Scientists from Tokyo Metropolitan University (TMU) have discovered that Drosophila fruit flies lose long-term memory of a traumatic event when kept in the dark—the first confirmation that environmental light can have such an effect. This research may lead to novel treatments for sufferers of trauma, perhaps even the erasure of life-altering traumatic memories.
When a shocking event is consolidated into our long-term memory, it can be devastating and potentially trigger post-traumatic stress disorder—something that many amputees struggle with.
Light, particularly the cycle of night and day, plays an important role in regulating animal physiology. A team led by Takaomi Sakai, PhD, set out to study how light exposure affects the memory of diurnal Drosophila fruit flies. As an instance of long-term memory or trauma, they studied male flies that were exposed to female flies that had already mated. Mated females are known to be unreceptive and exert a stress on male flies, which fail to mate. Once the experience is committed to long-term memory, they no longer attempt to court female flies.
The team found that conditioned male flies kept in the dark for two days or more no longer showed any reluctance to mate, while those on a normal day-night cycle did. This shows that environmental light somehow modified the retention of long-term memory. The team focused on a protein in the brain known to be expressed in response to light. They found that this protein regulated the transcription of another protein in a part of the brain known to be implicated in memory and learning. Thus, they identified the specific molecular mechanism by which light affects the retention of long-term memory.
Traumatic experiences are difficult to forget and can severely impair a person’s quality of life. The team’s discoveries show that these memories can be significantly affected by environmental factors.
This article was adapted from information provided by TMU.