Peer Review History
| Original SubmissionJune 27, 2024 |
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PONE-D-24-25018Deep learning analysis of fMRI data for predicting Alzheimer's Disease: a focus on convolutional neural networks and model interpretabilityPLOS ONE Dear Dr. Gerstein, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by Sep 09 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. Please include the following items when submitting your revised manuscript:
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We note you have included a table to which you do not refer in the text of your manuscript. Please ensure that you refer to Table 3 in your text; if accepted, production will need this reference to link the reader to the Table. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: No Reviewer #3: Yes ********** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: No Reviewer #2: No Reviewer #3: Yes ********** 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: Yes Reviewer #3: Yes ********** 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes Reviewer #3: Yes ********** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: This manuscript describes a new machine learning algorithm using convolutional networks to detect Alzheimer’s disease from fMRI scan data. The manuscript is well written and the following minor comments and suggestions should be addressed: 1. The authors should consider re-organizing their figure placement such that it appears closer to the section where they are discussed. 2. In the "Deep Learning Frameworks" section, more background information should be given on the baseline RNN and MLP models. The number of trainable parameters in all models should be listed for comparison. 3. Some statistical analysis should be added to see if the performance improvement is statistically significant compared to Gupta's model. 4. Did the authors use any data augmentation techniques to compensate the issue of class imbalance? Why or why not? The authors should provide some discussion on this. 5. Figure 3. The authors should indicate which model was used to generate this plot. If the authors' model was used, it might be worthwhile to compare that with a similar plot generated from Gupta's model for comparison. Reviewer #2: - ## paper summary: - This study aims to demonstrate feasibility of using fMRI + standard CNNs to predict risk of AD diagnosis with high performance despite low sample size and highly imbalanced training data. Post-hoc CNN feature map/SHAP explanations suggest that authors' CNN model relies on clinically known brain regions for assessing AD risk. - ## strengths: 1) publicly available code 2) post-hoc model interpretation seems to align with domain knowledge of AD/MCI - ## major issues: 1) the scientific goal, focus, or overall argument/hypothesis/structure of the study is not evident - Q: why is the focus of the study to build a CNN? what purpose is it expected to serve given prior models with AUROCs/accuracies above 0.95/95%? - the introduction is not thematically aligned with the running title of the paper 2) lack of overall scientific contributions: - Q: what exactly is the knowledge gap in past literature that this study wants to address/explore or is motivated by? - related literature and its limitations must be summarized under above context and not simply enumerated. - Q: is the only issue that past models/code were not publicly released? - Q: what novel insight is the reader supposed to take away from the interpretability analysis? 3) lack of clinical contribution: - study maybe based on a flawed/irrelevant experimental design - not sure if CN vs AD is a clinically relevant classification task at all (although it is convenient for training a ML/DL classifier). Given that this model and others before it all have achieved very high AUC/accuracy, why are these models not yet trusted for use in real-world clinical workflows? Perhaps a design that focuses on CN vs MCI may be more clinically impactful? - the interpretability analysis seems highly speculative/cherry-picked and affected by authors' confirmation bias, no expert-in-the-loop clinical assessment was done on the SHAP explanations/CNN feature maps nor were any counter-intuitive associations found/reported. The (presumably) overlapping train/val/test data splits during training further complicates the reliability of any post-hoc model interpretation. 4) experiment design: Q: what is the point of comparing your model with Gupta's study? What makes Gupta's study relevant to yours? In general, what is the purpose of the Table 2 comparisons and how do they support the goal of this study? 5) results: (Table 2) Judging by the 0.0 F1 and 0.50 AUC scores, none of these models seem to be trained properly. Are all high AUCs simply due to severe class imbalance in the test set? If so, what was done to protect against/reduce the impact of class imbalance during model training? 6) evaluation scheme: - (line 118) Q: were the train/val/test data splits done with overlapping subjects? in other words, did the fMRI data slices of one subject end up in both train and test sets? - Q: Are the classification results reported on test data collected from a seen site (whose data is present in train or val set) or previously unseen ADNI site? Overall, a rigorous evaluation scheme should test the model on an unseen ADNI site, using data of unseen subjects. 