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Memory engram

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https://www.readbyqxmd.com/read/28176459/reconsolidation-induced-rescue-of-a-remote-fear-memory-blocked-by-an-early-cortical-inhibition-involvement-of-the-anterior-cingulate-cortex-and-the-mediation-by-the-thalamic-nucleus-reuniens
#1
Rodrigo O Sierra, Lizeth K Pedraza, Querusche K Zanona, Fabiana Santana, Flávia Z Boos, Ana P Crestani, Josué Haubrich, Lucas de Oliveira Alvares, Maria Elisa Calcagnotto, Jorge A Quillfeldt
Systems consolidation is a time-dependent reorganization process involving neocortical and hippocampal networks underlying memory storage and retrieval. The involvement of the hippocampus during acquisition is well described, however we know much less about the concomitant contribution of cortical activity levels to the formation of stable remote memories. Here, after a reversible pharmacological inhibition of the anterior cingulate cortex (ACC) during the acquisition of a contextual fear conditioning, retrieval of both recent and remote memories were impaired, an effect that was reverted by a single memory reactivation session 48h after training, through a destabilization-dependent mechanism interpreted as reconsolidation, that restored the normal course of systems consolidation in order to rescue a remote memory...
February 8, 2017: Hippocampus
https://www.readbyqxmd.com/read/28174334/evidence-for-an-evolutionarily-conserved-memory-coding-scheme-in-the-mammalian-hippocampus
#2
Alexander Thome, Diano F Marrone, Timothy M Ellmore, Monica K Chawla, Peter Lipa, Victor Ramirez-Amaya, Sarah H Lisanby, Bruce L McNaughton, Carol A Barnes
: Decades of research identify the hippocampal formation as central to memory storage and recall. Events are stored via distributed population codes, whose parameters (e.g., sparsity and overlap) determine both storage capacity and fidelity. However, it remains unclear whether the parameters governing information storage are similar between species. Because episodic memories are rooted in the space in which they are experienced, the hippocampal response to navigation is often used as a proxy to study memory...
February 7, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28152467/prevention-of-recurrent-affective-episodes-using-extinction-training-in-the-reconsolidation-window-a-testable-psychotherapeutic-strategy
#3
REVIEW
Robert M Post, Robert Kegan
Stressors may initially precipitate affective episodes, but with sufficient numbers of recurrences, episodes can occur more autonomously. It is postulated the memory engram for these recurrent depressions moves from the conscious representational memory system to the unconscious habit memory system encoded in the striatum. If this were the case, cognitive behavior therapy targeted toward extinction of habit memories could be an effective maneuver for helping reverse the automaticity of affective episode recurrence...
January 20, 2017: Psychiatry Research
https://www.readbyqxmd.com/read/27938664/distinct-memory-engrams-in-the-infralimbic-cortex-of-rats-control-opposing-environmental-actions-on-a-learned-behavior
#4
Nobuyoshi Suto, Amanda Laque, Genna L De Ness, Grant E Wagner, Debbie Watry, Tony Kerr, Eisuke Koya, Mark R Mayford, Bruce T Hope, Friedbert Weiss
Conflicting evidence exists regarding the role of infralimbic cortex (IL) in the environmental control of appetitive behavior. Inhibition of IL, irrespective of its intrinsic neural activity, attenuates not only the ability of environmental cues predictive of reward availability to promote reward seeking, but also the ability of environmental cues predictive of reward omission to suppress this behavior. Here we report that such bidirectional behavioral modulation in rats is mediated by functionally distinct units of neurons (neural ensembles) that are concurrently localized within the same IL brain area but selectively reactive to different environmental cues...
December 10, 2016: ELife
https://www.readbyqxmd.com/read/27899292/engrampigenetics-epigenetics-of-engram-memory-cells
#5
Cristian Ripoli
For long time, the epidemiology of late-onset sporadic Alzheimer's disease (AD) risk factors has centered on adult life-style. Recent studies have, instead, focused on the role of early life experiences in progression of such disease especially in the context of prenatal and postnatal life. Although no single unfavorable environmental event has been shown to be neither necessary nor sufficient for AD development, it is possible that the sum of several environmentally induced effects, over time, contribute to its pathophysiology through epigenetic mechanisms...
