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Hippocampus and retrieval

Stéphanie Trouche, Vadim Koren, Natalie M Doig, Tommas J Ellender, Mohamady El-Gaby, Vítor Lopes-Dos-Santos, Hayley M Reeve, Pavel V Perestenko, Farid N Garas, Peter J Magill, Andrew Sharott, David Dupret
Retrieving and acting on memories of food-predicting environments are fundamental processes for animal survival. Hippocampal pyramidal cells (PYRs) of the mammalian brain provide mnemonic representations of space. Yet the substrates by which these hippocampal representations support memory-guided behavior remain unknown. Here, we uncover a direct connection from dorsal CA1 (dCA1) hippocampus to nucleus accumbens (NAc) that enables the behavioral manifestation of place-reward memories. By monitoring neuronal ensembles in mouse dCA1→NAc pathway, combined with cell-type selective optogenetic manipulations of input-defined postsynaptic neurons, we show that dCA1 PYRs drive NAc medium spiny neurons and orchestrate their spiking activity using feedforward inhibition mediated by dCA1-connected parvalbumin-expressing fast-spiking interneurons...
February 11, 2019: Cell
Emilie Noe, Nicolas Bonneau, Marie-Line Fournier, Stéphanie Caillé, Martine Cador, Catherine Le Moine
Opiate withdrawal induces an early aversive state which can be associated to contexts and/or cues, and re-exposure to either these contexts or cues may participate in craving and relapse. Nucleus accumbens (NAC), hippocampus (HPC) and basolateral amygdala (BLA) are crucial substrates for acute opiate withdrawal, and for withdrawal memory retrieval. Also HPC and BLA interacting with the NAC are suggested to respectively mediate the processing of context and cue representations of drug-related memories. Here we used a paradigm of conditioned suppression of operant food seeking, allowing to differentiate context and cue related responses, to study the influence of withdrawal memories on operant behavior and the underlying neural substrates...
February 13, 2019: Neurobiology of Learning and Memory
Signy Sheldon, Can Fenerci, Lauri Gurguryan
Autobiographical memory retrieval involves constructing mental representations of personal past episodes by associating together an array of details related to the retrieved event. This construction process occurs flexibly so that the event details can be associated together in different ways during retrieval. Here, we propose that differences in how this association occurs support a division in autobiographical remembering. We first review theories of autobiographical memory organization that suggest that episodic details of an experience are processed along a gradient of abstraction...
2019: Frontiers in Systems Neuroscience
Antonietta Gabriella Liuzzi, Patrick Dupont, Ronald Peeters, Rose Bruffaerts, Simon De Deyne, Gert Storms, Rik Vandenberghe
Knowledge of visual and nonvisual attributes of concrete entities is distributed over neocortical uni- and polymodal association cortex. Here we investigated the role of left perirhinal cortex in explicit knowledge retrieval from written words. We examined whether it extended across visual and nonvisual properties, animate and inanimate entities, how this differed from picture input and how specific it was for perirhinal cortex compared to surrounding structures. The semantic similarity between stimuli was determined on the basis of a word association-based model...
February 9, 2019: NeuroImage
Stanislau Hrybouski, Melanie MacGillivray, Yushan Huang, Christopher R Madan, Rawle Carter, Peter Seres, Nikolai V Malykhin
The functional role of the hippocampal formation in episodic memory has been studied using functional magnetic resonance imaging (fMRI) for many years. The hippocampus can be segmented into three major anteroposterior sections, called head, body and tail, and into the Cornu Ammonis (CA), dentate gyrus (DG), and subiculum (Sub) subfields based on its transverse axis. However, the exact role of these subregions and subfields in memory processes is less understood. In the present study we combined ultra-high resolution structural Magnetic Resonance Imaging (MRI) at 4...
February 8, 2019: NeuroImage
Annika Hanert, Anya Pedersen, Thorsten Bartsch
Day-to-day life involves the perception of events that resemble one another. For the sufficient encoding and retrieval of similar information, the hippocampus provides two essential computational processes. Pattern separation refers to the differentiation of overlapping memory representations, whereas pattern completion reactivates memories based on noisy or degraded input. Evidence from human and rodent studies suggest that pattern separation specifically relies on neuronal ensemble activity in hippocampal subnetworks in the dentate gyrus and CA3...
January 31, 2019: Hippocampus
Lizeth K Pedraza, Rodrigo O Sierra, Marcelo Giachero, Walquiria Nunes-Souza, Fernanda N Lotz, Lucas de Oliveira Alvares
Fear memory overgeneralization contributes to the genesis and persistence of anxiety disorders and is a central hallmark in the pathophysiology of post-traumatic stress disorder (PTSD). Recent findings suggest that fear generalization is closely related to hippocampal dependency during retrieval. The selective serotonin reuptake inhibitor (SSRI) fluoxetine has been used as a first-line treatment for PTSD; however, how it exerts its therapeutic effect remains a matter of debate. Here, using contextual fear conditioning in rats, we show that chronic fluoxetine treatment prevents fear generalization and enhances subsequent extinction...
