Absence of a control group might be the main limitation of the study. However, as stated by previous studies, ethical principles are against using a waiting or sham group for our treatment naïve patients. An active control group is suggested instead, but this will not solve the problem here, as the effect of confounding factors will not be distinguished. This is the reason for absence of a control group in several previous studies [35, 39, 40], as well as the present one. Another limitation of this study is that cortical activity during the session was not recorded. This issue is in fact similar to not having a control group because, without within-session data, it is still not clear whether the changes are a result of this specific intervention. However this situation is equal for both groups, and we have compared effect of the two protocols in a similar situation. Adding data obtained after a wash out period might also strengthen the relationship between the intervention and the result.