A recent study has revealed a mechanism the brain uses to update memories, helping organisms adapt to the constant changes in their environment.
Neuroscientists at the Friedrich Miescher Institute for Biomedical Research (FMI) have found that simply re-tasting a "sugar reward" in fruit flies can weaken the memories associated with it, without erasing them completely, which could open up possibilities for dealing with harmful memories in humans.
Memory plays a crucial role in animal survival, guiding their behavior toward food sources and warning them of dangers. However, a rapidly changing world demands a flexible memory capable of constantly updating its information. When rewards or threats lose their original meaning, the brain needs to re-evaluate past experiences rather than retaining them as they are.
In this study, scientists trained fruit flies to associate certain scents with a sugary reward. After a period of time, they reintroduced the sugar to the flies without associating it with any scent. As a result, the flies' attraction to the scents they had previously learned to seek out decreased.
Neurological analysis showed that the memories were not completely erased, but rather their trace remained in the brain, although their influence on behavior became weaker, indicating that the brain is capable of suppressing memories rather than deleting them.
The study showed that the environment and surrounding conditions play a crucial role in memory consolidation. When flies encountered sugar in a familiar environment, their acquired response weakened, while they retained the memory in unfamiliar environments or when learning new information simultaneously. This reflects the brain's reliance on environmental cues to determine when to modify memories.
Scientists also discovered that this memory impairment occurs independently of dopamine, a neurotransmitter associated with reward and learning, suggesting the existence of multiple mechanisms regulating information retrieval. They further observed that re-experiencing sugar affects all associated memories, offering a way to reassess the significance of past experiences when circumstances change.
Johannes Felsenberg, head of the FMI group, confirms that the study's findings, despite being conducted on fruit flies, align with research conducted on mammals and humans, particularly in the areas of fear and addiction. He says, "Our study shows that memories can be suppressed rather than erased, and that the environment and surrounding circumstances are the decisive factors in this, helping the brain achieve a balance between stability and flexibility."
Scientists hope that understanding these mechanisms will contribute in the future to the development of therapeutic methods that reduce the impact of negative memories without erasing them completely.
The study's findings were published in the journal Current Biology.
