Learning and memory

  • Article
    | Open Access

    Whether gut microbes drive cognitive differences in natural populations of animals remains unknown. Here, Li et al. demonstrate a causal link between increased symbiotic Lactobacillus Firm-5 species (L. apis) and improved long-term memory in bumblebees.

    • Li Li
    • , Cwyn Solvi
    •  & Wei Zhao
  • Article
    | Open Access

    The role of complex spikes in reinforcement learning is still unclear. Here, the authors show that complex spikes carry multiple context based, cell type specific and learning dependent signals that are independent of changes in any motor kinematics and unlikely to instruct the concurrent simple spike activity during reinforcement learning.

    • Naveen Sendhilnathan
    • , Anna Ipata
    •  & Michael E. Goldberg
  • Article
    | Open Access

    The authors used intracranial EEG recordings from patients with epilepsy to show that successful intentional forgetting is due to a selective modification of item-specific top-down connections and not simply a degradation of the memory traces.

    • Sanne Ten Oever
    • , Alexander T. Sack
    •  & Nikolai Axmacher
  • Article
    | Open Access

    The authors examine how we differentiate highly similar places from each other. They provide evidence for complementary neural mechanisms in the human hippocampus and prefrontal cortex involved in processing interfering and common elements important to remembering places that we have visited.

    • Li Zheng
    • , Zhiyao Gao
    •  & Arne D. Ekstrom
  • Article
    | Open Access

    The authors show that adult hippocampal neurogenesis is altered in the dentate gyrus of obese mice with subsequent inhibition of long-term potentiation and impairment of pattern separation. Inhibition of orexin-A action at orexin-1 receptors rescued both impairments in obese mice.

    • Nicola Forte
    • , Serena Boccella
    •  & Luigia Cristino
  • Article
    | Open Access

    Bilaterally projecting CA3 inputs may be crucial for integrating the left and right CA1 during memory but this has not been directly examined. Here, the authors show that projections from bilateral CA3 play a key role in the cross-hemispheric coordination of CA1 spatial coding.

    • Hefei Guan
    • , Steven J. Middleton
    •  & Thomas J. McHugh
  • 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

    Goal-directed behaviors require the brain to integrate information across many task-related dimensions. Here, the authors use a virtual context discrimination paradigm in mice to demonstrate the capacity for neurons in the retrosplenial cortex to exhibit multidimensional encoding across learning.

    • Weilun Sun
    • , Ilseob Choi
    •  & Alexander Dityatev
  • Article
    | Open Access

    Identical physical inputs can evoke non-identical percepts. Here, the authors investigate the sources of such variability and find that rats and humans, trained to judge tactile vibration strength, express a robust sequential effect that could be modeled as the trial-by-trial incorporation of sensory history.

    • I. Hachen
    • , S. Reinartz
    •  & M. E. Diamond
  • Article
    | Open Access

    Male and female mice need to generate spatial maps that integrate vomeronasal signals of territory owners in the hippocampus-dependent memory. The authors show that vomeronasal information influences learning-related activity in the hippocampus via the amygdaloid PMCo, lateral entorhinal cortex, and dorsal CA1.

    • María Villafranca-Faus
    • , Manuel Esteban Vila-Martín
    •  & Vicent Teruel-Martí
  • Article
    | Open Access

    New instrumental learning occurs through an unexpected delivery of a rewarding stimulus or the withdrawal of a punishing stimulus. The authors show that D1 receptor-expressing medium spiny neurons (MSNs) in the anterior dorsolateral striatum encode newly learned instrumental actions whereas D2 MSNs promote the expression of habitual actions.

    • Alexander C. W. Smith
    • , Sietse Jonkman
    •  & Paul J. Kenny
  • 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

    Previous work has shown that in rodents phase precession – the phase of action potentials relative to the theta oscillation – is associated with the representation of sequential locations. Here the authors demonstrate that phase precession also occurs in the human hippocampus using single neuron and LFP recordings.

    • Leila Reddy
    • , Matthew W. Self
    •  & Pieter R. Roelfsema
  • Article
    | Open Access

    The relative roles of visual, parietal, and frontal cortex in working memory have been actively debated. Here, the authors show that distraction impacts visual working memory representations in primary visual areas, indicating that these regions play a key role in the maintenance of working memory.

    • Grace E. Hallenbeck
    • , Thomas C. Sprague
    •  & Clayton E. Curtis
  • 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

    Scintillators emit visible luminescence when irradiated with X-rays and may enable remote optogenetic control of neurons deep in the brain. The authors inject an inorganic scintillator to activate and inhibit midbrain dopamine neurons in freely moving mice by X-ray irradiation to modulate place preference behavior.

    • Takanori Matsubara
    • , Takayuki Yanagida
    •  & Takayuki Yamashita
  • 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

    Intratelencephalic and pyramidal tract neurons are two major types of cortical excitatory neurons that project to cortical and subcortical structures. The authors show that in the prefrontal cortex the two populations have different roles for the maintenance of working memory and for tracking the passage of time.

