Academic literature on the topic 'Mammalian medial entorhinal cortex'
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Journal articles on the topic "Mammalian medial entorhinal cortex"
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Medina, Loreta, Antonio Abellán, and Ester Desfilis. "Contribution of Genoarchitecture to Understanding Hippocampal Evolution and Development." Brain, Behavior and Evolution 90, no. 1 (2017): 25–40. http://dx.doi.org/10.1159/000477558.
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The hippocampal formation is a highly conserved structure of the medial pallium that works in association with the entorhinal cortex, playing a key role in memory formation and spatial navigation. Although it has been described in several vertebrates, the presence of comparable subdivisions across species remained unclear. This panorama has started to change in recent years thanks to the identification of some of the genes that regulate the development of the hippocampal formation in the mouse and help to delineate its subdivisions based on molecular features. Some of these genes have been used to try to identify subdivisions in chicken and lizards comparable to those of the mammalian hippocampal formation and the entorhinal cortex. Here, we review some of these data, which suggest the existence of fields comparable to the dentate gyrus, CA3, CA1, subiculum, as well as medial and lateral parts of the entorhinal cortex in all amniotes. We also analyze available data suggesting the existence of serial connections between these fields, speculate on the possible existence of auto-associative loops in CA3, and discuss general principles governing the formation of the connections.
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Zhang, Sheng-Jia, Jing Ye, Jonathan J. Couey, Menno Witter, Edvard I. Moser, and May-Britt Moser. "Functional connectivity of the entorhinal–hippocampal space circuit." Philosophical Transactions of the Royal Society B: Biological Sciences 369, no. 1635 (February 5, 2014): 20120516. http://dx.doi.org/10.1098/rstb.2012.0516.
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The mammalian space circuit is known to contain several functionally specialized cell types, such as place cells in the hippocampus and grid cells, head-direction cells and border cells in the medial entorhinal cortex (MEC). The interaction between the entorhinal and hippocampal spatial representations is poorly understood, however. We have developed an optogenetic strategy to identify functionally defined cell types in the MEC that project directly to the hippocampus. By expressing channelrhodopsin-2 (ChR2) selectively in the hippocampus-projecting subset of entorhinal projection neurons, we were able to use light-evoked discharge as an instrument to determine whether specific entorhinal cell groups—such as grid cells, border cells and head-direction cells—have direct hippocampal projections. Photoinduced firing was observed at fixed minimal latencies in all functional cell categories, with grid cells as the most abundant hippocampus-projecting spatial cell type. We discuss how photoexcitation experiments can be used to distinguish the subset of hippocampus-projecting entorhinal neurons from neurons that are activated indirectly through the network. The functional breadth of entorhinal input implied by this analysis opens up the potential for rich dynamic interactions between place cells in the hippocampus and different functional cell types in the entorhinal cortex (EC).
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Cuneo, J., L. Barboni, N. Blanco, M. del Castillo, and J. Quagliotti. "ARM-Cortex M3-Based Two-Wheel Robot for Assessing Grid Cell Model of Medial Entorhinal Cortex: Progress towards Building Robots with Biologically Inspired Navigation-Cognitive Maps." Journal of Robotics 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/8069654.
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This article presents the implementation and use of a two-wheel autonomous robot and its effectiveness as a tool for studying the recently discovered use of grid cells as part of mammalian’s brains space-mapping circuitry (specifically the medial entorhinal cortex). A proposed discrete-time algorithm that emulates the medial entorhinal cortex is programed into the robot. The robot freely explores a limited laboratory area in the manner of a rat or mouse and reports information to a PC, thus enabling research without the use of live individuals. Position coordinate neural maps are achieved as mathematically predicted although for a reduced number of implemented neurons (i.e., 200 neurons). However, this type of computational embedded system (robot’s microcontroller) is found to be insufficient for simulating huge numbers of neurons in real time (as in the medial entorhinal cortex). It is considered that the results of this work provide an insight into achieving an enhanced embedded systems design for emulating and understanding mathematical neural network models to be used as biologically inspired navigation system for robots.
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Ye, Jing, Menno P. Witter, May-Britt Moser, and Edvard I. Moser. "Entorhinal fast-spiking speed cells project to the hippocampus." Proceedings of the National Academy of Sciences 115, no. 7 (January 31, 2018): E1627—E1636. http://dx.doi.org/10.1073/pnas.1720855115.
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The mammalian positioning system contains a variety of functionally specialized cells in the medial entorhinal cortex (MEC) and the hippocampus. In order for cells in these systems to dynamically update representations in a way that reflects ongoing movement in the environment, they must be able to read out the current speed of the animal. Speed is encoded by speed-responsive cells in both MEC and hippocampus, but the relationship between the two populations has not been determined. We show here that many entorhinal speed cells are fast-spiking putative GABAergic neurons. Using retrograde viral labeling from the hippocampus, we find that a subset of these fast-spiking MEC speed cells project directly to hippocampal areas. This projection contains parvalbumin (PV) but not somatostatin (SOM)-immunopositive cells. The data point to PV-expressing GABAergic projection neurons in MEC as a source for widespread speed modulation and temporal synchronization in entorhinal–hippocampal circuits for place representation.
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Sun, Chen, Takashi Kitamura, Jun Yamamoto, Jared Martin, Michele Pignatelli, Lacey J. Kitch, Mark J. Schnitzer, and Susumu Tonegawa. "Distinct speed dependence of entorhinal island and ocean cells, including respective grid cells." Proceedings of the National Academy of Sciences 112, no. 30 (July 13, 2015): 9466–71. http://dx.doi.org/10.1073/pnas.1511668112.
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Entorhinal–hippocampal circuits in the mammalian brain are crucial for an animal’s spatial and episodic experience, but the neural basis for different spatial computations remain unknown. Medial entorhinal cortex layer II contains pyramidal island and stellate ocean cells. Here, we performed cell type-specific Ca2+ imaging in freely exploring mice using cellular markers and a miniature head-mounted fluorescence microscope. We found that both oceans and islands contain grid cells in similar proportions, but island cell activity, including activity in a proportion of grid cells, is significantly more speed modulated than ocean cell activity. We speculate that this differential property reflects island cells’ and ocean cells’ contribution to different downstream functions: island cells may contribute more to spatial path integration, whereas ocean cells may facilitate contextual representation in downstream circuits.
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Krupic, Julija, Marius Bauza, Stephen Burton, Colin Lever, and John O'Keefe. "How environment geometry affects grid cell symmetry and what we can learn from it." Philosophical Transactions of the Royal Society B: Biological Sciences 369, no. 1635 (February 5, 2014): 20130188. http://dx.doi.org/10.1098/rstb.2013.0188.
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The mammalian hippocampal formation provides neuronal representations of environmental location but the underlying mechanisms are unclear. The majority of cells in medial entorhinal cortex and parasubiculum show spatially periodic firing patterns. Grid cells exhibit hexagonal symmetry and form an important subset of this more general class. Occasional changes between hexagonal and non-hexagonal firing patterns imply a common underlying mechanism. Importantly, the symmetrical properties are strongly affected by the geometry of the environment. Here, we introduce a field–boundary interaction model where we demonstrate that the grid cell pattern can be formed from competing place-like and boundary inputs. We show that the modelling results can accurately capture our current experimental observations.
