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hippocampus assemblies

Edward Basso, Mamiko Arai, Yuri Dabaghian
The mammalian hippocampus plays a crucial role in producing a cognitive map of space-an internalized representation of the animal's environment. We have previously shown that it is possible to model this map formation using a topological framework, in which information about the environment is transmitted through the temporal organization of neuronal spiking activity, particularly those occasions in which the firing of different place cells overlaps. In this paper, we discuss how gamma rhythm, one of the main components of the extracellular electrical field potential affects the efficiency of place cell map formation...
September 2016: PLoS Computational Biology
Arnaud Malvache, Susanne Reichinnek, Vincent Villette, Caroline Haimerl, Rosa Cossart
The chained activation of neuronal assemblies is thought to support major cognitive processes, including memory. In the hippocampus, this is observed during population bursts often associated with sharp-wave ripples, in the form of an ordered reactivation of neurons. However, the organization and lifetime of these assemblies remain unknown. We used calcium imaging to map patterns of synchronous neuronal activation in the CA1 region of awake mice during runs on a treadmill. The patterns were composed of the recurring activation of anatomically intermingled, but functionally orthogonal, assemblies...
September 16, 2016: Science
Marine Krzisch, Christine Fülling, Laura Jabinet, Jan Armida, Elias Gebara, Frédéric Cassé, Samia Habbas, Andrea Volterra, Jean-Pierre Hornung, Nicolas Toni
Postnatal hippocampal neurogenesis induces network remodeling and may participate to mechanisms of learning. In turn, the maturation and survival of newborn neurons is regulated by their activity. Here, we tested the effect of a cell-autonomous overexpression of synaptic adhesion molecules on the maturation and survival of neurons born postnatally and on hippocampal-dependent memory performances. Families of adhesion molecules are known to induce pre- and post-synaptic assembly. Using viral targeting, we overexpressed three different synaptic adhesion molecules, SynCAM1, Neuroligin-1B and Neuroligin-2A in newborn neurons in the dentate gyrus of 7- to 9-week-old mice...
July 29, 2016: Cerebral Cortex
Ayfer Yalcin, Elena Soddu, Ezgi Turunc Bayrakdar, Yigit Uyanikgil, Lutfiye Kanit, Guliz Armagan, Giovanna Rassu, Elisabetta Gavini, Paolo Giunchedi
β-Amyloid (Aβ) plaques are the key neurotoxic assemblies in Alzheimer disease. It has been suggested that an interaction occurs between membrane cholesterol and Aβ aggregation in the brain. Cyclodextrins can remove cholesterol from cell membranes and change receptor function. This study aimed to investigate the effect of hydroxypropyl-β-cyclodextrin (HP-CD) polymeric microspheres, based on chitosan or sodium alginate, on the levels of lipid peroxidation, reactive oxygen species production, and mitochondrial function in brain synaptosomes...
August 2016: Journal of Pharmaceutical Sciences
Kentaro Hoffman, Andrey Babichev, Yuri Dabaghian
The mammalian hippocampus plays a key role in spatial learning and memory, but the exact nature of the hippocampal representation of space is still being explored. Recently, there has been a fair amount of success in modeling hippocampal spatial maps in rats, assuming a topological perspective on spatial information processing. In this article, we use the topological approach to study the formation of a 3D spatial map in bats, which produces several insights into neurophysiological mechanisms of the hippocampal spatial leaning...
October 2016: Hippocampus
Sarah M Guadiana, Alexander K Parker, Gileno F Filho, Ashton Sequeira, Susan Semple-Rowland, Gerry Shaw, Ronald J Mandel, Thomas C Foster, Ashok Kumar, Matthew R Sarkisian
The primary cilia of forebrain neurons assemble around birth and become enriched with neuromodulatory receptors. Our understanding of the permanence of these structures and their associated signaling pathways in the aging brain is poor, but they are worthy of investigation because disruptions in neuronal cilia signaling have been implicated in changes in learning and memory, depression-like symptoms, and sleep anomalies. Here, we asked whether neurons in aged forebrain retain primary cilia and whether the staining characteristics of aged cilia for type 3 adenylyl cyclase (ACIII), somatostatin receptor 3 (SSTR3), and pericentrin resemble those of cilia in younger forebrain...
2016: Frontiers in Aging Neuroscience
Karl Friston, Gyorgy Buzsáki
This Opinion article considers the implications for functional anatomy of how we represent temporal structure in our exchanges with the world. It offers a theoretical treatment that tries to make sense of the architectural principles seen in mammalian brains. Specifically, it considers a factorisation between representations of temporal succession and representations of content or, heuristically, a segregation into when and what. This segregation may explain the central role of the hippocampus in neuronal hierarchies while providing a tentative explanation for recent observations of how ordinal sequences are encoded...
