Supplementary Materialfor

Focus of attention modulates the heartbeat evoked potential

Frederike H. Petzschner*1, Lilian A. Weber*1, Katharina V. Wellstein1, Gina Paolini1, Cao Tri Do1, Klaas E. Stephan1,2,3

1Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Switzerland; 2Wellcome Centre for Human Neuroimaging, University

College London, London, UK; 3 Max Planck Institute for Metabolism Research, Cologne, Germany

*joint first authorship

Overview

HEP analysis with 0.5 Hz highpass filter and TOI of 200 – 580ms cluster level HEP analysis with 0.3 Hz highpass filter and TOI of 200 – 652ms peak level FWE

HEP analysis with 0.5 Hz high-pass filter and TOI of 200 – 580ms

As mentioned in the main text recent work suggested that higher cutoff frequencies might cause artefacts in the ERP analysis 1,2. As per recommendation of one of the reviewers we therefore lowered the cutoff frequency to 0.3 Hz in the main paper. For comparison and transparency, here we show the original analysis with the previously used cutoff of frequency of 0.5 Hz and a time-of-interest (TOI) between 200 – 580 ms, as reported in our preprint 3. The topography and time of the effect are very similar to the results in the main paper albeit the overall effect and extension of the main cluster are smaller. (see Supplementary Table 1 and Supplementary Figure 1).

Supplementary Table 1: Test statistics for the effect of attention in the contrast HEART > SOUND on EEG amplitude for a high-pass filter of 0.5Hz and a TOI of 200 - 580 ms

Activation size

(voxels)

Cluster

p-value

(FWEcorr)

Peak

p-value

(FWEcorr)

Peak

T statistic

Peak

Z statistic

Peak coordinates (in

mm)

Peak latency

(ms)

Sign. time

window (ms)

1988 0.009* 0.049* 4.92 3.86 x = 34, y = -36 576 520 - 580

Significant whole brain FWE-corrected p-values at p<0.05 at the cluster-level are indicted by an asterisk. Latencies are provided with respect to the R peak onset

Supplementary Figure 1: Center: Space x time statistical parametric maps depicting the t-test for HEART

>SOUND. Black contour depicts the area of significant activation (whole brain FWE corrected at p < 0.05 at

the cluster-level, with a cluster-defining threshold of p<0.001). The blue line indicates location of peak

activation at 576ms. The gray bar to the right shows the temporal window of interest (TOI: 200 - 580 ms after R

peak) and the yellow area depicts time of significant activation (520 – 580 ms after R peak). Left: average HEP

amplitude over time in the area of significant activation indicated by the black contour in the center plot. Again,

the gray rectangle indicates the TOI, the yellow rectangle marks the time window of significant activation. Time

is indicated with respect to the timing of the R peak. Right: Scalp map of the T-statistic of the contrast HEART

>SOUND at time of the peak effect (576ms). The HEP difference is lateralized (right side) and in central to

posterior electrodes.

HEP analysis with 0.3 Hz high-pass filter and TOI of 200 – 652ms

In addition to the cluster-level FWE corrected main effects in the paper, here we provide a complementary perspective that examines significance with regard to activation amplitude and show the same results as in the main text under family-wise error correction at the peak level. This is done to illustrate the sensors of strongest effects more clearly and to visualize the extent of the strongest sub-cluster (see Supplementary Table 2 and Supplementary Figure 2). Again, the main cluster seems to be centered around central electrodes and around 548 ms after R.

Supplementary Table 2: Test statistics for the effect of attention in the contrast HEART > SOUND on EEG amplitude for a high-pass filter of 0.5Hz and a TOI of 200 - 580 ms

Activation size

(voxels)

Cluster

p-value

(FWEcorr)

Peak

p-value

(FWEcorr)

Peak

T statistic

Peak

Z statistic

Peak coordinates (in

mm)

Peak latency

(ms)

Sign. time

window (ms)

499 0.002* 0.002* 6.97 4.79 x = 17, y = -14 548 540 - 556

Significant whole brain FWE-corrected p-values at p<0.05 at the peak-level are indicted by an asterisk. Latencies are provided with respect to the R peak onset

Supplementary Figure 2: Center: Space x time statistical parametric maps depicting the t-test for HEART

>SOUND. Black contour depicts the area of significant activation (whole brain FWE corrected at p < 0.05 at

the cluster-level, with a cluster-defining threshold of p<0.001). The blue line indicates location of peak

activation at 548ms. The gray bar to the right shows the temporal window of interest (TOI: 200 - 620 ms after R

peak) and the yellow area depicts time of significant activation (540 – 556 ms after R peak). Left: average HEP

amplitude over time in the area of significant activation indicated by the black contour in the center plot. Again,

the gray rectangle indicates the TOI, the yellow rectangle marks the time window of significant activation. Time

is indicated with respect to the timing of the R peak. Right: Scalp map of the T-statistic of the contrast HEART

>SOUND at time of the peak effect (548ms). The HEP difference is lateralized (right side) and in central to

posterior electrodes.

References

1. Widmann, A., Schröger, E. & Maess, B. Digital filter design for electrophysiological data - a practical approach. J. Neurosci. Methods 250, 34–46 (2015).

2. Tanner, D., Morgan-Short, K. & Luck, S. J. How inappropriate high-pass filters can produce artifactual effects and incorrect conclusions in ERP studies of language and cognition. Psychophysiology 52, 997–1009 (2015).

3. Petzschner, F. H. et al. Focus of attention modulates the heartbeat evoked potential. bioRxiv 384305 (2018).