Assessing attentional control of breathing by reaction time

The effect of ketamine on delta-range coupling between prefrontal cortex and hippocampus supported by respiratory rhythmic input from the olfactory bulb

Respiratory rhythm plays an important role in cognitive functions in rodents, as well as in humans. Respiratory related oscillation (RRO), generated in the olfactory bulb (OB), is an extrinsic rhythm imposed on brain networks. In rats, RRO can couple with intrinsic brain oscillations at theta frequency during sniffing and in the delta range outside of such episodes. Disruption of gamma synchronization in cortical networks by ketamine is well established whereas its effects on slow rhythms are poorly understood. We found in this study, that RRO in prefrontal cortex (PFC) and hippocampus (HC) remains present after ketamine injection, even on the background of highly unstable respiratory rate, co-incident with "psychotic-like" behavior and abnormal cortical gamma activity. Guided by the timing of ketamine-induced gamma reaction, pairwise coherences between structures exhibiting RRO and their correlation structure was statistically tested in 5-min segments post-injection (0-25 min) and during recovery (1, 5, 10 h). As in control, RRO in the OB was firmly followed by cortical-bound OB exits directed toward PFC but not to HC. RRO between these structures, however, significantly correlated with OB-HC but not with OB-PFC. The only exception to this general observation was observed during a short transitional period, immediately after injection. Ketamine has a remarkable history in psychiatric research. Modeling chronic NMDA-hypofunction using acute NMDA-receptor blockade shifted the primary focus of schizophrenia research to dysfunctional cortical microcircuitry and the recent discovery of ketamine's antidepressant actions extended investigations to neurophysiology of anxiety and depression. Cortical oscillations are relevant for understanding their pathomechanism.

The influence of the respiratory cycle on reaction times in sensory-cognitive paradigms

Behavioural and electrophysiological studies point to an apparent influence of the state of respiration, i.e., whether we inhale or exhale, on brain activity and cognitive performance. Still, the prevalence and relevance of such respiratory-behavioural relations in typical sensory-cognitive tasks remain unclear. We here used a battery of six tasks probing sensory detection, discrimination and short-term memory to address the questions of whether and by how much behaviour covaries with the respiratory cycle. Our results show that participants tend to align their respiratory cycle to the experimental paradigm, in that they tend to inhale around stimulus presentation and exhale when submitting their responses. Furthermore, their reaction times, but not so much their response accuracy, consistently and significantly covary with the respiratory cycle, differing between inhalation and exhalation. This effect is strongest when analysed contingent on the respiratory state around participants' responses. The respective effect sizes of these respiration-behaviour relations are comparable to those seen in other typical experimental manipulations in sensory-cognitive tasks, highlighting the relevance of these effects. Overall, our results support a prominent relation between respiration and sensory-cognitive function and show that sensation is intricately linked to rhythmic bodily or interoceptive functions.

Respiratory modulation of intensity ratings and psychomotor response times to acoustic startle stimuli

Respiratory interoception may play an important role in the perception of respiratory symptoms in pulmonary diseases. As the respiratory cycle affects startle eye blink responses, startle modulation may be used to assess visceral-afferent signals from the respiratory system. To ascertain the potential impact of brainstem-relayed signals on cortical processes, we investigated whether this pre-attentive respiratory modulation of startle (RMS) effect is also reflected in the modulation of higher cognitive, evaluative processing of the startle stimulus. Twenty-nine healthy volunteers received 80 acoustic startle stimuli (100 or 105 dB(A); 50 ms), which were presented at end and mid inspiration and expiration, while performing a paced breathing task (0.25 Hz). Participants first responded to the startle probes by 'as fast as possible' button pushes and then rated the perceived intensity of the stimuli. Psychomotor response time was divided into 'reaction time' (RT; from stimulus onset to home button release; represents stimulus evaluation) and 'movement time' time (MT; from home button release to target button press). Intensity judgments were higher and RTs accelerated during mid expiration. No effect of respiratory cycle phase was found on eye blink responses and MTs. We conclude that respiratory cycle phase affects higher cognitive, attentional processing of startle stimuli.

