PT  - JOURNAL ARTICLE
AU  - Grund, Martin
AU  - Al, Esra
AU  - Pabst, Marc
AU  - Dabbagh, Alice
AU  - Stephani, Tilman
AU  - Nierhaus, Till
AU  - Gaebler, Michael
AU  - Villringer, Arno
TI  - Respiration, heartbeat, and conscious tactile perception
AID  - 10.1101/2021.03.22.436396
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.03.22.436396
4099  - http://biorxiv.org/content/early/2021/09/12/2021.03.22.436396.short
4100  - http://biorxiv.org/content/early/2021/09/12/2021.03.22.436396.full
AB  - Previous studies have shown that timing of sensory stimulation during the cardiac cycle interacts with perception. Given the natural coupling of respiration and cardiac activity, we investigated here their joint effects on tactile perception. Forty-one healthy participants reported conscious perception of finger near-threshold electrical pulses (33% null trials) and decision confidence while electrocardiography, respiratory activity, and finger photoplethysmography were recorded. Participants adapted their respiratory cycle to expected stimulus onsets to preferentially occur during late inspiration / early expiration. This closely matched heart rate variation (sinus arrhythmia) across the respiratory cycle such that most frequent stimulation onsets occurred during the period of highest heart rate probably indicating highest alertness and cortical excitability. Tactile detection rate was highest during the first quadrant after expiration onset. Inter-individually, stronger respiratory phase-locking to the task was associated with higher detection rates. Regarding the cardiac cycle, we confirmed previous findings that tactile detection rate was higher during diastole than systole and newly specified its minimum at 250 - 300 ms after the R-peak corresponding to the pulse wave arrival in the finger. Metacognitive efficiency for yes- responses was also modulated across the cardiac cycle reaching an optimum at the end of diastole. Expectation of stimulation induced a transient heart deceleration which was more pronounced for unconfident decision ratings. Inter-individually, stronger post-stimulus modulations of heart rate were linked to higher detection rates. In summary, we demonstrate how tuning to the respiratory cycle and integration of respiratory-cardiac signals are used to optimize performance of a tactile detection task.Significance statement Mechanistic studies on perception and cognition tend to focus on the brain neglecting contributions of the body. Here, we investigated how respiration and heartbeat influence tactile perception: Respiration phase-locking to expected stimulus onsets corresponds to highest heart rate (and presumably alertness/cortical excitability) and correlates with detection performance. Tactile detection varies across the heart cycle with a minimum 250 - 300 ms after heart contraction, when the pulse reaches the finger. Lower detection was associated with disturbed metacognition, indicating – together with our previous finding of unchanged early ERPs - that this effect is not a peripheral physiological artifact but a result of cognitive processes that model our body’s internal state, make predictions to guide behavior, and might also tune respiration to serve the task.Competing Interest StatementThe authors have declared no competing interest.