muscarinic receptor antagonist scopolamine...
June 19, 2017: Hippocampus
https://www.readbyqxmd.com/read/28609014/space-time-and-episodic-memory-the-hippocampus-is-all-over-the-cognitive-map
#2
Arne D Ekstrom, Charan Ranganath
In recent years, the field has reached an impasse between models suggesting that the hippocampus is fundamentally involved in spatial processing and models suggesting that the hippocampus automatically encodes all dimensions of experience in the service of memory. Here, we consider key conceptual issues that have impeded progress in our understanding of hippocampal function, and we review findings that establish the scope and limits of hippocampal involvement in navigation and memory. We argue that space and time serve as a primary scaffold to break up experiences into specific contexts, and to organize multimodal input that is to be associated within a context...
June 13, 2017: Hippocampus
https://www.readbyqxmd.com/read/28608989/seizure-severity-dependent-selective-vulnerability-of-the-granule-cell-layer-and-aberrant-neurogenesis-in-the-rat-hippocampus
#3
Takeshi Uemori, Keiko Toda, Tatsunori Seki
The pilocarpine-induced status epilepticus (SE) rodent model has been commonly used to analyze the mechanisms of human temporal lobe epilepsy. Recent studies using this model have demonstrated that epileptic seizures lead to increased adult neurogenesis of the dentate granule cells, and cause abnormal cellular organization in dentate neuronal circuits. In this study, we examined these structural changes in rats with seizures of varying severity. In rats with frequent severe seizures, we found a clear loss of Prox1 and NeuN expression in the dentate granule cell layer (GCL), which was confined mainly to the suprapyramidal blade of the GCL at the septal and middle regions of the septo-temporal axis of the hippocampus...
June 13, 2017: Hippocampus
https://www.readbyqxmd.com/read/28608960/theta-band-power-increases-in-the-posterior-hippocampus-predict-successful-episodic-memory-encoding-in-humans
#4
Jui Jui Lin, Michael Rugg, Sandhitsu Das, Joel Stein, Daniel Rizzuto, Michael Kahana, Bradley Lega
Functional differences in the anterior and posterior hippocampus during episodic memory processing have not been examined in human electrophysiological data. This is in spite of strong evidence for such differences in rodent data, including greater place cell specificity in the dorsal hippocampus, greater sensitivity to the aversive or motivational content of memories in ventral regions, connectivity analyses identifying preferential ventral hippocampal connections with the amygdala, and gene expression analyses identifying a dorsal-ventral gradient...
June 13, 2017: Hippocampus
https://www.readbyqxmd.com/read/28599071/predator-odor-evokes-sex-independent-stress-responses-in-male-and-female-wistar-rats-and-reduces-phosphorylation-of-cyclic-adenosine-monophosphate-response-element-binding-protein-creb-in-the-male-but-not-the-female-hippocampus
#5
Damek Homiack, Emma O'Cinneide, Sema Hajmurad, Brett Barrileaux, Mary Stanley, Michael R Kreutz, Laura Schrader
Post-traumatic stress disorder (PTSD) is characterized by memory disturbances following trauma. Acute predator threat has emerged as an ethological model of PTSD, yet the effects of predator odor on signaling cascades associated with long-term memory remain poorly understood. In this study, we exposed male and female Wistar rats to the synthetic predator odor 2,5-dihydro-2,4,5-trimethylthiazoline (TMT) to assess behavioral and physiological responses as well as rapid modulation of signal transduction cascades associated with learning and memory in the male and female hippocampus...
June 9, 2017: Hippocampus
https://www.readbyqxmd.com/read/28597498/different-implications-of-the-dorsal-and-ventral-hippocampus-on-contextual-memory-retrieval-after-stress
#6
C Pierard, R Dorey, N Henkous, N Mons, D Béracochéa
This study assessed the relative contributions of dorsal (dHPC) and ventral (vHPC) hippocampus regions in mediating the rapid effects of an acute stress on contextual memory retrieval. Indeed, we previously showed that an acute stress (3 electric footschocks; 0.9 mA each) delivered 15 min before the 24h-test inversed the memory retrieval pattern in a contextual discrimination task. Specifically, mice learned in a four-hole board two successive discriminations (D1 and D2) varying by the color and texture of the floor...
