Long-term memory

  • Article
    | Open Access

    Memories are assumed to undergo a time-dependent systems consolidation, during which hippocampal contributions to memory decrease while neocortical contributions increase. Here, the authors show that noradrenergic arousal after encoding may reverse this course of systems consolidation in humans

    • Valentina Krenz
    • , Tobias Sommer
    •  & Lars Schwabe
  • Article
    | Open Access

    When two memories are similar, their encoding and retrieval can be disrupted by each other. Here the authors show that memory interference is resolved through abrupt remapping of activity patterns in the human hippocampal CA3 and dentate gyrus.

    • Guo Wanjia
    • , Serra E. Favila
    •  & Brice A. Kuhl
  • Article
    | Open Access

    Making a decision requires one to differentiate between choice options, committing to one and leaving the other behind. Here, the authors show that decision-making paradoxically binds options together, such that the outcome of the choice ends up changing the value of both the chosen and the unchosen options, in opposite directions.

    • Natalie Biderman
    •  & Daphna Shohamy
  • Article
    | Open Access

    People can search for memories based on their content or context, defined as when and where they were formed. Here, the authors use direct brain recordings to provide evidence in line with the idea that separable neural systems retrieve these two types of information and predict whether recall is organized by time or content.

    • James E. Kragel
    • , Youssef Ezzyat
    •  & Michael J. Kahana
  • Article
    | Open Access

    Cellular activity level at the time of learning is thought to be a critical factor to determine which neurons are recruited to encode memory. Here, the authors show that competitive synaptic plasticity mechanisms influence which neurons will encode a fear memory.

    • Yire Jeong
    • , Hye-Yeon Cho
    •  & Jin-Hee Han
  • Article
    | Open Access

    Plastic reweighting of parallel fiber synaptic strength is a mechanism for the acquisition of cerebellum-dependent motor learning. Here, the authors found that optogenetic activation of PCs generates dendritic Ca2+ signals that induce plasticity in vitro and instruct learned changes to coincident eye movements in vivo.

    • Audrey Bonnan
    • , Matthew M. J. Rowan
    •  & Jason M. Christie
  • Article
    | Open Access

    Making sense of the world around us often requires flexible access to information from both semantic and episodic memory systems. Here, the authors show that controlled retrieval from functionally distinct long-term memory stores is supported by shared neural processes in the human brain.

    • Deniz Vatansever
    • , Jonathan Smallwood
    •  & Elizabeth Jefferies
  • Article
    | Open Access

    Haque et al. demonstrate that the episodic memory of a single visual scene is sufficient for humans to recognize if a visual scene has subsequently changed. A prediction error signal first arises in the visual association cortex when individuals recognize these changes.

    • Rafi U. Haque
    • , Sara K. Inati
    •  & Kareem A. Zaghloul
  • Article
    | Open Access

    When asked to imagine an event such as a party, individuals will vary in their mental imagery based on their specific experience of parties. Here, the authors show that such signatures of personal experience can be read from brain activity elicited as events are imagined.

    • Andrew James Anderson
    • , Kelsey McDermott
    •  & Feng V. Lin
  • Article
    | Open Access

    When our expectations are violated, it is adaptive to update our internal models to improve predictions in the future. Here, the authors show that during mnemonic violations, hippocampal networks are biased towards an encoding state and away from a retrieval state to potentially update these predictions.

    • Oded Bein
    • , Katherine Duncan
    •  & Lila Davachi
  • Article
    | Open Access

    Memory recollection involves reactivation of neural activity that occurred during the recalled experience. Here, the authors show that neural reactivation can be decomposed into visual-semantic features, is widely synchronized throughout the brain, and predicts memory vividness and accuracy.

    • Michael B. Bone
    • , Fahad Ahmad
    •  & Bradley R. Buchsbaum
  • Article
    | Open Access

    Odours are powerful stimuli used by most organisms to guide behaviour. Here, the authors identify populations of neurons within the anterior olfactory nucleus (AON) which are necessary and sufficient for the behavioural expression of odour memory.

    • Afif J. Aqrabawi
    •  & Jun Chul Kim
  • Article
    | Open Access

    Recent experimental work has revealed non-linear dendritic integration in interneurons. Here, the authors show, through detailed biophysical modeling, that fast spiking interneurons are better described with a 2-stage artificial neural network model calling into question the use of point neuron models.

    • Alexandra Tzilivaki
    • , George Kastellakis
    •  & Panayiota Poirazi
  • Article
    | Open Access

    Memory is hypothesised to depend on different brain regions that interact in a network. Here, the authors use case studies of stroke patients with amnesia from the literature to identify brain regions that are part of this network.

    • Michael A. Ferguson
    • , Chun Lim
    •  & Michael D. Fox
  • Article
    | Open Access

    The brain stores memories through a set of neurons known as engram cells. Here, the authors show that engram cells in the mouse hippocampus are organized into sub-ensembles representing distinct pieces of information, which are then orchestrated to constitute an entire memory.

    • Khaled Ghandour
    • , Noriaki Ohkawa
    •  & Kaoru Inokuchi
  • Article
    | Open Access

    Episodic memory retrieval is hypothesized to rely on hippocampal reinstatement of item-context associations which drives reinstatement of item information in cortex. Here, the authors confirm this sequence of events, using iEEG recordings from the human hippocampus and lateral temporal cortex.

