Dear Dr Zhang,

Thank you for submitting your manuscript entitled "Cognitive reserves hold back age-related upregulation of neural activities in speech-in-noise perception" for consideration as a Research Article by PLOS Biology.

Your manuscript has now been evaluated by the PLOS Biology editorial staff as well as by an academic editor with relevant expertise and I am writing to let you know that we would like to send your submission out for external peer review.

However, before we can send your manuscript to reviewers, we need you to complete your submission by providing the metadata that is required for full assessment. To this end, please login to Editorial Manager where you will find the paper in the 'Submissions Needing Revisions' folder on your homepage. Please click 'Revise Submission' from the Action Links and complete all additional questions in the submission questionnaire.

Once your full submission is complete, your paper will undergo a series of checks in preparation for peer review. After your manuscript has passed the checks it will be sent out for review. To provide the metadata for your submission, please Login to Editorial Manager (https://www.editorialmanager.com/pbiology) within two working days, i.e. by Feb 07 2025 11:59PM.

If your manuscript has been previously peer-reviewed at another journal, PLOS Biology is willing to work with those reviews in order to avoid re-starting the process. Submission of the previous reviews is entirely optional and our ability to use them effectively will depend on the willingness of the previous journal to confirm the content of the reports and share the reviewer identities. Please note that we reserve the right to invite additional reviewers if we consider that additional/independent reviewers are needed, although we aim to avoid this as far as possible. In our experience, working with previous reviews does save time.

If you would like us to consider previous reviewer reports, please edit your cover letter to let us know and include the name of the journal where the work was previously considered and the manuscript ID it was given. In addition, please upload a response to the reviews as a 'Prior Peer Review' file type, which should include the reports in full and a point-by-point reply detailing how you have or plan to address the reviewers' concerns.

During the process of completing your manuscript submission, you will be invited to opt-in to posting your pre-review manuscript as a bioRxiv preprint. Visit http://journals.plos.org/plosbiology/s/preprints for full details. If you consent to posting your current manuscript as a preprint, please upload a single Preprint PDF.

Feel free to email us at plosbiology@plos.org if you have any queries relating to your submission.

Kind regards,

Christian

Christian Schnell, PhD

Senior Editor

PLOS Biology

cschnell@plos.org

Dear Dr Zhang,

Thank you for your patience while your manuscript "Cognitive reserves hold back age-related upregulation of neural activities in speech-in-noise perception" was peer-reviewed at PLOS Biology. It has now been evaluated by the PLOS Biology editors, an Academic Editor with relevant expertise, and by several independent reviewers.

In light of the reviews, which you will find at the end of this email, we would like to invite you to revise the work to thoroughly address the reviewers' reports.

As you will see below, the reviewers have mostly positive comments about your study, but ask for some methodological clarifications and justifications (including the choices for statistical analyses), better integration into the literature and more careful phrasing regarding the cognitive reserve. Reviewer 1 also suggests a few additional analyses and better presentation of the data.

Given the extent of revision needed, we cannot make a decision about publication until we have seen the revised manuscript and your response to the reviewers' comments. Your revised manuscript is likely to be sent for further evaluation by all or a subset of the reviewers.

In addition to these revisions, you will need to complete some formatting changes, which you will receive in a follow up email. A member of our team will be in touch with a set of requests shortly.

We expect to receive your revised manuscript within 3 months. Please email us (plosbiology@plos.org) if you have any questions or concerns, or would like to request an extension.

At this stage, your manuscript remains formally under active consideration at our journal; please notify us by email if you do not intend to submit a revision so that we may withdraw it.

**IMPORTANT - SUBMITTING YOUR REVISION**

Your revisions should address the specific points made by each reviewer. Please submit the following files along with your revised manuscript:

1. A 'Response to Reviewers' file - this should detail your responses to the editorial requests, present a point-by-point response to all of the reviewers' comments, and indicate the changes made to the manuscript.

*NOTE: In your point-by-point response to the reviewers, please provide the full context of each review. Do not selectively quote paragraphs or sentences to reply to. The entire set of reviewer comments should be present in full and each specific point should be responded to individually, point by point.

