Exploring the Impact of Electroencephalography-Based Neurofeedback (EEG NFB) on Motor Deficits in Parkinson’s Disease: A Targeted Literature Review

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

I appreciate the opportunity to revew the entiteled manuscript: Exploring the Impact of Electroencephalography-Based Neurofeedback (EEG NFB) on Motor Deficits in Parkinson’s

Disease: A Targeted Literature Review submitted to Applied Sciences (applsci-3428952).

The authors present a relevant topic in health sciences, and EEG findings, and an interestig approach for a targeted systematic review.

 

My main concern lies on the limited amount of literature included on the review. The presented PRISMA diagram shows an initial sample of 3881, from 4 different databases, the authors should state the number of papers from each database. Also it is highly recommended to provide the search string or strings, in the PICO method it is not clear if trials were supposed to be included or excluded. Besides, the exclusion criteria are not clear, they only mention animal, observational, and narrative, and from these criteria 359 articles were discarded. In the comparison description in the method, the authors state “C (Comparison): In this targeted literature review, we compared studies that employed the EEG NFB method.” However, this kind of comparison should be intended to describe the effect of certain independent variable in a controlled trial. Also, in the outcome description the argument is O (Outcome): We specifically analyzed tests that were used to improve motor abilities.” Clinically, the tests are not intended to “improve motor abilities” but to assess its performance. Another important issue in this sense, is that no description regarding the outcomes is delivered in the results section, it is not clear if the above mentioned outcomes are the EEG features, or behavioral motor features, or motor performance tests.

 

Other concerns I would like to address are that the aims and research questions of the review are not clearly stated. For being a five literature review report, I think this manuscript lacks of substantial relevant information that should be extracted, and described from the sample.

 

 

 

Comments on the Quality of English Language

I am not qualified to revise the quality of English Language.

Author Response

Dear Reviewers,

 

Thank you for your valuable feedback and the time you dedicated to reviewing our manuscript. We greatly appreciate your constructive comments, which have helped enhance the quality of our work. We have carefully addressed each suggestion, and we believe the revisions have improved the paper’s clarity and rigor. Below is our point-by-point response to your comments.

 

1. Reviewer 1:
   • My main concern lies on the limited amount of literature included on the review. The presented PRISMA diagram shows an initial sample of 3881, from 4 different databases, the authors should state the number of papers from each database.

Thank you, Reviewer 1, for your thoughtful feedback and the time you dedicated to reviewing our manuscript. We greatly appreciate your constructive comments, which have helped enhance the quality of our work. We have carefully addressed each suggestion, and we believe the revisions have improved the paper’s clarity and rigor. Below is our point-by-point response to your comments.

We acknowledge that the review includes a limited number of studies and agree that a broader scope could enhance the depth of analysis. In the revised manuscript, we have provided a more detailed breakdown of the number of papers identified from each of the four databases, along with the specific keywords used in our search. This information is now clearly presented in the Methods section.  

• Also it is highly recommended to provide the search string or strings, in the PICO method it is not clear if trials were supposed to be included or excluded.

Thank you for this suggestion. We have now included more detailed inclusion and exclusion criteria in the PICO method.

• Besides, the exclusion criteria are not clear, they only mention animal, observational, and narrative, and from these criteria 359 articles were discarded.

Thank you for pointing this out. We have clarified the inclusion and exclusion criteria in the revised methods section, specifying the types of studies that were included and excluded, by the PICO method. We also revised the PRISMA diagram and added reasons for excluding articles.

• In the comparison description in the method, the authors state “C (Comparison): In this targeted literature review, we compared studies that employed the EEG NFB method.” However, this kind of comparison should be intended to describe the effect of certain independent variable in a controlled trial.

Thank you for your insightful comment. We agree that the term "comparison" within the PICO framework is traditionally used to describe the effect of an independent variable in controlled trials. In our targeted literature review, however, the comparison was not intended to evaluate an independent variable against a control condition directly. Rather, we compared the methodologies, interventions, and outcomes of studies employing the EEG NFB method to identify common trends, differences in protocols, and their impact on motor deficits in Parkinson’s disease.

The changed text is available as: "C (Comparison): In this targeted literature review, we compared the methodologies, intervention protocols, and outcomes of studies that employed the EEG NFB method, rather than comparing distinct experimental groups as in controlled trials."

 

• Also, in the outcome description the argument is O (Outcome): We specifically analyzed tests that were used to improve motor abilities.” Clinically, the tests are not intended to “improve motor abilities” but to assess its performance. Another important issue in this sense, is that no description regarding the outcomes is delivered in the results section, it is not clear if the above mentioned outcomes are the EEG features, or behavioral motor features, or motor performance tests.

Thank you for raising this issue. In the revised manuscript, we’ve added an explanation of the outcomes in the discussion section. We have clarified that the outcomes refer to motor performance tests, not EEG features.

 

• Other concerns I would like to address are that the aims and research questions of the review are not clearly stated. For being a five literature review report, I think this manuscript lacks of substantial relevant information that should be extracted, and described from the sample.

Thank you for this observation. We have now written more clearly what our research questions were and how we formulated them.

Reviewer 2 Report

Comments and Suggestions for Authors

The purpose of this review was to review the influence of EEG NFB on motor function in PD. The review had had several strengths. The study was well-written, easy to understand, and had few typographical or grammatical errors. The topic of research is obviously an important one. In general, the methodology and statistics appeared to be appropriate using PRISMA guidelines etc.  

So overall I think the authors did a good job on the study.