July 2016: Trends in Cognitive Sciences
Erno J Hermans, Jonathan W Kanen, Arielle Tambini, Guillén Fernández, Lila Davachi, Elizabeth A Phelps
After encoding, memories undergo a process of consolidation that determines long-term retention. For conditioned fear, animal models postulate that consolidation involves reactivations of neuronal assemblies supporting fear learning during postlearning "offline" periods. However, no human studies to date have investigated such processes, particularly in relation to long-term expression of fear. We tested 24 participants using functional MRI on 2 consecutive days in a fear conditioning paradigm involving 1 habituation block, 2 acquisition blocks, and 2 extinction blocks on day 1, and 2 re-extinction blocks on day 2...
May 30, 2016: Cerebral Cortex
Daniel Carneiro Carrettiero, Fernando Enrique Santiago, Anna Carolina Parracho Motzko-Soares, Maria Camila Almeida
Alzheimer's disease (AD), the most common dementia in the elderly, is characterized by cognitive impairment and severe autonomic symptoms such as disturbance in core body temperature (Tc), which may be predictors or early events in AD onset. Inclusions of phosphorylated Tau (p-Tau) are a hallmark of AD and other neurodegenerative disorders called "Tauopathies." Animal and human studies show that anesthesia augments p-Tau levels through reduction of Tc, with implications for AD. Additionally, hypothermia impairs memory and cognitive function...
October 2015: Temperature: Multidisciplinary Biomedical Journal
Qiang Lin, Wei Luo, Shiming Wan, Zexia Gao
Seahorse conservation has been performed utilizing various strategies for many decades, and the deeper understanding of genomic information is necessary to more efficiently protect the germplasm resources of seahorse species. However, little genetic information about seahorses currently exists in the public databases. In this study, high-throughput RNA sequencing for two seahorse species, Hippocampus erectus and H. mohnikei, was carried out, and de novo assembly generated 37,506 unigenes for H. erectus and 36,113 unigenes for H...
2016: PloS One
Tomoyuki Nishizaki
N-Ethylmaleimide (NEM)-sensitive factor (NSF) associates with soluble NSF attachment protein (SNAP), that binds to SNAP receptors (SNAREs) including syntaxin, SNAP25, and synaptobrevin. The complex of NSF/SNAP/SNAREs plays a critical role in the regulation of vesicular traffic. The present study investigated NEM-regulated α7 ACh receptor translocation. NSF associated with β-SNAP and the SNAREs syntaxin 1 and synaptobrevin 2 in the rat hippocampus. NSF also associated with the α7 ACh receptor subunit, the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunits GluA1 and GluA2, and the γ-aminobutyric acid A (GABAA) receptor γ2 subunit...
August 2016: Neurochemical Research
Melis Inan, Mingrui Zhao, Monica Manuszak, Cansu Karakaya, Anjali M Rajadhyaksha, Virginia M Pickel, Theodore H Schwartz, Peter A Goldstein, Giovanni Manfredi
Parvalbumin-expressing, fast spiking interneurons have high-energy demands, which make them particularly susceptible to energy impairment. Recent evidence suggests a link between mitochondrial dysfunction in fast spiking cortical interneurons and neuropsychiatric disorders. However, the effect of mitochondrial dysfunction restricted to parvalbumin interneurons has not been directly addressed in vivo. To investigate the consequences of mitochondrial dysfunction in parvalbumin interneurons in vivo, we generated conditional knockout mice with a progressive decline in oxidative phosphorylation by deleting cox10 gene selectively in parvalbumin neurons (PV-Cox10 CKO)...
September 2016: Neurobiology of Disease
Theresa Burt de Perera, Robert I Holbrook, Victoria Davis
In mammals, the so-called "seat of the cognitive map" is located in place cells within the hippocampus. Recent work suggests that the shape of place cell fields might be defined by the animals' natural movement; in rats the fields appear to be laterally compressed (meaning that the spatial map of the animal is more highly resolved in the horizontal dimensions than in the vertical), whereas the place cell fields of bats are statistically spherical (which should result in a spatial map that is equally resolved in all three dimensions)...
