Power Spectrum and Connectivity Analysis in EEG Recording during Attention and Creativity Performance in Children

Round 1

Reviewer 1 Report

This paper uses EEG signals of 15 children to study the power spectrum and connectivity analysis. The results of d2 test, CREA test and connectivity analysis indicate the effectiveness of the used methods. The paper is well organized and its findings are interesting.

My comments on the paper are as follows:
1. It lacks comparison to the existing methods in this field in Section 3.
2. There exist many issues of grammar, spelling, and styles in the paper. Please carefully correct them.

Author Response

Dear Reviewer,

                                 We would like to thank you for your contributions to this work, which have been of great help in improving it. The following we answer all the points raised by the reviewer.

 

1. It lacks comparison to the existing methods in this field in Section 3.

In this work, we have used two methods of analysis: Power spectrum density (PSD) and Phase Looking Index (PLI). The former is one of the most widely used methods in the study of EEG and is one of the few used to study creativity and attention (you can review the extensive bibliography described in the introduction and discussion sections). The second case is a measure of functional connectivity. As is well known, there are many measures of connectivity associated with the study of EEG. The most commonly used in the field is the Coherence measure (Clifford Carter, 1987). However, coherence is a linear measure which cannot capture all the information provided by EEG signals (which are highly non-linear). Because of this, we used a measure that can obtain the non-linear information of the signal. Because of the difference between the two metrics, a direct comparison is not possible.

The following paragraph was added in the text (Methods section) for a better explanation of the choice of the PLI metric.

PLI is a useful tool for the functional analysis of specific brain functions, as it enables to reflect brain anatomical boundaries due to its high intrinsic synchronization (cohen). Unlike other EGG connectivity brain measures, such as coherence (i.e., MSC; Clifford Carter, 1987), PLI does not rely on stationarity, and it is enough to conclude that two brain regions interact (Lachaux et al., 1999) either directly or through other groups of neural networks. Therefore, PLI would be a more suitable analysis than coherence when working with nonlinear and nonstationary signals, such as those of EEG (Bhattacharya & Petsche, 2005). Furthermore, as it has the additional benefit of enabling the detection of zero-phase lag events, it would be more useful in the study of how information is transferred and integrated in the brain (Hebert et al., 2005).

 

Clifford Carter G. (1987). Coherence and time delay estimation. Proceedings of the IEEE 75, 236–255.

Lachaux, J. P., Rodriguez, E., Martinerie, J., & Varela, F. J. (1999). Measuring phase synchrony in brain signals. Human brain mapping, 8(4), 194-208. https://doi.org/10.1002/(SICI)1097-0193(1999)8:4%3C194::AID-HBM4%3E3.0.CO;2-C

Bhattacharya, J., & Petsche, H. (2005). Phase synchrony analysis of EEG during music perception reveals changes in functional connectivity due to musical expertise. Signal Processing, 85(11), 2161-2177. https://doi.org/10.1016/j.sigpro.2005.07.007.

Hebert, R., Lehmann, D., Tan, G., Travis, F., & Arenander, A. (2005). Enhanced EEG alpha time-domain phase synchrony during Transcendental Meditation: Implications for cortical integration theory. Signal Processing, 85(11), 2213-2232. https://doi.org/10.1016/j.sigpro.2005.07.009

 

2. There exist many issues of grammar, spelling, and styles in the paper. Please carefully correct them.

We have had the work checked by an English language professional in order to improve the writing of the article.

 

Reviewer 2 Report

The manuscript “Power spectrum and connectivity analysis in EEG recording during attention and creativity performance in children” by Mateos et al. investigates EEG power spectrum and connectivity in children during creative performance. I find the paper very interesting, these are my comments.

-my main concern is the lack of an ethics paragraph, stating that the investigation was reviewed by an ethics comittee. This should be clarified

- I suggest improving the writing. Sometimes phrases are hard to understand and some words are non existent in english (i.e. disconnectivity).
- figure legends are not clear. For instance fig 1 has 5 panels that should be described in detail. 

- I would clarify how the threshold to consider a connection as significative. The authors cite two papers but methods should be clear in the methodological section. 
- A reference for left/right is missing in the topoplots.

Comments for author File: Comments.docx

Author Response

Dear Reviewer 

                                We would like to thank you for your contributions to this work, which have been of great help in improving it. The following we answer all the points raised by the reviewer.

1-My main concern is the lack of an ethics paragraph, stating that the investigation was reviewed by an ethics comittee. This should be clarified.

All the information about ethics research is:

Ethic Committee Name: Comité de Ética en Investigación de la Facultad de Ciencias de la Salud (FCS) de la Universidad Adventista del Plata (UAP)

Approval Code: 5.7/2019

Approval Date: 2019

This information was added in section 2.1.

 

2- I suggest improving the writing. Sometimes phrases are hard to understand and some words are non existent in english (i.e. disconnectivity).

We have had the work checked by an English language professional in order to improve the article writing.

Just to point out, the word disconnectivity has been used in many scientific papers as we show next

Begré, S., & König, T. (2008). Cerebral disconnectivity: an early event in schizophrenia. The Neuroscientist, 14(1), 19-45.

Rolls, E. T., Cheng, W., Gilson, M., Gong, W., Deco, G., Lo, C. Y. Z., ... & Feng, J. (2020). Beyond the disconnectivity hypothesis of schizophrenia. Cerebral Cortex, 30(3), 1213-1233.

Liang, M., Zhou, Y., Jiang, T., Liu, Z., Tian, L., Liu, H., & Hao, Y. (2006). Widespread functional disconnectivity in schizophrenia with resting-state functional magnetic resonance imaging. Neuroreport, 17(2), 209-213.

 

3- Figure legends are not clear. For instance fig 1 has 5 panels that should be described in detail.

Figure 1 was explained in depth with reference to each of its component panels.

 

4- I would clarify how the threshold to consider a connection as significative. The authors cite two papers but methods should be clear in the methodological section.

In the paragraph of section 2.7 (line 249 ) , we explain how we define the threshold.

 

5- A reference for left/right is missing in the topoplots.

The references were added to all the figures.

Round 2

Reviewer 2 Report

all concerns have been responded