You should also cite any additional relevant literature that has been published since the original submission and mention any additional citations in your response.

2. In addition to a clean copy of the manuscript, please also upload a 'track-changes' version of your manuscript that specifies the edits made. This should be uploaded as a "Revised Article with Changes Highlighted" file type.

*Re-submission Checklist*

When you are ready to resubmit your revised manuscript, please refer to this re-submission checklist: https://plos.io/Biology_Checklist

To submit a revised version of your manuscript, please go to https://www.editorialmanager.com/pbiology/ and log in as an Author. Click the link labelled 'Submissions Needing Revision' where you will find your submission record.

Please make sure to read the following important policies and guidelines while preparing your revision:

*Published Peer Review*

Please note while forming your response, if your article is accepted, you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out. Please see here for more details:

https://blogs.plos.org/plos/2019/05/plos-journals-now-open-for-published-peer-review/

*PLOS Data Policy*

Please note that as a condition of publication PLOS' data policy (http://journals.plos.org/plosbiology/s/data-availability) requires that you make available all data used to draw the conclusions arrived at in your manuscript. If you have not already done so, you must include any data used in your manuscript either in appropriate repositories, within the body of the manuscript, or as supporting information (N.B. this includes any numerical values that were used to generate graphs, histograms etc.). For an example see here: http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1001908#s5

*Blot and Gel Data Policy*

We require the original, uncropped and minimally adjusted images supporting all blot and gel results reported in an article's figures or Supporting Information files. We will require these files before a manuscript can be accepted so please prepare them now, if you have not already uploaded them. Please carefully read our guidelines for how to prepare and upload this data: https://journals.plos.org/plosbiology/s/figures#loc-blot-and-gel-reporting-requirements

*Protocols deposition*

To enhance the reproducibility of your results, we recommend that if applicable you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols

Thank you again for your submission to our journal. We hope that our editorial process has been constructive thus far, and we welcome your feedback at any time. Please don't hesitate to contact us if you have any questions or comments.

Sincerely,

Christian

Christian Schnell, PhD

Senior Editor

PLOS Biology

cschnell@plos.org

------------------------------------

REVIEWS:

Reviewer #1: This article by Zhang and colleagues reports an fMRI study that compares brain responses during syllable identification under noise conditions across three groups of participants: Older musicians (OMs), older non-musicians (ONMs) and young non-musicians (YNM). The research builds upon the broader context of investigating how cognitive resources derived from positive lifestyle factors, such as music learning, influence compensatory neural mechanisms associated with aging and observed in numerous previous studies.

The authors compare two possibilities: the "Bolster Compensation Hypothesis" suggesting that the greater availability of cognitive resources increase compensatory activity in older adults during cognitive tasks; and the "Hold-Back Upregulation hypothesis" suggesting instead that high cognitive resources mitigate age-related decline in perception and cognition, thus decreasing compensatory activity compared to age-matched control participants.

The authors consider a task of syllable identification (four choice) in noise, with three noise levels (-8db, 0 db, 8 db). As a measure of compensatory neural activity, the authors use the psychophysiological interaction between speech-related regions (posterior STG) and a set of parietal and frontal regions belonging to the dorsal auditory stream. Increased PPI is taken as a measure of increased compensatory activity, and thus an increase across groups (YNM < ONM < OM) is taken to support the first hypothesis, while intermediate levels for OMs (OM - YNM < ONM - YNM) are taken as evidence that older participants with greater cognitive resources are more similar than age-matched controls to young participants and thus support the second hypothesis. Reported behavioural and neural results support this latter hypothesis, highlighting the role of compensatory neural mechanisms in managing cognitive challenges associated with aging.

The study provides novel evidence suggesting that music training may play a significant role in improving neurocognitive resilience and it may be relevant for researchers studying the relationship between musicality and age-related cognitive changes. In general, the study is well-designed; however, several aspects require clarifications and improvements. These aspects concern the study description, which can be improved easily, but also relevant methodological choices, which now seem ad hoc and require further justification. I detail my considerations below:

- Title (and scope): I would prefer a title that is closer to the experimental manipulation and experiments conducted, and thus I would replace "Cognitive reserves" with "Musical training" or "Musical expertise" as the equivalence Musical training = Higher cognitive reserves is an assumption that has not been tested in this study.