 

The study however has one major issue that is hard to get around. The review only included 5 studies with 1 being a case study, 1 a pilot, and 3 more elaborate studies. I feel like that is simply too few to have a review article on. The vast majority of review articles have traditionally covered topics where there are many more papers available to review so more concrete conclusions can be drawn. It is not really the authors fault that less exists but it is hard to justify a review article that only has 3-4 “real” research studies (case study is very weak evidence). Perhaps the authors can justify this.

Author Response

Dear Reviewers,

 

Thank you for your valuable feedback and the time you dedicated to reviewing our manuscript. We greatly appreciate your constructive comments, which have helped enhance the quality of our work. We have carefully addressed each suggestion, and we believe the revisions have improved the paper’s clarity and rigor. Below is our point-by-point response to your comments.

 

Reviewer 2:

• • The study however has one major issue that is hard to get around. The review only included 5 studies with 1 being a case study, 1 a pilot, and 3 more elaborate studies. I feel like that is simply too few to have a review article on. The vast majority of review articles have traditionally covered topics where there are many more papers available to review so more concrete conclusions can be drawn. It is not really the authors fault that less exists but it is hard to justify a review article that only has 3-4 “real” research studies (case study is very weak evidence). Perhaps the authors can justify this.

Thank you, Reviewer 2, for your thoughtful comment. We understand that the small number of studies may raise concerns about the strength of our conclusions. This limitation reflects the current scarcity of research specifically focused on EEG NFB and motor abilities in individuals with Parkinson’s disease.

To address this, we have added a justification in the Study Limitations section, highlighting that while the number of studies is limited, they represent the most relevant and available evidence in this area. Additionally, we have emphasized that the findings should be considered preliminary, underscoring the need for further research with larger sample sizes and more robust study designs.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Research questions, and aims need to have consistency through the manuscript, meaning that it is highly suggested that the authors explain their objectives in the abstract, the introduction, and the discussion sections. In previous comment, I addressed research questions and aims. The newly presented research questions in the method section, are an effort to guide the reasons that motivated this research, but they do not explain how these questions are related to a targeted literature review. The research questions and aims still need to be revised in terms of consistency with the actions of this work, and the aims are still not stated.

 

Table 1 do authors refer to headache or headage?.

 

Lines 157-161, the authors now included the key words used for the search in the literature review. It is still recommended that they provide the search string, so the readers could find the results arising from that search.

I still see a small account of literature, providing scarce qualitative analysis for being a literature review. The results section provides two tables with a literature synthesis of treatment factors, and EEG features, but a qualitative description from the findings in the literature would improve and enhance these tables explain.

The discussion section presents a very short (lines 207-213) literature discussion, it is highly suggested that the authors consider comparing their conclusions and answers to their research questions with those arising from the revised literature, if the findings from the related work are scarce, the authors could take advantage from the literature presented in the introduction section.

 

Author Response

Dear reviewers,

 

We thank you for your time to read our article and to provide us with the thoughtful comments.

 

Reviewer 1:

• Research questions, and aims need to have consistency through the manuscript, meaning that it is highly suggested that the authors explain their objectives in the abstract, the introduction, and the discussion sections. In previous comment, I addressed research questions and aims. The newly presented research questions in the method section, are an effort to guide the reasons that motivated this research, but they do not explain how these questions are related to a targeted literature review. The research questions and aims still need to be revised in terms of consistency with the actions of this work, and the aims are still not stated.

Thank you once again for your time and effort in reviewing our manuscript. We appreciate your valuable feedback, which has helped us refine our work. We have now expanded the explanation of the research questions and explicitly stated the aim of our study. To ensure clarity and coherence, the research questions are consistently addressed in the abstract, introduction, and discussion sections, aligning them with the overall focus and objectives of the manuscript.

 

• Table 1 do authors refer to headache or headage?.

We have corrected the typographical error in Table 1 by replacing "headage" with "headache." Furthermore, we thoroughly reviewed the manuscript to ensure accuracy and consistency in terminology.

• Lines 157-161, the authors now included the key words used for the search in the literature review. It is still recommended that they provide the search string, so the readers could find the results arising from that search.

We appreciate your suggestion. We have now included the full search string used for the targeted literature review, specifying the combinations of keywords in the appendix. Additionally, we have listed the databases consulted to ensure transparency and replicability of our search process.

• I still see a small account of literature, providing scarce qualitative analysis for being a literature review. The results section provides two tables with a literature synthesis of treatment factors, and EEG features, but a qualitative description from the findings in the literature would improve and enhance these tables explain.

To address this, we have added a more descriptive analysis after the tables to better explain the results. This qualitative description highlights key findings from the literature and provides a more comprehensive context for the synthesis in the tables.

• The discussion section presents a very short (lines 207-213) literature discussion, it is highly suggested that the authors consider comparing their conclusions and answers to their research questions with those arising from the revised literature, if the findings from the related work are scarce, the authors could take advantage from the literature presented in the introduction section.

Thank you for your suggestion. We have expanded the discussion section to more thoroughly compare our conclusions with the findings from the relevant literature. We have addressed both of our research questions in greater detail and incorporated relevant findings from the literature presented in the introduction section.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have improved the paper and responded to my prior issue of there not being enough papers on the topic. They have added this to the limitations section. I still think the number of studies is now but this is probably up to the editor to ultimately decide.

Author Response

Dear reviewers,

We thank you for your time to read our article and to provide us with the thoughtful comments.

We made another round of revisions requested by review 1.

Thank you and kind regards,

Laura Blaznik and Uros Marusic