Engrams and circuits crucial for systems consolidation of a memory

By T. Kitamura, Sachie K. Ogawa, Dheeraj S. Roy, T. Okuyama, Mark D. Morrissey, Lillian M. Smith, R. Redondo, S. Tonegawa. 2017

929 citations recorded by the source corpus.

The representation of contextual fear memories evolves over time in the hippocampus, amygdala, and prefrontal cortex. The network of memory consolidation Memories are thought to be formed in the hippocampus and later moved to the neocortex for long-term storage. However, little is known about the mechanisms that underlie the formation and maturation of neocortical memories and their interaction with the hippocampal network. Kitamura et al. discovered that at the onset of learning, neurons for contextual fear memory are quickly produced in the prefrontal cortex. This process depends on the activity of afferents from both the hippocampus and the amygdala. Over time, the prefrontal neurons consolidate their role in memory expression. In contrast, the hippocampal neurons slowly lose this function. Science, this issue p. 73 Episodic memories initially require rapid synaptic plasticity within the hippocampus for their formation and are gradually consolidated in neocortical networks for permanent storage. However, the engrams and circuits that support neocortical memory consolidation have thus far been unknown. We found that neocortical prefrontal memory engram cells, which are critical for remote contextual fear memory, were rapidly generated during initial learning through inputs from both the hippocampal–entorhinal cortex network and the basolateral amygdala. After their generation, the prefrontal engram cells, with support from hippocampal memory engram cells, became functionally mature with time. Whereas hippocampal engram cells gradually became silent with time, engram cells in the basolateral amygdala, which were necessary for fear memory, were maintained. Our data provide new insights into the functional reorganization of engrams and circuits underlying systems consolidation of memory.

Subfields: Cellular and Molecular Neuroscience, Cognitive Neuroscience, Neuroscience

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Citations in the corpus

Lifelong Learning of Spatiotemporal Representations With Dual-Memory Recurrent Self-Organization (2018, background): “Kemker and Kanan (2018) proposed the FearNet model for incremental class learning inspired by studies of memory recall and consolidation in the mammalian brain during fear conditioning (Kitamura et al., 2017).”
FearNet: Brain-Inspired Model for Incremental Learning (2017, background): “, 1995), which has considerable experimental support from neuroscience (Frankland et al., 2004; Takashima et al., 2006; Kitamura et al., 2017; Bontempi et al., 1999; Taupin & Gage, 2002; Gais et al., 2007).”
Replay in Deep Learning: Current Approaches and Missing Biological Elements (2021, neutral): “Initially, the hippocampus is used to retrieve new memories, but over time, the medial prefrontal cortex is instead used for retrieval (Kitamura et al., 2017).”
Tracking the Same Neurons across Multiple Days in Ca2+ Imaging Data (2017, background): “…studies that registered cells across sessions (Ziv et al., 2013; Jennings et al., 2015; Rubin et al., 2015; Cai et al., 2016; Liberti et al., 2016; Kitamura et al., 2017), regardless of whether using manual or automatic routines, did not provide a quantitative evaluation of registration accuracy…”
Memory engrams: Recalling the past and imagining the future (2020, background): “Systems consolidationwas recently examined at the level of the engram in the hippocampus and mPFC, where findings indicate time-dependent silencing of active engrams and conversions of silent engrams to active engrams (51, 199).”
The Role of Hippocampal Replay in Memory and Planning (2018, methodology): “[109] in which c-Fos expression was used to identify a cortical engram, hence determining its”
The hippocampus and related neocortical structures in memory transformation. (2018, background): “4 In addition to direct connections between the hippocampus and mPFC, interactions between these structures during the transformation process may be facilitated by indirect connections via the entorhinal cortex [91].”
Don’t Forget to Buy Milk: Contextually Aware Grocery Reminder Household Robot (2022, methodology): “The prediction module compares the data in STCM and LTCM to predict missing groceries in the household, which can be accessed by the user using a GUI. support in neuroscience [18].”