keyword
https://read.qxmd.com/read/38532011/active-forgetting-and-neuropsychiatric-diseases
#1
REVIEW
Jacob A Berry, Dana C Guhle, Ronald L Davis
Recent and pioneering animal research has revealed the brain utilizes a variety of molecular, cellular, and network-level mechanisms used to forget memories in a process referred to as "active forgetting". Active forgetting increases behavioral flexibility and removes irrelevant information. Individuals with impaired active forgetting mechanisms can experience intrusive memories, distressing thoughts, and unwanted impulses that occur in neuropsychiatric diseases. The current evidence indicates that active forgetting mechanisms degrade, or mask, molecular and cellular memory traces created in synaptic connections of "engram cells" that are specific for a given memory...
March 26, 2024: Molecular Psychiatry
https://read.qxmd.com/read/38523798/sleep-dependent-engram-reactivation-during-hippocampal-memory-consolidation-associated-with-subregion-specific-biosynthetic-changes
#2
JOURNAL ARTICLE
Lijing Wang, Lauren Park, Weisheng Wu, Dana King, Alexis Vega-Medina, Frank Raven, Jessy Martinez, Amy Ensing, Katherine McDonald, Zhongying Yang, Sha Jiang, Sara J Aton
Post-learning sleep is essential for hippocampal memory processing, including contextual fear memory consolidation. We labeled context-encoding engram neurons in the hippocampal dentate gyrus (DG) and assessed reactivation of these neurons after fear learning. Post-learning sleep deprivation (SD) selectively disrupted reactivation of inferior blade DG engram neurons, linked to SD-induced suppression of neuronal activity in the inferior, but not superior DG blade. Subregion-specific spatial profiling of transcripts revealed that transcriptomic responses to SD differed greatly between hippocampal CA1, CA3, and DG inferior blade, superior blade, and hilus...
April 19, 2024: IScience
https://read.qxmd.com/read/38507477/termination-of-convulsion-seizures-by-destabilizing-and-perturbing-seizure-memory-engrams
#3
JOURNAL ARTICLE
Shirong Lai, Libo Zhang, Xinyu Tu, Xinyue Ma, Yujing Song, Kexin Cao, Miaomiao Li, Jihong Meng, Yiqiang Shi, Qing Wu, Chen Yang, Zifan Lan, Chunyue Geoffrey Lau, Jie Shi, Weining Ma, Shaoyi Li, Yan-Xue Xue, Zhuo Huang
Epileptogenesis, arising from alterations in synaptic strength, shares mechanistic and phenotypic parallels with memory formation. However, direct evidence supporting the existence of seizure memory remains scarce. Leveraging a conditioned seizure memory (CSM) paradigm, we found that CSM enabled the environmental cue to trigger seizure repetitively, and activating cue-responding engram cells could generate CSM artificially. Moreover, cue exposure initiated an analogous process of memory reconsolidation driven by mammalian target of rapamycin-brain-derived neurotrophic factor signaling...
March 22, 2024: Science Advances
https://read.qxmd.com/read/38483907/astrocytes-control-recent-and-remote-memory-strength-by-affecting-the-recruitment-of-the-ca1%C3%A2-acc-projection-to-engrams
#4
JOURNAL ARTICLE
Ron Refaeli, Tirzah Kreisel, Tamar Ravins Yaish, Maya Groysman, Inbal Goshen
The maturation of engrams from recent to remote time points involves the recruitment of CA1 neurons projecting to the anterior cingulate cortex (CA1→ACC). Modifications of G-protein-coupled receptor pathways in CA1 astrocytes affect recent and remote recall in seemingly contradictory ways. To address this inconsistency, we manipulated these pathways in astrocytes during memory acquisition and tagged c-Fos-positive engram cells and CA1→ACC cells during recent and remote recall. The behavioral results were coupled with changes in the recruitment of CA1→ACC projection cells to the engram: Gq pathway activation in astrocytes caused enhancement of recent recall alone and was accompanied by earlier recruitment of CA1→ACC projecting cells to the engram...
March 13, 2024: Cell Reports
https://read.qxmd.com/read/38454052/reactivation-of-encoding-ensembles-in-the-prelimbic-cortex-supports-temporal-associations
#5
JOURNAL ARTICLE
Thays Brenner Santos, Cesar Augusto de Oliveira Coelho, Juliana Carlota Kramer-Soares, Paul W Frankland, Maria Gabriela Menezes Oliveira
Fear conditioning is encoded by strengthening synaptic connections between the neurons activated by a conditioned stimulus (CS) and those activated by an unconditioned stimulus (US), forming a memory engram, which is reactivated during memory retrieval. In temporal associations, activity within the prelimbic cortex (PL) plays a role in sustaining a short-term, transient memory of the CS, which is associated with the US after a temporal gap. However, it is unknown whether the PL has only a temporary role, transiently representing the CS, or is part of the neuronal ensembles that support the retrieval, i...