    • D. Pacheco Estefan
    • , M. Sánchez-Fibla
    •  & P. F. M. J. Verschure
  • Article
    | Open Access

    We can recognize an object from one of its features, e.g. hearing a bark leads us to think of a dog. Here, the authors show using fMRI that the brain combines bits of information into object representations, and that presenting a few features of an object activates representations of its other attributes.

    • Sasa L. Kivisaari
    • , Marijn van Vliet
    •  & Riitta Salmelin
  • Article
    | Open Access

    While memory is often studied using voluntary recollection, the neural correlates of involuntary memory recall and its effect on cognition are unclear. Here, Ren and colleagues show that the effective connectivity from the anterior hippocampus to the precuneus can predict the strength of involuntary retrieval of episodic memory.

    • Yudan Ren
    • , Vinh T. Nguyen
    •  & Christine C. Guo
  • Article
    | Open Access

    The success of extinction learning is not predictive of long-term retrieval of an extinction memory. Using fMRI to study consolidation of fear extinction in human subjects, the authors show that reactivation in the ventromedial prefrontal cortex during memory retrieval predicts extinction memory retrieval, and that increasing dopaminergic signaling increases the number of these activations.

    • A. M. V. Gerlicher
    • , O. Tüscher
    •  & R. Kalisch
  • Article
    | Open Access

    Memory lapses can occur due to ineffective encoding, but it is unclear if targeted brain stimulation can improve memory performance. Here, authors use a closed-loop system to decode and stimulate periods of ineffective encoding, showing that stimulation of lateral temporal cortex can enhance memory.

    • Youssef Ezzyat
    • , Paul A. Wanda
    •  & Michael J. Kahana
  • Article
    | Open Access

    While non-caloric artificial sweeteners (NAS) are used as food additives, it’s unclear whether animals perceive NAS as positive or negative percept. Here, Musso and colleagues show in Drosophila that NAS is a negative percept, encoded in a new type of memory.

    • Pierre-Yves Musso
    • , Aurélie Lampin-Saint-Amaux
    •  & Thomas Preat
  • Article
    | Open Access

    Distinct subsets of dopaminergic PAM neurons have been shown to be involved in short-term and long-term memory for sugar reward. Here the authors report the neural circuits and the cellular and molecular mechanisms for short-term and long-term memory for water reward in thirstyDrosophila.

    • Wei-Huan Shyu
    • , Tai-Hsiang Chiu
    •  & Chia-Lin Wu
  • Article
    | Open Access

    Astrocytes regulate synaptic signalling via EAAT glutamate uptake, though whether they play a role in Hebbian plasticity is unknown. Here, the authors find targeting EAAT2 disrupts the emergence of spike timing-dependent plasticity, which highlights the role of astrocytes as gatekeepers for Hebbian plasticity.

    • Silvana Valtcheva
    •  & Laurent Venance
  • Article
    | Open Access

    Transcriptional regulation is necessary for maintaining long-term memories (LTM) but the mechanistic details are not completely defined. Here the authors identify transcriptional machinery and histone modifiers required for LTM maintenance inDrosophilaand show that transcriptional regulation for LTM maintenance is distinct from that for LTM formation.

    • Yukinori Hirano
    • , Kunio Ihara
    •  & Minoru Saitoe
  • Article
    | Open Access

    Learning and memory are subject to circadian variation, though the molecular mechanisms behind this are unclear. Here, the authors show SCOP, a regulator of hippocampal memory, undergoes circadian changes in CA1 membrane raft dynamics and contributes to time-dependent changes in long-term memory.

    • Kimiko Shimizu
    • , Yodai Kobayashi
    •  & Yoshitaka Fukada
  • Article
    | Open Access

    Short-term memories (STM) can become long-term memories when occurring alongside novel experiences. Here, the authors investigate the neural mechanisms behind such 'behavioural tagging' and find STM neural populations are preferentially incorporated into the ensembles encoding novel experiences.

    • Masanori Nomoto
    • , Noriaki Ohkawa
    •  & Kaoru Inokuchi
  • Article
    | Open Access

    Flexible fear-related responses may be advantageous in adolescence. Here the authors use microprisms to image prefrontal cortical spine maturation across development and report that plasticity in adolescent fear extinction responses is associated with dynamic reorganization in the amygdalahippocampal-PFC circuit.

    • Siobhan S. Pattwell
    • , Conor Liston
    •  & Francis S. Lee
  • Article
    | Open Access

    Recalled memories enter a labile state and are thought to be restabilized through reconsolidation. Here, the authors challenge the long-held notion that reconsolidation is a distinct memory process and demonstrate that the molecular events initiated at recall act instead to constrain premature extinction.

    • Simon Trent
    • , Philip Barnes
    •  & Kerrie L. Thomas
  • Article |

    The protein kinase CaMKII modulates synaptic plasticity and learning in both vertebrate and invertebrate organisms. In this study, the authors demonstrate a role for autophosphorylated CaMKII (pT305-CaMKII) in maintaining memory consolidation after classical conditioning in the invertebrate species Lymnaea.

    • Souvik Naskar
    • , Huimin Wan
    •  & György Kemenes
  • Article |

    Suprachiasmatic nucleus circadian oscillatory protein (SCOP) is implicated in long-term potentiation. Here, the authors show that μ-calpain-mediated SCOP degradation contributes to long-term potentiation induction, whereas m-calpain-mediated stimulation of SCOP synthesis restricts long-term potentiation.

    • Yubin Wang
    • , Guoqi Zhu
    •  & Michel Baudry