November 27, 2016: Behavioural Brain Research
https://www.readbyqxmd.com/read/27818176/a-putative-biochemical-engram-of-long-term-memory
#6
Liying Li, Consuelo Perez Sanchez, Brian D Slaughter, Yubai Zhao, Mohammed Repon Khan, Jay R Unruh, Boris Rubinstein, Kausik Si
How a transient experience creates an enduring yet dynamic memory remains an unresolved issue in studies of memory. Experience-dependent aggregation of the RNA-binding protein CPEB/Orb2 is one of the candidate mechanisms of memory maintenance. Here, using tools that allow rapid and reversible inactivation of Orb2 protein in neurons, we find that Orb2 activity is required for encoding and recall of memory. From a screen, we have identified a DNA-J family chaperone, JJJ2, which facilitates Orb2 aggregation, and ectopic expression of JJJ2 enhances the animal's capacity to form long-term memory...
December 5, 2016: Current Biology: CB
https://www.readbyqxmd.com/read/27806290/linking-memories-across-time-via-neuronal-and-dendritic-overlaps-in-model-neurons-with-active-dendrites
#7
George Kastellakis, Alcino J Silva, Panayiota Poirazi
Memories are believed to be stored in distributed neuronal assemblies through activity-induced changes in synaptic and intrinsic properties. However, the specific mechanisms by which different memories become associated or linked remain a mystery. Here, we develop a simplified, biophysically inspired network model that incorporates multiple plasticity processes and explains linking of information at three different levels: (1) learning of a single associative memory, (2) rescuing of a weak memory when paired with a strong one, and (3) linking of multiple memories across time...
November 1, 2016: Cell Reports
https://www.readbyqxmd.com/read/27764215/experimental-evidence-of-classical-conditioning-and-microscopic-engrams-in-an-electroconductive-material
#8
Nicolas Rouleau, Lukasz M Karbowski, Michael A Persinger
Synthetic experimental substrates are indispensable tools which can allow researchers to model biological processes non-invasively in three-dimensional space. In this study, we investigated the capacities of an electroconductive material whose properties converge upon those of the brain. An electrically conductive material composed of carbohydrates, proteins, fats, ions, water, and trace amounts of other organic compounds and minerals was classically conditioned as inferred by electrophysiological measurements...
2016: PloS One
https://www.readbyqxmd.com/read/27720868/the-use-of-the-emotional-object-recognition-as-an-assay-to-assess-learning-and-memory-associated-to-an-aversive-stimulus-in-rodents
#9
Anna Brancato, Gianluca Lavanco, Angela Cavallaro, Fulvio Plescia, Carla Cannizzaro
BACKGROUND: Emotionally salient experiences induce the formation of explicit memory traces, besides eliciting automatic or implicit emotional memory in rodents. This study aims at investigating the implementation of a novel task for studying the formation of limbic memory engrams as a result of the acquisition- and retrieval- of fear-conditioning - biased declarative memory traces, measured by animal discrimination of an "emotional-object". Moreover, by using this new method we investigated the potential interactions between stimulation of cannabinoid transmission and integration of emotional information and cognitive functioning...
December 1, 2016: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/27639988/pharmacogenetic-reactivation-of-the-original-engram-evokes-an-extinguished-fear-memory
#10
Takahiro Yoshii, Hiroshi Hosokawa, Naoki Matsuo
Fear memory extinction has several characteristic behavioral features, such as spontaneous recovery, renewal, and reinstatement, suggesting that extinction training does not erase the original association between the conditioned stimulus (CS) and the unconditioned stimulus (US). However, it is unclear whether reactivation of the original physical record of memory (i.e., memory trace) is sufficient to produce conditioned fear response after extinction. Here, we performed pharmacogenetic neuronal activation using transgenic mice expressing hM3Dq DREADD (designer receptor exclusively activated by designer drug) under the control of the activity-dependent c-fos gene promoter...
