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

Tomaiuolo M, Katche C, Viola H, Medina JH - Neural Plast. (2015)

Bottom Line: 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 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.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biología Celular y Neurociencias "Dr. Eduardo De Robertis", Facultad de Medicina, Universidad de Buenos Aires, C1121ABG Buenos Aires, Argentina.

ABSTRACT
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.

No MeSH data available.


Related in: MedlinePlus

(a) A novel, but not a familiar, open field exposure promotes the durability of IA memory. (A1) Schematic representation of the experimental protocol is presented on the top of the panel. (A2) Animals (“Familiar” and “New” groups) were exposed for 30 min to the OF 24 h before IA training. On the day of the training, we used a different OF only for the labeled “New” group. Novel group of rats were exposed to a single OF session the day of the IA training and the control group of animals did not explore the OF. (b) Bar graph represents the number of quadrant crosses (B1) or rearings (B2) in a new or familiar OF during 5 min. Data are presented as mean ± SEM.
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fig2: (a) A novel, but not a familiar, open field exposure promotes the durability of IA memory. (A1) Schematic representation of the experimental protocol is presented on the top of the panel. (A2) Animals (“Familiar” and “New” groups) were exposed for 30 min to the OF 24 h before IA training. On the day of the training, we used a different OF only for the labeled “New” group. Novel group of rats were exposed to a single OF session the day of the IA training and the control group of animals did not explore the OF. (b) Bar graph represents the number of quadrant crosses (B1) or rearings (B2) in a new or familiar OF during 5 min. Data are presented as mean ± SEM.

Mentions: To directly address whether long-lasting LTM is induced by the novel nature of the environment, we subjected animals to an open field 30 min on the previous day. On the day of training, 11 h after a weak IA training, we use the same open field (Familiar group) or a different one with respect to which they were exposed the day before (New group). In contrast to what is observed when a new environment is explored no long-lasting LTM evaluated at 7 days is induced when a familiar environment is presented (Figure 2(a)) (Control versus Novel: ∗∗P < 0.05, n = 15; Familiar versus New: ∗P < 0.05, n = 16; Newman-Keuls test after ANOVA). We registered the number of crossings (Figure 2(b), (B1)) and the number of rearings (Figure 2(b), (B2)) during the 5 min new or familiar OF sessions, observing a significant decrease in these parameters in the familiar group of rats (OF New versus OF Familiar; interaction crossings: ∗P < 0.05, interaction rearings: ∗P < 0.05, repeated measures, two-way ANOVA followed by Bonferroni test). These data reflect the habituated response of rats when they explore a familiar environment. In contrast, a high exploratory activity in the New group is consistent with the recognition of the arena as a novel place.


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

Tomaiuolo M, Katche C, Viola H, Medina JH - Neural Plast. (2015)

(a) A novel, but not a familiar, open field exposure promotes the durability of IA memory. (A1) Schematic representation of the experimental protocol is presented on the top of the panel. (A2) Animals (“Familiar” and “New” groups) were exposed for 30 min to the OF 24 h before IA training. On the day of the training, we used a different OF only for the labeled “New” group. Novel group of rats were exposed to a single OF session the day of the IA training and the control group of animals did not explore the OF. (b) Bar graph represents the number of quadrant crosses (B1) or rearings (B2) in a new or familiar OF during 5 min. Data are presented as mean ± SEM.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4561985&req=5

fig2: (a) A novel, but not a familiar, open field exposure promotes the durability of IA memory. (A1) Schematic representation of the experimental protocol is presented on the top of the panel. (A2) Animals (“Familiar” and “New” groups) were exposed for 30 min to the OF 24 h before IA training. On the day of the training, we used a different OF only for the labeled “New” group. Novel group of rats were exposed to a single OF session the day of the IA training and the control group of animals did not explore the OF. (b) Bar graph represents the number of quadrant crosses (B1) or rearings (B2) in a new or familiar OF during 5 min. Data are presented as mean ± SEM.
Mentions: To directly address whether long-lasting LTM is induced by the novel nature of the environment, we subjected animals to an open field 30 min on the previous day. On the day of training, 11 h after a weak IA training, we use the same open field (Familiar group) or a different one with respect to which they were exposed the day before (New group). In contrast to what is observed when a new environment is explored no long-lasting LTM evaluated at 7 days is induced when a familiar environment is presented (Figure 2(a)) (Control versus Novel: ∗∗P < 0.05, n = 15; Familiar versus New: ∗P < 0.05, n = 16; Newman-Keuls test after ANOVA). We registered the number of crossings (Figure 2(b), (B1)) and the number of rearings (Figure 2(b), (B2)) during the 5 min new or familiar OF sessions, observing a significant decrease in these parameters in the familiar group of rats (OF New versus OF Familiar; interaction crossings: ∗P < 0.05, interaction rearings: ∗P < 0.05, repeated measures, two-way ANOVA followed by Bonferroni test). These data reflect the habituated response of rats when they explore a familiar environment. In contrast, a high exploratory activity in the New group is consistent with the recognition of the arena as a novel place.

Bottom Line: 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 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.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biología Celular y Neurociencias "Dr. Eduardo De Robertis", Facultad de Medicina, Universidad de Buenos Aires, C1121ABG Buenos Aires, Argentina.

ABSTRACT
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.

No MeSH data available.


Related in: MedlinePlus