The research, which answers a long-standing question about which neuronal subtypes are involved in memory consolidation, has potential implications for novel targets for medication for disorders such as Alzheimer’s disease & autism, which involve altered memory processes.
A multi-institutional research team headed by McGill University, has shown that when we consolidate our memory, two or more distinct processes are simultaneously occurring in two different brain networks — the inhibitory and the excitatory neurotransmitters. Interestingly, the latter are concerned with generating a memory trace, while the former, enable long-term learning, and block out background noise.
In addition to this, the team, headed by McGill Professors, Arkady Khoutorsky and Nahum Sonenberg; Université de Montréal Professor, Jean-Claude Lacaille; and University of Haifa Professor Kobi Rosenblump; also discovered that when it is selectively manipulated, each neuronal system can control long-term memory. All these findings have been published in the journal, Nature.
Finding the Neurons Which Participate in Memory Consolidation
How do short-term memories (which last just a few hours) transform into long-term memories (which may last years)? It’s been known for decades that this process, called memory consolidation, requires the synthesis of new proteins in brain cells.Yet until the results of this study, no one knew which neuron subtypes were engaged in the process.
In order to pinpoint which neuronal networks are needed for our memory consolidation, the scientists used transgenic mice to manipulate a particular molecular pathway (eIF2α), in specific types of neurons. This pathway had already been shown to play a key role in controlling the formation of long-term memories and regulating protein synthesis in neurons. Further, previous studies had regarded eIF2α as a crucial aspect for both neurodegenerative and neurodevelopmental diseases.
Both Inhibitory & Excitatory Systems Have a Role in Memory Consolidation
Dr. Kobi Rosenblum noted, “we found that stimulation of protein synthesis via eIF2α in the excitatory neurons of the hippocampus was sufficient to enhance memory formation and modification of synapses (the sites of communication between neurons).” Yet, as Dr. Jean-Claude Lacaille stated: “we also found that stimulation of protein synthesis via eIF2α in a specific class of inhibitory neurons, was also sufficient to augment long-term memory by tuning the plasticity of neuronal connections.”
Hope For The Future
As the paper’s first author, Dr. Vijendra Sharma, remarked, “It is fascinating to be able to show that these new players — inhibitory neurons — have an important role in memory consolidation. It had been assumed, until now, that eIF2α pathway regulates memory via excitatory neurons.”
And there is great hope for future treatments. As Dr. Nahum Sonenberg concluded, “These new findings identify protein synthesis in inhibitory neurons, and specifically somatostatin cells, as a novel target for possible therapeutic interventions in disorders such as Alzheimer’s disease and autism.”
Hopefully, there is a good chance that the findings from this innovative research will improve the design of both post-diagnosis and preventative treatments for the countless patients suffering from memory deficit disorders.