Erratum to: Testing the potential of a virtual reality neurorehabilitation system during performance of observation, imagery and imitation of motor actions recorded by wireless functional near-infrared spectroscopy (fNIRS)
verfasst von:
Lisa Holper, Thomas Muehlemann, Felix Scholkmann, Kynan Eng, Daniel Kiper, Martin Wolf
Following publication of our article [1], we realised that some of the statistical tests used were not appropriate. We have now conducted the appropriate statistical tests, and updated the relevant tables, figures five and six (Figures 1 and 2 here, respectively) and conclusions accordingly.
Figure 1
Unilateral group recorded over contralateral hemisphere: shown are the Δ[O2Hb] amplitude changes with standard error of the mean (SEM) and statistical significances of repeated measures ANOVA.
Figure 2
Bilateral group recorded over contra- (dark gray) and ipsilateral (light gray) hemisphere: shown are the Δ[O2Hb] amplitude changes with standard error of the mean (SEM) and statistical significances of repeated measures ANOVA.
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For both the unilateral and the bilateral groups, analyses were recalculated.
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Intra-condition differences:
original publication [1]: paired t-test using means per trial for unilateral and bilateral group
update: one-way repeated measures ANOVA using means per subject for unilateral and bilateral group
Inter-condition differences:
original publication [1]: one-way ANOVA using means per trial for unilateral and bilateral group
update: one-way repeated measures ANOVA using means per subject for unilateral and bilateral group
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Conclusions
For the unilateral group (Table 1 and Figure 1), no changes in significance levels were found in Δ[O2Hb] signals. For the bilateral group (Table 2 and Figure 2), the main differences compared to the original publication are that the intra-condition differences ([O2Hb]rest versus [O2Hb]stim) for the two conditions ‘Observation Right’ (O_R, p = 0.077) and ‘Observation Left’ (O_L, p = 0.080) recorded over the ipsilateral hemisphere do not reach significant level any more. Hence, the paragraphs discussing the intra-condition significances in those two conditions (sections Observation, imagery and imitation and Bilateral oxygenation of the Discussion) are only applicable for the contralateral hemisphere. Further, in both groups changes in significance levels were found for Δ[HHb]. However, since the Discussion and Conclusion of the originally published article only focuses on the concentration changes found in Δ[O2Hb], this aspect does not change these sections.
(Top) Mean signal amplitudes (μmol/l ± SD) of channels with significant concentration changes. Separate calculations for increases in [O2Hb], decreases in [HHb] in response to the four conditions for each group. Numbers were rounded to four decimal places. (Middle) Intra-condition statistical significance of the mean changes between [O2Hb]rest and [O2Hb]stim and [HHb]rest and [HHb]stim repeated measures ANOVA. (Bottom) Inter-condition statistical significance of mean changes of ∆ [O2Hb] and ∆ [HHb] between the four conditions using repeated measures ANOVA. Shown are post-hoc tests (with Bonferroni correction); significant values (p ≤ 0.05) are highlighted by * (observation = O, motor imagery = MI, observation & motor imagery = O & MI, imitation = IM).
(Top) Mean signal amplitudes (μmol/l ± SD) of channels with significant concentration changes. Separate calculations for increases in [O2Hb], decreases in [HHb] in response to the four conditions for each group. Numbers were rounded to four decimal places. (Middle) Intra-condition statistical significance of the mean change between [O2Hb]rest and [O2Hb]stim and [HHb]rest and [HHb]stim using repeated measures ANOVA. (Bottom) Inter-condition statistical significance of mean changes of ∆ [O2Hb] and ∆ [HHb] between the four conditions using repeated measures ANOVA. Shown are post-hoc tests (with Bonferroni correction); significant values (p ≤ 0.05) are highlighted by * (observation left = O_L, observation right = O_R, imitation left = IM_L, imitation right = IM_R).
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Erratum to: Testing the potential of a virtual reality neurorehabilitation system during performance of observation, imagery and imitation of motor actions recorded by wireless functional near-infrared spectroscopy (fNIRS)
verfasst von
Lisa Holper Thomas Muehlemann Felix Scholkmann Kynan Eng Daniel Kiper Martin Wolf
