The Longevity of Hippocampus-Dependent Memory Is Orchestrated by the Locus Coeruleus-Noradrenergic System

The locus coeruleus is connected to the dorsal hippocampus via strong fiber projections. It becomes activated after arousal and novelty, whereupon noradrenaline is released in the hippocampus. Noradrenaline from the locus coeruleus is involved in modulating the encoding, consolidation, retrieval, and reversal of hippocampus-based memory. Memory storage can be modified by the activation of the locus coeruleus and subsequent facilitation of hippocampal long-term plasticity in the forms of long-term depression and long-term potentiation. Recent evidence indicates that noradrenaline and dopamine are coreleased in the hippocampus from locus coeruleus terminals, thus fostering neuromodulation of long-term synaptic plasticity and memory. Noradrenaline is an inductor of epigenetic modifications regulating transcriptional control of synaptic long-term plasticity to gate the endurance of memory storage. In conclusion, locus coeruleus activation primes the persistence of hippocampus-based long-term memory.

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Evidence of Maintenance Tagging in the Hippocampus for the Persistence of Long-Lasting Memory Storage

Neural Plasticity ◽

10.1155/2015/603672 ◽

2015 ◽

Vol 2015 ◽

pp. 1-9 ◽

Cited By ~ 9

Author(s):

Micol Tomaiuolo ◽

Cynthia Katche ◽

Haydee Viola ◽

Jorge H. Medina

Keyword(s):

Time Window ◽

Dorsal Hippocampus ◽

Training Session ◽

Critical Time ◽

Long Term Potentiation ◽

Memory Storage ◽

Long Term Memory ◽

Memory Persistence ◽

Synaptic Tagging And Capture

The synaptic tagging and capture (STC) hypothesis provides a compelling explanation for synaptic specificity and facilitation of long-term potentiation. Its implication on long-term memory (LTM) formation led to postulate the behavioral tagging mechanism. Here we show that a maintenance tagging process may operate in the hippocampus late after acquisition for the persistence of long-lasting memory storage. The proposed maintenance tagging has several characteristics: (1) the tag is transient and time-dependent; (2) it sets in a late critical time window after an aversive training which induces a short-lasting LTM; (3) exposing rats to a novel environment specifically within this tag time window enables the consolidation to a long-lasting LTM; (4) a familiar environment exploration was not effective; (5) the effect of novelty on the promotion of memory persistence requires dopamine D1/D5 receptors and Arc expression in the dorsal hippocampus. The present results can be explained by a broader version of the behavioral tagging hypothesis and highlight the idea that the durability of a memory trace depends either on late tag mechanisms induced by a training session or on events experienced close in time to this tag.

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Integrated Overview of the Memory System

International Journal for Research in Applied Science and Engineering Technology ◽

10.22214/ijraset.2021.35690 ◽

2021 ◽

Vol 9 (VI) ◽

pp. 3328-3338

Author(s):

Ishanee Das Sharma

Keyword(s):

Molecular Mechanisms ◽

Short Term Memory ◽

Long Term Potentiation ◽

Point Of View ◽

Memory Storage ◽

Long Term Memory ◽

Special Focus ◽

Term Memory ◽

Term Potentiation

This review aims to clarify and classify memory from psychological and neuroscientific point of view, delving into the molecular mechanisms taking place as well. The main forms of memory are sensory memory, short term memory and long-term memory. We also try to specify the flow of information through various memory models. The concept of synaptic plasticity and long-term potentiation is highlighted, with special focus on the physiological parts of the brain that are involved in memory storage. Overall, this study will help expand our knowledge on the intrinsic details of memory storage and the functioning of our brain.

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The immediate early gene Arc is not required for hippocampal long-term potentiation

10.1101/2020.01.03.893305 ◽

2020 ◽

Cited By ~ 1

Author(s):

M. Kyrke-Smith ◽

L.J. Volk ◽

S.F. Cooke ◽

M.F. Bear ◽

R.L. Huganir ◽

...

Keyword(s):

Immediate Early Gene ◽

Long Term Potentiation ◽

Memory Storage ◽

Early Gene ◽

Immediate Early ◽

Long Term Memory ◽

Memory Encoding ◽

Term Potentiation ◽

Mrna And Protein Expression

ABSTRACTThe immediate early gene Arc is critical for maintenance of long-term memory. How Arc mediates this process remains unclear, but it has been proposed to sustain Hebbian synaptic potentiation, which is a key component of memory encoding. This form of plasticity is modelled experimentally by induction of long-term potentiation (LTP), which increases Arc mRNA and protein expression. However, mechanistic data implicates Arc in the endocytosis of AMPA-type glutamate receptors and the weakening of synapses. Here, we took a comprehensive approach to determine if Arc is necessary for hippocampal LTP. We find that Arc is not required for LTP maintenance and must regulate memory storage through alternative mechanisms.

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