The Experts below are selected from a list of 81222 Experts worldwide ranked by ideXlab platform
Jerry W. Rudy - One of the best experts on this subject based on the ideXlab platform.
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context preexposure prevents forgetting of a contextual fear Memory implication for regional changes in brain activation patterns associated with recent and remote Memory tests
2007Co-Authors: Joseph C Biedenkapp, Jerry W. RudyAbstract:Contextual fear conditioning was maintained over a 15-day retention interval suggesting no forgetting of the conditioning experience. However, a more subtle generalization test revealed that, as the retention interval increased, rats showed enhanced generalized fear to an altered context. Preexposure to the training context prior to conditioning, however, prevented this enhanced generalized fear from developing. These results support the hypothesis that the Memory Representation of the context degrades as the Memory ages and is responsible for enhanced generalization. The implications of these results for systems consolidation versus forgetting interpretations of regional changes in neural activation patterns that occur as memories age are discussed.
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the ventral hippocampus supports a Memory Representation of context and contextual fear conditioning implications for a unitary function of the hippocampus
2005Co-Authors: Jerry W. Rudy, Patricia MatusamatAbstract:The authors report that either inactivating the ventral hippocampus (VH) with muscimol prior to context preexposure or injecting anisomycin into the VH after preexposure significantly impaired rats' Memory for context. Injecting anisomycin into the VH prior to contextual fear conditioning also greatly reduced long-term Memory (48-hr retention test) but had no effect on short-term Memory (1-hr retention test) for contextual fear. Together with other results, these data suggest that the Memory for a novel context is distributed throughout the longitudinal extent of the hippocampus and that this Representation helps to support contextual fear conditioning.
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the role of the dorsal hippocampus in the acquisition and retrieval of context Memory Representations
2004Co-Authors: Patricia Matusamat, Ruth M Barrientos, Emily A Higgins, Jerry W. RudyAbstract:It is argued that the hippocampus contributes to contextual fear conditioning by supporting the acquisition of a conjunctive Memory Representation of context, which associates with shock. This function was examined by studying the context pre-exposure facilitation effect (CPFE). A rat that is shocked immediately after being placed into a context subsequently displays almost no fear of that context. However, if it is pre-exposed to the context the day before immediate shock, it displays significant freezing to that context. By using 5-aminomethyl-3-hydroxysoxazole to temporarily inactivate the dorsal hippocampus (DH) at three different phases of the procedure, which produces the CPFE, we show that the hippocampus is necessary for the following: (1) acquisition of the context Memory, (2) retrieval of this Memory at the time of immediate shock, and (3) retrieval of the context-shock Memory at the time of testing. In contrast, inactivating the DH before a standard contextual shock experience had no effect on contextual fear conditioning. These results support the view that two processes can support contextual fear conditioning: (1) conditioning to the conjunctive Representation, which depends on the hippocampus, and (2) conditioning to the features that make up the context, which does not.
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Memory for context is impaired by injecting anisomycin into dorsal hippocampus following context exploration
2002Co-Authors: Ruth M Barrientos, Randall C Oreilly, Jerry W. RudyAbstract:Pre-exposure to the context facilitates the small amount of contextual fear conditioning that is normally produced by immediate shock. This context pre-exposure facilitation effect provides a convenient way to study the rat's learning about context. We recently reported that anterograde damage to dorsal hippocampus prevents this facilitation. The present experiments strengthen this conclusion by showing that the protein synthesis inhibitor, anisomycin, injected bilaterally into the dorsal hippocampus following context pre-exposure also significantly reduces the facilitation effect. The same treatment given immediately after immediate shock, however, had no effect on facilitation. These results support theories that assume that, (a) contextual fear involves two processes, acquiring and storing a conjunctive Representation of a context and associating that Representation with fear; and (b) the hippocampus contributes to contextual fear by participating in the storage of the Memory Representation of the context.
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Memory for context is impaired by a post context exposure injection of interleukin 1 beta into dorsal hippocampus
2002Co-Authors: Ruth M Barrientos, Jerry W. Rudy, Emily A Higgins, David Sprunger, Linda R Watkins, Steven F MaierAbstract:Prior research has revealed that treatments that elevate the level of the pro-inflammatory cytokine IL-1β in the brain, if given after training, impair contextual but not auditory-cue fear conditioning. The present experiments add to these finding by showing that, (a) IL-1β exerts its effect on contextual fear conditioning by impairing consolidation processes that support the storage of the Memory Representation of the context; (b) the dorsal hippocampus is a critical site for the effect of IL-1β; (c) the effect of IL-1β cannot be attributed to its effect on glucocorticoid levels; and (d) IL-1β injected into dorsal hippocampus either, immediately, 3, or 24 h, but not 48 h, after training produces this impairment. At this time the mechanisms responsible for this impairment are not understood, but may involve late-phase protein synthesis processes associated with LTP, because later consolidation processes are being disrupted.
Tim Curran - One of the best experts on this subject based on the ideXlab platform.
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functional role of gamma and theta oscillations in episodic Memory
2010Co-Authors: Erika Nyhus, Tim CurranAbstract:The primary aim of this review is to examine evidence for a functional role of gamma and theta oscillations in human episodic Memory. It is proposed here that gamma and theta oscillations allow for the transient interaction between cortical structures and the hippocampus for the encoding and retrieval of episodic memories as described by the hippocampal Memory indexing theory (Teyler and DiScenna, 1986). Gamma rhythms can act in the cortex to bind perceptual features and in the hippocampus to bind the rich perceptual and contextual information from diverse brain regions into episodic Representations. Theta oscillations act to temporally order these individual episodic Memory Representations. Through feedback projections from the hippocampus to the cortex these gamma and theta patterns could cause the reinstatement of the entire episodic Memory Representation in the cortex. In addition, theta oscillations could allow for top-down control from the frontal cortex to the hippocampus modulating the encoding and retrieval of episodic memories. Published by Elsevier Ltd.
