We are very grateful for this impressively thorough and insightful review! And we are very happy that you found our work interesting. Your feedback is very useful and we are currently working on implementing some of your points, along with those we received by journal reviewers.
It is surprising that you couldn’t access the supplemental figures. I just checked again and they are still available on BiorXiv. A link to the pdf should show up when clicking on Supplemental Material.
Major concerns
-       The authors propose a dichotomy between so-called “odor cells” and “time cells” in CA1, however this distinction may be overly simplified and is only partially supported by the data presented here. Fig. 3D shows that odor cells decode odor better than time cells, suggesting they might be functionally different populations. However, it is equally fair to say that “early time cells” decode odor better than “late time cells” without considering this odor/time dichotomy. That is because the criterion distinguishing an odor cell from a time cell is whether it fires during the odor delivery window, which does not actually assess selectivity to odor per se. Additionally, odor presentations only occur at 1-2 sec, so odor delivery is conflated with the beginning time intervals of the trial. And since cells firing later in the sequence have higher variance than those firing earlier (which frequently occurs in these types of sequences), that variance is probably contributing to worse performance, explaining why time cells may have worse decoding properties than odor cells.
-       In a similar way, it would be equally fair to say that early time cells (versus odor cells) are more stable across days than late time cells (Fig. 4C). To test whether odor cells are actually a distinct population from time cells, the authors would need to present odors outside of the task and confirm that they activate the neurons labeled as odor cells (but not the neurons labeled as time cells) when there is no delay. Another possibility would be to run the same analyses on odor versus time cells using an odor selectivity criterion to separate these populations rather than selectivity to the odor delivery time window.