How Engram Research is Changing What We Know About Memory

 One of the most interesting talks this semester focused on how the brain stores and recalls memories. The speaker explained that memories aren’t just random pieces of information floating around, but are instead stored in specific patterns of neurons called engrams. These engram cells are activated when a memory forms, and the same cells are reactivated when we recall that experience. What stood out to me most was the idea that even if we forget something, the memory might still exist in the brain. It just isn’t being accessed properly.

This went hand in hand with the article by Sheena Josselyn and Susumu Tonegawa (2020) titled “Memory Engrams: Recalling the Past and Imagining the Future.” In this paper, the authors discuss how researchers have begun to identify and even control specific neurons that make up an engram. In the article, when these neurons are artificially activated in mice, the animals behave as if they are reliving a past experience. That means the memory itself never truly disappeared; it was still stored in the brain, just waiting to be reactivated.

Another interesting point from the article is how optogenetics, a method that uses light to control neurons. Optogenetics allows scientists to switch memories on or off. For example, when mice developed amnesia and couldn’t recall a learned behavior, shining light on their engram cells instantly restored the “lost” memory. This shows that the memory isn’t erased, but rather blocked from retrieval. That finding connects perfectly to what we learned in class; memory loss doesn’t always mean brain cells are destroyed. Sometimes the pathway to the memory is just disconnected as the brain is a pathway of connection.

The article also discusses how inhibitory neurons can silence or block specific engrams, which controls which memories we access. This implies that some memories may still be preserved in the brain but are being suppressed, making them inaccessible. The findings have a major impact on mental health conditions, including Alzheimer's and PTSD. The way we treat memory-related disorders may change if researchers can discover a technique to release these hidden memories or quiet the ones that are excessively active. It raises serious issues regarding identity: does our identity change if we could alter which memories we can access?

Both the discussion and the paper redefine memory as something flexible rather than fixed, which significantly stood out to me because it challenged my perception on what memories are. This educated me on viewing memory more as patterns that may evolve, adapt, and even be recreated; they are more than collections of the past. We can see the future through the same systems that allow us to recall the past, showing that memory is about more than just storing information, but it's also about creativity and survival.

Overall, the connection between the talk and this study helped me see memory in a new way. Understanding engrams isn’t just about solving memory loss, but about understanding how experience itself is built into the structure of who we are. This research not only deepens our understanding of neuroscience but also gives hope for restoring memory in those who have lost it.