A group of researchers at Osaka University, succeeded in reproduction of the same phenomenon as memory consolidation by using organotypic slice cultures of the cerebral cortex and revealed that stress interfered with memory consolidation. As cultures can be maintained for a long period, it is possible to examine long-term effects. This group’s achievement will be useful for developing therapeutic methods for and preventive measures against stress-induced memory defects.
Keiko Tominaga-Yoshino, Associate Professor and Akihiko Ogura, Professor at Graduate School of Frontier Biosciences, Osaka University had previously found that repeated stimulus to organotypic slice cultures of the cerebral cortex formed new synapses, which is the same phenomenon as the repetition-dependent memory consolidation process, and examined its mechanism.
In this research, the group elucidated that synapse formation is inhibited by the reproduction of stress known to cause memory defects.
Humans and animals have innate self-protecting mechanisms for alleviating stress. This is why it was difficult to determine if the results of animal experiments were affected by the stress applied by experimenters or by the effects from animals’ homeostatic response. Therefore, some conflicting results had been reported. However, in the in vitro system, the effects applied by experimenters can be directly examined and will be helpful for the development of drugs or treatments that reduce stress-related brain defects.
About this psychology research
Funding: The study was funded by the Ministry of Education, Culture, Sports, Science and Technology of Japan.
Source: Akihiko Ogura – Osaka University Image Credit: The image is credited to Osaka University. Original Research: Full open access research for “An in vitro reproduction of stress-induced memory defects: Effects of corticoids on dendritic spine dynamics” by Shinichi Saito, Satoshi Kimura, Naoki Adachi, Tadahiro Numakawa, Akihiko Ogura & Keiko Tominaga-Yoshino in Scientific Reports. Published online January 14 2016 doi:10.1038/srep19287
An in vitro reproduction of stress-induced memory defects: Effects of corticoids on dendritic spine dynamics
Previously, in organotypic slice culture of rodent hippocampus we found that three repeated inductions of LTP, but not a single induction, led to a slow-developing long-lasting enhancement of synaptic strength coupled with synapse formation. Naming this structural plasticity RISE (repetitive LTP-induced synaptic enhancement) and assuming it to be a potential in vitro reproduction of repetition-dependent memory consolidation, we are analyzing its cellular mechanisms. Here, we applied a glucocorticoid to the culture to mimic acute excess stress and demonstrated its blockade of RISE. Since excess stress interferes with behavioral memory consolidation, the parallelism between RISE in vitro and memory consolidation in vivo is supported. We recently reported that RISE developed after stochastic processes. Here we found that the glucocorticoid interfered with RISE by suppressing the increment of dendritic spine fluctuation that precedes a net increase in spine density. The present study provides clues for understanding the mechanism of stress-induced memory defects.
“An in vitro reproduction of stress-induced memory defects: Effects of corticoids on dendritic spine dynamics” by Shinichi Saito, Satoshi Kimura, Naoki Adachi, Tadahiro Numakawa, Akihiko Ogura & Keiko Tominaga-Yoshino in Scientific Reports. Published online January 14 2016 doi:10.1038/srep19287