February 2017: Neuropharmacology
https://www.readbyqxmd.com/read/27601979/how-does-the-sparse-memory-engram-neurons-encode-the-memory-of-a-spatial-temporal-event
#11
REVIEW
Ji-Song Guan, Jun Jiang, Hong Xie, Kai-Yuan Liu
Episodic memory in human brain is not a fixed 2-D picture but a highly dynamic movie serial, integrating information at both the temporal and the spatial domains. Recent studies in neuroscience reveal that memory storage and recall are closely related to the activities in discrete memory engram (trace) neurons within the dentate gyrus region of hippocampus and the layer 2/3 of neocortex. More strikingly, optogenetic reactivation of those memory trace neurons is able to trigger the recall of naturally encoded memory...
2016: Frontiers in Neural Circuits
https://www.readbyqxmd.com/read/27512601/cognitive-neuroepigenetics-the-next-evolution-in-our-understanding-of-the-molecular-mechanisms-underlying-learning-and-memory
#12
Paul Marshall, Timothy W Bredy
A complete understanding of the fundamental mechanisms of learning and memory continues to elude neuroscientists. Although many important discoveries have been made, the question of how memories are encoded and maintained at the molecular level remains. To date, this issue has been framed within the context of one of the most dominant concepts in molecular biology, the central dogma, and the result has been a protein-centric view of memory. Here we discuss the evidence supporting a role for neuroepigenetic mechanisms, which constitute dynamic and reversible, state-dependent modifications at all levels of control over cellular function, and their role in learning and memory...
2016: NPJ Science of Learning
https://www.readbyqxmd.com/read/27477539/cellular-tagging-as-a-neural-network-mechanism-for-behavioural-tagging
#13
Masanori Nomoto, Noriaki Ohkawa, Hirofumi Nishizono, Jun Yokose, Akinobu Suzuki, Mina Matsuo, Shuhei Tsujimura, Yukari Takahashi, Masashi Nagase, Ayako M Watabe, Fusao Kato, Kaoru Inokuchi
Behavioural tagging is the transformation of a short-term memory, induced by a weak experience, into a long-term memory (LTM) due to the temporal association with a novel experience. The mechanism by which neuronal ensembles, each carrying a memory engram of one of the experiences, interact to achieve behavioural tagging is unknown. Here we show that retrieval of a LTM formed by behavioural tagging of a weak experience depends on the degree of overlap with the neuronal ensemble corresponding to a novel experience...
2016: Nature Communications
https://www.readbyqxmd.com/read/27463673/competition-between-engrams-influences-fear-memory-formation-and-recall
#14
Asim J Rashid, Chen Yan, Valentina Mercaldo, Hwa-Lin Liz Hsiang, Sungmo Park, Christina J Cole, Antonietta De Cristofaro, Julia Yu, Charu Ramakrishnan, Soo Yeun Lee, Karl Deisseroth, Paul W Frankland, Sheena A Josselyn
Collections of cells called engrams are thought to represent memories. Although there has been progress in identifying and manipulating single engrams, little is known about how multiple engrams interact to influence memory. In lateral amygdala (LA), neurons with increased excitability during training outcompete their neighbors for allocation to an engram. We examined whether competition based on neuronal excitability also governs the interaction between engrams. Mice received two distinct fear conditioning events separated by different intervals...
July 22, 2016: Science
https://www.readbyqxmd.com/read/27422019/parvalbumin-interneurons-constrain-the-size-of-the-lateral-amygdala-engram
#15
Dano J Morrison, Asim J Rashid, Adelaide P Yiu, Chen Yan, Paul W Frankland, Sheena A Josselyn
Memories are thought to be represented by discrete physiological changes in the brain, collectively referred to as an engram, that allow patterns of activity present during learning to be reactivated in the future. During the formation of a conditioned fear memory, a subset of principal (excitatory) neurons in the lateral amygdala (LA) are allocated to a neuronal ensemble that encodes an association between an initially neutral stimulus and a threatening aversive stimulus. Previous experimental and computational work suggests that this subset consists of only a small proportion of all LA neurons, and that this proportion remains constant across different memories...
