Can’t remember something? Try waiting until later in the day. Researchers identified a gene in mice that seems to influence memory recall at different times of day. They tracked how it causes mice to be more forgetful just before they normally wake up.
“We may have identified the first gene (in mice) specific to memory retrieval,” said Professor Satoshi Kida from the University of Tokyo Department of Applied Biological Chemistry.
Every time you forget something, it could be because you didn’t truly learn it — like the name of the person you were just introduced to a minute ago; or it could be because you are not able to recall the information from where it is stored in your brain — like the lyrics of your favorite song slipping your mind.
Many memory researchers study how new memories are made. The biology of forgetting is more complicated to study because of the difficulties of distinguishing between not knowing and not recalling.
“We designed a memory test that can differentiate between not learning versus knowing but not being able to remember,” said Kida.
Researchers tested the memories of young adult male and female mice. In the “learning,” or training, phase of the memory tests, researchers allowed mice to explore a new object for a few minutes.
Mice trained just before they normally woke up and tested just after they normally went to sleep did recognize the object.
Mice trained at the same time — just before they normally woke up — but tested 24 hours later did not recognize the object.
Something about the time of day just before they normally wake up, when BMAL1 hormone levels are normally low, causes mice to not recall something they definitely learned and know.
According to Kida, the memory research community has previously suspected that the body’s internal, or circadian, clock that is responsible for regulating sleep-wake cycles also affects learning and memory formation.
“Now we have evidence that the circadian clocks are regulating memory recall,” said Kida.
However, the purpose of having memory recall abilities that naturally fluctuate depending on the time of day remains a mystery.
“We really want to know what is the evolutionary benefit of having naturally impaired memory recall at certain times of day,” said Kida.