Scientists believe suppressed memories are created by a process called state-dependent learning. When the brain creates memories in a certain mood or state, particularly of stress or trauma, those memories become inaccessible in a normal state of consciousness. Suppressed memories can then best be retrieved when the brain is back in that state.
The brain will sometimes hide particularly stressful, traumatic or fear-related memories. This can be protective in the short term, when the emotional pain of recalling the event is still profound. However, in the long term, suppressed memories can create emotional health concerns such as depression, post-traumatic stress disorder (PTSD) and dissociative disorders.
When patients are unable to remember their experiences, therapists can struggle to help them identify and treat the root cause of their symptoms.
The new study suggests the best way to access hidden memories is to return the brain to the same state of consciousness it was in when the memory was formed.
“The brain functions in different states, much like a radio operates at AM and FM frequency bands,” Dr. Radulovic said. “It’s as if the brain is normally tuned to FM stations to access memories, but needs to be tuned to AM stations to access subconscious memories.”