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Stemmler, Martin, Alexander Mathis, and Andreas V. M. Herz. "Connecting multiple spatial scales to decode the population activity of grid cells." Science Advances 1, no. 11 (December 2015): e1500816. http://dx.doi.org/10.1126/science.1500816.
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Mammalian grid cells fire when an animal crosses the points of an imaginary hexagonal grid tessellating the environment. We show how animals can navigate by reading out a simple population vector of grid cell activity across multiple spatial scales, even though neural activity is intrinsically stochastic. This theory of dead reckoning explains why grid cells are organized into discrete modules within which all cells have the same lattice scale and orientation. The lattice scale changes from module to module and should form a geometric progression with a scale ratio of around 3/2 to minimize the risk of making large-scale errors in spatial localization. Such errors should also occur if intermediate-scale modules are silenced, whereas knocking out the module at the smallest scale will only affect spatial precision. For goal-directed navigation, the allocentric grid cell representation can be readily transformed into the egocentric goal coordinates needed for planning movements. The goal location is set by nonlinear gain fields that act on goal vector cells. This theory predicts neural and behavioral correlates of grid cell readout that transcend the known link between grid cells of the medial entorhinal cortex and place cells of the hippocampus.
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Schwartz, David M., and O. Ozan Koyluoglu. "On the Organization of Grid and Place Cells: Neural Denoising via Subspace Learning." Neural Computation 31, no. 8 (August 2019): 1519–50. http://dx.doi.org/10.1162/neco_a_01208.
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Place cells in the hippocampus (HC) are active when an animal visits a certain location (referred to as a place field) within an environment. Grid cells in the medial entorhinal cortex (MEC) respond at multiple locations, with firing fields that form a periodic and hexagonal tiling of the environment. The joint activity of grid and place cell populations, as a function of location, forms a neural code for space. In this article, we develop an understanding of the relationships between coding theoretically relevant properties of the combined activity of these populations and how these properties limit the robustness of this representation to noise-induced interference. These relationships are revisited by measuring the performances of biologically realizable algorithms implemented by networks of place and grid cell populations, as well as constraint neurons, which perform denoising operations. Contributions of this work include the investigation of coding theoretic limitations of the mammalian neural code for location and how communication between grid and place cell networks may improve the accuracy of each population's representation. Simulations demonstrate that denoising mechanisms analyzed here can significantly improve the fidelity of this neural representation of space. Furthermore, patterns observed in connectivity of each population of simulated cells predict that anti-Hebbian learning drives decreases in inter-HC-MEC connectivity along the dorsoventral axis.
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Netoff, Theoden I., Matthew I. Banks, Alan D. Dorval, Corey D. Acker, Julie S. Haas, Nancy Kopell, and John A. White. "Synchronization in Hybrid Neuronal Networks of the Hippocampal Formation." Journal of Neurophysiology 93, no. 3 (March 2005): 1197–208. http://dx.doi.org/10.1152/jn.00982.2004.
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Understanding the mechanistic bases of neuronal synchronization is a current challenge in quantitative neuroscience. We studied this problem in two putative cellular pacemakers of the mammalian hippocampal theta rhythm: glutamatergic stellate cells (SCs) of the medial entorhinal cortex and GABAergic oriens-lacunosum-moleculare (O-LM) interneurons of hippocampal region CA1. We used two experimental methods. First, we measured changes in spike timing induced by artificial synaptic inputs applied to individual neurons. We then measured responses of free-running hybrid neuronal networks, consisting of biological neurons coupled (via dynamic clamp) to biological or virtual counterparts. Results from the single-cell experiments predicted network behaviors well and are compatible with previous model-based predictions of how specific membrane mechanisms give rise to empirically measured synchronization behavior. Both cell types phase lock stably when connected via homogeneous excitatory-excitatory (E-E) or inhibitory-inhibitory (I-I) connections. Phase-locked firing is consistently synchronous for either cell type with E-E connections and nearly anti-synchronous with I-I connections. With heterogeneous connections (e.g., excitatory-inhibitory, as might be expected if members of a given population had heterogeneous connections involving intermediate interneurons), networks often settled into phase locking that was either stable or unstable, depending on the order of firing of the two cells in the hybrid network. Our results imply that excitatory SCs, but not inhibitory O-LM interneurons, are capable of synchronizing in phase via monosynaptic mutual connections of the biologically appropriate polarity. Results are largely independent of synaptic strength and synaptic kinetics, implying that our conclusions are robust and largely unaffected by synaptic plasticity.
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Biella, Gerardo, and Marco de Curtis. "Olfactory Inputs Activate the Medial Entorhinal Cortex Via the Hippocampus." Journal of Neurophysiology 83, no. 4 (April 1, 2000): 1924–31. http://dx.doi.org/10.1152/jn.2000.83.4.1924.
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The lateral and medial regions of the entorhinal cortex differ substantially in terms of connectivity and pattern of activation. With regard to olfactory input, a detailed and extensive physiological map of the olfactory projection to the entorhinal cortex is missing, even if anatomic studies suggest that the olfactory afferents are confined to the lateral and rostral entorhinal region. We studied the contribution of the medial and lateral entorhinal areas to olfactory processing by analyzing the responses induced by lateral olfactory tract stimulation in different entorhinal subfields of the in vitro isolated guinea pig brain. The pattern of synaptic activation of the medial and lateral entorhinal regions was reconstructed either by performing simultaneous multisite recordings or by applying current source density analysis on field potential laminar profiles obtained with 16-channel silicon probes. Current source density analysis demonstrated the existence of a direct monosynaptic olfactory input into the superficial 300 μm of the most rostral part of the lateral entorhinal cortex exclusively, whereas disynaptic sinks mediated by associative fibers arising from the piriform cortex were observed at 100–350 μm depth in the entire lateral aspect of the cortex. No local field responses were recorded in the medial entorhinal region unless a large population spike was generated in the hippocampus (dentate gyrus and CA1 region) by a stimulus 3–5× the intensity necessary to obtain a maximal monosynaptic response in the piriform cortex. In these conditions, a late sink was recorded at a depth of 600-1000 μm in the medial entorhinal area (layers III–V) 10.6 ± 0.9 (SD) msec after a population spike was simultaneously recorded in CA1. Diffuse activation of the medial entorhinal region was also obtained by repetitive low-intensity stimulation of the lateral olfactory tract at 2–8 Hz. Higher or lower stimulation frequencies did not induce hippocampal-medial entorhinal cortex activation. These results suggest that the medial and the lateral entorhinal regions have substantially different roles in processing olfactory sensory inputs.
Dissertations / Theses on the topic "Mammalian medial entorhinal cortex"
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Stensola, Tor. "Population codes in medial entorhinal cortex." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for nevromedisin, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25419.
