PONE-D-24-48341Home cage-based insights into motor learning and strategy adaptation in a Huntington Disease mouse modelPLOS ONE

Dear Dr. Raymond,

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Miriam A Hickey, PhD

Academic Editor

PLOS ONE

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Additional Editor Comments:

Please provide F statistics with numerator and denominator for all ANOVAs.

For all graphs, please define error bars.

Figure 3

Please discuss this in a little more detail - Fig 3C shows a quite large reduction in variability in the zQ175 group at 26d approx - what could underlie this?

Fig 3E Are these data from all trials? Have the authors examined at e.g., day 56 versus day 21 and day 1?

Figure 3E - X axis, please consider providing a more explanatory title, e.g., (number of consecutive trials within a single entry)

Methods

To adhere to ARRIVE guidelines

--please briefly discuss the group sizes used (e.g., sample size calculations and power analyses).

--please briefly discuss housing (were mice of different genotypes housed together)

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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: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

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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

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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

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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: Preclinical research into neurodegenerative diseases, including Huntington’s Disease, depends in part upon motor, cognitive, and social assays performed in disease-modeling animals. However, laboratory animals are highly sensitive to environmental changes and individual handlers, making it challenging to execute these experiments and to interpret results. Automated behavior tasks performed in the home cage can mitigate those challenges, allowing animals to behave in a more natural, unstressed manner, without an observer present.

Here, the authors convincingly demonstrate the feasibility and value of a novel home-cage behavior monitoring apparatus requiring subject mice to press a lever to receive drinking water. As the animals master the skill, the duration for which they must hold the lever increases, necessitating a flexible problem-solving strategy on the part of the animals. The zQ175 knock-in Huntington’s Disease model mice acquired the initial motor skill similarly to their wild type littermates, but struggled to adapt to the progressive hold-challenge, resulting in fewer, shorter hold bouts. The authors also found that wild type mice, but not HD mice, had more successful trials if they followed a successful “good influencer,” suggesting a possible social learning deficit as part of the mouse’s HD symptomology. Finally, the authors found an increase in fEPSPs in the left hemisphere of wild type mice who had completed this hold-reward experiment compared to the same mouse’s right hemisphere, indicating an increase in plasticity contralateral to the gripping paw. No such difference in lateralization was observed in the HD mice.

This home-cage system has several compelling advantages. In particular, it allows for social housing, which is profoundly important for animal wellbeing as well as for eliciting the most naturalistic behavior results. This is also helped by the trials being run in the home cage, a familiar and comfortable environment. The RFID scanner detects individuals entering the trial box and presents them with a lever-pull challenge customized to their level of ability, allowing co-housed animals to progress at different rates. This reviewer is satisfied that the authors have a good system in place to minimize the effects of thirst itself on animal health. The tone played for a successful trial allowed the researchers to observe subtle and very interesting social behaviors in animals. This is especially interesting, as few tests exist to measure the social transmission of knowledge among mice.

There is a punctuation error on line 235, and I encourage the authors to triple-check their punctuation around parentheses. This comment aside, this reviewer feels the authors have demonstrated an interesting and valuable method of measuring motor learning and cognition with the ability to detect learning and coordination deficits in mouse models of neurodegeneration. This method should be of particular interest to the field as it allows for the dissection of subtle social behaviors that would be difficult to capture outside of the mouse’s home environment. This reviewer happily recommends this manuscript for publication without the need for major revisions. The author’s are to be congratulated for a well conducted study and excellently prepared manuscript.

Reviewer #2: Many thanks for the opportunity to review this manuscript. The study provides interesting data on assessing a specific pattern of upper limb motor function control in mice, using a home cage lever-pulling device. Furthermore, the study shows some comparative data collected by this device in zQ175 mice as a model of HD and WT mice- showing some valuable differences on the capacity to readjust to specific pulling task that the authors claimed may be associated with the onset of HD phenotype as also assess further by changes on electrophysiological patterns on the striatum. As such, the study is interesting, demonstration further the benefit of such home based and more naturalistic approaches to assess motor dysfunction in mouse models.

