THE ROLE OF BODY-BRAIN INTERACTIONS IN VISUAL AND SOMATOSENSORY PERCEPTION

The brain constantly communicates with the rest of the body, and the cardiorespiratory state modulates our ability to perceive the external world. However, previous studies find a more consistent decrease in perceptual performance during cardiac systole (vs. diastole) in the somatosensory than the visual modality. Preferred respiratory phases at stimulus onset, and pre-stimulus heartbeat-evoked potentials (HEP) also show inconsistent correlations with perceptual performance across studies in these modalities. Our within-subjects study aims to investigate the role of cardiorespiratory signals in visual and somatosensory perception. So far, we recorded EEG, ECG, and respiration signals from non-clinical young adults (N=27*, age: 18-35) during threshold-level visual and somatosensory stimulus detection tasks, with each 300 trials (20% stimulus-absent) split into six modality-interleaved blocks (Figure A). In each trial, participants were presented with a near-threshold (50% detection) stimulus and they gave binary responses for detection (Y:yes / N:no) and confidence (C:confident, U:unconfident). Cardiac phase effect was observed only in the somatosensory modality, with decreased stimulus detection accuracy (hit rate) during systole versus diastole (Figure B-left). Despite modality-indifferent rates of anticipatory cardiac deceleration, overall heart rate was lower in somatosensory compared to visual blocks (Figure B-right). The difference in heart rate was not accompanied by differences in respiratory period. In conclusion, additional cardiac slowing in the somatosensory domain might have a functional relevance for better perceptual performance by decreasing the frequency of ‘noisy’ heartbeats and prolonging the ‘quiet’ diastole, in line with the baroreceptor hypothesis.
*Our final presentation will include 35 participants and further EEG/HEP analysis.