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Populasjonskoder i mediale entorhinal korteks Hjernebarken utfører kontinuerlig et velde av kompliserte funksjoner, hvis mekanismer vi kan tjene mye på å forstå. Nevrovitenskap er et relativt nytt fag, men med utrolig moment. Mye vites i dag om enkle nevroners egenskaper, men nevral komputering foregår i store trekk i interaksjonene mellom celler. Men på dette planet er det mange hindere som må overkommes; teknologisk nyvinning og konseptuell modning har ført til at nevrovitenskap gjennom de senere år har kunnet tilnærme seg spørsmal som fanger mekanismer på systemnivå. Hippokampus, som inneholder stedsselektive celler, utgjør et eksperimentelt system som tillater spørsmål om visse kjernemekanismer, slik som hukommelsesfunskjon og intern representasjonsdynamikk, uten streng ekpserimentell kontroll på innkommende og utgående signaler slik man baserer seg på i for eksempel sansenevrovitenskap. I hippokampusforskning er dyrets naturlige adferd en enorm ressurs. På grunn av den sterke tilknytningen til rom kan man ved å korrelere nevral aktivitet til dyrets adferd etablere svært robuste forhold mellom nevronenes aktivitet og funksjon på adferdnivå. Dette har ført til at hippokampusforskning har blitt en foregangsfront på innsamling av store datasett i dyr under normal adferd, samt tolkning av denne i adferdskontekst. Et stort skritt mot å forstå hvordan stedsselektiviteten i hippokampus oppstår og brukes kom med funnet av gitterceller, celler som er aktive i et gittermønster som dekker hele miljøet. Vi vet mye om disse cellenes oppførsel på enkeltcellenivå, men på grunn av teknisk krevende innspillingsteknikk har det vært vanskelig å spille inn nok celler til å forstå hvordan disse kombinerer til en populasjonskode for rom. Denne hindringen har vi nå overkommet, og i første arbeid brukte vi nye teknikker for å spille inn store antall gitterceller innen dyr og viser at gittercellekartet er organisert i moduler, hver med sin egen kartgeometri. Vi viser hvordan disse modulene er fordelt i vevet, og utviklet nye analyser for å beskive modulenes egenskaper. Vi viser at gitterkart i forskjellige moduler inad i dyr ikke bare kan innta forskjellig geometriske former, men også utføre separate operasjoner samtidig på samme eksperimentelle manipulering. Dette er første bevis på slik uavhengig funksjon i gitterkartet, og foreslår hvordan stedsceller kan generere høykapasitetslagring av representasjoner for forskjellige miljø. I andre arbeid beskriver vi hvordan en annen funksjonelt definert cellegruppe i entorhinal korteks fungerer på populasjonsnivå, denne gangen for celler som koder retning til dyret i forhold til miljøet. Vi viser at denne populasjonen har en topografisk fordeling langs samme akse i vevet som gitterceller utviser topografi, men at denne er kontinuerlig i motsetning til gitterkartets modulære fordeling. I siste arbeid viser vi at miljøets geometri bestemmer hvordan gitterkartet ankres til det eksterne rom. Vi beskriver en universal ankringsstrategi som er optimal for å skape størst mulig forskjell mellom populasjonskoder for områder langs rommets grenser. Dette brukes kanskje til å forhindre sanseforvirring av gitterkartet i miljø med geometrisk ambiguøse segmenter. Avhandlingen legger frem første beskrivelser av nevrale mekanismer på populasjonsnivå i entorhinal korteks, og gir flere innsikter i generell organisering av nettverkene som er involvert i stedssans og hukommelseCurrent systems neuroscience has unprecedented momentum, in terms of both technological and conceptual development. It is crucial to study systems mechanisms and their associated functions with behavior in mind. Hippocampal and parahippocampal cortices has proved a highly suitable experimental system because the high level functions that are performed here, including episodic memory formation, are accessible through the clear readout of spatial behavior. Grid cells in medial entorhinal cortex (MEC) have been proposed to account for the spatial selectivity in downstream hippocampal place cells. Until now, however, entorhinal grid cells have only been studied on single cell– or small local ensemble level. The main reason for population studies lagging behind that of hippocampus is the technical difficulties associated with entorhinal implantation and recording. Here we have overcome some of the main technical hurdles, and recorded unprecedented number of cells from distinct functional classes in MEC. We show in Paper 1 that the entorhinal grid map is organized into sub-maps–or modules–that contain grid cells sharing numerous features including spatial pattern scale, orientation, deformation and temporal modulation. We also demonstrate that grid modules in the same system can operate independently on the same input, raising the possibility that hippocampal capacity for encoding distinct spatial representations is enabled by the grid input. We further show in Paper 2 that also head direction cells in entorhinal cortex distribute according to a functional topography along the dorsoventral axis. The head direction system, however, was not modular in contrast to the grid system. Finally, Paper 3 details a common grid anchoring strategy shared across animals and environments. The grid pattern displayed a striking tendency to align to the cardinal axes of the environment, but systematically offset 7.5°. Through simulations, we show that this constitutes an optimal orientation of the grid to maximally decorrelate population encoding of environment border segments, providing a possible link to border-selective cells in the mechanisms that embeds internal representation of space into external frames of reference. These findings have implications for our understanding of entorhinal and hippocampal computations and add several new venues for further investigation.
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Tang, Qiusong. "Structure function relationships in medial entorhinal cortex." Doctoral thesis, Humboldt-Universität zu Berlin, Lebenswissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17163.
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In dieser Arbeit werden Struktur-Funktionsbeziehungen in der medialen entorhinalen Hirnrinde untersucht. Schicht 2 Neurone im medialen entorhinalen Cortex unterteilen sich in calbindin-positive Pyramidenzellen und calbindin-negative Sternzellen. Calbindin-positive Pyramidenzellen bündeln ihre apikalen Dendriten zusammen und formen Zellhaufen, die in einem hexagolen arrangiert sind. Das Gitter von calbindin-positiven Pyramidenzellhaufen ist an Schicht 1 Axonen und dem Parasubiculum ausgerichtet und wird durch cholinerge Eingänge innerviert. Calbindin-positive Pyramidenzellen zeigen stark theta-modulierte Aktivität. Sternzellen sind vertreut in der Schicht 2 angeordnet und zeigen nur schwach theta-modulierte Aktivität, ein Befund, der gegen eine Rolle von zell-intrinsischen Oszillationen in der Entstehung von Theta-Modulation spricht. In der Arbeit wurden Methoden entwickelt, um durch die juxtazelluläre Färbung und Identifikation von Zellen, die räumlichen Feuermuster von Schicht 2 Sternzellen und Pyramidenzellen zu bestimmen. Insbesondere wird gezeigt, dass die zeitlichen Feuermuster von Sternzellen und Pyramidenzellen so unterschiedlich sind, dass auch Daten von nichtidentifizierten extrazellulär abgeleiteten Zellen Sternzellen und Pyramidenzellen zugeordnet werden können. Die Ergebnisse zeigen, dass Gitterzell (engl. grid cell) Feuermuster relativ selten sind und in der Regel in Pyramidenzellen beobachtet werden. Grenzzell (engl. border cell) Feuermuster sind dagegen meistens in Sternzellen zu beobachten. Weiterhin wurde die Anatomie und Physiologie des Parasubiculums untersucht. Die Ergebnisse deuten auf die Existenz eines hexagonalen ‘Gitterzell-gitters’ in der entorhinalen Hirnrinde hin und sprechen für starke Struktur-Funktionsbeziehungen in diesem Teil der Hirnrinde.Little is known about how medial entorhinal cortical microcircuits contribute to spatial navigation. Layer 2 principal neurons of medial entorhinal cortex divide into calbindin-positive pyramidal cells and dentate-gyrus-projecting calbindin-negative stellate cells. Calbindin-positive pyramidal cells bundled dendrites together and formed patches arranged in a hexagonal grid aligned to layer 1 axons, parasubiculum and cholinergic inputs. Calbindin-positive pyramidal cells were strongly theta modulated. Calbindin-negative stellate cells were distributed across layer 2 but avoided centers of calbindin-positive pyramidal patches, and were weakly theta modulated. We developed techniques for anatomical identification of single neurons recorded in trained rats engaged in exploratory behavior. Furthermore, we assigned unidentified juxtacellular and extracellular recordings based on spike phase locking to field potential theta. In layer 2 of medial entorhinal cortex, weakly hexagonal spatial discharges and head direction selectivity were observed in both cell types. Clear grid discharges were predominantly pyramidal cells. Border cells were mainly stellate neurons. Thus, weakly theta locked border responses occurred in stellate cells, whose dendrites sample large input territories, whereas strongly theta-locked grid discharges occurred in pyramidal cells, which sample small input territories in patches organized in a hexagonal ‘grid-cell-grid’. In addition, we investigated anatomical structures and neuronal discharge patterns of the parasubiculum. The parasubiculum is a primary target of medial septal inputs and parasubicular output preferentially targeted patches of calbindin-positive pyramidal cells in layer 2 of medial entorhinal cortex. Parasubicular cells were strongly theta modulated and carried mostly head-direction and border information, and might contribute to shape theta-rhythmicity and the (dorsoventral) integration of information across entorhinal grid scales.
