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Decreased motor cortex excitability mirrors own hand disembodiment during the rubber hand illusion

  1. Francesco della Gatta
  2. Francesca Garbarini  Is a corresponding author
  3. Guglielmo Puglisi
  4. Antonella Leonetti
  5. Annamaria Berti
  6. Paola Borroni
  1. University of Milan, Italy
  2. University of Milan Medical School, Italy
  3. University of Turin, Italy
Short Report
Cite this article as: eLife 2016;5:e14972 doi: 10.7554/eLife.14972
3 figures and 1 additional file

Figures

Experimental setup.

The white square indicates the opening in the experimental wooden box through which the rubber hand is visible to the subject. Subjects could see only the rubber hand being stroked by the experimenter’s right hand. In A, main experiment, MEPs were acquired from the stimulated (right) hand’s FDI muscle; in B, control experiment, MEPs were acquired from non-stimulated (left) hand’s FDI muscle. In C, timeline of the study and experimental conditions are plotted.

https://doi.org/10.7554/eLife.14972.003
Behavioral results following asynchronous and synchronous condition.

The average values for proprioceptive drift and emb-q-rating are plotted in A1 and A2, respectively, for the main experiment, and in B1 and B2, respectively, for the control experiments. In B3 are reported average values for disemb-q-rating. Error bars indicate 95% CI. Significant levels: *p<0.05; ***p<0.0001. Linear regressions between emb-q rating and disemb-q-rating in both syncronous and asyncronous conditions and in the delta syncronous minus asyncronous are plotted in C1, C2, C3, respectively. All subjects behavioural data are available in the additional source data file (see Figure 2—source data 1 and 2).

https://doi.org/10.7554/eLife.14972.004
Figure 2—source data 1

Main experiment behavioral results following asynchronous and synchronous condition.

(A) MAIN EXPERIMENT. For each subject, the proprioceptive drift (estimation of right index finger felt position) mean values, calculated as the difference between pre and post stimulation in synchronous (mean ± sd = 4.51 ± 4.2) and asynchronous (mean ± sd = 2.08 ± 2.75), are reported. (B) MAIN EXPERIMENT. For each subject, the mean rating value of the three ownership statements in synchronous (mean ± sd = 2.4 ± 0.64) and asynchronous (mean ± sd = -2.04 ± 0.9) are reported.

https://doi.org/10.7554/eLife.14972.005
Figure 2—source data 2

Control experiment behavioral results following asynchronous and synchronous condition.

(A) CONTROL EXPERIMENT. For each subject, the proprioceptive drift (estimation of right index finger felt position) mean values, calculated as the difference between pre and post stimulation in synchronous (mean ± sd = 2.47 ± 2.707) and asynchronous (mean ± sd = 0.075 ± 2.461), are reported. (B) CONTROL EXPERIMENT. For each subject, the mean rating value of the three ownership statements in synchronous (mean ± sd = 2 ± 0.763) and asynchronous (mean ± sd = -0.97 ± 1.387) are reported. (C) CONTROL EXPERIMENT. For each subject, the mean rating value of the three disownership statements in synchronous (mean ± sd = 0.153 ± 1.427) and asynchronous (mean ± sd = -1.15 ± 1.371) are reported.

https://doi.org/10.7554/eLife.14972.006
Physiological results for the baseline, asynchronous and synchronous conditions.

Average MEP amplitude variation in the FDI muscle recorded across all subjects are plotted in A1, for the main experiment, and in B1 for the control experiments. Histograms represent the peak-to-peak MEP mean amplitude (normalized) ± 95% CI in the baseline, asynchronous and synchronous conditions, respectively. Significant levels: **p<0.005; ***p<0.0001. Average MEP amplitude profile recorded across all subjects in the synchronous condition areplotted in A2 for the main experiment and in B2 for the control experiment; points represent the peak-to-peak MEP mean amplitude (normalized), ± 95% CI, at four time-points after induction of the illusion (90 s, 180 s, 270 s 360 s); significance level: **p<0.005. Examples of average raw MEPs recorded from two representative subjects (for the main and control experiments) in the baseline (main: 609 µVolt; control: 619 µVolt), asynchronous (main: 771 µVolt; control: 601 µVolt) and synchronous (main:150 µVolt; control:583 µVolt) conditions. All subjects' physiological data are available in an additional source data file (see Figure 3—source data 1 and 2).

https://doi.org/10.7554/eLife.14972.007
Figure 3—source data 1

Main experiment physiological results during baseline, asynchronous and synchronous condition.

(A) MAIN EXPERIMENT. For each subject, the mean MEPs amplitude (row values in µV), recorded during baseline (mean ± sd = 945.204 ± 535.076), asynchronous condition (mean ± sd = 918.075 ± 635.777) and synchronous condition (mean ± sd = 527.328 ± 325.998), are reported. (B) MAIN EXPERIMENT. For each subject, the mean MEPs amplitude (normalized z-scores), recorded during baseline (mean ± sd = 0.277 ± 0.691), asynchronous condition (mean ± sd = 0.205 ± 0.395) and synchronous condition (mean ± sd = -0.367 ± 0.362), are reported. In the z-scores computation, the mean and the sd of the three conditions were used to normalized row data according to the formula x-mean/sd. (C) MAIN EXPERIMENT. For each subject, mean amplitude of 5 MEPs (normalized z-scores) at four time-point recorded during synchronous condition are reported (respectively mean ± sd of TIME 1, 2, 3, 4: -0.239 ± 0.425, -0.284 ± 0.620, -0.389 ± 0.385, -0.548 ± 0.394).

https://doi.org/10.7554/eLife.14972.008
Figure 3—source data 2

Control experiment physiological results during baseline, asynchronous and synchronous condition.

(A) CONTROL EXPERIMENT. For each subject, the mean MEPs amplitude (row values in µV), recorded during baseline (mean ± sd = 725.665 ± 365.104), asynchronous condition (mean ± sd = 734.398 ± 416.262) and synchronous condition (mean ± sd = 685.368 ± 469.286), are reported. (B) CONTROL EXPERIMENT. For each subject, the mean MEPs amplitude (normalized z-scores), recorded during baseline (mean ± sd = 0.057 ± 0.368), asynchronous condition (mean ± sd = 0.045 ± 0.262) and synchronous condition (mean ± sd = -0.104 ± 0.399), are reported. In the z-scores computation, the mean and the sd of the three conditions were used to normalized row data according to the formula x-mean/sd. (C) CONTROL EXPERIMENT. For each subject, mean amplitude of 5 MEPs (normalized z-scores) at four time-point recorded during synchronous condition are reported (respectively mean ± sd of TIME 1, 2, 3, 4: −0.092 ± 0.483, −0.224 ± 0.435, −0.093 ± 0.656, −0.009 ± 0.587).

https://doi.org/10.7554/eLife.14972.009

Additional files

Supplementary file 1

Supplementary Materials.

https://doi.org/10.7554/eLife.14972.010

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