Engrams and circuits crucial for systems consolidation of a memory

Abstract

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 remain unknown. We found that neocortical prefrontal memory engram cells, critical for remote contextual fear memory, were rapidly generated during initial learning via inputs from both hippocampal-entorhinal cortex and 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, are maintained. Our data provide new insights into the functional reorganization of engrams and circuits underlying systems consolidation of memory.Memories are thought to be initially stored within the hippocampal-entorhinal cortex (HPC-EC) (recent memory) and over-time are slowly consolidated within the neocortex for permanent storage (remote memory) (1-7). Systems memory consolidation models suggest that the interaction between the HPC-EC and the neocortex during and after an experience is crucial (8)(9)(10)(11)(12). Experimentally, prolonged inhibition of hippocampal or neocortical networks during the consolidation period produces deficits in remote memory formation (13-15). However, little is known regarding specific neural circuit mechanisms underlying the formation and maturation of neocortical memories through interactions with the HPC-EC network. By employing activity-dependent cell labeling technology (16-18) combined with viral vector-based transgenic, anatomical (19, 20), and optogenetic strategies (19, 21) for We first traced entorhinal projections to frontal cortical structures (the medial prefrontal cortex (PFC), caudal anterior cingulate cortex (cACC), retrosplenial cortex (RSC)) involved in contextual fear memory, and the basolateral amygdala (BLA), with injections of the retrograde tracer cholera toxin subunit B (CTB)-Alexa555 into these regions ( fig. S1). CTB injections resulted in labeling in the medial entorhinal cortex (MEC) specifically in cells in layer Va (Fig. 1A-D, H and fig. S1A-D (Fig. 1F). Terminal inhibition during memory recall tests did not affect memory retrieval (Fig. 1G). Finally, terminal inhibition in the cACC or RSC during CFC or recall had no effect on memory throughout these periods (Fig. 1J-L and fig. S2G-I).The above results suggest that MEC-Va input into the PFC during CFC is crucial for the eventual formation of remote memory. This hypothesis was supported by several findings. First, CFC increased the number of c-Fos + cells in the PFC compared to that of homecage mice ( Fig. 1M-O), whereas context only exposure did not increase c-Fos activity in the PFC (Fig. 1O). Second, optogenetic terminal inhibition of MEC-Va projections within the PFC during CFC inhibited the observed incr...

Noradrenergic activation of the basolateral amygdala maintains hippocampus-dependent accuracy of remote memory

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Multi-modal and inertial sensor solutions for navigation-type factor graphs

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Untitled

“…In that sense, multidisciplinary research, encompassing technology and science and the corresponding interpretation from the point of view of the broader fields of humanities, such as arts, religion and philosophy, is therefore not a volatile trend but an unavoidable current necessity. In line with the above considerations, in this article we deal with current developments in the sex industry, and corresponding sexual trends, and the intersection with the developments in the broader scientific community in terms of computation, materials science, recent findings in neurology [3] and even the modeling of human interactions [4,5]. In this respect, recently, a human-sized robotized sex-doll, claimed to be capable of simulating common human reactions by interpreting simple physical interactions, has attracted considerable attention in the popular media [6][7][8].…”

“…Then the model, in that particular state, has a given set of values for the denominators controlling the memory of the system (Eqs. [3][4][5][6]. If events SS take place, the system might switch from a state, i.e.…”

“…In principle the PG can control long and short term memory, i.e. the analogous of biological mechanisms that are still being elucidated 3 , the relevance or weight of a given Interaction Root (IR) or single physical interaction (PI) to the overall EP, and many other mechanisms such as the memory of a given family of Interaction or Root, i.e. FIR MAX , RIR MAX , SIR MAX or CFA MAX , and even the capacity to forget "positive" and "negative" interactions.…”