The only main comment I have concerns retrieval mode. I think it is far from settled whether a retrieval mode must be initiated BEFORE a cue can interact with engrams or whether REMO can be initiated by a cue (such as a face) and then in turn lead to ecphory. In short, can episodic retrieval happen without an initial intention (eg probed by a question) to retrieve.
Dear Reviewer B,
Thank you very much for your well-stated comment. We agree that this issue is far from settled and that "retrieval mode" may potentially be activated either voluntarily or involuntarily. We have made the appropriate changes in the article to reflect this point.
Dear Reviewer A,
Thank you very much for your comments. Please find below a detailed response to each.
1) The hypothesized monohierarchical relation between episodic and semantic memory is an assertion related to the theory of episodic memory. In order to make this point clearer we have prefaced this section with the following, “According to the theory of episodic memory…” We have also included references to the theory of episodic memory in earlier parts of the article to make this more apparent. Further, we acknowledge that various cases have been presented suggesting that semantic memory may be impaired with relative sparing of episodic memory. However, we point out that, in describing the relations between episodic and semantic memory, we state that episodic memory requires “relevant components of semantic memory” to function. Hence, it is completely possible for some patients to exist who possess semantic deficits of one sort, but who still retain episodic functioning in relation to other, preserved, semantic knowledge. For instance, that a patient may not remember various public events should not have any bearing on their ability to remember episodic memories associated with family members, but it should preclude them from being able to remember any episodic memories associated with those events.
2) Regarding the transmodal nature of episodic and semantic memory, we have added the following sentence to make the point clearer. (“both remembered experiences and knowledge can be stored independent of the modality through which they were acquired.”)
3) Regarding the role of consciousness, your point that various processes involved in episodic and semantic retrieval may occur beyond one’s awareness. We have added a sentence to make this clear to the reader. (“Of course, various processes that underlie the retrieval of episodic and semantic memory may take place beyond conscious awareness.”)
4) Re: Brain damage more likely to impair episodic than semantic memory. Yes, this is an issue that is not easy to evaluate empirically. This is why we say, cautiously, “tends to.” But we are describing a theory, and in theory the assertion we make is consistent with others. Indeed, the theory could be said to be “falsified” if it could be convincingly demonstrated that “brain damage” is “more likely” to impair “semantic knowing” than “episodic remembering.
5) We have removed the term “full-fledged” when comparing the episodic capacities of humans and animals.
6) The idea that the neural correlates of episodic memory build upon those involved in semantic memory is also an attribute of the theory of episodic memory. As mentioned above, we have already added several references to the theory of episodic memory near the beginning of the article to make that clearer.
7) Regarding autobiographical memory, we believe that adding any information regarding the nature of recent and remote autobiographical episodic and semantic memory is beyond the scope of an article meant to outline the basis of the theory of episodic memory.
8) We have changed evolutionary niches to “ecological” niches.
9) Regarding episodic memory in nonhuman animals, we have softened our tone and now write that “we are unaware of any findings that unequivocally attribute autonoetic consciousness to nonhuman animals.”