Researchers from the University of Toronto in Canada have uncovered the reason why sometimes we fail to remember the details of the past. Conducting the study on rats, Kaori Takehara-Nishiuchi, the senior author, says that there are neurons in the medial prefrontal cortex (mPFC), which is the region most associated with long-term memory. These neurons are responsible for coding and storing relevant and general information taken from multiple experiences. In its process, the minor details unique to each individual experience is lost!
The research team predicted that the process behind it is that mPFC simply builds larger representations of general information during memory consolidation compared to the build of representations for details. To test this, they had rats encode both shared features of stimuli and the features unique to each stimulus. They discovered that as time went on, the neural coding actually became more sensitive to the shared features of the stimuli compared to the unique features. Over time, the coding for the unique features were not consolidated and were lost.
These results imply that people don't just "forget", but that neurons lose their selectivity to encode details that is considered irrelevant. Neurons just consolidate shared information of different experiences more readily into long-term memory.
Source material from Science Daily