Overall I read the manuscript with interest and I agree with the authors comments on the value of continue developing such technical approaches to study more naturalistic behaviour in prey species like the lab mouse. However, I do think the study has some major challenges once we thoroughly analysed the data and the conclusions that the authors draw form the data. Firstly, the main aim of the study is to validate a new/ revised operant task system, PiPaw2.0 to assess deficits on voluntary movement on these zQ175 HD mice- but the authors already published some early work using similar approaches on a PiPaw system-using the same mice (see reference Woodard CL, Sepers MD, Raymond LA. Impaired Refinement of Kinematic Variability in 821 Huntington Disease Mice on an Automated Home Cage Forelimb Motor Task. J Neurosci.822 2021 Oct 13;41(41):8589–602. While the authors indeed, are now presenting further data- there is no direct comparative analysis on the data acquired by using initial PiPaw system and importantly, how the new 2.0 system is improving the outcomes- note also that looking at the results, many of the data is non-significant which could also query the sensitivity of the system to detect suttled changes. Yes, the reviewer still believes that the data provided in the this paper is of interest. Secondly, there is little information on the study plan and the frequency of study in individual animals- as some of this tasks may be associated with fatigue and exhaustion, it would be good to see a clear experimental design pattern supported by physiological data such as changes on body weight between the animals and groups, any changes on body conditions, any signs of distress on the animals-that could also be an important confounding factor on the overall performance ability of an individual animal. Thirdly, while the authors do a good job on defining many behaviour parameters and their analysis- sometimes it feels like there is an overarching assumption between a specific behaviour and the biological relevance of such functional response. The study mostly provides functional data-with very limited biological data and/or any other type of biomarker data that could aligned the functional data with some clear changes on the brain- atm, this is lacking. There is some informative data on electrophys with some LTP potentiation data- but is this enough to fully associated such changes on the striatum with a HD phenotype on these animals? I would recommend the authors to :

-provide further clarity and experimental data on how this system improved and goes further beyond to the earlier piPaw data (group study in 2021) as this is described as main objective

- provides some further physiological/phenotype data on the animals studies including BW, body conditions, pain. distress along with other HD biomarkers of HD disease- I agree that some of these may be challenging some support on biological data would be very useful. Also provide further clarity of cumulative effects on animals during testing to understand the dynamics of study and effects on fatigue.

-further biomarker/ biological qualification on the WT and HD mouse models so that functional changes are better studies with some biological support. The authors may have some paralel data on the HD mice on what would be their disease phenotype at 6-7 months.

The results showed many parameters, and many of them of valuable relevance but sometimes there is a far too direct pressumption on who such changes may be linked to the onset /progress of the HD phenotype on the studies mice (QZ174) -so further biological data should be provided to confirm such hypothetized causative effects. This is important to provide further scientific robustness to the fucnctional data- as otherwise the study may be better aligned to a development technical approach with restricted predictability value on the HD models.

There are some other minor issues such as:

a) any differences between sexes?

b? why 6-7months were selected on the study and what would be the differences in body weight curves between the HA and WT line?

c) what are the WT mice-was is the background for the qZ175 mice?

d) please provide info on bedding and cage sizes vs group density per cage as this may affect social interaction and the effects of inter-mouse effects

e)water supply? how was this regulated for the operant conditioning test?

f) did animals ever reac a 20% body weight loss- this would be considered a severe level of distress so how would you envisage such animals to perform in a non-clinical illness stage and show naturalistic functional outcomes- any animals with a ill-associated homeostasis is very likely that will impact on functional assessments?-how much of the effects detected are seen by such critical physiological status vs the onset/progress of HD phenotype?

g) please provide a better outline methodology on cumulative effects on the animals studied so there is better information associated to risk for fatigue/ exhaustion/boredomness/ motivation.

Many thanks again for the opportunity to revise this work; as abovementioned, it is of valuable interest but needs further data support and certain clarity in some methodological aspects to strengthen the predictive impact of the functional data provided.

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Reviewer #1: No

Reviewer #2: No

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Home cage-based insights into motor learning and strategy adaptation in a Huntington Disease mouse model

PONE-D-24-48341R1

Dear Dr. Raymond,

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.

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Kind regards,

Miriam Ann Hickey, PhD

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

All Editor and Reviewer comments have now been addressed.

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 #2: All comments have been addressed

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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 #2: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

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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 #2: Yes

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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 #2: Yes

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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 #2: Many thanks for the detail answers to my comments and suggestions- good to see the revised manuscript with the addition of some physiological data and further clarifications on the text and methodology. I am happy with the revised version. Just a note that a 20% body weight would be categorised as severe procedure and most likely requiring a HEP. But i do understand that this may required some broader perspectives on the specific of the strain and some local legislation. Thanks for providing further details on this.

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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 #2: No

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