Unlocking the Beat: Dopamine and Eye Blink Response to Classical Music

Round 1

Reviewer 1 Report

This is an interesting paper. It deals with a hot topic (the role of dopamine in a musical experience) in current research, and provides a beautiful overview as well as some interesting new avenues for future research. The paper is well written, is quite readable and understandable, and the used methodology seems to be sound. I suggest to accept the paper for publication.

General remarks

·      The English language use is OK.

·      The style of writing is quite fluent.

·      The readability and understandability of the text is quite high.

·      The theoretical background is quite clear with a good balance between general overviews and a more nuanced approach. There is, however, a danger of some generalizations (see detailed comments) which are not always well motivated.

·      The research question is clear, but the whole paper is descriptive rather than explanatory. More could be said about the underlying mechanism that relate eyeblink and dopamine release. It is only stated that spontaneous eye blinks are a proxy measure but the “why”-questions if not really solved. Even if there is currently not yet conclusive evidence, the question should be raised and an attempt should be made to sketch at least future avenues for research in this regard.

·      The used methodology is sound, but some technical terms could be explained somewhat more in detail (e.g. the odd ball paradigm; some components of the ERP; the contents of some of the used questionnaires).

Detailed comments

·      Line 142: it is hypothesized here that the used music (Winter) will be valued by the listeners as sad music. This is, however, a quite unmotivated claim, as there are many modulating factors (personality, individual learning history, contextual factors, etc.) which may result in a different appraisal by some of the participants. Perhaps this methodological issue should be elaborated somewhat more in depth.

·      Line 165: the design of the study is not sufficiently clear. Explain very shortly and intuitively was is meant with an odd-ball task (even if this is common knowledge for many readers, not all readers are familiar with this technique). It is also not immediately clear what is meant with the three movement blocks (fast, slow, fast).

·      Line 174: P3a ERP component. Not all readers are familiar with ERP. Explain shortly, and intuitively, what is meant with P3 and what does P3a mean in particular. This can be very short, but P3a is not common knowledge, even for readers familiar with neuroscience.

·      Line 181: provide some more information about the used questionnaires. What are they questioning (their principal aims) and which questions are asked. Some examples can be used to clarify things, either in the main text, or as an appendix.

·      Line 219: what is meant with the LSD procedure? The abbreviation is not explained. Provide a short description.

·      Line 362: this is quite generalizing. It seems as is there is a linear-causal relationship between sad music and mood regulation. More nuance and more empirical grounding (additional references) could make this claim stronger. Some caveats should be expressed here as well.

Additional reference (suggestion):

Demiral, Ş. B., Liu, C. K., Benveniste, H., Tomasi, D., & Volkow, N. D. (2023). Activation of brain arousal networks coincident with eye blinks during resting state. Cerebral Cortex, bhad001. ht

Author Response

Line 142: it is hypothesized here that the used music (Winter) will be valued by the listeners as sad music. This is, however, a quite unmotivated claim, as there are many modulating factors (personality, individual learning history, contextual factors, etc.) which may result in a different appraisal by some of the participants. Perhaps this methodological issue should be elaborated somewhat more in depth.

We have extended our discussion of Winter and what constitutes ‘sad’ to aid the reader in this aspect of the rationale.

• Line 165: the design of the study is not sufficiently clear. Explain very shortly and intuitively was is meant with an oddball task (even if this is common knowledge for many readers, not all readers are familiar with this technique). It is also not immediately clear what is meant with the three movement blocks (fast, slow, fast).

We have added details as requested to the design section. Further information regarding the nature of the oddball task are also included in the procedure section.

• Line 174: P3a ERP component. Not all readers are familiar with ERP. Explain shortly, and intuitively, what is meant with P3 and what does P3a mean in particular. This can be very short, but P3a is not common knowledge, even for readers familiar with neuroscience.

We have added the extra detail regarding the P300, specifically the P3a related to dopamine function.

• Line 181: provide some more information about the used questionnaires. What are they questioning (their principal aims) and which questions are asked. Some examples can be used to clarify things, either in the main text, or as an appendix.

We have now added further details, as requested for both the Bond Lader and Stomp questionnaires, in the Materials section.

• Line 219: what is meant with the LSD procedure? The abbreviation is not explained. Provide a short description.

We have now written in full as well as the abbreviation.

• Line 362: this is quite generalizing. It seems as is there is a linear-causal relationship between sad music and mood regulation. More nuance and more empirical grounding (additional references) could make this claim stronger. Some caveats should be expressed here as well.

On reflection, this aspect of the discussions is weak. We have extended the discussion considerably as recommended and added key references.

More general comment and Additional reference (suggestion):

We thank the reviewer for the suggested reference. We added this to the discussion and indicated that work of this nature drives our understanding of blink indices and associated brain responses. We anticipate this reference to be key in the area, and a similar, more systematic approach should be adopted. This paper also links to other work in our lab, i.e. the default mode network. Therefore, the suggested article will generally be useful to the team.

Reviewer 2 Report

Here is a very interesting study about the influence of music on DA levels (measured indirectly by means of EBR, P3a ERP component, and reaction time). The research is original and I believe that could be of interest for readers not just in the neuroscinces field. 

I have just few minor concerns, about participants selection: 

- authors should state that participants were not affected by any neurological disorder (particularly parkinsonisms or blepharospasm), as well as any ophtalmologic or psychiatric one. Moreover, subjects should not have used any drug with any influence on DA levels (e.g. antidopaminergic effects of antiemetics) for a reasonable time. I am not an expert of EBR, but I believe that even any influence on vegetative system should have been standardized before the procedure (e.g. a normal night of sleep on the day before the esamination, no coffee or cigarettes on the day of examination, no alcohol use, etc). Lastly, any stressful condition should have been investigated and avoided before intervention (even a VAS evaluation on the level of self-perceived stress could be suitable). 

Author Response

Further details of participants-

We have made a minor change to the participant section to indicate inclusion criteria. However, we agree with the reviewer regarding more careful consideration of influencing factors. These suggestions/feedback will be beneficial for future studies of this nature in our laboratory.