This 2014 rodent study showed that fear extinction doesn’t depend on memory retrieval:
“These results show that extinction and retrieval are separate processes and strongly suggest that extinction is triggered or gated by the conditioned stimulus even in the absence of retrieval.”
The key to my understanding this finding came from a definition in another summary study by the authors, The learning of fear extinction, where they stated:
“Extinction is the learned inhibition of retrieval of previously acquired responses.”
These two studies and the Hippocampal mechanisms involved in the enhancement of fear extinction caused by exposure to novelty study should inform the researchers of studies such as If rodent training has beneficial epigenetic effects, how can the next step be human gene therapy? study of desirable alternative treatments rather than studying rodent training and proceeding directly to human gene therapy.
http://www.pnas.org/content/112/2/E230.full “Extinction learning, which consists of the inhibition of retrieval, can be learned without retrieval”