Chromatic Induction in Migraine

Round 1

Reviewer 1 Report

This study investigated the effect of migraine on visual information processing using the powerful color-induced illusion discovered by Monnier & Shevell. The color-induced illusion used here is the synergy of color assimilation and color contrast. In the neurophysiological aspect, it is presumed to be caused by excitatory and inhibitory synaptic connections. Therefore, patients with migraine, who are thought to have abnormal synaptic connections, may perform different neural processing and consequently see the illusion differently. As in their previous psychophysical experiments, the authors investigated the differences between the subject groups with appropriate experimental design and statistical analysis. The results showed that the migraine group caused a more pronounced illusion effect. There are no major problems with the research, but the value of this study would be enhanced by providing some details that the reader may want to know.

This study is a case study. In the case study, as the authors mentioned in the discussion, the degree, frequency, and phase of symptoms vary from individual to individual even in the migraine group. The type of aura should be classified according to their internal description of aura. The experimental results only show the average of the group and not the data of individuals. The results for each individual should be displayed. The data sharing in the Sample availability is very useful but unfriendly. It should be shown in the main figure as the result of the analysis by the authors.

Minor points
L120: 3 i 5 -> 3 & 5

L154: in [53]. -> in R [53].
 
L239: Moreover, Condition 2 causes a stronger assimilation in the s axis than Condition 4.
This sounds opposite to the data in Fig. 3.

 

Author Response

Please, see the attatchment

Author Response File: Author Response.docx

Reviewer 2 Report

This study dealt with the chromatic induction, which is thought to be driven by lateral interactions. This means that the activity of a central neuron is modified by stimuli outside its classical receptive field through excitatory-inhibitory mechanisms. The authors tested 2 hypotheses in this research work. They compared chromatic induction in migraine and non-migraine groups to see if these are different in response to the chromatic induction. They found a difference in the strength of induction between the two groups, with stronger induction effects in migraine group. They also tested if a difference existed between migraine with aura compared with migraine without aura. No difference was found in here. Collectively, findings from this study demonstrate that an increased induction effect is present in individuals with migraine compared with non-migraineurs that can support the theory of excitation/inhibition imbalance in migraine. This study provides novel and interesting data, but as the authors have also indicated, the study is not free from limitations. Future studies are required to confirm if the presented data are reproducible. There are a number of points that authors are encouraged to clarify:

Page 2, lines 38-40: please add the classification of ICH as a reference. ICHD-3 is now available in digital format: https://ihs-headache.org/wp-content/uploads/2020/05/ICHD-3-Pocket-version.pdf

Page 3, participants: Please add into the demographic of the participants, age and gender. It is read now that total of 23 subjects took part in the experiment: 8 had migraine with aura (MA), 8 migraine without aura (MO) and 7 were control subjects with no migraine. Are those control subjects matched in terms of age and sex with the patient group? This is because it is important to know if chromatic induction effect is varying with age and sex as these factors also influence migraine clinical features.

The authors have mentioned that they have tested the color vision of the participants as inclusion criteria to be normal. What other factors were considered as inclusion-exclusion criteria. Please clarify if the eyesight can influence this phenomenon or not, for example being short sighted.

Does the result mean that increased induction effect in individuals with migraine supports that excitation is higher than inhibition? Or is that a susceptibility? This is important to know as migraine is a cyclic disorder and migraine patients go through phases and outside the attack phase most of the patients function normally. The tests here have been done outside the attack and hence it is assumed that based on the findings here the migraine patients are in state of hyper excitability reflected on the increased induction effect. Is that a correct assumption?

Please add how these data can be used in the clinic? For prognosis? Diagnosis or response to treatment?

Author Response

Please see the attachment.

Author Response File: Author Response.docx