- The experiment, task and rationale for the analyses need to be introduced more extensively before the results description. Currently, it is not possible to follow the results section without first reading the methods section.

- Pg. 3, 77-81: Fig.1D should be Fig. 1C, Fig 1E should be Fig. 1D

- Pg. 3 91: SIN perception: "SIN" should be defined

- It is unclear if the behavioural data (and their analysis) refer to data collected during the fMRI measurements or outside the scanner.

- The SNR manipulation is interesting and the beahvioural results provide a perfect context for the analysis of the fMRI data. They show that OM performed worse than YNMs under all SNRs (as expected) but better than ONMs only under the intermediate and high SNR. I wonder why this SNR dependence has not been explored more extensively in the analysis of fMRI data as well.

- The main analysis of the fMRI data relies on ROI-based PPI. However, PPI (and connectivity analyses in general) may be difficult to interpret without contextualizing the effects with a conventional voxel-wise analysis of brain activation and brain activation differences.

- The authors only report regional activations in a suppl. Table. However, I would prefer to see the activation maps for the three groups and be able to judge whether these maps, at least t to inspect whether the activation across the three groups is qualitatively similar (that is are all ROIs active in the three groups?).

Furthermore, I think that a GLM-based analysis of the voxel-wise between-group differences and the interaction between group and SNR could be very informative and should be presented to the readers.

-Related to the GLM analysis, is was unclear what are the "Six conditions of four syllables" (pg. 14, line 420). More in general, the experimental design, the timing of the stimuli and the separation of condition in blocks was not clear to me, and it could be improved (maybe with an illustration?).

- Pg 15, 450: Unclear: "Mixed-design ANOVAs (group*SNRs) were performed for A and visual enhancement"

- For the PPI analysis, it is stated "PPI regressors, the seed time series, and the regressors of the original GLM model were included in the model". What did enter the ANOVA analysis? Are the betas for the PPI regressors? Were they significant? Or, in other words, did the PPI regressor explain additional variance that was not explain by the original GLM predictors?

- Why an ad hoc non parametric analysis is needed to test the contrast (ONM - YNM <> OM - YNM)? Can't this be done in the context of the prametric statistical framework of the main analyses (ANOVA, linear mixed effects modeling)?

- The analysis based on the spatial alignment of the connectivity patterns needs a rationale justification. I am not convinced that some shift in the mean coordinate of a few voxels across groups can be easily interpreted? What would be the neural substrate for this observation?

Reviewer #2: Dear Authors,

thank you for the wonderful work done! Nevertheless, some additional questions and comments:

1) Introduction should include more detailed explanation why you expect differences between groups based on occupation and age. It is unclear in the current text.

2) I would argue that, while occupation (in this case - musician) is an element of cognitive reserve, it can not be used as the only measure of CR. Even more, within the introduction, authors introduce different models of cognitive compensatory ageing, but omit The Cogntive Reserve theory, providing only references to aged publications by Stern et al. If authors are adamant in keeping occupation-musician as the only measure of cognitive reserve, I would definately suggest integrating more information on the actual theory. In addition, current consensus on cognitive reserve is that it should be (a) measured longitudinally and (b) considered as a moderator between the brain and cognitive functioning in case of pathology. Please, refer to the publication by Reserve and Resilience Framework Group: Stern, Y., Albert, M., Barnes, C. A., Cabeza, R., Pascual-Leone, A., & Rapp, P. R. (2023). A framework for concepts of reserve and resilience in aging. Neurobiology of aging, 124, 100-103.

3) Comments and recommendations regarding participants:

- did you also consider specific areas of music? There are studies suggesting instrument-specific activities.

