Interactions between cardiac activity and conscious somatosensory perception

Paweł Motyka^1,2, Martin Grund², Norman Forschack^2,3, Esra Al^2,4, Arno Villringer^2,4,5, and Michael Gaebler<sup>2,4,6

1</sup>Faculty of Psychology, University of Warsaw, 00-183 Warsaw, Poland
²Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, 04103 Leipzig, Germany
³Department of Psychology, University of Leipzig, 04109 Leipzig, Germany
⁴Berlin School of Mind and Brain, Humboldt-Universität zu Berlin, 10117 Berlin, Germany
⁵Clinic for Cognitive Neurology, University Hospital Leipzig, 04103 Leipzig, Germany
⁶Faculty of Medicine, University of Leipzig, 40103 Leipzig, Germany

Corresponding author: Paweł Motyka, e-mail: pawel.motyka{at}psych.uw.edu.pl

Abstract:

Fluctuations in the heart’s activity can modulate the access of external stimuli to consciousness. The link between perceptual awareness and cardiac signals has been investigated mainly in the visual and auditory domain. We here investigated whether the phase of the cardiac cycle and the pre-stimulus heart rate influence conscious somatosensory perception. We also tested how conscious detection of somatosensory stimuli affects the heart rate. Electrocardiograms (ECG) of 33 healthy volunteers were recorded while applying near-threshold electrical pulses at a fixed intensity to the left index finger. Conscious detection was not uniformly distributed across the cardiac cycle but significantly higher in diastole than in systole. We found no evidence that the heart rate before a stimulus influenced its detection but hits (correctly detected somatosensory stimuli) led to a more pronounced cardiac deceleration than misses. Our findings demonstrate interactions between cardiac activity and conscious somatosensory perception, which highlights the importance of internal bodily states for sensory processing beyond the auditory and visual domain.

Performing data analysis:

The folder "_scripts" contains the codes used for the main and supplementary analyses. If you want to run your own preprocessing (performed in the sections 1-3 of the main code: CCSomato_analysis_main.html), please contact the corresponding author for the raw data. The folder "_dataframes" contains the preprocessed data saved as the outputs from particular sections of the code. This enables starting the analysis of preprocessed data at different sections of the code by reading the relevant data frames using the prepared lines at the beginnings of sections. For example, one could read "CCSomato_ECG_data(output_from_section_3)" at the beginning of section 4 and run the following sections or start directly from the later sections by reading outputs from sections nr 4 or 7. The same procedure holds for supplementary results. The codes along with their outputs and plots can be also viewed by downloading and opening the revelant html files from "_scripts". The folder "_figures" contains the plots from the main and supplementary results.