2016: Frontiers in Behavioral Neuroscience
Johannes Weller, Christian Steinhäuser, Gerald Seifert
Based on their intimate spatial association with synapses and the capillary, astrocytes are critically involved in the control of ion, transmitter, and energy homeostasis as well as regulation of the cerebral blood flow. Under pathophysiological conditions, dysfunctional astrocytes can no longer assure homeostatic control although the underlying mechanisms are poorly understood. Specifically, neurological diseases are often accompanied by acidification of the extracellular space, but the properties of astrocytes in such an acidic environment are still a matter of debate...
2016: Advances in Protein Chemistry and Structural Biology
Joseph J Cicchese, Stephen D Berry
Typical information processing is thought to depend on the integrity of neurobiological oscillations that may underlie coordination and timing of cells and assemblies within and between structures. The 3-7 Hz bandwidth of hippocampal theta rhythm is associated with cognitive processes essential to learning and depends on the integrity of cholinergic, GABAergic, and glutamatergic forebrain systems. Since several significant psychiatric disorders appear to result from dysfunction of medial temporal lobe (MTL) neurochemical systems, preclinical studies on animal models may be an important step in defining and treating such syndromes...
2016: Frontiers in Psychiatry
Ricardo J Rodrigues, Teresa Almeida, Miguel Díaz-Hernández, Joana M Marques, Rafael Franco, Carles Solsona, María Teresa Miras-Portugal, Francisco Ciruela, Rodrigo A Cunha
Previous studies documented a cross-talk between purinergic P2X (P2XR) and nicotinic acetylcholine receptors (nAChR) in heterologous expression systems and peripheral preparations. We now investigated if this occurred in native brain preparations and probed its physiological function. We found that P2XR and nAChR were enriched in hippocampal terminals, where both P2X1-3R and α3, but not α4, nAChR subunits were located in the active zone and in dopamine-β-hydroxylase-positive hippocampal terminals. Notably, P2XR ligands displaced nAChR binding and nAChR ligands displaced P2XR binding to hippocampal synaptosomes...
June 2016: Neuropharmacology
Lei Wang, Zaizhong Chen, Xiangjun Leng, Jianzhong Gao, Xiaowu Chen, Zhongpu Li, Peiying Sun, Yuming Zhao
In this study, the complete mitogenome sequence of the big-belly seahorse, Hippocampus abdominalis (Lesson, 1827) (Syngnathiformes: Syngnathidae), has been sequenced by the next-generation sequencing method. The assembled mitogenome is 16 521 bp in length which includes 13 protein-coding genes, 22 transfer RNAs, and 2 ribosomal RNAs genes. The overall base composition of the seahorse is 31.1% for A, 23.6% for C, 16.0% for G, 29.3% for T and shows 87% identities similar to tiger tail seahorse, Hippocampus comes...
December 28, 2015: Mitochondrial DNA
Gunes Unal, Abhilasha Joshi, Tim J Viney, Viktor Kis, Peter Somogyi
Temporal coordination of neuronal assemblies among cortical areas is essential for behavioral performance. GABAergic projections from the medial septum and diagonal band complex exclusively innervate GABAergic interneurons in the rat hippocampus, contributing to the coordination of neuronal activity, including the generation of theta oscillations. Much less is known about the synaptic target neurons outside the hippocampus. To reveal the contribution of synaptic circuits involving the medial septum of mice, we have identified postsynaptic cortical neurons in wild-type and parvalbumin-Cre knock-in mice...
December 2, 2015: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Natalia Borovok, Elimelech Nesher, Yishai Levin, Michal Reichenstein, Albert Pinhasov, Izhak Michaelevski
Spatial memory depends on the hippocampus, which is particularly vulnerable to aging. This vulnerability has implications for the impairment of navigation capacities in older people, who may show a marked drop in performance of spatial tasks with advancing age. Contemporary understanding of long-term memory formation relies on molecular mechanisms underlying long-term synaptic plasticity. With memory acquisition, activity-dependent changes occurring in synapses initiate multiple signal transduction pathways enhancing protein turnover...
February 2016: Molecular & Cellular Proteomics: MCP
Max Anstötz, Hao Huang, Ivan Marchionni, Iris Haumann, Gianmaria Maccaferri, Joachim H R Lübke
Cajal-Retzius (CR) cells are early generated neurons, involved in the assembly of developing neocortical and hippocampal circuits. However, their roles in networks of the postnatal brain remain poorly understood. In order to get insights into these latter functions, we have studied their morphological and synaptic properties in the postnatal hippocampus of the CXCR4-EGFP mouse, where CR cells are easily identifiable. Our data indicate that CR cells are nonuniformly distributed along different subfields of the hippocampal formation, and that their postnatal decline is regulated in a region-specific manner...
February 2016: Cerebral Cortex
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