Neural activity related to volitional regulation of cortical excitability
- Kathy Ruddy
- Joshua Balsters
- Dante Mantini
- Quanying Liu
- Pegah Kassraian-Fard
- Nadja Enz
- Ernest Mihelj
- Bankim Subhash Chander
- Surjo R Soekadar
- Nicole Wenderoth
- ETH Zürich, Switzerland
- Trinity College Dublin, Ireland
- University of London, United Kingdom
- KU Leuven, Belgium
- University of Tübingen, Germany
- Charité – University Medicine Berlin, Germany
Figures
Figure 1 with 1 supplement
Outline of experimental setup.
Each trial of neurofeedback training commenced with a display of four circles (A) each representing the background EMG in one of the recorded hand muscles (right FDI, ADM and OP, and left FDI). The …
Figure 1—figure supplement 1
Power analysis to compute sample size.
Conducted using G*Power software version 3.1, based on the inclusion of two groups, an alpha value of 0.05, and an effect size of 0.81 (Cohen’s d reported by Majid et al., 2015) in a study training …
Figure 2 with 4 supplements
MEP amplitudes during neurofeedback.
Panel (A) depicts MEP amplitude in millivolts during the two types of MEP neurofeedback. UP training is shown in orange and DOWN training in blue, across all 10 training blocks. Unfilled triangles …
Figure 2—figure supplement 1
Percentage change in MEP amplitude.
Panel (A) shows the % change from baseline at each block for the experimental group (ie. 0 represents no change in MEP amplitude from baseline). Stars indicate blocks in which the % change deviated …
Figure 2—figure supplement 2
MEP amplitudes during neurofeedback for all participants.
Panel A and B in this figure are analogous to Figure 2 in the main manuscript, but here all individual participant datapoints are plotted as dots in line with their means (triangles). Panel A shows …
Figure 2—figure supplement 3
Individual representative subjects’ performance across trials.
Change in MEP amplitude from baseline is shown (in mV) for one representative subject from the experimental group (panel A) and control group (panel B) for each neurofeedback training block in each …
Figure 2—figure supplement 4
Scatterplots showing individual MEP data trials across learning.
Panels (A) and (B) show MEP amplitudes from individual trials from the UP and DOWN conditions respectively, from a representative subject (same as Figure 2—figure supplement 3) in the experimental …
Figure 3
Retention, aftereffects and feedback-free measurements.
Filled bars represent blocks of neurofeedback, and unfilled bars represent MEPs collected at rest. Shown are MEP amplitudes with their preceding resting baseline values subtracted. Values above 0 …
Figure 4
Investigation into mechanisms of MEP neurofeedback.
The data show paired pulse TMS measurements taken during neurofeedback blocks to probe distinct neurophysiological processes. In all subsequent panels, unfilled bars represent baseline MEP …
Figure 5 with 4 supplements
Neural oscillations associated with the trained brain states.
Panels (b-f) show topographical representations of the relative power (in % of whole spectrum) in the UP condition minus the DOWN condition, for five distinct frequency bands (averaged group data, n …
Figure 5—figure supplement 1
Boxplots showing relative power in the Up condition minus the Down condition for the electrode corresponding to the hotspot in the opposite (non-feedback) hemisphere.
https://doi.org/10.7554/eLife.40843.012
Figure 5—figure supplement 2
Non-significant frequency band topographies.
This figure shows the remaining frequency bands not shown in Figure 4. Variations in the power of Delta, Low Beta and High Beta were not significant predictors of MEP amplitude. The blue-red range …
Figure 5—figure supplement 3
Regression plots of MEP amplitude with relative power for one representative subject.
Panels (a-d) show scatterplots with lines of best fit for the regression performed on MEP amplitudes with relative power in each frequency band (only those with significant associations are …
Figure 5—figure supplement 4
Control group EEG data.
Data shown are relative power values in the UP-DOWN states, extracted for each participant’s hotspot electrode. Values greater than 0 indicate larger amplitude oscillations in the UP condition, and …
Additional files
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Supplementary file 1
Supplementary Table 1: Results of linear classifier distinguishing between UP and DOWN states based on EEG power.
Also shown are accuracies of ‘null models’ with random label permutation performed on the same data, along with statistical comparison across subjects of true accuracies vs randomly permuted accuracies (Wilcoxon signed rank tests).
Supplementary Table 2: F tests following mixed effects models comparing background EMG across conditions and blocks. Shown is feedback type (UP,DOWN) by block number interactions on each session.
Supplementary Table 3: Percentage of EMG trials retained. Shown is the percentage (of total number of collected MEP trials) that were retained per block and per session for analysis following post-processing screening of background EMG amplitude.
Supplementary Table 4: Results of mixed effects models on the percentage of retained background EMG trials during neurofeedback. The dependant variable was the percentage of trials that were retained following screening for background EMG crossing the criterion threshold. Four models were performed; One on data during all neurofeedback trials (10 levels of ‘trial’) modelling changes over the duration of training (across trials) that were modulated by trial type (UP or DOWN), demonstrating no systematic effects of MEP amplitude modulation on the quantity of trials that were retained for analysis. The three remaining models were conducted separately on the data from Session 1, Session two and Session 3, again revealing no significant modulation on any session. Mixed models employed a compound symmetry covariance matrix, fixed effects of ‘trial’ and ‘trial type’, and random effect of ‘participant’.
Supplementary Table 5: F tests following mixed effects models comparing background EMG across conditions and blocks for the retention test conducted months following initial training. Shown is feedback type (UP, DOWN) by block number two levels, baseline + retention) interactions for each of the four recorded muscles.
Supplementary Table 6: In debriefing following the experiment, all participants were asked to write down their final strategies for the UP and DOWN conditions, in their own words.
Supplementary Table 7: Outline of experimental timeline for each day of testing. Each block of data collection is shown in a separate cell, with the beginning of testing indicated by red vertical lines. Each row depicts testing carried out on separate days unless indicated otherwise (Session 3). Blocks in which MEP neurofeedback was conducted are shaded in grey. All other measurements were taken at rest. Sessions 1 and 2 (blocks 1-8) were considered as ‘training’, as auditory and small financial rewards were presented during feedback. All subsequent blocks of neurofeedback (Session three onwards) were conducted post-training, without financial rewards. Auditory feedback was removed only for the EEG session, to avoid auditory-evoked potentials. The order of UP and DOWN feedback session types was counterbalanced across participants for all sessions. Assessment of resting motor threshold (RMT) was carried out at the beginning of every day of testing. A recruitment curve measurement was performed only at the beginning of the first day in order to establish TMS intensity (as a % of RMT) that evoked MEPs of an amplitude that was 50% of the individual’s maximum before plateau. This % of RMT was used on every subsequent session to elicit MEPs during neurofeedback and for resting blocks.
- https://doi.org/10.7554/eLife.40843.016
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Transparent reporting form
- https://doi.org/10.7554/eLife.40843.017