Respiratory modulation of cognitive performance during the retrieval process

Recent research suggests that cognitive performance might be altered by the respiratory-synchronized activity generated in the brain. Previous human studies, however, have yielded inconsistent results when assessing task performance during distinct respiratory phases (inspiratory phase vs. expiratory phase). We therefore tested whether cognitive performance was regulated based on the timing of breathing components (e.g., expiratory-to-inspiratory (EI) phase transition) during the retrieval process. To determine the role of respiration in performance, the present study employed healthy subjects (n = 18) in a delayed matching-to-sample visual recognition task where a test cue was given in the respiratory phase-locked (Phased) or regularly paced (Non-phased) presentation paradigm. During the Phased session but not during the Non-phased session, the response time (RT) of the task increased by 466 ms (p = 0.003), and accuracy decreased by 21.4% (p = 0.004) when the retrieval process encompassed the EI transition. Breathing-dependent changes were particularly prominent when the EI transition occurred during the middle step of the retrieval process. Meanwhile, changes in the RT and accuracy were not observed when the retrieval process encompassed the inspiratory-to-expiratory phase transition. This is the first time that a certain phase transition in the respiratory cycle has been shown to modulate performance on a time scale of several seconds in a cognitive task. We propose that attenuation of these breathing-dependent cognitive fluctuations might be crucial for the maintenance and stability of successful performance in daily life and sports.

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

In spite of its importance as a life-defining rhythmic movement and its constant rhythmic contraction and relaxation of the body, respiration has not received attention in Embodied Cognition (EC) literature. Our paper aims to show that (1) respiration exerts significant and unexpected influence on cognitive processes, and (2) it does so by modulating neural synchronization that underlies specific cognitive processes. Then, (3) we suggest that the particular example of respiration may function as a model for a general mechanism through which the body influences cognitive functioning. Finally, (4) we work out the implications for EC, draw a parallel to the role of gesture, and argue that respiration sometimes plays a double, pragmatic and epistemic, role, which reduces the cognitive load. In such cases, consistent with EC, the overall cognitive activity includes a loop-like interaction between neural and non-neural elements.

Hippocampal sharp-wave ripples in awake mice are entrained by respiration

Several recent studies have shown that respiration modulates oscillatory neuronal activity in the neocortex and hippocampus on a cycle-by-cycle basis. It was suggested that this respiratory influence on neuronal activity affects cognitive functions, including memory. Sharp-wave ripples (SWRs) are high-frequency local field potential activity patterns characteristic for the hippocampus and implicated in memory consolidation and recall. Here we show that the timing of SWR events is modulated by the respiratory cycle, with a significantly increased probability of SWRs during the early expiration phase. This influence of respiration on SWR occurrence was eliminated when olfactory bulb activity was inhibited. Our findings represent a possible neuronal mechanism for a direct influence of the respiratory cycle on memory function.

Breathing as a Fundamental Rhythm of Brain Function

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 the 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.

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

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 CO₂-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'.

The cerebral cost of breathing: an FMRI case-study in congenital central hypoventilation syndrome

Certain motor activities - like walking or breathing - present the interesting property of proceeding either automatically or under voluntary control. In the case of breathing, brainstem structures located in the medulla are in charge of the automatic mode, whereas cortico-subcortical brain networks - including various frontal lobe areas - subtend the voluntary mode. We speculated that the involvement of cortical activity during voluntary breathing could impact both on the “resting state” pattern of cortical-subcortical connectivity, and on the recruitment of executive functions mediated by the frontal lobe. In order to test this prediction we explored a patient suffering from central congenital hypoventilation syndrome (CCHS), a very rare developmental condition secondary to brainstem dysfunction. Typically, CCHS patients demonstrate efficient cortically-controlled breathing while awake, but require mechanically-assisted ventilation during sleep to overcome the inability of brainstem structures to mediate automatic breathing. We used simultaneous EEG-fMRI recordings to compare patterns of brain activity between these two types of ventilation during wakefulness. As compared with spontaneous breathing (SB), mechanical ventilation (MV) restored the default mode network (DMN) associated with self-consciousness, mind-wandering, creativity and introspection in healthy subjects. SB on the other hand resulted in a specific increase of functional connectivity between brainstem and frontal lobe. Behaviorally, the patient was more efficient in cognitive tasks requiring executive control during MV than during SB, in agreement with her subjective reports in everyday life. Taken together our results provide insight into the cognitive and neural costs of spontaneous breathing in one CCHS patient, and suggest that MV during waking periods may free up frontal lobe resources, and make them available for cognitive recruitment. More generally, this study reveals how the active maintenance of cortical control over a continuous motor activity impacts on brain functioning and cognition.

Reaction time following yoga bellows-type breathing and breath awareness

The reaction time (RT) was assessed in two groups of healthy males, yoga group (M age = 29.0 yr.) and non-yoga or control group (M age = 29.0 yr.), with 35 participants each. The yoga group had an average experience of 6 months, while the control group was yoga-naïve. The yoga group was assessed in two sessions, (i) bhastrika pranayama or bellows breathing and (ii) breath awareness, while the control group had a single control session. The two experimental sessions, one with each type of breathing, and the control session consisted of pre- (5 min.), during (18 min.), and post-session epochs (5 min.). Assessments were made in the pre- and post-session epochs using a Multi-Operational Apparatus for Reaction Time. Following 18 min. of bhastrika pranayama there was a statistically significant reduction in number of anticipatory responses compared to before the practice. This suggests that the immediate effect of bhastrika pranayama is to inhibit unnecessary responding to stimuli.