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Ray, Saikat. "Functional architecture of the medial entorhinal cortex." Doctoral thesis, Humboldt-Universität zu Berlin, Lebenswissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17595.
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Schicht 2 des mediale entorhinale Kortex (MEK) beinhaltet die größte Anzahl von Gitterzellen, welche durch ein hexagonales Aktivitätsmuster während räumlicher Exploration gekennzeichnet sind. In dieser Arbeit wurde gezeigt, dass spezielle Pyramidenzellen, die das Protein Calbindin exprimieren, in einem hexagonalen Gitter im Gehirn der Ratte angeordnet sind und cholinerg innerviert werden. Es ist bekannt, dass die cholinerge Innervation wichtig für die Aktivität von Gitterzellen ist. Weiterhin ergaben neuronale Ableitungen und Methoden zur Identifikaktion einzelner Neurone in frei verhaltenden Ratten, dass Calbindin-positive Pyramidenzellen (Calbindin+) eine große Anzahl von Gitterzellen beinhalten. Reelin-positive Sternzellen (Reelin+) im MEK, zeigten keine anatomische Periodizität und ihre Aktivität orientierte sich an den Begrenzungen der Umgebung. Eine weitere Studie untersucht die Architektur des MEK in verschiedenen Säugetieren, die von der Etrusker Spitzmaus, bis hin zum Menschen ~100 Millionen Jahre evolutionäre Vielfalt und ~20,000 fache Variation der Gehirngröße umfassen. Alle Arten zeigten jeweils eine periodische Anhäufung der Calbindin+ Zellen, was deren evolutive Bedeutung unterstreicht. Eine Studie zur Ontogenese der Calbindin Anhäufungen ergab, dass die periodische Struktur der Calbindin+ Zellen, sowie die verstreute Anordnung der Reelin+ Sternzellen schon zum Zeitpunkt der Geburt erkennbar war. Weitere Ergebnisse zeigen, dass Calbindin+ Zellen strukturell später ausreifen als Reelin+ Sternzellen - passend zu der Erkenntnis, dass Gitterzellen funktionell später reifen als Grenzzellen. Eine Untersuchung des Parasubiculums ergab, dass Verbindungen zum MEK präferiert in die Calbindin Anhäufungen in Schicht 2 projizieren. Zusammenfassend beschreibt diese Doktorarbeit eine Dichotomie von Struktur und Funktion in Schicht 2 des MEK, welche fundamental für das Verständnis von Gedächtnisbildung und deren zugrundeliegenden Mikroschaltkreisen ist.The medial entorhinal cortex (MEC) is an important hub in the memory circuit in the brain. This thesis comprises of a group of studies which explores the architecture and microcircuits of the MEC. Layer 2 of MEC is home to grid cells, neurons which exhibit a hexagonal firing pattern during exploration of an open environment. The first study found that a group of pyramidal cells in layer 2 of the MEC, expressing the protein calbindin, were clustered in the rat brain. These patches were physically arranged in a hexagonal grid in the MEC and received preferential cholinergic-inputs which are known to be important for grid-cell activity. A combination of identified single-cell and extracellular recordings in freely behaving rats revealed that grid cells were mostly calbindin-positive pyramidal cells. Reelin-positive stellate cells in MEC were scattered throughout layer 2 and contributed mainly to the border cell population– neurons which fire at the borders of an environment. The next study explored the architecture of the MEC across evolution. Five mammalian species, spanning ~100 million years of evolutionary diversity and ~20,000 fold variation in brain size exhibited a conserved periodic layout of calbindin-patches in the MEC, underscoring their importance. An investigation of the ontogeny of the MEC in rats revealed that the periodic structure of the calbindin-patches and scattered layout of reelin-positive stellate cells was present around birth. Further, calbindin-positive pyramidal cells matured later in comparison to reelin-positive stellate cells mirroring the difference in functional maturation profiles of grid and border cells respectively. Inputs from the parasubiculum, selectively targeted calbindin-patches in the MEC indicating its role in shaping grid-cell function. In summary, the thesis uncovered a structure-function dichotomy of neurons in layer 2 of the MEC which is a fundamental aspect of understanding the microcircuits involved in memory formation.
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Wågen, Rine Sørlie. "Functional Dissection of Local Medial Entorhinal Cortex Subcircuit." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for nevromedisin, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25537.
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The superficial layers of the medial entorhinal cortex(MEC) contain serval functionally specialized spatial cell types. suck a grid cells, head direction cells, border cells and cells with conjunctive properties. It is currently not know how the firing patterns of these vell populations map onto the architecture og the MEC circuit. Results from recent work suggest that there are two largely non-overlapping neuronal populations within superficial layers of MEC with different prosjecting targets. One of them target the hippocampus while the other prosjects extrahippocampally. It has been shown that all funtional MEC cell types prosject to the hippocampus, and a large part of these cells were grid cells. Based on these observations we wanted to investigate if there is a firrerence in fruntional cell distribution of MEC cells projecting to the contralateral MEC and cells prosjecting to hippocampus. Retrogradely transportable recombinant adeno-associated virus expressing Flag-tagged channelrhodopsin-2(ChR2), was injected in left MEC of 6 rats. This introduced optogenetic control over MEC neurons with direct årosjection to the contralateral MEC. Combining optogenetic and electrophysiological in vivo recordings, allowed identification of functional cell types with direct prosjection to the contralateral MEC, as these cells showed minimal response latencies to laser stimulations in the medial entorhinal cortex. We found border cells, head direction cells, non-spatial cells and interneurons with direct projection to the MEC, but no grid cells. This distrubution is in contrasts with the one found to project to the hippocampus, where grid cells are the predominant spatial cell type. More data are requred to determine if the sparsity of respnsive grid cells reflects limited sampling, or if the contralaterally--projecting cell population has distinct functional properties.