- considering the size of the sample, replacing outliers with the group average might not be the best approach, as it increases the risk of Type I error (e.g. see Gress, T. W., Denvir, J., & Shapiro, J. I. (2018). Effect of removing outliers on statistical inference: implications to interpretation of experimental data in medical research. Marshall journal of medicine, 4(2), 9. and Vankov, I. I. (2023). The hazards of dealing with response time outliers. Frontiers in Psychology, 14, 1220281. for differences in outlier treatment methods). While I do not claim this is the case, my suggestion would be to triangulate the data analysis using different approaches to removing outliers, to ensure that the correct approach has been chosen.

4) Regarding data analysis:

- while exclusion of education as is discussed in the supplementary text, it should be discussed more in the body of the text as well. It should also be clarifies, what is meant by "the self-reported years of education cannot represent the education level of the older subjects reliably". It might not represent the level of knowledge, however, it can quantify the formal and informal education, which is the most common way of measuring education (even if not the best). In any case, I would suggest to briefly clarify this in the body of the text as well.

- In general, Results section is well structured and appropriate data analysis methods are used.

5) Discussion:

- while the authors have presented their results within the context of the current literature, the limitations of the study are not really discussed. I would encourage the authors to address the impact of the issues like sample size and characteristics, research design, task type etc. on the study results.

- to add to the comment at the beginning, the concept of cognitive reserve in the discussion section is used very loosely.

Overall, this is a well-structured article with well conducted data analysis, however, some work on the theoretical framework is suggested.

Dear Dr Zhang,

Thank you for your patience while we considered your revised manuscript "Musical expertise holds back age-related upregulation of neural activities in speech-in-noise perception" for publication as a Research Article at PLOS Biology. This revised version of your manuscript has been evaluated by the PLOS Biology editors, the Academic Editor and the original reviewers.

Based on the reviews and on our Academic Editor's assessment of your revision, we are likely to accept this manuscript for publication, provided you satisfactorily address the following data and other policy-related requests:

* We would like to suggest a different title to improve its accessibility for our broad audience:

Long-term musical training can protect against age-related upregulation of neural activity in speech-in-noise perception

* Please add the links to the funding agencies in the Financial Disclosure statement in the manuscript details.

* Please include the approval/licences number of the ethical approval of this study.

* Please include information in the Methods section whether the study has been conducted according to the principles expressed in the Declaration of Helsinki.

* Please move supplementary methods, discussion and references to the main manuscript file. We do not have a word count limit for methods.

* DATA POLICY:

You may be aware of the PLOS Data Policy, which requires that all data be made available without restriction: http://journals.plos.org/plosbiology/s/data-availability. For more information, please also see this editorial: http://dx.doi.org/10.1371/journal.pbio.1001797

Note that we do not require all raw data. Rather, we ask that all individual quantitative observations that underlie the data summarized in the figures and results of your paper be made available in one of the following forms:

1) Supplementary files (e.g., excel). Please ensure that all data files are uploaded as 'Supporting Information' and are invariably referred to (in the manuscript, figure legends, and the Description field when uploading your files) using the following format verbatim: S1 Data, S2 Data, etc. Multiple panels of a single or even several figures can be included as multiple sheets in one excel file that is saved using exactly the following convention: S1_Data.xlsx (using an underscore).

2) Deposition in a publicly available repository. Please also provide the accession code or a reviewer link so that we may view your data before publication.

Regardless of the method selected, please ensure that you provide the individual numerical values that underlie the summary data displayed in the following figure panels as they are essential for readers to assess your analysis and to reproduce it: 2, 3C, 4BEF and 5.

NOTE: the numerical data provided should include all replicates AND the way in which the plotted mean and errors were derived (it should not present only the mean/average values).

Please also ensure that figure legends in your manuscript include information on where the underlying data can be found, and ensure your supplemental data file/s has a legend.

Please ensure that your Data Statement in the submission system accurately describes where your data can be found.

* CODE POLICY

Per journal policy, if you have generated any custom code during the course of this investigation, please make it available without restrictions. Please ensure that the code is sufficiently well documented and reusable, and that your Data Statement in the Editorial Manager submission system accurately describes where your code can be found.