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functional role of gamma and theta oscillations in episodic Memory
2010Co-Authors: Erika Nyhus, Tim CurranAbstract:The primary aim of this review is to examine evidence for a functional role of gamma and theta oscillations in human episodic Memory. It is proposed here that gamma and theta oscillations allow for the transient interaction between cortical structures and the hippocampus for the encoding and retrieval of episodic memories as described by the hippocampal Memory indexing theory (Teyler and DiScenna, 1986). Gamma rhythms can act in the cortex to bind perceptual features and in the hippocampus to bind the rich perceptual and contextual information from diverse brain regions into episodic Representations. Theta oscillations act to temporally order these individual episodic Memory Representations. Through feedback projections from the hippocampus to the cortex these gamma and theta patterns could cause the reinstatement of the entire episodic Memory Representation in the cortex. In addition, theta oscillations could allow for top-down control from the frontal cortex to the hippocampus modulating the encoding and retrieval of episodic memories.
Guillaume Rizk - One of the best experts on this subject based on the ideXlab platform.
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space efficient and exact de bruijn graph Representation based on a bloom filter
2013Co-Authors: Rayan Chikhi, Guillaume RizkAbstract:Background The de Bruijn graph data structure is widely used in next-generation sequencing (NGS). Many programs, e.g. de novo assemblers, rely on in-Memory Representation of this graph. However, current techniques for representing the de Bruijn graph of a human genome require a large amount of Memory (≥30 GB).
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space efficient and exact de bruijn graph Representation based on a bloom filter
2012Co-Authors: Rayan Chikhi, Guillaume RizkAbstract:The de Bruijn graph data structure is widely used in next-generation sequencing (NGS). Many programs, e.g. de novo assemblers, rely on in-Memory Representation of this graph. However, current techniques for representing the de Bruijn graph of a human genome require a large amount of Memory (≥30 GB). We propose a new encoding of the de Bruijn graph, which occupies an order of magnitude less space than current Representations. The encoding is based on a Bloom filter, with an additional structure to remove critical false positives. An assembly software implementing this structure, Minia, performed a complete de novo assembly of human genome short reads using 5.7 GB of Memory in 23 hours.
Erika Nyhus - One of the best experts on this subject based on the ideXlab platform.
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functional role of gamma and theta oscillations in episodic Memory
2010Co-Authors: Erika Nyhus, Tim CurranAbstract:The primary aim of this review is to examine evidence for a functional role of gamma and theta oscillations in human episodic Memory. It is proposed here that gamma and theta oscillations allow for the transient interaction between cortical structures and the hippocampus for the encoding and retrieval of episodic memories as described by the hippocampal Memory indexing theory (Teyler and DiScenna, 1986). Gamma rhythms can act in the cortex to bind perceptual features and in the hippocampus to bind the rich perceptual and contextual information from diverse brain regions into episodic Representations. Theta oscillations act to temporally order these individual episodic Memory Representations. Through feedback projections from the hippocampus to the cortex these gamma and theta patterns could cause the reinstatement of the entire episodic Memory Representation in the cortex. In addition, theta oscillations could allow for top-down control from the frontal cortex to the hippocampus modulating the encoding and retrieval of episodic memories. Published by Elsevier Ltd.
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functional role of gamma and theta oscillations in episodic Memory
2010Co-Authors: Erika Nyhus, Tim CurranAbstract:The primary aim of this review is to examine evidence for a functional role of gamma and theta oscillations in human episodic Memory. It is proposed here that gamma and theta oscillations allow for the transient interaction between cortical structures and the hippocampus for the encoding and retrieval of episodic memories as described by the hippocampal Memory indexing theory (Teyler and DiScenna, 1986). Gamma rhythms can act in the cortex to bind perceptual features and in the hippocampus to bind the rich perceptual and contextual information from diverse brain regions into episodic Representations. Theta oscillations act to temporally order these individual episodic Memory Representations. Through feedback projections from the hippocampus to the cortex these gamma and theta patterns could cause the reinstatement of the entire episodic Memory Representation in the cortex. In addition, theta oscillations could allow for top-down control from the frontal cortex to the hippocampus modulating the encoding and retrieval of episodic memories.
Rayan Chikhi - One of the best experts on this subject based on the ideXlab platform.
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space efficient and exact de bruijn graph Representation based on a bloom filter
2013Co-Authors: Rayan Chikhi, Guillaume RizkAbstract:Background The de Bruijn graph data structure is widely used in next-generation sequencing (NGS). Many programs, e.g. de novo assemblers, rely on in-Memory Representation of this graph. However, current techniques for representing the de Bruijn graph of a human genome require a large amount of Memory (≥30 GB).
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space efficient and exact de bruijn graph Representation based on a bloom filter
2012Co-Authors: Rayan Chikhi, Guillaume RizkAbstract:The de Bruijn graph data structure is widely used in next-generation sequencing (NGS). Many programs, e.g. de novo assemblers, rely on in-Memory Representation of this graph. However, current techniques for representing the de Bruijn graph of a human genome require a large amount of Memory (≥30 GB). We propose a new encoding of the de Bruijn graph, which occupies an order of magnitude less space than current Representations. The encoding is based on a Bloom filter, with an additional structure to remove critical false positives. An assembly software implementing this structure, Minia, performed a complete de novo assembly of human genome short reads using 5.7 GB of Memory in 23 hours.
