Ongoing fluctuations of neuronal activity have long been considered intrinsic noise that introduces unavoidable and unwanted variability into neuronal processing, which the brain eliminates by averaging across population activity (Georgopoulos et al., 1986;Lee et al., 1988;Shadlen and Newsome, 1994;Maynard et al., 1999). It is now understood, that the seemingly random fluctuations of cortical activity form highly structured patterns, including oscillations at various frequencies, that modulate evoked neuronal responses (Arieli et al., 1996;Poulet and Petersen, 2008;He, 2013) and affect sensory perception (Linkenkaer-Hansen et al., 2004;Boly et al., 2007;Sadaghiani et al., 2009;Vinnik et al., 2012;Palva et al., 2013). Ongoing cortical activity is driven by proprioceptive and interoceptive inputs. In addition, it is partially intrinsically generated in which case it may be related to mental processes (Fox and Raichle, 2007;Deco et al., 2011). Here we argue that respiration, via multiple sensory pathways, contributes a rhythmic component to ongoing cortical activity. We suggest that this rhythmic activity modulates the temporal organization of cortical neurodynamics, thereby linking higher cortical functions to the process of breathing.

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Breathing as a Fundamental Rhythm of Brain Function

Rhythms of the body, rhythms of the brain: Respiration, neural oscillations, and embodied cognition.

Cardiorespiratory and cardiosomatic psychophysiology

Subjects were instructed to synchronize finger tapping with visual signals of various frequencies. It was found that breathing rate became entrained to tapping rate if the latter fell within a range of two breaths per minute of the subject’s previous breathing rate. Entrainment did not occur when the subject merely monitored the visual stimuli but only during performance of tapping. The effect occurred without subjects’ awareness and was observed only in the absence of deliberate adjustments in respiratory frequency on the part of the subject. Temporal restrictions on the neural events responsible for motor output appear to be responsible for the phenomenon.

/pdf/entrainment-of-respiration-to-repetitive-finger-tapping-49iv72957j.pdf

Entrainment of respiration to repetitive finger tapping

Current approaches to assess interoception of respiratory functions cannot differentiate between the physiological basis of interoception, i.e. visceral-afferent signal processing, and the psychological process of attention focusing. Furthermore, they typically involve invasive procedures, e.g. induction of respiratory occlusions or the inhalation of CO 2 -enriched air. The aim of this study was to test the capacity of startle methodology to reflect respiratory-related afferent signal processing, independent of invasive procedures. Forty-two healthy participants were tested in a spontaneous breathing and in a 0.25 Hz paced breathing condition. Acoustic startle noises of 105 dB(A) intensity (50 ms white noise) were presented with identical trial frequency at peak and on-going inspiration and expiration, based on a new pattern detection method, involving the online processing of the respiratory belt signal. The results show the highest startle magnitudes during on-going expiration compared with any other measurement points during the respiratory cycle, independent of whether breathing was spontaneous or paced. Afferent signals from slow adapting phasic pulmonary stretch receptors may be responsible for this effect. This study is the first to demonstrate startle modulation by respiration. These results offer the potential to apply startle methodology in the non-invasive testing of interoception-related aspects in respiratory psychophysiology. This article is part of the themed issue ‘Interoception beyond homeostasis: affect, cognition and mental health’.

https://royalsocietypublishing.org/doi/pdf/10.1098/rstb.2016.0019

Respiratory modulation of startle eye blink: a new approach to assess afferent signals from the respiratory system.

Previous studies have implicated respiration as a source of intra-S variation in visual signal detection tasks. In the present study, pneumographic respiration records were obtained on 22 female undergraduates during a visual signal detection task. The analysis of signal detection with respect to respiration phase showed that signals presented during exhalation were detected more frequently than those presented during inhalation. These findings suggest that the intra-S variation in signal detection performance may be partially accounted for by respiratory behavior at the moment of signal presentation.

/pdf/respiratory-phase-and-visual-signal-detection-yc7ruo0tha.pdf

Jerry E. Flexman

Papers

Respiratory phase and visual signal detection