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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) The promoting effect of OF is time-dependent. (A1, B1) Schematic representation of the experimental protocol is presented on the top of each panel. (A2) Animals were trained in the IA and exposed to an OF 5 h, 8 h, 11 h, or 24 h after a weak IA training. Test was performed 7 days after training. Only the exposure to an OF 11 h after training promotes the durability of IA memory. Data are presented as mean ± SEM. (b) Exploration of an open field 11 h after training promotes the persistence of weak IA memory. (B2) Animals were trained in the IA and exposed to an OF 11 h later. Test was performed in independent groups of animals at 1 day, 2 days, and 7 days after training. A retest was performed at 13 days only with the animals that had been tested at 7 days (note a small increase of latency in this control group probably due to the retest effect). Data are presented as mean ± SEM.
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fig1: (a) The promoting effect of OF is time-dependent. (A1, B1) Schematic representation of the experimental protocol is presented on the top of each panel. (A2) Animals were trained in the IA and exposed to an OF 5 h, 8 h, 11 h, or 24 h after a weak IA training. Test was performed 7 days after training. Only the exposure to an OF 11 h after training promotes the durability of IA memory. Data are presented as mean ± SEM. (b) Exploration of an open field 11 h after training promotes the persistence of weak IA memory. (B2) Animals were trained in the IA and exposed to an OF 11 h later. Test was performed in independent groups of animals at 1 day, 2 days, and 7 days after training. A retest was performed at 13 days only with the animals that had been tested at 7 days (note a small increase of latency in this control group probably due to the retest effect). Data are presented as mean ± SEM.

Mentions: After recovery from surgery, animals were handled once a day for two days and then trained in inhibitory avoidance (IA) as described previously [16]. Briefly the apparatus was a 50 × 25 × 25 cm opaque acrylic box whose floor was a grid made of 1 mm caliber stainless steel bars. The left end of the grid was covered by a 12 cm wide, 5.0 cm high platform. During the handling session animals were manipulated in the same way they were during intracerebral infusions. Briefly, they were grasped by hand and slightly restrained in the lap or the arm of the investigator. During the second day of this manipulation in most animals there were no evident signs of stress. For training, animals were gently placed on the platform and, as they stepped down onto the grid, received a single 3 sec, 0.4 mA scrambled foot-shock. The parameter evaluated during training and testing sessions is the latency to step down from the platform. Rats were tested for retention at either 1 day, 2 days, 7 days, or 13 days after training, depending on the experiment. In the test sessions the footshock was omitted and the latency was evaluated for a maximum of 300 seconds. All animals were tested only once (except one group of Figure 1(b)). Training was always performed between 8:30 and 9:30 A.M. For each experiment the number of animals in each group is detailed in the Results.


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) The promoting effect of OF is time-dependent. (A1, B1) Schematic representation of the experimental protocol is presented on the top of each panel. (A2) Animals were trained in the IA and exposed to an OF 5 h, 8 h, 11 h, or 24 h after a weak IA training. Test was performed 7 days after training. Only the exposure to an OF 11 h after training promotes the durability of IA memory. Data are presented as mean ± SEM. (b) Exploration of an open field 11 h after training promotes the persistence of weak IA memory. (B2) Animals were trained in the IA and exposed to an OF 11 h later. Test was performed in independent groups of animals at 1 day, 2 days, and 7 days after training. A retest was performed at 13 days only with the animals that had been tested at 7 days (note a small increase of latency in this control group probably due to the retest effect). Data are presented as mean ± SEM.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4561985&req=5

fig1: (a) The promoting effect of OF is time-dependent. (A1, B1) Schematic representation of the experimental protocol is presented on the top of each panel. (A2) Animals were trained in the IA and exposed to an OF 5 h, 8 h, 11 h, or 24 h after a weak IA training. Test was performed 7 days after training. Only the exposure to an OF 11 h after training promotes the durability of IA memory. Data are presented as mean ± SEM. (b) Exploration of an open field 11 h after training promotes the persistence of weak IA memory. (B2) Animals were trained in the IA and exposed to an OF 11 h later. Test was performed in independent groups of animals at 1 day, 2 days, and 7 days after training. A retest was performed at 13 days only with the animals that had been tested at 7 days (note a small increase of latency in this control group probably due to the retest effect). Data are presented as mean ± SEM.
Mentions: After recovery from surgery, animals were handled once a day for two days and then trained in inhibitory avoidance (IA) as described previously [16]. Briefly the apparatus was a 50 × 25 × 25 cm opaque acrylic box whose floor was a grid made of 1 mm caliber stainless steel bars. The left end of the grid was covered by a 12 cm wide, 5.0 cm high platform. During the handling session animals were manipulated in the same way they were during intracerebral infusions. Briefly, they were grasped by hand and slightly restrained in the lap or the arm of the investigator. During the second day of this manipulation in most animals there were no evident signs of stress. For training, animals were gently placed on the platform and, as they stepped down onto the grid, received a single 3 sec, 0.4 mA scrambled foot-shock. The parameter evaluated during training and testing sessions is the latency to step down from the platform. Rats were tested for retention at either 1 day, 2 days, 7 days, or 13 days after training, depending on the experiment. In the test sessions the footshock was omitted and the latency was evaluated for a maximum of 300 seconds. All animals were tested only once (except one group of Figure 1(b)). Training was always performed between 8:30 and 9:30 A.M. For each experiment the number of animals in each group is detailed in the Results.

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