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Berndtsson, Christin H. "The Specificity of Output from Medial Entorhinal Cortex." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for nevromedisin, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25538.
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The hippocampal formation(HF) and the parahippocampal region (PHR) have been implicated in learning and memory functions. These regions and their subregions form a highly interconnected and complex microcircuitry, where the entorhinal cortex consitutes the nodal point between the hippocampal formation and the cortex. The entorhinal cortex conssists of ywo functionally distinct subregions. It had been suggested that this diffrence in functional output results from differences in microcircuitry, and input and output characteristics whithin the regions. Therefore, in order to understand the function of the entorhinal cortex and how it contributes to the rest of the HF-PHR network, it is necessary to understand the microcircuity whitin the region. This study investigates the specificity of output from cell populations located in superficial layers of the medial entorhinal cortex. Fluorescent retrograde traces were injected into dorsal dentate gyrus(DG)and the dorsal medial enthorhinal cortex(MEC). Additional immunohistochemistry was performed in order to investigate the chemical markers for the retrogradely labelled cell populations. Labelled cells and possible colocalization of markers were analysedwith fluorescent microscopy. The results indicate the presence of a least three separate cell populations in superficial layers of MEC with different projection patterns and chemical markers. It remains to be seen how the cell populations described here relate to the functionally defined cell populations found in MEC.
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Schmidt-Helmstaedter, Helene. "Large-scale circuit reconstruction in medial entorhinal cortex." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19197.
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Es ist noch weitgehend ungeklärt, mittels welcher Mechanismen die elektrische Aktivität von Nervenzellpopulationen des Gehirns Verhalten ermöglicht. Die Orientierung im Raum ist eine Fähigkeit des Gehirns, für die im Säugetier der mediale entorhinale Teil der Großhirnrinde als entscheidende Struktur identifiziert wurde. Hier wurden Nervenzellen gefunden, die die Umgebung des Individuums in einer gitterartigen Anordnung repräsentieren. Die neuronalen Schaltkreise, welche diese geordnete Nervenzellaktivität im medialen entorhinalen Kortex (MEK) ermöglichen, sind noch wenig verstanden.
Die vorliegende Dissertation hat eine Klärung der zellulären Architektur und der neuronalen Schaltkreise in der zweiten Schicht des MEK der Ratte zum Ziel. Zunächst werden die Beiträge zur Entdeckung der hexagonal angeordneten zellulären Anhäufungen in Schicht 2 des MEK sowie zur Beschreibung der Dichotomie der Haupt-Nervenzelltypen dargestellt. Im zweiten Teil wird erstmalig eine konnektomische Analyse des MEK beschrieben. Die detaillierte Untersuchung der Architektur einzelner exzitatorischer Axone ergab das überraschende Ergebnis der präzisen Sortierung von Synapsen entlang axonaler Pfade. Die neuronalen Schaltkreise, in denen diese Neurone eingebettet sind, zeigten eine starke zeitliche Bevorzugung der hemmenden Neurone.
Die hier erhobenen Daten tragen zu einem detaillierteren Verständnis der neuronalen Schaltkreise im MEK bei. Sie enthalten die erste Beschreibung überraschend präziser axonaler synaptischer Ordnung im zerebralen Kortex der Säugetiere. Diese Schaltkreisarchitektur lässt einen Effekt auf die Weiterleitung synchroner elektrischer Populationsaktivität im MEK vermuten. In zukünftigen Studien muss insbesondere geklärt werden, ob es sich bei den hier berichteten Ergebnissen um eine Besonderheit des MEK oder ein generelles Verschaltungsprinzip der Hirnrinde des Säugetiers handelt.The mechanisms by which the electrical activity of ensembles of neurons in the brain give rise to an individual’s behavior are still largely unknown. Navigation in space is one important capacity of the brain, for which the medial entorhinal cortex (MEC) is a pivotal structure in mammals. At the cellular level, neurons that represent the surrounding space in a grid-like fashion have been identified in MEC. These so-called grid cells are located predominantly in layer 2 (L2) of MEC. The detailed neuronal circuits underlying this unique activity pattern are still poorly understood. This thesis comprises studies contributing to a mechanistic description of the synaptic architecture in rat MEC L2. First, this thesis describes the discovery of hexagonally arranged cell clusters and anatomical data on the dichotomy of the two principle cell types in L2 of the MEC. Then, the first connectomic study of the MEC is reported. An analysis of the axonal architecture of excitatory neurons revealed synaptic positional sorting along axons, integrated into precise microcircuits. These microcircuits were found to involve interneurons with a surprising degree of axonal specialization for effective and fast inhibition. Together, these results contribute to a detailed understanding of the circuitry in MEC. They provide the first description of highly precise synaptic arrangements along axons in the cerebral cortex of mammals. The functional implications of these anatomical features were explored using numerical simulations, suggesting effects on the propagation of synchronous activity in L2 of the MEC. These findings motivate future investigations to clarify the contribution of precise synaptic architecture to computations underlying spatial navigation. Further studies are required to understand whether the reported synaptic specializations are specific for the MEC or represent a general wiring principle in the mammalian cortex.
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Heys, James Gerard. "Cellular mechanisms underlying spatial processing in medial entorhinal cortex." Thesis, Boston University, 2013. https://hdl.handle.net/2144/12780.
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Thesis (Ph.D.)--Boston University
PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.Functional brain recordings from several mammalian species including rodents, bats and humans demonstrate that neurons in the medial entorhinal cortex (mEC) represent space in a similar way. Single neurons in mEC, termed 'grid cells' (GCs), fire at regular repeating spatial intervals as the animal moves throughout the environment. In rodents, models GCs have been inspired by research that suggests a relationship between theta rhythmic electrophysiology in mEC and GC firing behavior. The h current time constant and frequency of membrane potential resonance (MPR) changes systematically along the dorsal to ventral axis of mEC, which correlates with systematic gradations in the spacing of the GC firing fields along the same anatomical axis. Despite significant efforts, the mechanism generating this periodic spatial representation remains an open question and the work presented in this thesis is directed towards answering this question One major class of models that have been put forth to explain the grid pattern use interference between oscillations that are frequency modulated as a function of the animal's heading direction and running speed. Parts one and two of this thesis demonstrate how cholinergic modulation of MPR frequency could account for the expansion of grid field spacing that occurs during exploration of a novel environment. The result from these experiments demonstrate that activation of muscarinic acetylcholin receptors produces a decrease in the h current amplitude which causes a decrease in the MPR frequency. Recently unit recordings have shown that GC firing pattern may exist in the mEC of the bat in the absence of these characteristic theta-rhythmic physiological mechanisms. The third section of the thesis details experiments in bat brain slices that were conducted to investigate the cellular physiology of principal neurons in layer II of mEC in the bat and directly test or intrinsic cellular mechanisms that could generate theta in mEC of the bat. Together this work reveals that significant h current is present in rodents and bats. However, the time course of the h current may differ between species such that theta band membrane potential resonance is present in the rodents but is not produced in bat neurons in mEC.
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D'Albis, Tiziano. "Models of spatial representation in the medial entorhinal cortex." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19306.
