A team of scientists led by Andrés Ozaita, principal investigator at the Laboratory of Neuropharmacology-NeuroPhar at UPF, reveals that not all long-term memories have previously been short-term memories, as had previously been thought. The study was conducted in rodent models and is published in the journal Molecular Neurobiology.

The dogma about the consolidation of episodic memory says it is encoded in a short-term memory for later consolidation into a long-term memory that may last weeks, months, years, or even a lifetime. This step of consolidation between short-term memory and long-term memory is considered primarily sequential, and therefore, according to what we currently know, long-term memory should first be a recent or a short-term memory.

In this paper, the researchers studied the relevant molecular mechanisms for the process of memory consolidation. Lorena Galera-López, co-first author of the study, explains that “there are several elements involved in memory formation, we have analysed the role of proteins known as kinase C, which control key aspects of the plasticity of neural connections”.

Mice lacking the protein kinase C gamma gene are mice with good long-term memory capabilities, but have problems in encoding the short-term memory.

To do so, they used mouse models, in which short-term memory and long-term memory can be assessed performing the memory test shortly after the generation of the memory or a day after memory generation.

“We have observed that mice lacking the protein kinase C gamma gene are mice with good long-term memory capabilities, but have problems in encoding the short-term memory”, details Maria Gomis-González, article co-first author. This shows that not all long-term memories have previously been short-term memories, and indicates that short- and long-term memory can be encoded in parallel.

Supporting the memory test observations, they have also found that neuronal activation in the mouse that does not have the protein kinase C gamma gene is deficient in the hippocampus, a key brain region for generating memories, “which indicates that this protein is crucial in producing the cellular footprints associated with memory encoding”, explains Andrés Ozaita, full professor at the UPF Department of Experimental and Health Sciences (DCEXS).

The study also involved researchers from the Hospital del Mar Medical Research Institute (IMIM), Universidad Francisco de Vitoria and the University of Surrey.

Funding

The work has been funded by the Spanish Ministry of Economy, Innovation and Competitiveness (MINECO); the Carlos III Health Institute; the Ministry of Science, Innovation and Universities; the Generalitat (Government) of Catalunya; the Catalan Institution for Research and Advanced Studies (ICREA); the “Maria de Maeztu Unit of Excellence”; Plan E (Spanish plan to boost the economy and employment), and the EDRF.

Reference article

Gomis-González, M., Galera-López, L., Ten-Blanco, M. et al. Protein Kinase C-Gamma Knockout Mice Show Impaired Hippocampal Short-Term Memory While Preserved Long-Term Memory. Mol Neurobiol (2020). https://doi.org/10.1007/s12035-020-02135-6.