A neural circuit mechanism involved in preserving the specificity of memories has been identified by investigators from the Massachusetts General Hospital (MGH) Center for Regenerative Medicine and the Harvard Stem Cell Institute (HSCI).
They also identified a genetic “switch” that can slow down memory generalization — the loss of specific details over time that occurs in both age-related memory impairment and in post-traumatic stress disorder (PTSD), in which emotions originally produced by traumatic experiences are elicited in response to innocuous cues that have little resemblance to the traumatic memory.
“The circuit mechanism we identified in mice allows us to preserve the precision or the details of memories over the passage of time in adult as well as aged animals,” says Amar Sahay of the MGH Center for Regenerative Medicine and HSCI, corresponding author of a paper appearing in Nature Medicine. “These findings have implications for the generalization of traumatic memories in PTSD and for memory imprecision in aging.”
Memories are generated in the seahorse-shaped brain structure called the hippocampus and stored in the prefrontal cortex at the front of the brain.
Memory formation involves cells in a portion of the hippocampus called the dentate gyrus, and memories are thought to be conveyed to the prefrontal cortex via the CA subregions of the hippocampus, specifically subregions CA3 and CA1.
The hippocampus also is believed to play a continuing role in the stabilization of memories in the cortex — maintaining the precise details that keep one memory from being confused with another and preventing issues ranging from not being able to remember last week’s dinner selections to age-related memory loss.