Memory engrams: Recalling the past and imagining the future

Science, Journal Year: 2020, Volume and Issue: 367(6473)

Published: Jan. 3, 2020

In 1904, Richard Semon introduced the term "engram" to describe neural substrate for storing memories. An experience, proposed, activates a subset of cells that undergo off-line, persistent chemical and/or physical changes become an engram. Subsequent reactivation this engram induces memory retrieval. Although Semon's contributions were largely ignored in his lifetime, new technologies allow researchers image and manipulate brain at level individual neurons has reinvigorated research. We review recent progress studying engrams, including evaluation evidence existence importance intrinsic excitability synaptic plasticity lifetime Together, these findings are beginning define as basic unit memory.

Language: Английский

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The complete connectome of a learning and memory centre in an insect brain

Nature, Journal Year: 2017, Volume and Issue: 548(7666), P. 175 - 182

Published: Aug. 1, 2017

Language: Английский

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A connectome of a learning and memory center in the adult Drosophila brain

eLife, Journal Year: 2017, Volume and Issue: 6

Published: July 18, 2017

Understanding memory formation, storage and retrieval requires knowledge of the underlying neuronal circuits. In Drosophila, mushroom body (MB) is major site associative learning. We reconstructed morphologies synaptic connections all 983 neurons within three functional units, or compartments, that compose adult MB's α lobe, using a dataset isotropic 8 nm voxels collected by focused ion-beam milling scanning electron microscopy. found Kenyon cells (KCs), whose sparse activity encodes sensory information, each make multiple en passant synapses to MB output (MBONs) in compartment. Some MBONs have inputs from KCs, while others differentially sample modalities. Only 6% KC>MBON receive direct synapse dopaminergic neuron (DAN). identified two unanticipated classes synapses, KC>DAN DAN>MBON. DAN activation produces slow depolarization MBON these DAN>MBON can weaken recall.

Language: Английский

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The connectome of the adult Drosophila mushroom body provides insights into function

eLife, Journal Year: 2020, Volume and Issue: 9

Published: Dec. 14, 2020

Making inferences about the computations performed by neuronal circuits from synapse-level connectivity maps is an emerging opportunity in neuroscience. The mushroom body (MB) well positioned for developing and testing such approach due to its conserved architecture, recently completed dense connectome, extensive prior experimental studies of roles learning, memory, activity regulation. Here, we identify new components MB circuit Drosophila, including visual input output neurons (MBONs) with direct connections descending neurons. We find unexpected structure sensory inputs, transfer information different modalities MBONs, modulation that dopaminergic (DANs). provide insights into circuitry used integrate outputs, between central complex inputs DANs, feedback MBONs. Our results a foundation further theoretical work.

Language: Английский

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Do the right thing: neural network mechanisms of memory formation, expression and update in Drosophila

Current Opinion in Neurobiology, Journal Year: 2017, Volume and Issue: 49, P. 51 - 58

Published: Dec. 16, 2017

When animals learn, plasticity in brain networks that respond to specific cues results a change the behavior these elicit. Individual network components mushroom bodies of fruit fly Drosophila melanogaster represent cues, learning signals and behavioral outcomes learned experience. Recent findings have highlighted importance dopamine-driven activity feedback feedforward connections, between various elements body neural network. These computational motifs been shown be crucial for long term olfactory memory consolidation, integration internal states, re-evaluation updating information. The often recurrent circuit anatomy prolonged requirement parts underlying networks, suggest self-sustained precisely timed is fundamental feature computations insect brain. Together processes allow flies continuously adjust content their knowledge direct way best represents expectations serves most pressing current needs.

Language: Английский

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Inhibitory Plasticity: Balance, Control, and Codependence

Annual Review of Neuroscience, Journal Year: 2017, Volume and Issue: 40(1), P. 557 - 579

Published: June 9, 2017

Inhibitory neurons, although relatively few in number, exert powerful control over brain circuits. They stabilize network activity the face of strong feedback excitation and actively engage computations. Recent studies reveal importance a precise balance inhibition neural circuits, which often requires exquisite fine-tuning inhibitory connections. We review synaptic plasticity its roles shaping both feedforward control. discuss necessity complex, codependent mechanisms to build nontrivial, functioning networks, we end by summarizing experimental evidence such interactions.