January 31, 2019: Translational Psychiatry
Maddalena Boccia, Valentina Sulpizio, Alice Teghil, Liana Palermo, Laura Piccardi, Gaspare Galati, Cecilia Guariglia
Mental imagery and visual perception rely on the same content-dependent brain areas in the high-level visual cortex (HVC). However, little is known about dynamic mechanisms in these areas during imagery and perception. Here we disentangled local and inter-regional dynamic mechanisms underlying imagery and perception in the HVC and the hippocampus (HC), a key region for memory retrieval during imagery. Nineteen healthy participants watched or imagined a familiar scene or face during fMRI acquisition. The neural code for familiar landmarks and faces was distributed across the HVC and the HC, although with a different representational structure, and generalized across imagery and perception...
January 31, 2019: Human Brain Mapping
Akimasa Kurozumi, Tetsuya Hara, Shunichi Sakamoto, Daisuke Araki, Sachiyo Iida-Tamada, Chisa Kuroda-Ishimine, Shogo Minagi
PURPOSE: Animal experiments have shown that the loss of occlusal support causes impairments in spatial cognition. Many reports have focused on the memory encoding process, and only few studies have investigated the effect on memory retrieval. This study aimed to examine the effects of both the loss and reconstruction of occlusal support on the memory retrieval process and on the number of hippocampal pyramidal cells. METHODS: The experimental animals were divided into a molarless group, in which molars were extracted, a denture-wearing molarless group with experimental dentures inserted after molar extraction, and a control group...
January 25, 2019: Journal of Prosthodontic Research
Ana F Almeida-Santos, Vinícius R Carvalho, Laura F Jaimes, Caio M de Castro, Hyorrana P Pinto, Tadeu P D Oliveira, Luciene B Vieira, Márcio F D Moraes, Grace S Pereira
The absence of companion may jeopardize mental health in social animals. Here, we tested the hypothesis that social isolation impairs social recognition memory by altering the excitability and the dialog between the olfactory bulb (OB) and the dorsal hippocampus (dHIP). Adult male Swiss mice were kept grouped (GH) or isolated (SI) for 7 days. Social memory (LTM) was evaluated using social recognition test. SI increased glutamate release in the OB, while decreased in the dHIP. Blocking AMPA and NMDA receptors into the OB or activating AMPA into the dHIP rescued LTM in SI mice, suggesting a cause-effect relationship between glutamate levels and LTM impairment...
January 24, 2019: Scientific Reports
María Isabel Cuartero, Juan de la Parra, Alberto Pérez-Ruiz, Isabel Bravo-Ferrer, Violeta Durán-Laforet, Alicia García-Culebras, Juan Manuel García-Segura, Jagroop Dhaliwal, Paul W Frankland, Ignacio Lizasoain, María Àngeles Moro
Post-stroke cognitive impairment is considered one of the main complications during the chronic phase of ischemic stroke. In the adult brain, the hippocampus regulates both encoding and retrieval of new information through adult neurogenesis. Nevertheless, the lack of predictive models and studies based on the forgetting processes hinder the understanding of memory alterations after stroke. Our aim was to explore whether post-stroke neurogenesis participates in the development of long-term memory impairment...
January 24, 2019: Journal of Clinical Investigation
Fatima Zahra Sadiki, Mostafa El Idrissi, Oana Cioanca, Adriana Trifan, Monica Hancianu, Lucian Hritcu, Paula Alexandra Postu
BACKGROUND: Tetraclinis articulata is used in traditional medicine and has been reported to possess antibacterial, antifungal, cytotoxic, anti-inflammatory and antioxidant properties. PURPOSE: This study investigated the effects of T. articulata essential oil on memory and brain oxidative stress in amyloid-β peptide 1-42 (Aβ1-42)-induced an Alzheimer's disease amyloidosis model. Moreover, the underlying mechanism for memory enhancement and antioxidant activity was investigated, thus supporting its traditional use with scientific evidence for further studies...
October 31, 2018: Phytomedicine: International Journal of Phytotherapy and Phytopharmacology
Norberto Eiji Nawa, Hiroshi Ando
Autobiographical memories (AMs) are often colored by emotions experienced during an event or those arising following further appraisals. However, how affective components of memories affect the brain-wide network recruited during the recollection of AMs remains largely unknown. Here, we examined effective connectivity during the elaboration of AMs - when retrieved episodic details are integrated to form a vivid construct - in the network composed by ventromedial prefrontal cortex (vmPFC), hippocampus and amygdala, three key regions associated with memory and affective processes...
