Respiration, heartbeat, and conscious tactile perception

Abstract

Cardiac activity has been shown to interact with conscious tactile perception: Detecting near-threshold tactile stimuli is more likely during diastole than systole and heart slowing is more pronounced for detected compared to undetected stimuli. Here, we investigated how cardiac cycle effects on conscious tactile perception relate to respiration given the natural coupling of these two dominant body rhythms. Forty-one healthy participants had to report conscious perception of weak electrical pulses applied to the left index finger (yes/no) and confidence about their yes/no-decision (unconfident/confident) while electrocardiography (ECG), respiratory activity (chest circumference), and finger pulse oximetry were recorded. We confirmed the previous findings of higher tactile detection rate during diastole and unimodal distribution of hits in diastole, more specifically, we found this only when participants were confident about their detection decision. Lowest tactile detection rate occurred 250-300 ms after the R-peak corresponding to pulse-wave onsets in the finger. Inspiration was locked to tactile stimulation, and this was more consistent in hits than misses. Respiratory cycles accompanying misses were longer as compared to hits and correct rejections. Cardiac cycle effects on conscious tactile perception interact with decision confidence and coincide with pulse-wave arrival, which suggests the involvement of higher cognitive processing in this phenomenon possibly related to predictive coding. The more consistent phase-locking of inspiration with stimulus onsets for hits than misses is in line with previous reports of phase-locked inspiration to cognitive task onsets which were interpreted as tuning the sensory system for incoming information.

What Might Interoceptive Inference Reveal about Consciousness?

“…The theory thus proposes that, when estimating our own future reliability or precision, agents intrinsically sample from and predict their own visceral rhythms. Conversely, on shorter timescales, agents can optimize the 'signal-to-noise' ratio of ongoing sensorimotor dynamics through ballistic alterations of those same visceral rhythms [132,133]. A simple example here is that of the trained sharpshooter, who modulates their breathing in order to align the timing of a trigger pull with the quiescent period.…”

What might interoceptive inference reveal about consciousness?

“…The theory thus proposes that, when estimating our own future reliability or precision, agents intrinsically sample from and predict their own visceral rhythms. Conversely, on shorter timescales, agents can optimize the 'signal-to-noise' ratio of ongoing sensorimotor dynamics through ballistic alterations of those same visceral rhythms [129,130]. A simple example here is that of the trained sharpshooter, who modulates their breathing in order to align the timing of a trigger pull with the quiescent period.…”

“The great mixing machine”: multisensory integration and brain-breath coupling in the cerebral cortex

“…The influence of respiration on neuronal rhythms in brain areas involved in cognitive and affective functions suggest that the act of breathing could influence cognition and emotion at a behavioral level. This has now been confirmed in several studies showing that cognitive and affective functions are significantly modulated by respiration [3,26,31,37,39,56] (for recent reviews see: [27,28,48]). How respiration drives this seemingly brainwide rhythm is not fully understood.…”