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Komplexe kognitive Funktionen wie Gedächtnisbildung, Navigation und Entscheidungsprozesse hängen von der Kommunikation zwischen Hippocampus und Neokortex ab. An der Schnittstelle dieser beiden Gehirnregionen liegt der entorhinale Kortex - ein Areal, das Neurone mit bemerkenswerten räumlichen Repräsentationen enthält: Gitterzellen. Gitterzellen sind Neurone, die abhängig von der Position eines Tieres in seiner Umgebung feuern und deren Feuerfelder ein dreieckiges Muster bilden. Man vermutet, dass Gitterzellen Navigation und räumliches Gedächtnis unterstützen, aber die Mechanismen, die diese Muster erzeugen, sind noch immer unbekannt. In dieser Dissertation untersuche ich mathematische Modelle neuronaler Schaltkreise, um die Entstehung, Weitervererbung und Verstärkung von Gitterzellaktivität zu erklären.
Zuerst konzentriere ich mich auf die Entstehung von Gittermustern. Ich folge der Idee, dass periodische Repräsentationen des Raumes durch Konkurrenz zwischen dauerhaft aktiven, räumlichen Inputs und der Tendenz eines Neurons, durchgängiges Feuern zu vermeiden, entstehen könnten. Aufbauend auf vorangegangenen theoretischen Arbeiten stelle ich ein Einzelzell-Modell vor, das gitterartige Aktivität allein durch räumlich-irreguläre Inputs, Feuerratenadaptation und Hebbsche synaptische Plastizität erzeugt.
Im zweiten Teil der Dissertation untersuche ich den Einfluss von Netzwerkdynamik auf das Gitter-Tuning. Ich zeige, dass Gittermuster zwischen neuronalen Populationen weitervererbt werden können und dass sowohl vorwärts gerichtete als auch rekurrente Verbindungen die Regelmäßigkeit von räumlichen Feuermustern verbessern können. Schließlich zeige ich, dass eine entsprechende Konnektivität, die diese Funktionen unterstützt, auf unüberwachte Weise entstehen könnte.
Insgesamt trägt diese Arbeit zu einem besseren Verständnis der Prinzipien der neuronalen Repräsentation des Raumes im medialen entorhinalen Kortex bei.High-level cognitive abilities such as memory, navigation, and decision making rely on the communication between the hippocampal formation and the neocortex. At the interface between these two brain regions is the entorhinal cortex, a multimodal association area where neurons with remarkable representations of self-location have been discovered: the grid cells. Grid cells are neurons that fire according to the position of an animal in its environment and whose firing fields form a periodic triangular pattern. Grid cells are thought to support animal's navigation and spatial memory, but the cellular mechanisms that generate their tuning are still unknown. In this thesis, I study computational models of neural circuits to explain the emergence, inheritance, and amplification of grid-cell activity. In the first part of the thesis, I focus on the initial formation of grid-cell tuning. I embrace the idea that periodic representations of space could emerge via a competition between persistently-active spatial inputs and the reluctance of a neuron to fire for long stretches of time. Building upon previous theoretical work, I propose a single-cell model that generates grid-like activity solely form spatially-irregular inputs, spike-rate adaptation, and Hebbian synaptic plasticity. In the second part of the thesis, I study the inheritance and amplification of grid-cell activity. Motivated by the architecture of entorhinal microcircuits, I investigate how feed-forward and recurrent connections affect grid-cell tuning. I show that grids can be inherited across neuronal populations, and that both feed-forward and recurrent connections can improve the regularity of spatial firing. Finally, I show that a connectivity supporting these functions could self-organize in an unsupervised manner. Altogether, this thesis contributes to a better understanding of the principles governing the neuronal representation of space in the medial entorhinal cortex.
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Mena, Armando. "Electrophysiological and morphological characterization of medial entorhinal cortex layer III neurons." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0006/MQ29754.pdf.
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Mena, Armando. "Electrophysiological and morphological characterization of medial entorhinal cortex layer III neurons." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27379.
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The superficial layers of the entorhinal cortex (EC) are responsible for the transfer of neocortical input to the hippocampal formation (HPC) via the perforant path (PP). A significant, albeit not well characterized, component of the PP originates in EC layer III pyramidal cells and terminates directly in area CA1 of the HPC, circumventing the classical trisynaptic circuit. In an attempt to elaborate the input-output properties of this pathway, neurons of this layer were characterized both morphologically and electrophysiologically in an in vitro rat brain slice preparation using intracellular labeling and recording techniques with sharp micropipettes and under current-clamp conditions. These cells showed a typical pyramidal cell morphology. Analysis of the voltage-current relations demonstrated a rather linear membrane voltage behavior in the subthreshold range with the exception of pronounced inward rectification in the depolarizing direction due to a persistent Na$ sp+$-type current. This depolarizing current may provide the drive for the tonic discharge observed at rest in many of these neurons. Also, blockade of Ca$ sp{2+}$-conductances suggests that there is a high-threshold Ca$ sp{2+}$ component responsible for the shape of the spike, and indirectly responsible for both the spike AHP and the slow AHP following a train of spikes. The intrinsic electroresponsiveness of EC layer III pyramidal cells suggests that these neurons may perform a rather high-fidelity transfer function of incoming neocortical sensory information directly to the CA1 hippocampal subfield. This feedforward signal may function to gate the result of the information processing through entorhinal layer II and the trisynaptic pathway.
Books on the topic "Mammalian medial entorhinal cortex"
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Bertram, Edward H. Temporal Lobe Epilepsy. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199937837.003.0038.
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Temporal lobe epilepsy, as discussed in this chapter, is a focal epilepsy that involves primarily the limbic structures of the medial temporal lobe (amygdala, hippocampus, and entorhinal cortex). In recent years animal models have been developed that mirror the pathology and pathophysiology of this disease. This chapter reviews the human condition, the structural and physiological changes that support the development of seizures. The neural circuitry of seizure initiation will be reviewed with a goal of creating a framework for developing more effective treatments for this disease.
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Erdem, Uğur Murat, Nicholas Roy, John J. Leonard, and Michael E. Hasselmo. Spatial and episodic memory. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199674923.003.0029.
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The neuroscience of spatial memory is one of the most promising areas for developing biomimetic solutions to complex engineering challenges. Grid cells are neurons recorded in the medial entorhinal cortex that fire when rats are in an array of locations in the environment falling on the vertices of tightly packed equilateral triangles. Grid cells suggest an exciting new approach for enhancing robot simultaneous localization and mapping (SLAM) in changing environments and could provide a common map for situational awareness between human and robotic teammates. Current models of grid cells are well suited to robotics, as they utilize input from self-motion and sensory flow similar to inertial sensors and visual odometry in robots. Computational models, supported by in vivo neural activity data, demonstrate how grid cell representations could provide a substrate for goal-directed behavior using hierarchical forward planning that finds novel shortcut trajectories in changing environments.
Book chapters on the topic "Mammalian medial entorhinal cortex"
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Insausti, Ricardo. "The Rat Entorhinal Cortex. Limited Cortical Input, Extended Cortical Output." In The Mammalian Cochlear Nuclei, 457–66. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4615-2932-3_37.
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Winer, Jeffery A. "The Functional Architecture of the Medial Geniculate Body and the Primary Auditory Cortex." In The Mammalian Auditory Pathway: Neuroanatomy, 222–409. New York, NY: Springer New York, 1992. http://dx.doi.org/10.1007/978-1-4612-4416-5_6.