Learning in respiratory control

In this article, it is argued that learning participates to fulfill the metabolic requirements by adapting respiratory control to changing internal and external states. Recent classical-conditioning experiments in newborn mice or adult rats show the close link between conditioned respiratory and arousal responses. The conditioned fear model may be a suitable and largely unexplored model of emotionally induced hyperventilation. The parabrachial nucleus and periacqueducal grey may play a pivotal role in the ventilatory component of conditioned fear. The sensitivity of breathing to conditioning in newborn and adult animals suggests that learning processes may shape breathing pattern throughout life.

Reaktionskraft inSondierreiz-Aufgaben:

Zusammenfassung. In der Sondierreiz-Aufgabe von Posner und Boies (1971 ) muss mit zwei Fingern einer Hand eine Wahlreaktionsaufgabe (Primäraufgabe) bearbeit werden, während mit der anderen Hand eine Einfachreaktion auf zufällig eingestreute Sondierreize abgegeben wird (Sekundäraufgabe). Die klassische Interpretation, wonach die Reaktionszeit der Sekundäraufgabe ein Index für die Kapazität ist, die die Primäraufgabe zum jeweiligen Zeitpunkt beansprucht, wurde verschiedentlich angezweifelt. Als Alternativen zur Kapazitätsannahme wurden Hemmungsmechanismen und Verzögerung durch einen zentralen Flaschenhalsprozess vorgeschlagen. In einer Replikation des Sondierreiz-Experiments wurde zusätzlich die Reaktionskraft gemessen, um zwischen den drei Erklärungen zu unterscheiden. Auf den Sondierreiz wurde deutlich kräftiger reagiert, wenn er während der Bearbeitung der Primäraufgabe dargeboten wurde. Dieses Ergebnis ist am besten mit der Annahme von aktiver Hemmung ( Neumann, 1987 , 1992), in Verbindung mit einem erweiterten Modell der motorischen Vorbereitung, vereinbar.

Hyperventilation and attention: effects of hypocapnia on performance in a stroop task

This study aimed to investigate the effect of hypocapnia on attentional performance. Hyperventilation, producing hypocapnia, is associated with physiological changes in the brain and with subjective symptoms of dizziness, concentration problems and derealization. In this study (N=42), we examined cognitive performance on a Stroop-like task, following either 3 min of hypocapnic or normocapnic overbreathing. Both overbreathing trials were run on separate days, each preceded by a baseline trial with the same task during normal breathing. More and other symptoms were reported after hypocapnia compared to normocapnia. Also, more errors were made and progressively slower reaction times (RT's) were observed during recovery from hypocapnia. These performance deficits were only found in participants characterized by apneas. The number of symptoms did not correlate with RT's or errors. The pattern of data suggested that hypoxia, as a result of apneas during recovery from hypocapnia, caused the cognitive performance deficit.

Effects of voluntary changes in breathing frequency on respiratory comfort

Previous experiments on voluntary breathing have suggested that spontaneous breathing is partly determined by the minimization of respiratory sensations. However, during instructed breathing, respiratory sensations may be confounded with difficulty in achieving the prescribed pattern. In the present experiment, we tested the hypothesis that the subjective assessment of respiratory comfort and the difficulty in following breathing instructions are closely related. A total of 15 subjects adjusted breathing frequency to prescribed values ranging from 40 to 250% of individual spontaneous levels. Then, they scored the difficulty of this task and the discomfort associated with the target frequency. Difficulty scores sharply increased above 100% (spontaneous level) and discomfort scores displayed a similar shape. A significant positive correlation between discomfort and difficulty was found, thus suggesting a possible influence of the difficulty to follow ventilatory instructions on respiratory sensation scores.