Please note that we cannot accept sole deposition of code in GitHub, as this could be changed after publication. However, you can archive this version of your publicly available GitHub code to Zenodo. Once you do this, it will generate a DOI number, which you will need to provide in the Data Accessibility Statement (you are welcome to also provide the GitHub access information). See the process for doing this here: https://docs.github.com/en/repositories/archiving-a-github-repository/referencing-and-citing-content

As you address these items, please take this last chance to review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the cover letter that accompanies your revised manuscript.

In addition to these revisions, you will need to complete some formatting changes, which you will receive in a follow up email. A member of our team will be in touch with a set of requests shortly.

We expect to receive your revised manuscript within two weeks.

To submit your revision, please go to https://www.editorialmanager.com/pbiology/ and log in as an Author. Click the link labelled 'Submissions Needing Revision' to find your submission record. Your revised submission must include the following:

- a cover letter that should detail your responses to any editorial requests, if applicable, and whether changes have been made to the reference list

- a Response to Reviewers file that provides a detailed response to the reviewers' comments (if applicable, if not applicable please do not delete your existing 'Response to Reviewers' file.)

- a track-changes file indicating any changes that you have made to the manuscript.

NOTE: If Supporting Information files are included with your article, note that these are not copyedited and will be published as they are submitted. Please ensure that these files are legible and of high quality (at least 300 dpi) in an easily accessible file format. For this reason, please be aware that any references listed in an SI file will not be indexed. For more information, see our Supporting Information guidelines:

https://journals.plos.org/plosbiology/s/supporting-information

*Published Peer Review History*

Please note that you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out. Please see here for more details:

https://plos.org/published-peer-review-history/

*Press*

Should you, your institution's press office or the journal office choose to press release your paper, please ensure you have opted out of Early Article Posting on the submission form. We ask that you notify us as soon as possible if you or your institution is planning to press release the article.

*Protocols deposition*

To enhance the reproducibility of your results, we recommend that if applicable you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols

Please do not hesitate to contact me should you have any questions.

Sincerely,

Christian

Christian Schnell, PhD

Senior Editor

cschnell@plos.org

PLOS Biology

------------------------------------------------------------------------

Reviewer remarks:

Reviewer #1: I thank the authors for their response and for the changes implemented in the manuscript. The manuscript can be accepted for publication.

Dear Dr Zhang,

Thank you for the submission of your revised Research Article "Long-term musical training can protect against age-related upregulation of neural activity in speech-in-noise perception" for publication in PLOS Biology. On behalf of my colleagues and the Academic Editor, Laura Lewis, I am pleased to say that we can in principle accept your manuscript for publication, provided you address any remaining formatting and reporting issues. These will be detailed in an email you should receive within 2-3 business days from our colleagues in the journal operations team; no action is required from you until then. Please note that we will not be able to formally accept your manuscript and schedule it for publication until you have completed any requested changes.

Please take a minute to log into Editorial Manager at http://www.editorialmanager.com/pbiology/, click the "Update My Information" link at the top of the page, and update your user information to ensure an efficient production process.

PRESS

We frequently collaborate with press offices. If your institution or institutions have a press office, please notify them about your upcoming paper at this point, to enable them to help maximize its impact. If the press office is planning to promote your findings, we would be grateful if they could coordinate with biologypress@plos.org. If you have previously opted in to the early version process, we ask that you notify us immediately of any press plans so that we may opt out on your behalf.

We also ask that you take this opportunity to read our Embargo Policy regarding the discussion, promotion and media coverage of work that is yet to be published by PLOS. As your manuscript is not yet published, it is bound by the conditions of our Embargo Policy. Please be aware that this policy is in place both to ensure that any press coverage of your article is fully substantiated and to provide a direct link between such coverage and the published work. For full details of our Embargo Policy, please visit http://www.plos.org/about/media-inquiries/embargo-policy/.

Thank you again for choosing PLOS Biology for publication and supporting Open Access publishing. We look forward to publishing your study. 

Sincerely, 

Christian

Christian Schnell, PhD

Senior Editor

PLOS Biology

cschnell@plos.org