This 2015 French rodent study found:

“Memories can be established and maintained without de novo protein synthesis and that experimental amnesia may not result from a disruption of memory consolidation/reconsolidation.

Posttraining/postreactivation treatments induce an internal state, which becomes encoded with the memory, and should be present at the time of testing to ensure a successful retrieval.

This integration concept includes most of the previous explanations of memory recovery after retrograde amnesia and critically challenges the traditional memory consolidation/reconsolidation hypothesis, providing a more dynamic and flexible view of memory.”

From Neuroskeptic’s analysis of the study:

“A different drug, lithium chloride, produces the same pattern of effects – it blocks ‘reconsolidation’, but this can be reversed by a second dose at the time of recall. However, lithium chloride is not an amnestic [a drug that blocks memory formation] – it doesn’t block protein synthesis. Rather, it causes nausea.

The implication of the lithium experiment is that any drug that causes an ‘internal state change’, even if it’s just nausea, can trigger state-dependent memory and behave just like an ‘amnestic’.”

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As this study may apply to humans, a drug wouldn’t necessarily be required to “induce an internal state.” If the findings of studies such as Are 50 Shades of Grey behaviors learned in infancy? extend to humans, an emotional or physical experience may be sufficient to produce a state-dependent memory. For example, A study that provided evidence for basic principles of Primal Therapy found, albeit with rodents and use of a drug:

“Fear-inducing memories can be state dependent, meaning that they can best be retrieved if the brain states at encoding and retrieval are similar.”

Memories triggered while in a brain state reentered through an emotion or a physical reaction are experienced by Primal Therapy patients and observed by therapists every day. However, as mentioned in What scientific evidence can be offered for Primal Therapy’s capability to benefit people’s lives? there’s a difficulty in developing human evidence for such state-dependent emotional memories.

Standard procedures would use human subjects and control groups in a way that retrieved memories according to the researchers’ schedule and experimental parameters. In order for the retrieval of an emotional memory to be therapeutic, though, the methods of an experiential therapy such as Dr. Arthur Janov’s Primal Therapy leave the timing of entering a triggering brain state up to the patient.

When a brain state protects a human emotional memory from being accessed, it probably wouldn’t be therapeutic to:

• Force a return to that brain state, and thereby
• Remove the memory’s protection, then
• Retrieve and re-experience the memory

just for the sake of research.

The evidence for retrieving and re-experiencing a state-dependent memory lies mainly within the individual’s experiences.

A challenge is to find innovative ways to document human evidence for state-dependent emotional memories while ensuring a therapeutic process.

http://www.jneurosci.org/content/35/33/11623 “Integration of New Information with Active Memory Accounts for Retrograde Amnesia: A Challenge to the Consolidation/Reconsolidation Hypothesis?”