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Dendritic spine dynamics in synaptogenesis after repeated LTP inductions: dependence on pre-existing spine density.

Oe Y, Tominaga-Yoshino K, Hasegawa S, Ogura A - Sci Rep (2013)

Bottom Line: Here we examined the dynamics of individual dendritic spines after repeated LTP-inductions and found the existence of two phases in the spines' stochastic behavior that eventually lead to the increase in spine density.This spine dynamics occurred preferentially in the dendritic segments having low pre-existing spine density.Our results may provide clues for understanding the cellular bases underlying the repetition-dependent consolidation of memory.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, Osaka University Graduate School of Frontier Biosciences, Suita, Osaka, Japan. oguraa@fbs.osaka-u.ac.jp

ABSTRACT
Not only from our daily experience but from learning experiments in animals, we know that the establishment of long-lasting memory requires repeated practice. However, cellular backgrounds underlying this repetition-dependent consolidation of memory remain largely unclear. We reported previously using organotypic slice cultures of rodent hippocampus that the repeated inductions of LTP (long-term potentiation) lead to a slowly developing long-lasting synaptic enhancement accompanied by synaptogenesis distinct from LTP itself, and proposed this phenomenon as a model system suitable for the analysis of the repetition-dependent consolidation of memory. Here we examined the dynamics of individual dendritic spines after repeated LTP-inductions and found the existence of two phases in the spines' stochastic behavior that eventually lead to the increase in spine density. This spine dynamics occurred preferentially in the dendritic segments having low pre-existing spine density. Our results may provide clues for understanding the cellular bases underlying the repetition-dependent consolidation of memory.

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Requirement of spontaneous activity for the development of RISE.(a) Timeline of experimental procedures. Tetrodotoxin (TTX; 1 μM) was applied during the period indicated in gray to both No stim and 3FK specimens. (b) Time-sequenced images of representative dendritic segments. Scale bar indicates 5 μm. (c) TTX suppressed the increase in spine density. This result serves also as collateral evidence for the formation of functional synapses on the newly generated spines. The number of dendritic segments examined are 9 and 9, for No stim/TTX and 3FK/TTX samples, respectively. The data for 3FK are cited from Fig. 1d (ratios were re-calculated). Statistic comparison was made by 2-way ANOVA followed by Bonferroni's test for each time point. P values are 8.8 × 10−4 for ***1, 4.4 × 10−5 for ***2, 5.2 × 10−4 for ***3 and 4.3 × 10−5 for ***4.
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f8: Requirement of spontaneous activity for the development of RISE.(a) Timeline of experimental procedures. Tetrodotoxin (TTX; 1 μM) was applied during the period indicated in gray to both No stim and 3FK specimens. (b) Time-sequenced images of representative dendritic segments. Scale bar indicates 5 μm. (c) TTX suppressed the increase in spine density. This result serves also as collateral evidence for the formation of functional synapses on the newly generated spines. The number of dendritic segments examined are 9 and 9, for No stim/TTX and 3FK/TTX samples, respectively. The data for 3FK are cited from Fig. 1d (ratios were re-calculated). Statistic comparison was made by 2-way ANOVA followed by Bonferroni's test for each time point. P values are 8.8 × 10−4 for ***1, 4.4 × 10−5 for ***2, 5.2 × 10−4 for ***3 and 4.3 × 10−5 for ***4.

Mentions: To know whether or not the spine number increase proceeds automatically once it is triggered irrespectively to the neuronal activity, we applied tetrodotoxin (TTX) to block spontaneous activity at PS day 4–5 (for 24 h). As shown Fig. 8, the spine number increase was prohibited, suggesting that the spontaneous activity of neurons is necessary for the development of RISE.


Dendritic spine dynamics in synaptogenesis after repeated LTP inductions: dependence on pre-existing spine density.

Oe Y, Tominaga-Yoshino K, Hasegawa S, Ogura A - Sci Rep (2013)

Requirement of spontaneous activity for the development of RISE.(a) Timeline of experimental procedures. Tetrodotoxin (TTX; 1 μM) was applied during the period indicated in gray to both No stim and 3FK specimens. (b) Time-sequenced images of representative dendritic segments. Scale bar indicates 5 μm. (c) TTX suppressed the increase in spine density. This result serves also as collateral evidence for the formation of functional synapses on the newly generated spines. The number of dendritic segments examined are 9 and 9, for No stim/TTX and 3FK/TTX samples, respectively. The data for 3FK are cited from Fig. 1d (ratios were re-calculated). Statistic comparison was made by 2-way ANOVA followed by Bonferroni's test for each time point. P values are 8.8 × 10−4 for ***1, 4.4 × 10−5 for ***2, 5.2 × 10−4 for ***3 and 4.3 × 10−5 for ***4.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3674431&req=5

f8: Requirement of spontaneous activity for the development of RISE.(a) Timeline of experimental procedures. Tetrodotoxin (TTX; 1 μM) was applied during the period indicated in gray to both No stim and 3FK specimens. (b) Time-sequenced images of representative dendritic segments. Scale bar indicates 5 μm. (c) TTX suppressed the increase in spine density. This result serves also as collateral evidence for the formation of functional synapses on the newly generated spines. The number of dendritic segments examined are 9 and 9, for No stim/TTX and 3FK/TTX samples, respectively. The data for 3FK are cited from Fig. 1d (ratios were re-calculated). Statistic comparison was made by 2-way ANOVA followed by Bonferroni's test for each time point. P values are 8.8 × 10−4 for ***1, 4.4 × 10−5 for ***2, 5.2 × 10−4 for ***3 and 4.3 × 10−5 for ***4.
Mentions: To know whether or not the spine number increase proceeds automatically once it is triggered irrespectively to the neuronal activity, we applied tetrodotoxin (TTX) to block spontaneous activity at PS day 4–5 (for 24 h). As shown Fig. 8, the spine number increase was prohibited, suggesting that the spontaneous activity of neurons is necessary for the development of RISE.

Bottom Line: Here we examined the dynamics of individual dendritic spines after repeated LTP-inductions and found the existence of two phases in the spines' stochastic behavior that eventually lead to the increase in spine density.This spine dynamics occurred preferentially in the dendritic segments having low pre-existing spine density.Our results may provide clues for understanding the cellular bases underlying the repetition-dependent consolidation of memory.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, Osaka University Graduate School of Frontier Biosciences, Suita, Osaka, Japan. oguraa@fbs.osaka-u.ac.jp

ABSTRACT
Not only from our daily experience but from learning experiments in animals, we know that the establishment of long-lasting memory requires repeated practice. However, cellular backgrounds underlying this repetition-dependent consolidation of memory remain largely unclear. We reported previously using organotypic slice cultures of rodent hippocampus that the repeated inductions of LTP (long-term potentiation) lead to a slowly developing long-lasting synaptic enhancement accompanied by synaptogenesis distinct from LTP itself, and proposed this phenomenon as a model system suitable for the analysis of the repetition-dependent consolidation of memory. Here we examined the dynamics of individual dendritic spines after repeated LTP-inductions and found the existence of two phases in the spines' stochastic behavior that eventually lead to the increase in spine density. This spine dynamics occurred preferentially in the dendritic segments having low pre-existing spine density. Our results may provide clues for understanding the cellular bases underlying the repetition-dependent consolidation of memory.

Show MeSH