7) lack of methodological novelty or technical contributions: all the presented insights on class imbalance and low sample size are well-known in the ML/DL for healthcare community, this study does not present any new approach that can address any of the known/acknowledged issues. - ## minor issues: 1) manuscript needs significant language and scientific prose/style/structure review: - one example: ROC plot/performance metrics and interpretability tools must first be introduced in methods section, not in results section! 2) (line 126) missing technical signal preprocessing details 3) should remove all gene-related details from the main text if focus is entirely on fMRI analysis 4) (line 169) can move all NN related details to supplement since these are all standard and well-known. 5) (line 197) Q: what exactly makes the CNN architecture "unified" and not simply a standard CNN? How exactly is adaptation to different input sizes achieved with a fully connected layer (line 183)? 6) (table 1) Q: Are the healthy controls age-matched and sex-matched to the AD/MCI patients? If not, the model may have learnt to predict age or sex instead of disease state. 7) Q: how was data normalization done for this multi-centre dataset, assuming site-specific effects exist and are non-negligible? is this normalization/standardization process used/documented previously by the ML/DL for fMRI community? - ## misc. questions/comments on interpretability: 1) maybe an interesting ablative experiment: if certain brain regions are known to be associated with AD, does training models after masking those brain regions steeply hurt the model performance or does it learn to use some other feature of the data instead? 2) robustness of interpretation: most model explanation methods have known limitations and robustness issues, i.e., their outputs are not always reliable. There is a serious general issue of author bias when looking at model interpretability results - we overlook the results that we don't expect to see and focus more on what matches our expectations. Some additional experiments are needed to establish robustness of presented insights. 3) model convergence: Q: Do all the compared models use the same set of brain regions when assessing AD risk? or do you get different explanations for each model? Reviewer #3: The paper proposed an improvement for Alzheimer's Disease (AD) early detection by utilizing 3D Convolutional Neural Network (CNN) to analize fMRI scans. Deep learning has proven effective in many domains, and its application to AD diagnosis represents a novel and powerful approach. The authors employed a substantial dataset and conducted rigorous experiments, demonstrating that 3D CNN-based analysis of fMRI scans achieves high accuracy. Furthermore, their results indicate that gene processing—a commonly used method for AD detection—is less effective than the proposed 3D CNN approach. For future development, I recommend that the authors design a neural network architecture specifically tailored for AD fMRI analysis. ********** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No Reviewer #2: No Reviewer #3: No ********** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step. |
| Revision 1 |
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Deep learning analysis of fMRI data for predicting Alzheimer's Disease: a focus on convolutional neural networks and model interpretability PONE-D-24-25018R1 Dear Dr. Gerstein, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. If you have any questions relating to publication charges, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Xiaohui Zhang Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation. Reviewer #1: All comments have been addressed ********** 2. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes ********** 3. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes ********** 4. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes ********** 5. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes ********** 6. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: The authors have sufficiently addressed the reviewer comments, the manuscript can now be considered for publication. ********** 7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No ********** |
| Formally Accepted |
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PONE-D-24-25018R1 PLOS ONE Dear Dr. Gerstein, I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team. At this stage, our production department will prepare your paper for publication. This includes ensuring the following: * All references, tables, and figures are properly cited * All relevant supporting information is included in the manuscript submission, * There are no issues that prevent the paper from being properly typeset If revisions are needed, the production department will contact you directly to resolve them. If no revisions are needed, you will receive an email when the publication date has been set. At this time, we do not offer pre-publication proofs to authors during production of the accepted work. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few weeks to review your paper and let you know the next and final steps. Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. If we can help with anything else, please email us at customercare@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Xiaohui Zhang Academic Editor PLOS ONE |
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