January 18, 2019: NeuroImage
Ajinkya S Sase, Sonia I Lombroso, Brandon A Santhumayor, Rozalyn R Wood, Carissa J Lim, Rachael L Neve, Elizabeth A Heller
BACKGROUND: Sex differences in the expression and prevalence of trauma- and stress-related disorders have led to a growing interest in the sex-specific molecular and epigenetic mechanisms underlying these diseases. Cyclin-dependent kinase 5 (CDK5) is known to underlie both fear memory and stress behavior in male mice. Given our recent finding that targeted histone acetylation of Cdk5 regulates stress responsivity in male mice, we hypothesized that such a mechanism may be functionally relevant in female mice as well...
December 5, 2018: Biological Psychiatry
Christine Stubbendorff, Ed Hale, Helen J Cassaday, Tobias Bast, Carl W Stevenson
RATIONALE: Dopamine D1 receptor (D1R) signalling is involved in contextual fear conditioning. The D1R antagonist SCH23390 impairs the acquisition of contextual fear when administered systemically or infused locally into the dorsal hippocampus or basolateral amygdala. OBJECTIVES: We determined if state dependency may account for the impairment in contextual fear conditioning caused by systemic SCH23390 administration. We also examined if the dorsomedial prefrontal cortex (dmPFC), nucleus accumbens (NAc), and ventral hippocampus (VH) are involved in mediating the effect of systemic SCH23390 treatment on contextual fear conditioning...
January 17, 2019: Psychopharmacology
Ángel Romero-Martínez, Macarena González, Marisol Lila, Enrique Gracia, Luis Martí-Bonmatí, Ángel Alberich-Bayarri, Rebeca Maldonado-Puig, Amadeo Ten-Esteve, Luis Moya-Albiol
Introduction: There is growing scientific interest in understanding the biological mechanisms affecting and/or underlying violent behaviors in order to develop effective treatment and prevention programs. In recent years, neuroscientific research has tried to demonstrate whether the intrinsic activity within the brain at rest in the absence of any external stimulation (resting-state functional connectivity; RSFC) could be employed as a reliable marker for several cognitive abilities and personality traits that are important in behavior regulation, particularly, proneness to violence...
January 15, 2019: Behavioral Sciences
Saima Zameer, Mohd Akhtar, Divya Vohora
BACKGROUND: Currently, a large number of people throughout the world are affected by neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, Huntington's disease which appear with a lapse in recall, attention and altered cognitive functions. Learning and memory, the fundamental indices defining cognitive functions, are the complex psychological processes governing acquisition, consolidation, and retrieval of stored information. These processes are synchronized by the coordination of various parts of the brain including hippocampus, striatum and amygdala...
January 12, 2019: CNS & Neurological Disorders Drug Targets
Lucy Sykes, Nicholas E Clifton, Jeremy Hall, Kerrie L Thomas
CACNA1C encodes the Cav 1.2 L-type voltage-gated calcium channel. Generic variation in CACNA1C has been consistently identified as associated with risk for psychiatric disorders including schizophrenia, bipolar disorder, major depressive disorder and autism. Psychiatric risk loci are also enriched for genes involved in the regulation of synaptic plasticity. Here, we show that the expression of Cacna1c is regulated in the rat hippocampus after context exposure, contextual fear conditioning and fear memory retrieval in a manner that correlates to specific memory processes...
December 2018: Molecular Neuropsychiatry
Sylvie L Lesuis, Paul J Lucassen, Harm J Krugers
Programming of the brain by early life stress has been associated with alterations in structure and function of the dorsal hippocampus. Yet, the underlying molecular mechanisms remain largely elusive. In this study, we examined the effects of early life stress (ELS) - by housing mouse dams with limited nesting and bedding material from postnatal days 2-9 and examined in 6 month old offspring; 1) auditory fear conditioning, 2) expression of the hippocampal N-methyl-d-aspartate receptor (NMDA-R) subunits 2A and 2B (GluN2A, GluN2B), and expression of PSD-95 and synaptophysin, and 3) short- and long-term (LTP) synaptic plasticity...
January 11, 2019: Neuropharmacology
Clarissa Penha Farias, Cristiane Regina Guerino Furini, Eduarda Godfried Nachtigall, Jonny Anderson Kielbovicz Behling, Eduardo Silva de Assis Brasil, Letícia Bühler, Ivan Izquierdo, Jociane de Carvalho Myskiw
Extinction of contextual fear conditioning (CFC) in the presence of a familiar nonfearful conspecific (social support), such as that of others tasks, can occur regardless of whether the original memory is retrieved during the extinction training. Extinction with social support is blocked by the protein synthesis inhibitors anisomycin and rapamycin and by the inhibitor of gene expression 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole infused immediately after extinction training into the ventromedial prefrontal cortex (vmPFC) but unlike regular CFC extinction not in the CA1 region of the dorsal hippocampus...
January 11, 2019: Proceedings of the National Academy of Sciences of the United States of America
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