June 8, 2017: Hippocampus
https://www.readbyqxmd.com/read/28597491/hippocampal-neurogenesis-and-pattern-separation-a-meta-analysis-of-behavioral-data
#7
Thiago F A França, Alexandre M Bitencourt, Naiana R Maximilla, Daniela M Barros, José M Monserrat
The generation of new neurons in the hippocampus of adult mammals has become a widely accepted phenomenon, but the functional significance of the adult neurogenesis in the hippocampus is not fully understood. One of the main hypotheses currently investigated suggests that neurogenesis contributes to pattern separation in the dentate gyrus. Many behavioral studies were conducted aiming to test this hypothesis using rodents as animal model. In those studies, researches ablated neurogenesis in the animals and subsequently evaluate them in tests of behavioral pattern separation, that is, behaviors that are thought to rely on the computational process of pattern separation...
June 8, 2017: Hippocampus
https://www.readbyqxmd.com/read/28569408/aerobic-exercise-reduces-hippocampal-erk-and-p38-activation-and-improves-memory-of-middle-aged-rats
#8
Fabrízio Dos Santos Cardoso, Erivelton Fernandes França, Fernando Tadeu Serra, Angélica Begatti Victorino, Alexandre Aparecido de Almeida, Jansen Fernandes, Francisco Romero Cabral, Daniel Paulino Venancio, Ricardo Mario Arida, Sérgio Gomes da Silva
Aging is often accompanied by cognitive decline, memory impairment, and an increased susceptibility to neurodegenerative disorders. Although the physiological processes of aging are not fully understood, these age-related changes have been interpreted by means of various cellular and molecular theories. Among these theories, alterations in the intracellular signaling pathways associated with cell growth, proliferation, and survival have been highlighted. Based on these observations and on recent evidence showing the beneficial effects of exercise on cognitive function in the elderly, we investigated the cell signaling pathways in the hippocampal formation of middle-aged rats (18 months old) submitted to treadmill exercise over 10 days...
June 1, 2017: Hippocampus
https://www.readbyqxmd.com/read/28558154/theta-paced-flickering-between-place-cell-maps-in-the-hippocampus-a-model-based-on-short-term-synaptic-plasticity
#9
Shirley Mark, Sandro Romani, Karel Jezek, Misha Tsodyks
Hippocampal place cells represent different environments with distinct neural activity patterns. Following an abrupt switch between two familiar configurations of visual cues defining two environments, the hippocampal neural activity pattern switches almost immediately to the corresponding representation. Surprisingly, during a transient period following the switch to the new environment, occasional fast transitions of activity patterns between the representations (flickering) were observed (Jezek et al. 2011)...
May 30, 2017: Hippocampus
https://www.readbyqxmd.com/read/28558129/somatostatin-depresses-the-excitability-of-subicular-bursting-cells-roles-of-inward-rectifier-k-channels-kcnq-channels-and-epac
#10
Binqi Hu, Nicholas I Cilz, Saobo Lei
The hippocampus is a crucial component for cognitive and emotional processing. The subiculum provides much of the output for this structure but the modulation and function of this region is surprisingly under-studied. The neuromodulator somatostatin (SST) interacts with five subtypes of SST receptors (sst1 to sst5 ) and each of these SST receptor subtypes is coupled to Gi proteins resulting in inhibition of adenylyl cyclase (AC) and decreased level of intracellular cAMP. SST modulates many physiological functions including cognition, emotion, autonomic responses and locomotion...