July 12, 2016: Neurobiology of Learning and Memory
https://www.readbyqxmd.com/read/27199674/theory-of-connectivity-nature-and-nurture-of-cell-assemblies-and-cognitive-computation
#16
Meng Li, Jun Liu, Joe Z Tsien
Richard Semon and Donald Hebb are among the firsts to put forth the notion of cell assembly-a group of coherently or sequentially-activated neurons-to represent percept, memory, or concept. Despite the rekindled interest in this century-old idea, the concept of cell assembly still remains ill-defined and its operational principle is poorly understood. What is the size of a cell assembly? How should a cell assembly be organized? What is the computational logic underlying Hebbian cell assemblies? How might Nature vs...
2016: Frontiers in Neural Circuits
https://www.readbyqxmd.com/read/27197636/what-is-memory-the-present-state-of-the-engram
#17
Mu-Ming Poo, Michele Pignatelli, Tomás J Ryan, Susumu Tonegawa, Tobias Bonhoeffer, Kelsey C Martin, Andrii Rudenko, Li-Huei Tsai, Richard W Tsien, Gord Fishell, Caitlin Mullins, J Tiago Gonçalves, Matthew Shtrahman, Stephen T Johnston, Fred H Gage, Yang Dan, John Long, György Buzsáki, Charles Stevens
The mechanism of memory remains one of the great unsolved problems of biology. Grappling with the question more than a hundred years ago, the German zoologist Richard Semon formulated the concept of the engram, lasting connections in the brain that result from simultaneous "excitations", whose precise physical nature and consequences were out of reach of the biology of his day. Neuroscientists now have the knowledge and tools to tackle this question, however, and this Forum brings together leading contemporary views on the mechanisms of memory and what the engram means today...
May 19, 2016: BMC Biology
https://www.readbyqxmd.com/read/27187069/neuronal-allocation-to-a-hippocampal-engram
#18
Sungmo Park, Emily E Kramer, Valentina Mercaldo, Asim J Rashid, Nathan Insel, Paul W Frankland, Sheena A Josselyn
The dentate gyrus (DG) is important for encoding contextual memories, but little is known about how a population of DG neurons comes to encode and support a particular memory. One possibility is that recruitment into an engram depends on a neuron's excitability. Here, we manipulated excitability by overexpressing CREB in a random population of DG neurons and examined whether this biased their recruitment to an engram supporting a contextual fear memory. To directly assess whether neurons overexpressing CREB at the time of training became critical components of the engram, we examined memory expression while the activity of these neurons was silenced...
December 2016: Neuropsychopharmacology: Official Publication of the American College of Neuropsychopharmacology
https://www.readbyqxmd.com/read/27146266/mnemonic-functions-for-nonlinear-dendritic-integration-in-hippocampal-pyramidal-circuits
#19
Patrick Kaifosh, Attila Losonczy
We present a model for neural circuit mechanisms underlying hippocampal memory. Central to this model are nonlinear interactions between anatomically and functionally segregated inputs onto dendrites of pyramidal cells in hippocampal areas CA3 and CA1. We study the consequences of such interactions using model neurons in which somatic burst-firing and synaptic plasticity are controlled by conjunctive processing of these separately integrated input pathways. We find that nonlinear dendritic input processing enhances the model's capacity to store and retrieve large numbers of similar memories...
May 4, 2016: Neuron
https://www.readbyqxmd.com/read/27122991/which-neurons-will-be-the-engram-activated-neurons-and-or-more-excitable-neurons
#20
REVIEW
Ji-Il Kim, Hye-Yeon Cho, Jin-Hee Han, Bong-Kiun Kaang
During past decades, the formation and storage principle of memory have received much attention in the neuroscience field. Although some studies have attempted to demonstrate the nature of the engram, elucidating the memory engram allocation mechanism was not possible because of the limitations of existing methods, which cannot specifically modulate the candidate neuronal population. Recently, the development of new techniques, which offer ways to mark and control specific populations of neurons, may accelerate solving this issue...
April 2016: Experimental Neurobiology
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