The effects of emotional behaviour on components of the respiratory cycle

The present study was designed to examine affect-related respiratory responses during film scenes, reaction time (RT) and cold pressor (CP) tasks. In addition, I investigated whether affect-related respiratory responses could be characterised by a number of underlying dimensions, such as positive versus negative affect and active versus passive coping. Respiratory output was indexed by a detailed analyses of various volumetric and timing components of the breathing cycle. There were fundamental differences in respiratory responses to different types of affective and cognitively demanding tasks. The emotionally loaded film stimuli showed clear effects on respiration whenever the films elicited amusement and disgust. That is, amusement (laughter) induced a decrease in inspiratory time and tidal volume, whereas disgust could be linked to a prolongation of inspiratory pauses (breath-holding). Relative to a pretask baseline, RT performance elicited a relatively fast, shallow and regular breathing pattern. The pattern of breathing in response to CP was in stark contrast to the RT task, in that a substantial increase in tidal volume, minute ventilation, mean inspiratory flow and breathing irregularity was accompanied by no change in total cycle duration. The implications of these results are discussed with regard to specificity and dimensional models. It is suggested that specificity models might apply to phasic respiratory activity such as breath-holding in disgust and pain. On the other hand, breathing irregularity and expiratory pause duration appears to correspond to emotion dimensions (positive versus negative affect) that cut across the boundaries of emotion categories. Lastly, there were the respiratory patterns that could be more readily interpreted in terms of a task-involvement or active versus passive coping attitude.

The effect of attentional load on the breathing pattern in children

Experiments designed to establish the effects of video games on breathing patterns have led to contradictory results. Several authors reported that video games tended to increase breathing frequency (i.e. to reduce breath duration), whereas others reported the opposite. We postulated that video games contain different psychophysiological components which may have opposite effects on breathing pattern. On the one hand, arousal and emotion may tend to stimulate breathing. On the other, focusing attention on the game may prompt subject to inhibit any movement--including breathing--which might be a potential nuisance variable. The aim of this study was to assess the specific effects of the attentional load in an experimental environment characterized by its low emotional impact. We measured breathing variables, cardiac frequency and cortisol levels in 10 healthy children (mean age = 9.2 +/- 1.5 years) who were familiar with the environment, the experimenter and the video game. Breath duration rose significantly, from 2.56 to 3.16 s, as a function of game difficulty. Cortisol levels, heart rate and the thoracic contribution to breathing displayed no significant changes. Taken together, these data suggest that focusing attention on the game tended to inhibit breathing and that previous contradictory reports in this respect were due to the confounding effects of emotion.

Ventilatory responses to imagined exercise

We studied whether the ventilatory responses to imagined exercise are influenced by automatic processes. Twentynine athletes produced mental images of a sport event with successive focus on the environment, the preparation, and the exercise. Mean breathing frequency increased from 15 to 22 breaths/min. Five participants reported having voluntarily controlled breathing, two of them during preparation. Twenty participants reported that their breathing pattern changed during the experiment: 11 participants were unable to correctly report on the direction of changes in frequency, and 13 incorrectly reported changes in amplitude. This finding suggests that these changes were not voluntary in most participants and may therefore reveal automatic forebrain influences on exercise hyperpnea. However, these changes may also reflect nonspecific processes (e.g., arousal) different from those occurring during actual exercise.

Relation between reaction time and the phase of spontaneous and controlled breathing patterns

In this study simple reaction time (simple RT) to a visual stimulus of a single subject was measured during spontaneous and controlled breathing, in which the duration of expiration was prolonged (Asian technique). The phases of breathing were classified as the pause between expiration and inspiration, the inspiration phase, the transition from inspiration to expiration, and the expiration phase. Analysis of data from about 6000 trials indicated that RT to the stimulus was shortest during the transition from inspiration to expiration in controlled breathing.

Relation between Reaction Time and the Phase of Spontaneous and Controlled Breathing Patterns

In this study simple reaction time (simple RT) to a visual stimulus of a single subject was measured during spontaneous and controlled breathing, in which the duration of expiration was prolonged (Asian technique). The phases of breathing were classified as the pause between expiration and inspiration, the inspiration phase, the transition from inspiration to expiration, and the expiration phase. Analysis of data from about 6000 trials indicated that RT to the stimulus was shortest during the transition from inspiration to expiration in controlled breathing.

Changes in auditory-vocal reaction times within and across experimental sessions: preliminary observations

Changes in auditory-vocal reaction times (AVRTs) within and across experimental sessions were studied in 13 healthy university students, all females. Subjects were required to listen to a series of synthesized vowels and utter each of the vowels as soon as they heard it. The vowels were /i/, /u/, /a/, /o/, and /ae/, each presented 14 times and all presented in random order and at irregular intervals (2.5-4.5 sec). The stimuli and the instructions were prerecorded and presented to the subjects binaurally at a comfortable intensity level via headphones in an IAC booth. Each subject performed the experimental task twice, a week apart. The stimuli and the vocal responses were tape recorded and later digitized and computer analyzed. Serial analysis of successive AVRTs revealed significant intra- and intersession decreases in AVRTs in the majority of the subjects. Increases in AVRTs were also seen, but much less frequently. The implications of these findings are discussed.