May 30, 2017: Hippocampus
https://www.readbyqxmd.com/read/28558121/early-life-stress-diminishes-the-increase-in-neurogenesis-after-exercise-in-adult-female-mice
#11
M R Abbink, E F G Naninck, P J Lucassen, A Korosi
Exposure to early-life stress (ES) has long-lasting consequences for later cognition and hippocampal plasticity, including adult hippocampal neurogenesis (AHN), i.e., the generation of new neurons from stem/progenitor cells in the adult hippocampal dentate gyrus. We had previously demonstrated a sex-specific vulnerability to ES exposure; female mice exposed to ES from P2-P9 exhibited only very mild cognitive changes and no reductions in AHN as adult, whereas ES-exposed male mice showed impaired cognition closely associated with reductions in AHN...
May 30, 2017: Hippocampus
https://www.readbyqxmd.com/read/28556462/gsk3-activity-regulates-rhythms-in-hippocampal-clock-gene-expression-and-synaptic-plasticity
#12
Rachel C Besing, Courtney O Rogers, Jodi R Paul, Lauren M Hablitz, Russell L Johnson, Lori L McMahon, Karen L Gamble
Hippocampal rhythms in clock gene expression, enzymatic activity, and long-term potentiation (LTP) are thought to underlie day-night differences in memory acquisition and recall. Glycogen synthase kinase 3-beta (GSK3β) is a known regulator of hippocampal function, and inhibitory phosphorylation of GSK3β exhibits region-specific differences over the light-dark cycle. Here, we sought to determine whether phosphorylation of both GSK3α and GSK3β isoforms has an endogenous circadian rhythm in specific areas of the hippocampus and whether chronic inhibition or activation alters the molecular clock and hippocampal plasticity (LTP)...
May 27, 2017: Hippocampus
https://www.readbyqxmd.com/read/28512860/intrinsic-cellular-and-molecular-properties-of-in-vivo-hippocampal-synaptic-plasticity-are-altered-in-the-absence-of-key-synaptic-matrix-molecules
#13
Stephan Jansen, Christine Gottschling, Andreas Faissner, Denise Manahan-Vaughan
Hippocampal synaptic plasticity comprises a key cellular mechanism for information storage. In the hippocampus, both long-term potentiation (LTP) and long-term depression (LTD) are triggered by synaptic Ca(2+) -elevations that are typically mediated by the opening of voltage-gated cation channels, such as N-methyl-D-aspartate receptors (NMDAR), in the postsynaptic density. The integrity of the post-synaptic density is ensured by the extracellular matrix (ECM). Here, we explored whether synaptic plasticity is affected in adult behaving mice that lack the ECM proteins brevican, neurocan, tenascin-C and tenascin-R (TG)...
May 17, 2017: Hippocampus
https://www.readbyqxmd.com/read/28500650/aberrant-cognitive-phenotypes-and-altered-hippocampal-bdnf-expression-related-to-epigenetic-modifications-in-mice-lacking-the-post-synaptic-scaffolding-protein-shank1-implications-for-autism-spectrum-disorder
#14
A Özge Sungur, Magdalena C E Jochner, Hani Harb, Ayşe Kılıç, Holger Garn, Rainer K W Schwarting, Markus Wöhr
Autism spectrum disorder (ASD) is a class of neurodevelopmental disorders characterized by persistent deficits in social communication/interaction, together with restricted/repetitive patterns of behavior. ASD is among the most heritable neuropsychiatric conditions, and while available evidence points to a complex set of genetic factors, the SHANK gene family has emerged as one of the most promising candidates. Here, we assessed ASD-related phenotypes with particular emphasis on social behavior and cognition in Shank1 mouse mutants in comparison to heterozygous and wildtype littermate controls across development in both sexes...
May 12, 2017: Hippocampus
https://www.readbyqxmd.com/read/28498605/brain-structural-connectivity-and-context-dependent-extinction-memory
#15
Andrea Hermann, Rudolf Stark, Carlo R Blecker, Mohammed R Milad, Christian J Merz
BACKGROUND: Extinction of conditioned fear represents an important mechanism in the treatment of anxiety disorders. Return of fear after successful extinction or exposure therapy in patients with anxiety disorders might be linked to poor temporal or contextual generalization of extinction due to individual differences in brain structural connectivity. The goal of this magnetic resonance imaging study was therefore to investigate the association of context-dependent extinction recall with brain structural connectivity...