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Gauthier, Monique, and Claude Destrade. "Involvement of the Entorhinal Cortex in Memory Processes: Differentiation of Lateral and Medial Parts." In Brain Plasticity, Learning, and Memory, 560. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4684-5003-3_70.
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Nolan, Matt. "A Model for Grid Firing and Theta-Nested Gamma Oscillations in Layer 2 of the Medial Entorhinal Cortex." In Springer Series in Computational Neuroscience, 567–84. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-99103-0_15.
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Moser, Edvard I., Menno P. Witter, and May-Britt Moser. "Entorhinal Cortex." In Handbook of Brain Microcircuits, edited by Gordon M. Shepherd and Sten Grillner, 227–44. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190636111.003.0019.
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While decades of study have unraveled some of the basic principles of hippocampal structure and function, the adjacent entorhinal cortex (EC) has remained terra incognita in many respects. Recent studies suggest that the medial part of the entorhinal cortex is part of a two-dimensional metric map of the animal’s changing location in the environment. A key component of this map is the grid cell, which fires selectively at hexagonally spaced positions in the animal’s environment. Grid cells colocalize with other recently discovered medial entorhinal cell types, such as head direction cells, conjunctive grid × head direction cells, border cells, and speed cells. This chapter provides an overview of these functional cell types, their possible relationship to morphological cell types, the intrinsic architecture of the system (including laminar, longitudinal, and modular organization), and the extrinsic connectivity and possible function of both the medial and lateral subdivisions of the entorhinal cortex.
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"Medial Entorhinal Cortex (MEC)." In Encyclopedia of Animal Cognition and Behavior, 4153. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-319-55065-7_301352.
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Austin, James H. "Early Distinctions between Self and Other, Focal and Global, Are Coded in the Medial Temporal Lobe." In Living Zen Remindfully. The MIT Press, 2016. http://dx.doi.org/10.7551/mitpress/9780262035088.003.0006.
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This chapter reviews 2014 Nobel Prize-winning research on the hippocampus and parahippocampus. It considers place cells and grid cells and emphasizes that early primate studies had identified egocentric and allocentric responses in the hippocampus. It also notes that both direction codes and landmark location codes are represented in the retrosplenial cortex as well as in the entorhinal cortex.
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Grossberg, Stephen. "Learning Maps to Navigate Space." In Conscious Mind, Resonant Brain, 572–617. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780190070557.003.0016.
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This chapter explains how humans and other animals learn to learn to navigate in space. Both reaching and route-based navigation use difference vector computations. Route navigation learns a labeled graph of angles and distances moved. Spatial navigation requires neurons to learn navigable spaces that can be many meters in size. This is again accomplished by a spectrum of cells. Such spectral spacing supports learning of medial entorhinal grid cells and hippocampal place cells. The model responds to realistic rat navigational trajectories by learning grid cells with hexagonal grid firing fields of multiple spatial scales, and place cells with one or more firing fields, that match neurophysiological data about their development in juvenile rats. Both grid and place cells develop in a hierarchy of self-organizing maps by detecting, learning and remembering the most frequent and energetic co-occurrences of their inputs. Model parsimonious properties include: similar ring attractor mechanisms process linear and angular path integration inputs that drive map learning; the same self-organizing map mechanisms can learn both grid cell and place cell receptive fields; and the learning of the dorsoventral organization of multiple grid cell modules through medial entorhinal cortex to hippocampus uses a gradient of rates that is homologous to a rate gradient that drives adaptively timed learning at multiple rates through lateral entorhinal cortex to hippocampus (‘neural relativity’). The model clarifies how top-down hippocampal-to-entorhinal ART attentional mechanisms stabilize map learning, simulates how hippocampal, septal, or acetylcholine inactivation disrupts grid cells, and explains data about theta, beta and gamma oscillations.
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McComas, Alan J. "Speculations on Spatial Maps and Other Issues." In Aranzio's Seahorse and the Search for Memory and Consciousness, 283—C43.N15. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780192868244.003.0045.
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Abstract During evolution of the mammalian hippocampus place cells may have increased their range of activity by coding for ‘what’ regardless of ‘where,’ thereby creating semantic memory. Is the hippocampus continually creating ever-changing spatial maps? Are the arrays of grid cells in the entorhinal cortex related to the map of odour-specific glomeruli in the olfactory bulb?
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Zaborszky, Laszlo, and Peter Gombkoto. "The Cholinergic Multicompartmental Basal Forebrain Microcircuit." In Handbook of Brain Microcircuits, edited by Gordon M. Shepherd and Sten Grillner, 163–84. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190636111.003.0015.
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The basal forebrain (BF) is composed of an affiliation of structures, including the medial septum, ventral pallidum (VP), vertical diagonal band (VDB) and horizontal diagonal band (HDB) nuclei, substantia innominata/extended amygdala (SI/EA), and peripallidal regions. Together, they constitute one of the most extensive multicompartmental microcircuits in the brain. A prominent feature of the mammalian BF is the presence of aggregated and nonaggregated, large, cholinergic neurons, which project to the cerebral cortex, the hippocampal complex, and the amygdala. This highly complex system has been implicated in cortical activation, attention, motivation, and memory, as well as neuropsychiatric disorders such as Alzheimer’s disease, Parkinson’s disease, schizophrenia, and drug abuse. Advances in modern tracing, genetic, and refined pharmacological techniques have dramatically increased the understanding of how the BF cholinergic system can support both phasic acetylcholine (ACh) release in attention, memory, and sensory processing and tonic ACh release over broad cortical areas as part of a general arousal effect.
Conference papers on the topic "Mammalian medial entorhinal cortex"
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Wang, Zongxia, Naigong Yu, and Hejie Yu. "Computational Models of Stellate Cells in Layer II of Medial Entorhinal Cortex." In 2021 China Automation Congress (CAC). IEEE, 2021. http://dx.doi.org/10.1109/cac53003.2021.9728543.
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Socher, Karen, Douglas Nunes, Deborah Lopes, Artur Coutinho, Daniele Faria, Paula Squarzoni, Geraldo Busatto Filho, Carlos Buchpighel, Ricardo Nitrini,, and Sonia Brucki. "VISUAL MEDIAL TEMPORAL ATROPHY SCALES IN CLINICIAN PRACTICE." In XIII Meeting of Researchers on Alzheimer's Disease and Related Disorders. Zeppelini Editorial e Comunicação, 2021. http://dx.doi.org/10.5327/1980-5764.rpda102.