March 7, 2024: Neuropsychopharmacology
https://read.qxmd.com/read/38447576/excitability-mediates-allocation-of-pre-configured-ensembles-to-a-hippocampal-engram-supporting-contextual-conditioned-threat-in-mice
#6
JOURNAL ARTICLE
Andrew J Mocle, Adam I Ramsaran, Alexander D Jacob, Asim J Rashid, Alessandro Luchetti, Lina M Tran, Blake A Richards, Paul W Frankland, Sheena A Josselyn
Little is understood about how engrams, sparse groups of neurons that store memories, are formed endogenously. Here, we combined calcium imaging, activity tagging, and optogenetics to examine the role of neuronal excitability and pre-existing functional connectivity on the allocation of mouse cornu ammonis area 1 (CA1) hippocampal neurons to an engram ensemble supporting a contextual threat memory. Engram neurons (high activity during recall or TRAP2-tagged during training) were more active than non-engram neurons 3 h (but not 24 h to 5 days) before training...
February 27, 2024: Neuron
https://read.qxmd.com/read/38401120/engram-reactivation-mimics-cellular-signatures-of-fear
#7
JOURNAL ARTICLE
Rebecca L Suthard, Ryan A Senne, Michelle D Buzharsky, Anh H Diep, Angela Y Pyo, Steve Ramirez
Engrams, or the physical substrate of memory, recruit heterogeneous cell types. Targeted reactivation of neurons processing discrete memories drives the behavioral expression of memory, though the underlying landscape of recruited cells and their real-time responses remain elusive. To understand how artificial stimulation of fear affects intra-hippocampal neuron-astrocyte dynamics as well as their behavioral consequences, we express channelrhodopsin-2 in an activity-dependent manner within dentate gyrus neurons while recording both cell types with fiber photometry in hippocampal ventral CA1 across learning and memory...
February 23, 2024: Cell Reports
https://read.qxmd.com/read/38396226/distinct-engrams-control-fear-and-extinction-memory
#8
JOURNAL ARTICLE
Jordana Griebler Luft, Bruno Popik, Débora Aguirre Gonçalves, Fabio Cardoso Cruz, Lucas de Oliveira Alvares
Memories are stored in engram cells, which are necessary and sufficient for memory recall. Recalling a memory might undergo reconsolidation or extinction. It has been suggested that the original memory engram is reactivated during reconsolidation so that memory can be updated. Conversely, during extinction training, a new memory is formed that suppresses the original engram. Nonetheless, it is unknown whether extinction creates a new engram or modifies the original fear engram. In this study, we utilized the Daun02 procedure, which uses c-Fos-lacZ rats to induce apoptosis of strongly activated neurons and examine whether a new memory trace emerges as a result of a short or long reactivation, or if these processes rely on modifications within the original engram located in the basolateral amygdala (BLA) and infralimbic (IL) cortex...
February 23, 2024: Hippocampus
https://read.qxmd.com/read/38375501/contextual-memory-engrams-and-the-neuromodulatory-influence-of-the-locus-coeruleus
#9
REVIEW
Stephanie L Grella, Tia N Donaldson
Here, we review the basis of contextual memory at a conceptual and cellular level. We begin with an overview of the philosophical foundations of traversing space, followed by theories covering the material bases of contextual representations in the hippocampus (engrams), exploring functional characteristics of the cells and subfields within. Next, we explore various methodological approaches for investigating contextual memory engrams, emphasizing plasticity mechanisms. This leads us to discuss the role of neuromodulatory inputs in governing these dynamic changes...
2024: Frontiers in Molecular Neuroscience
https://read.qxmd.com/read/38370006/is-the-papez-circuit-the-location-of-the-elusive-episodic-memory-engram
#10
JOURNAL ARTICLE
Steven Hall
All of the brain structures and white matter that make up Papez' circuit, as well as the circuit as a whole, are implicated in the literature in episodic memory formation and recall. This paper shows that Papez' circuit has the detailed structure and connectivity that is evidently required to support the episodic memory engram, and that identifying Papez' circuit as the location of the engram answers a number of long-standing questions regarding the role of medial temporal lobe structures in episodic memory...