May 12, 2017: Hippocampus
https://www.readbyqxmd.com/read/28474795/running-promotes-spatial-bias-independently-of-adult-neurogenesis
#16
Jason S Snyder, Shaina P Cahill, Paul W Frankland
Different memory systems offer distinct advantages to navigational behavior. The hippocampus forms complex associations between environmental stimuli, enabling flexible navigation through space. In contrast, the dorsal striatum associates discrete cues and favorable behavioral responses, enabling habit-like, automated navigation. While these two systems often complement one another, there are instances where striatal-dependent responses (e.g. approach a cue) conflict with hippocampal representations of spatial goals...
May 5, 2017: Hippocampus
https://www.readbyqxmd.com/read/28449397/differential-proteome-profiling-in-the-hippocampus-of-amnesic-mice
#17
Meghraj Singh Baghel, Mahendra Kumar Thakur
Amnesia or memory loss is associated with brain aging and several neurodegenerative pathologies including Alzheimer's disease (AD). This can be induced by a cholinergic antagonist scopolamine but the underlying molecular mechanism is poorly understood. This study of proteome profiling in the hippocampus could provide conceptual insights into the molecular mechanisms involved in amnesia. To reveal this, mice were administered scopolamine to induce amnesia and memory impairment was validated by novel object recognition test...
April 27, 2017: Hippocampus
https://www.readbyqxmd.com/read/28449208/complex-modulation-by-stress-of-the-effect-of-seizures-on-long-term-potentiation-in-mouse-hippocampal-slices
#18
Nicola Maggio, Efrat Shavit Stein, Menahem Segal
Stress has a profound effect on ability to express neuronal plasticity, learning and memory. Likewise, epileptic seizures lead to massive changes in brain connectivity, and in ability to undergo long term changes in reactivity to afferent stimulation. In the present study we analyzed possible long lasting interactions between a stressful experience and reactivity to pilocarpine, on the ability to produce long term potentiation (LTP) in a mouse hippocampus. Pilocarpine lowers paired pulse potentiation (PPP) as well as LTP in CA1 region of the mouse hippocampal slice...
April 27, 2017: Hippocampus
https://www.readbyqxmd.com/read/28346765/the-medial-temporal-memory-system-in-down-syndrome-translating-animal-models-of-hippocampal-compromise
#19
Caron A C Clark, Fabian Fernandez, Stella Sakhon, Goffredina Spanò, Jamie O Edgin
Recent studies have highlighted the dentate gyrus as a region of increased vulnerability in mouse models of Down syndrome (DS). It is unclear to what extent these findings are reflected in the memory profile of people with the condition. We developed a series of novel tasks to probe distinct medial temporal functions in children and young adults with DS, including object, spatial, and temporal order memory. Relative to mental age-matched controls (n = 45), individuals with DS (n = 28) were unimpaired on subtests involving short-term object or configural recall that was divorced from spatial or temporal contexts...
March 27, 2017: Hippocampus
https://www.readbyqxmd.com/read/28449268/ventral-but-not-dorsal-hippocampus-inactivation-impairs-reward-memory-expression-and-retrieval-in-contexts-defined-by-proximal-cues
#20
Sadia Riaz, Anett Schumacher, Seyon Sivagurunathan, Matthijs Van Der Meer, Rutsuko Ito
The hippocampus (HPC) has been widely implicated in the contextual control of appetitive and aversive conditioning. However, whole hippocampal lesions do not invariably impair all forms of contextual processing, as in the case of complex biconditional context discrimination, leading to contention over the exact nature of the contribution of the HPC in contextual processing. Moreover, the increasingly well-established functional dissociation between the dorsal (dHPC) and ventral (vHPC) subregions of the HPC has been largely overlooked in the existing literature on hippocampal-based contextual memory processing in appetitively motivated tasks...
July 2017: Hippocampus
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