Language: Английский

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Integration of Parallel Opposing Memories Underlies Memory Extinction

Cell, Journal Year: 2018, Volume and Issue: 175(3), P. 709 - 722.e15

Published: Sept. 20, 2018

Accurately predicting an outcome requires that animals learn supporting and conflicting evidence from sequential experience. In mammals invertebrates, learned fear responses can be suppressed by experiencing predictive cues without punishment, a process called memory extinction. Here, we show extinction of aversive memories in Drosophila specific dopaminergic neurons, which indicate omission punishment is remembered as positive Functional imaging revealed co-existence intracellular calcium traces different places the mushroom body output neuron network for both original new appetitive memory. Light ultrastructural anatomy are consistent with parallel competing being combined within neurons direct avoidance. Indeed, extinction-evoked plasticity pair these neutralizes potentiated odor response imposed learning. Therefore, flies track accuracy expectations accumulating integrating events.

Language: Английский

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Drosophila mushroom bodies integrate hunger and satiety signals to control innate food-seeking behavior

eLife, Journal Year: 2018, Volume and Issue: 7

Published: March 16, 2018

The fruit fly can evaluate its energy state and decide whether to pursue food-related cues. Here, we reveal that the mushroom body (MB) integrates hunger satiety signals control food-seeking behavior. We have discovered five pathways in MB essential for hungry flies locate approach food. Blocking MB-intrinsic Kenyon cells (KCs) output neurons (MBONs) these impairs Starvation bi-directionally modulates MBON responses a food odor, suggesting controls occur at KC-to-MBON synapses. These are mediated by six types of dopaminergic (DANs). By manipulating DANs, could inhibit behavior or promote seeking fed flies. Finally, show DANs potentially receive multiple inputs signals. This work demonstrates an information-rich central circuit brain hunger-driven

Language: Английский

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The Drosophila Mushroom Body: From Architecture to Algorithm in a Learning Circuit

Annual Review of Neuroscience, Journal Year: 2020, Volume and Issue: 43(1), P. 465 - 484

Published: April 14, 2020

The Drosophila brain contains a relatively simple circuit for forming Pavlovian associations, yet it achieves many operations common across memory systems. Recent advances have established clear framework learning and revealed the following key operations: a) pattern separation, whereby dense combinatorial representations of odors are preprocessed to generate highly specific, nonoverlapping odor patterns used learning; b) convergence, in which sensory information is funneled small set output neurons that guide behavioral actions; c) plasticity, where changing mapping input requires strong reinforcement signal, also modulated by internal state environmental context; d) modularization, consists multiple parallel traces, distinct stability flexibility exist anatomically well-defined modules within network. Cross-module interactions allow higher-order effects past experience influences future learning. Many these parallels with processes formation action selection more complex brains.

Language: Английский

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Multisensory learning binds neurons into a cross-modal memory engram

Nature, Journal Year: 2023, Volume and Issue: 617(7962), P. 777 - 784

Published: April 26, 2023

Associating multiple sensory cues with objects and experience is a fundamental brain process that improves object recognition memory performance. However, neural mechanisms bind features during learning augment expression are unknown. Here we demonstrate multisensory appetitive aversive in Drosophila. Combining colours odours improved performance, even when each modality was tested alone. Temporal control of neuronal function revealed visually selective mushroom body Kenyon cells (KCs) to be required for enhancement both visual olfactory after training. Voltage imaging head-fixed flies showed binds activity between streams modality-specific KCs so unimodal input generates multimodal response. Binding occurs regions the KC axons, which receive valence-relevant dopaminergic reinforcement, propagated downstream. Dopamine locally releases GABAergic inhibition permit specific microcircuits within KC-spanning serotonergic neurons as an excitatory bridge previously 'modality-selective' streams. Cross-modal binding thereby expands representing engram into those other. This broadening performance permits single feature retrieve experience.

Language: Английский

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