June 2024: IBRO neuroscience reports
https://read.qxmd.com/read/38352478/a-multiple-arc-marc-tagging-system-to-uncover-the-organizational-principles-of-multiple-memories
#11
Michelle Stackmann, Tushar D Yelhekar, Meizhen Meng, Xiaochen Sun, Joseph Nthumba, Nicholas E Bulthuis, Nick Vaughan, Elaine Zhu, Yingxi Lin, Christine A Denny
UNLABELLED: Engrams or memory traces are the neuronal ensembles that collectively store individual experiences. Genetic strategies based on immediate early genes (IEGs), such as Arc/Arg3.1 , allow us to tag the ensembles active during memory encoding and compare them to those active during retrieval. However, these strategies only allow for the tagging of one neural ensemble. Here, we developed a multiple Arc (mArc) system that allows for the tagging of two Arc + ensembles. We validated this system by investigating how context, time, and valence influence neuronal ensemble reactivation in the dentate gyrus (DG)...
February 2, 2024: bioRxiv
https://read.qxmd.com/read/38331127/mystery-of-the-memory-engram-history-current-knowledge-and-unanswered-questions
#12
REVIEW
M R Lopez, S M H Wasberg, C M Gagliardi, M E Normandin, I A Muzzio
The quest to understand the memory engram has intrigued humans for centuries. Recent technological advances, including genetic labeling, imaging, optogenetic and chemogenetic techniques, have propelled the field of memory research forward. These tools have enabled researchers to create, and erase memory components. While these innovative techniques have yielded invaluable insights, they often focus on specific elements of the memory trace. Genetic labeling may rely on a particular immediate early gene as a marker of activity, optogenetics may activate or inhibit one specific type of neuron, and imaging may capture activity snapshots in a given brain region at specific times...
February 6, 2024: Neuroscience and Biobehavioral Reviews
https://read.qxmd.com/read/38326616/spatial-transcriptomics-reveal-neuron-astrocyte-synergy-in-long-term-memory
#13
JOURNAL ARTICLE
Wenfei Sun, Zhihui Liu, Xian Jiang, Michelle B Chen, Hua Dong, Jonathan Liu, Thomas C Südhof, Stephen R Quake
Memory encodes past experiences, thereby enabling future plans. The basolateral amygdala is a centre of salience networks that underlie emotional experiences and thus has a key role in long-term fear memory formation1 . Here we used spatial and single-cell transcriptomics to illuminate the cellular and molecular architecture of the role of the basolateral amygdala in long-term memory. We identified transcriptional signatures in subpopulations of neurons and astrocytes that were memory-specific and persisted for weeks...
February 7, 2024: Nature
https://read.qxmd.com/read/38293183/neuromodulation-via-muscarinic-acetylcholine-pathway-can-facilitate-distinct-complementary-and-sequential-roles-for-nrem-and-rem-states-during-sleep-dependent-memory-consolidation
#14
Michael Satchell, Blaine Fry, Zahraa Noureddine, Alexis Simmons, Nicolette N Ognjanovski, Sara J Aton, Michal R Zochowski
UNLABELLED: Across vertebrate species, sleep consists of repeating cycles of NREM followed by REM. However, the respective functions of NREM, REM, and their stereotypic cycling pattern are not well understood. Using a simplified biophysical network model, we show that NREM and REM sleep can play differential and critical roles in memory consolidation primarily regulated, based on state-specific changes in cholinergic signaling. Within this network, decreasing and increasing muscarinic acetylcholine (ACh) signaling during bouts of NREM and REM, respectively, differentially alters neuronal excitability and excitatory/inhibitory balance...
January 16, 2024: bioRxiv
https://read.qxmd.com/read/38243089/dynamic-and-selective-engrams-emerge-with-memory-consolidation
#15
JOURNAL ARTICLE
Douglas Feitosa Tomé, Ying Zhang, Tomomi Aida, Olivia Mosto, Yifeng Lu, Mandy Chen, Sadra Sadeh, Dheeraj S Roy, Claudia Clopath
Episodic memories are encoded by experience-activated neuronal ensembles that remain necessary and sufficient for recall. However, the temporal evolution of memory engrams after initial encoding is unclear. In this study, we employed computational and experimental approaches to examine how the neural composition and selectivity of engrams change with memory consolidation. Our spiking neural network model yielded testable predictions: memories transition from unselective to selective as neurons drop out of and drop into engrams; inhibitory activity during recall is essential for memory selectivity; and inhibitory synaptic plasticity during memory consolidation is critical for engrams to become selective...