    • Jung Won Bae
    • , Huijeong Jeong
    •  & Min Whan Jung
  • Article
    | Open Access

    Sleep is known to promote memory consolidation, but the extent to which this is dependent on the memory’s relevance remains unclear. Here, the authors use a brain decoding approach to show that neural representations of rewarded experiences undergo a privileged reactivation during sleep, favouring their consolidation.

    • Virginie Sterpenich
    • , Mojca K. M. van Schie
    •  & Sophie Schwartz
  • 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

    Hippocampal place cells contribute to navigation and memory formation. Here, the authors use in vivo glutamate imaging to reveal patterns of excitatory input received by place cell dendrites and find more spatially tuned and functionally organized inputs arriving in the place field.

    • Michael D. Adoff
    • , Jason R. Climer
    •  & Daniel A. Dombeck
  • Article
    | Open Access

    Changes in poly-unsaturated free fatty acids (FFAs) have been associated with LTP. Here, using lipidomics analysis the authors characterise FFA changes in the rat brain associated with fear conditioning, and demonstrate that increases in saturated FFAs represent the major change.

    • Tristan P. Wallis
    • , Bharat G. Venkatesh
    •  & Frédéric A. Meunier
  • Article
    | Open Access

    Here the authors compare place cell sequence coding during correct and error trials in a spatial memory task. Sequences coded paths that were longer and more temporally compressed during correct trials and developed a bias to replay paths to a goal location during rest periods of correct but not error trials.

    • Chenguang Zheng
    • , Ernie Hwaun
    •  & Laura Lee Colgin
  • Article
    | Open Access

    To understand how spatial representations emerge and evolve across hippocampal subfields, we compared trial-to-trial dynamics of place cells in CA1 and CA3 in new environments and across days. CA1 place fields form early, shift backwards and partially remap across days whereas in CA3 they develop gradually and are more stable, suggesting distinct functional roles in representing space.

    • Can Dong
    • , Antoine D. Madar
    •  & Mark E. J. Sheffield
  • Article
    | Open Access

    New microgrid recordings on the human hippocampal surface reveal that oscillations travel in reversing directions. The route of travel at a given moment was related to behavior and topographic patterns of activity strength, suggesting directions may be biomarkers of hippocampal cognitive processes.

    • Jonathan K. Kleen
    • , Jason E. Chung
    •  & Edward F. Chang
  • Article
    | Open Access

    Dopamine neurons in the mushroom body help Drosophila learn to approach rewards and avoid punishments. Here, the authors propose a model in which dopaminergic learning signals encode reinforcement prediction errors by utilising feedback reinforcement predictions from mushroom body output neurons.

    • James E. M. Bennett
    • , Andrew Philippides
    •  & Thomas Nowotny
  • Article
    | Open Access

    The Tachykinin 2 (Tac2) pathway in the central amygdala is sufficient and necessary for modulating fear memory consolidation. The authors show that silencing Tac2 neurons in the amygdala of male mice reduces fear expression, while fear expression in female mice is increased when manipulations are made during proestrus.

    • A. Florido
    • , E. R. Velasco
    •  & R. Andero
  • Article
    | Open Access

    How thalamic sensory relays participate in plasticity upon associative fear learning and stable long-term sensory coding remains unknown. The authors show that auditory thalamus neurons exhibit heterogeneous plasticity patterns after learning while population level encoding of auditory stimuli remains stable across days.

    • James Alexander Taylor
    • , Masashi Hasegawa
    •  & Jan Gründemann
  • Article
    | Open Access

    Higher-order sequence learning using a structured graph representation - clone-structured cognitive graphs (CSCG) – can explain how the hippocampus learns cognitive maps. CSCG provides novel explanations for transferable schemas and transitive inference in the hippocampus, and for how place cells, splitter cells, lap-cells and a variety of phenomena emerge from the same set of fundamental principles.

    • Dileep George
    • , Rajeev V. Rikhye
    •  & Miguel Lázaro-Gredilla
  • 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

    Epitranscriptomic modifications can regulate learning and memory. Here, the authors provide proteomic and functional analysis of N6-methyladenosine (m6A)-binding proteins in D. melanogaster and unveil behavioral and regulatory defects for m6A/Ythdf mutants.

    • Lijuan Kan
    • , Stanislav Ott
    •  & Eric C. Lai
  • Article
    | Open Access

    Unexpected omission of aversive outcome is encoded as reward via activation of reward-encoding dopaminergic neurons in animals. The authors identify the Drosophila neural circuit through which reward-encoding dopaminergic neurons are activated when an olfactory cue is no longer paired with punishment.

    • Li Yan McCurdy
    • , Preeti Sareen
    •  & Michael N. Nitabach
  • Article
    | Open Access

    Here, the authors show that beta-band coordination between prefrontal and temporal cortex predicts working memory performance. Moreover, inferior temporal neurons exhibits greater memory activity when coordination between these areas is high, suggesting that this interaction supports object memory maintenance.

    • Ehsan Rezayat
    • , Mohammad-Reza A. Dehaqani
    •  & Behrad Noudoost