Additional to old theories regarding memory formation, Massachusetts Institute of Technology (MIT) reveals that long-term memory is formed in specialized neurons in the prefrontal cortex called "engram cells". Memories are initially formed in the hippocampus and are transferred from short to long term storage.

The new study was pioneered by Takashi Kitamura along with; Sachie Ogawa, Teruhiro Okuyama, Mark Morrissey, Dheeraj Roy, Lillian Smith, and Roger Redondo. According to Psychology Today, the findings and result of the new study provide a comprehensive and organized circuit mechanism for consolidation of memory.

The researchers were able to block inputs in different areas of the brain under conditioning and three-week memory recall; this is to determine which particular areas of the cerebral cortex is essential in forming long-term memory. The results proved that the memory (long term) remains "silent" in the prefrontal cortex for two weeks before developing, maturing and transforming into long-term memory.

There is an existence of cortical engram cells, however; they are not formed gradually over time, as stated by Kitamura. The study illustrates the mechanism of other brain regions in allowing cortical engram cells to develop and mature into long-term memory in the pre-frontal cortex in the span of 12 days.

The three regions of the brain were labeled by the researchers; the prefrontal cortex, the hippocampus (HPC), and the basolateral amygdala (BLA). BLA was discovered to store both positive and negative emotional associations to memory with the help of PFC and HPC. The research suggests that traditional theories of long-term memory may only be partially accurate.

Meanwhile, according to The Human Memory, the brain's cerebral cortex plays a key role in memory, attention, perceptual awareness, language, and consciousness. Hippocampus, on the other hand, is essential in memory function most particularly the development of short to long-term memory.

The MIT researchers plan to further the investigation on the maturation process concerning the engram cells in the prefrontal cortex. The latest discovery regarding long term memory is very important as it could help in determining the disease process of neurological disorders including the discovery on the advancement of treatment approach.