What happens to memories as days, weeks and years go by has long been a fundamental question in neuroscience and psychology. For decades, researchers have attempted to identify the brain regions in which memory is formed and to follow its changes across time. The theory of systems consolidation of memory (SCM) suggests that changes in circuitry and brain networks are required for the maintenance of a memory with time. Various mechanisms by which such changes may take place have been hypothesized. Recently, several studies have provided insight into the brain networks driving SCM through the characterization of memory engram cells, their biochemical and physiological changes and the circuits in which they operate. In this Review, we place these findings in the context of the field and describe how they have led to a revamped understanding of SCM in the brain.
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http://dx.doi.org/10.1038/s41583-018-0031-2 | DOI Listing |
Behav Brain Res
January 2025
Department of Neurology, Changzhi People's Hospital, Changzhi, 046000, Shanxi Province, China. Electronic address:
Memory is the ability to acquire and store information following an experience, which can be retrieved by related context exposure. Pioneering studies have demonstrated that sparsely distributed neuronal ensembles or engram cells can serve as neural substrates for storing and recalling memory traces. Many studies of neuronal ensembles have focused on the hippocampus, and increasing evidence has indicated that the neuronal oscillation is closely associated with hippocampal memory functions, including both encoding and retrieval processes.
View Article and Find Full Text PDFFront Behav Neurosci
December 2024
Department of Psychology, University of California, Davis, Davis, CA, United States.
Molecular and genetic techniques now allow selective tagging and manipulation of the population of neurons, often referred to as "engram cells," that were active during a specific experience. One common approach to labeling these cells is to use the transgenic mouse (TetTag). In addition to tagging cells active during learning, it is common to examine the reactivation of these cells using immediate early gene (IEG) expression as an index of neural activity.
View Article and Find Full Text PDFbioRxiv
December 2024
Cerebral Codes and Circuits Connectivity team, Brain Plasticity Unit, CNRS, ESPCI Paris, PSL Research University; Paris, France.
How are associative memories formed? Which cells represent a memory, and when are they engaged? By visualizing and tagging cells based on their calcium influx with unparalleled temporal precision, we identified non-overlapping dorsal CA1 neuronal ensembles that are differentially active during associative fear memory acquisition. We dissected the acquisition experience into periods during which salient stimuli were presented or certain mouse behaviors occurred and found that cells associated with specific acquisition periods are sufficient alone to drive memory expression and contribute to fear engram formation. This study delineated the different identities of the cell ensembles active during learning, and revealed, for the first time, which ones form the core engram and are essential for memory formation and recall.
View Article and Find Full Text PDFChaos
December 2024
School of Mathematics and Statistics, Northwestern Polytechnical University, Xi'an 710129, China.
Alcohol Clin Exp Res (Hoboken)
November 2024
Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology (SIAT), Chinese Academy of Sciences, Shenzhen, China.
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