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Background: Visual atrophy scales from the medial temporal region are auxiliary biomarker methods in Alzheimer’s Disease(AD).They may correlated with progression from preclinical to clinical AD. Objective: We aimed to compare medial temporal lobe atrophy (MTA) and entorhinal cortex atrophy (ERICA) scales for magnetic resonance image as a useful tool for probable AD diagnosis and evaluate their accuracy, sensitivity and specificity, regarding clinical diagnosis and 11C-PIB-PET. Methods: 2 neurologists blinded to diagnosis classified 113 adults (over 65y) through MTA and ERICA scales and correlated with sociodemographic data, amyloid brain cortical burden through the 11C-PIB-PET and clinical cognitive status, divided into 30 cognitive unimpaired (CU) individuals, 52 MCI and 31 dementia compatible with AD (DCAD). Results: Inter-rater reliability of these atrophy scales was excellent (0.8- 1) by Cohen analysis. CU group had significantly lower MTA scores (median value 0) than ERICA (median value 1)for both hemispheres. 11C-PIB-PET was positive in 45% of the whole sample. In MCI and DCAD groups, ERICA depicted greater sensitivity and MTA greater specificity. Accuracy was under 70% for both scores in all clinical groups. Conclusion: Our study achieved a moderate sensitivity for ERICA score and could be a better screening tool for DCAD or MCI than MTA score. But, none of them could be considered a useful biomarker in preclinical AD.
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Macedo, Arthur Cassa, Luciano Inácio, Mariano Elisa De Paula França Resende, Antônio Lúcio Teixeira Júnior, Sarah Teixeira Camargos, Francisco Eduardo Costa Cardoso, Paulo Caramelli, and Leonardo Cruz De Souza. "EPISODIC MEMORY IMPAIRMENT IN PROGRESSIVE SUPRANUCLEAR PALSY (PSP): A NEUROIMAGING INVESTIGATION." In XIII Meeting of Researchers on Alzheimer's Disease and Related Disorders. Zeppelini Editorial e Comunicação, 2021. http://dx.doi.org/10.5327/1980-5764.rpda016.
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Background: Progressive supranuclear palsy (PSP) has been classically considered a “subcortical dementia” with a frontal pattern of cognitive decline, but episodic memory dysfunction also occurs in most patients. However, it remains uncertain whether this is due to executive dysfunction or to the involvement of key brain areas responsible for memory processes. Objective: We aim to identify the specific brain regions underlying episodic memory impairment in PSP. Methods: In this cross-sectional study, we included 21 patients with PSP and 20 healthy controls matched for age, sex, and schooling. Participants underwent the Brief Cognitive Battery (BCB, including the Figures Test for episodic memory) and had brain MRI. Both standard exploratory voxel‐based morphometry and region of interest analyses were performed with FSL software. Results: Compared to controls, PSP patients performed worse (p < 0.001) on the BCB (delayed recall). Adjusting for both age and Frontal Assessment Battery scores, neuroimaging analyses of the correlation between delayed recall (5 minutes) and grey matter volumes yielded significant clusters on medial temporal structures, including the hippocampus, entorhinal cortex, and parahippocampal gyrus (FWE, p < 0.05). Conclusion: Our results suggest that atrophy of medial temporal structures may play a role in episodic memory impairment in PSP, indicating that amnesia in PSP is not due to executive dysfunction.
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Mariano, Lunizia Mattos, Guilherme dos Santos Sousa, Lucas Barbosa Napolitano de Moraes, Yasmim Nadime José Frigo, Ana Flavia Andrade Lemos, Arthur Oscar Schelp, and Luiz Eduardo Betting. "Use of lamotrigine in impulse control and social cognition in patients with temporal lobe epilepsy." In XIV Congresso Paulista de Neurologia. Zeppelini Editorial e Comunicação, 2023. http://dx.doi.org/10.5327/1516-3180.141s1.654.
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Temporal lobe epilepsy (TLE) is a type of focal epilepsy that can begin in one or more regions of the temporal lobe and spread to adjacent brain tissue via neural connections and can be divided into two types according to the Classification of Epileptic Syndromes (ILAE 2017). The most common is mesial temporal lobe epilepsy, which affects temporal regions such as the hippocampus, entorhinal cortex, amygdala, and parahippocampal gyrus. The second type is lateral or neocortical, where seizures occur in the temporal neocortex (superior, medial and inferior temporal, temporooccipital and temporoparietal gyri and associative senses for auditory, visual and verbal functions). Approximately 60% of patients with mesial TLE associated with hippocampal atrophy are unable to control their seizures even after optimal treatment with various antiepileptic drugs. For these patients, epilepsy surgery can be an effective alternative treatment. After a series of preoperative studies, including medical history and careful neurological examination, complex neurophysiological studies (surface, surface and invasive electroencephalographic video electroencephalogram), neuroimaging studies and neuropsychological evaluations for selected cases. Notably, according to Wiebe and Engel, 2012, surgical treatment of TLE is superior to long-term medical therapy in these selected cases. Because the pathophysiological course of mesial TLE may favor preservation of epileptogenesis even after removal of the primary regions, effective cure in these patients is not always guaranteed. Furthermore, due to the location of mesiotemporal lesions, patients with TLE suffer from stigma, associated with seizure and psychiatric disorders, which affects the quality of life and functioning of these patients. Therefore, this study aims to investigate the efficacy of using antiseizure medications, especially lamotrigine on impulse control, which is also impaired in some mood disorders. Bear Fedio Inventory (BFI) was used to study the effect of lamotrigine and other antizeiures medications on impulse control in patients with TLE. Patients with TLE confirmed by clinical semiology and magnetic resonance imaging findings treated with lamotrigine or other antiseizure medications were included. Only patients older than 18 years and younger than 60 years were investigated. Patients with psychotic symptoms were excluded from this analysis. The BFI was used and applied together with the International Personality Disorder Examination (IPDE). All participants received the questionnaires and were allowed to omit any demographic data that they felt might lead to disclosure of their identity. Ethical approval was obtained from the Ethics Committee of the Botucatu Medical School. The inventory consists of 100 items that must be marked as true or false. Each group of five statements examines one of the following areas: writing tendencies, hypermorality, religious beliefs, anger and impatience, tendency to organize or order, decreased libido, fear and anxiety, guilt, seriousness, sadness, emotion, suspicious and detail-oriented, cosmic interest, belief in personal predestination, persistence and reproducibility, hatred and revenge, addiction, euphoria, and somatization. A high score is 2 or more true items in each domain, or 20 or more items marked true in total. The IPDE, on the other hand, describes personality traits according to ICD-10 and identifies them based on a set of 5 responses with at least two being true to assume that the respondent has that trait, such as impulsivity or borderline. 36 respondents answered the questionnaires and the responses were stored and categorized into two groups, those who take lamotrigine medication and those who do not. With this separation in mind, the answers that defined the personality trait according to the inventories were selected and grouped, the answers were yes or no, and the accumulation of the answers and the score of the accumulation were applied, and the positive and negative cases for the trait were grouped so that the chi-square test could be applied. Nine of the 36 respondents were taking lamotrigine and 27 were taking other medications. For the IPED with the score of impulsivity, there were 7 positives and 2 negatives, the 27 who did not use lamotrigine, 21 with a positive score and 6 negatives. For the BFI, the Hate and Vengeance and Euphoria traits were selected for comparison and to test the hypothesis of decreased impulsivity traits. There was no change in the respondents who use lamotrigine, of the 9, only 2 had a positive score and 7 a negative score, for the non-users tested in this criterion 16 positive and 11 negative. There was not difference for hatred and revenge trail between the groups (P = 0.0543). For the euphoria trait, the values for lamotrigine users were 8 positive and 1 negative, and for non-users were 21 positive and 6 negative (P = 0.466). This preliminary investigation did not show difference for impulse control between patients taking lamotrigine or not. A larger sample size is currently underway to support this observation.