When we think of memory, we often imagine a static storage area in the brain, like files in a cabinet. However, recent research reveals that memory formation is anything but static—it’s a dynamic and continuous process shaped profoundly by epigenetics.
A study recently reported that 92% of eligible neurons in specific brain regions undergo significant epigenetic changes during memory encoding [1].
Epigenetics in neuronal selection
Memory is encoded in the brain by forming what scientists call “memory traces” or “engrams,” which are clusters of neurons that fire together when a memory is recalled.
Not all neurons are eligible to participate in these engrams, and it has been a mystery why certain neurons are selected over others.
New insights from a study focused on the lateral amygdala, a brain region critical for processing emotional memories, suggest that epigenetics—specifically, changes in chromatin plasticity—is a deciding factor [2].
Chromatin plasticity
Chromatin, the complex of DNA and proteins found in cells, undergoes structural changes that affect gene expression.
In neurons, these changes can enhance or suppress the neuron’s potential to participate in encoding new memories.
Research has shown that neurons with higher levels of histone acetylation, a form of chromatin modification, are more likely to be recruited into memory traces.
This discovery indicates that epigenetic processes are crucial in the formation of neurons and in their contribution to memory functions [2].
Experimental insights into epigenetic mechanisms
Researchers artificially modified histone acetylation levels in mice to explore how chromatin modifications affect memory.
Increasing histone acetylation led to a higher probability of neurons being recruited for memory formation.
Conversely, reducing acetylation decreased this likelihood. This manipulation confirmed chromatin plasticity’s role in memory encoding and demonstrated its impact on neuronal excitability and synaptic connections [2].
This study opens new avenues for researching neurodegenerative diseases like Alzheimer’s, where memory loss is a prominent feature.
If epigenetic alterations can influence memory formation, they might also be targeted therapeutically to enhance or recover memory functions in degenerative conditions.
Moreover, the discovery of chromatin plasticity challenges the traditional notion of memory as a passive recall of information, presenting it as an active and dynamic process.
[1] Medical Xpress. How epigenetics influence memory formation
[2] Science. Chromatin plasticity predetermines neuronal eligibility for memory trace formation