January 19, 2024: Nature Neuroscience
https://read.qxmd.com/read/38238073/divergent-learning-related-transcriptional-states-of-cortical-glutamatergic-neurons
#16
JOURNAL ARTICLE
Katie L Dunton, Nathan G Hedrick, Saber Meamardoost, Chi Ren, James R Howe, Jing Wang, Cory M Root, Rudiyanto Gunawan, Takaki Komiyama, Ying Zhang, Eun Jung Hwang
Experience-dependent gene expression reshapes neural circuits, permitting learning of knowledge and skills. Most learning involves repetitive experiences during which neurons undergo multiple stages of functional and structural plasticity. Currently, the diversity of transcriptional responses underlying dynamic plasticity during repetition-based learning is poorly understood. To close this gap, we analyzed single-nucleus transcriptomes of L2/3 glutamatergic neurons of the primary motor cortex after 3-day motor skill training or home-cage control in water-restricted male mice...
January 18, 2024: Journal of Neuroscience
https://read.qxmd.com/read/38228367/amnesia-after-repeated-head-impact-is-caused-by-impaired-synaptic-plasticity-in-the-memory-engram
#17
JOURNAL ARTICLE
Daniel P Chapman, Sarah D Power, Stefano Vicini, Tomás J Ryan, Mark P Burns
Subconcussive head impacts are associated with the development of acute and chronic cognitive deficits. We recently reported that high-frequency head impact (HFHI) causes chronic cognitive deficits in mice through synaptic changes. To better understand the mechanisms underlying HFHI-induced memory decline, we used TRAP2/Ai32 transgenic mice to enable visualization and manipulation of memory engrams. We labeled the fear memory engram in male and female mice exposed to an aversive experience and subjected them to sham or HFHI...
February 21, 2024: Journal of Neuroscience
https://read.qxmd.com/read/38220126/hippocampal-trauma-memory-processing-conveying-susceptibility-to-traumatic-stress
#18
JOURNAL ARTICLE
Bart C J Dirven, Lennart van Melis, Teya Daneva, Lieke Dillen, Judith R Homberg, Tamas Kozicz, Marloes J A G Henckens
While the majority of the population is ever exposed to a traumatic event during their lifetime, only a fraction develops posttraumatic stress disorder (PTSD). Disrupted trauma memory processing has been proposed as a core factor underlying PTSD symptomatology. We used transgenic Targeted-Recombination-in-Active-Populations (TRAP) mice to investigate potential alterations in trauma-related hippocampal memory engrams associated with the development of PTSD-like symptomatology. Mice were exposed to a stress-enhanced fear learning paradigm, in which prior exposure to a stressor affects the learning of a subsequent fearful event (contextual fear conditioning using foot shocks), during which neuronal activity was labeled...
January 12, 2024: Neuroscience
https://read.qxmd.com/read/38157861/memory-encoding-and-retrieval-by-retrosplenial-parvalbumin-interneurons-are-impaired-in-alzheimer-s-disease-model-mice
#19
JOURNAL ARTICLE
Kyerl Park, Michael M Kohl, Jeehyun Kwag
Memory deficits in Alzheimer's disease (AD) show a strong link with GABAergic interneuron dysfunctions.1 , 2 , 3 , 4 , 5 , 6 , 7 The ensemble dynamics of GABAergic interneurons represent memory encoding and retrieval,8 , 9 , 10 , 11 , 12 but how GABAergic interneuron dysfunction affects inhibitory ensemble dynamics in AD is unknown. As the retrosplenial cortex (RSC) is critical for episodic memory13 , 14 , 15 , 16 and is affected by β-amyloid accumulation in early AD,17 , 18 , 19 , 20 , 21 we address this question by performing Ca2+ imaging in RSC parvalbumin (PV)-expressing interneurons during a contextual fear memory task in healthy control mice and the 5XFAD mouse model of AD...
December 21, 2023: Current Biology: CB
https://read.qxmd.com/read/38103203/examining-memory-linking-and-generalization-using-scflare2-a-temporally-precise-neuronal-activity-tagging-system
#20
JOURNAL ARTICLE
Jung Hoon Jung, Ying Wang, Asim J Rashid, Tao Zhang, Paul W Frankland, Sheena A Josselyn
How memories are organized in the brain influences whether they are remembered discretely versus linked with other experiences or whether generalized information is applied to entirely novel situations. Here, we used scFLARE2 (single-chain fast light- and activity-regulated expression 2), a temporally precise tagging system, to manipulate mouse lateral amygdala neurons active during one of two 3 min threat experiences occurring close (3 h) or further apart (27 h) in time. Silencing scFLARE2-tagged neurons showed that two threat experiences occurring at distal times are dis-allocated to orthogonal engram ensembles and remembered discretely, whereas the same two threat experiences occurring in close temporal proximity are linked via co-allocation to overlapping engram ensembles...
December 15, 2023: Cell Reports
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