2023-05-07 12:00:00
The brain remains a mystery in many ways. One of them is the mechanism that manages to transform short-term memories into long-term memory. This process, called ‘memory consolidation’, is crucial to understanding how our neurons work and how they store information in the brain. In addition, it is a key piece to better understand certain neurodegenerative diseases, such as Alzheimer’s, or disorders such as autism. Scientists know that this process of memory consolidation is crucial to the synthesis of proteins present in neuronsalthough to date it was not known what types of neurons were involved in this process.
Now, a multi-institutional scientific team, led by experts from McGill University in Montreal, has discovered what kind of cellular processes are responsible for our long-term memories, a discovery that could be of great help in the study of diseases. or disorders related to memory impairment.
The importance of neural networks
First, the researchers realized that in any phase of memory consolidation there are at least two distinct processes that take place in equally distinct neural networks: neuronsexciters’which participate in the creation of the memory trail that our brain follows, and ‘inhibitory’ neuronsresponsible for blocking background noise, key in long-term learning.
The experts, led by McGill University professors Nahum Sonenberg and Arkady Khoutorsky, as well as Professor Jean-Claude Lacaille of the University of Montreal and Professor Kobi Rosenblum of the University of Haifa, found thatthat every neural process could be manipulated selectively to ‘control’ long-term memory.
Neurons involved in memory consolidation
So how does something we remember in the short term, sometimes lasting a few hours, become a memory that can last for years? It has been known for decades that this process requires the synthesis of new proteins by neurons, but it is known that not all neural networks work in the same way, so it was first necessary to determine the object of study.
Memory consolidation requires the synthesis of proteins in neurons
To do this, the researchers used transgenic mice to manipulate a particular molecular pathway, called elF2α, in specific types of neurons. Experts knew that this pathway plays a crucial role in the formation of long-term memories and in the synthesis of proteins in neurons. In addition, previous research had determined that elF2α was essential for the treatment of neurodegenerative diseasesand neurological development. But how do you incentivize these cellular pathways to have an effect on long-term memory? What type of neurons are involved in the process? That was precisely the crux of the matter.
Protein synthesis
“Lived experiences drive neuronal activity in the brain that promotes the production of new proteins (protein synthesis) at different specific points. These protein synthesis cause changes in neuronal connections, strengthen neuronal circuits and contribute to forming a trace from memory,” explains Vijendra Sharma, a research associate in Professor Sonenberg’s lab and first author of the paper, to National Geographic España through an email.
The so-called eukaryotic initiation factor 2 (eIF2α) It has an important role in the translation of the components that lead to the production of new proteins. “For example, under certain conditions of cellular stress, the eIF2α factor causes the inhibition of the cellular protein synthesis process, and protects said cells,” says Sonenberg. “However, each time the brain registers a new experience, eIF2α activates that same process, causing changes in neural circuits that lead to the formation of new memoriess”, explains the expert.
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Different types of neurons, the same goal
However, one of the most interesting points of the research was to verify that eIF2α also synthesized proteins in a specific class of inhibitory neurons, the somatostatin interneurons.
When activated, somatostatin-expressing neurons release an inhibitory neurotransmitter called gamma-aminobutyric acid (GABA) that triggers the excitation of a specific brain network responsible for carrying out complex cognitive functions, explains Vijendra Sharma. In addition, the expert clarifies, somatostatin acts as a neurotransmitter, so it also contributes to memory formation. The researchers found that increasing protein synthesis in somatostatin-expressing inhibitory neurons in the hippocampus enhances long-term memory formation.
“It’s exciting to show that these new players, inhibitory neurons, have an important role in memory consolidation,” says Sharma. “Until now, it has been assumed that the eIF2α pathway regulates memory consolidation through excitatory neurons,” she concludes.
The new discoveries, say the scientists, make it possible to refine the target of the new treatments towards a specific type of neurons: those of somatostanin, which could be the new target of future drugs to combat diseases such as Alzheimer’s or autism, says Dr. Nahum Sonenberg. “We hope this will aid in the design of both preventative and post-diagnosis treatments for those with disorders involving memory deficits.”
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