Negative emotional stimulation decreases respiratory sensory gating in healthy humans

Neural mechanisms of respiratory interoception

Respiratory interoception is one of the internal bodily systems that is comprised of different types of somatic and visceral sensations elicited by different patterns of afferent input and respiratory motor drive mediating multiple respiratory modalities. Respiratory interoception is a complex system, having multiple afferents grouped into afferent clusters and projecting into both discriminative and affective centers that are directly related to the behavioral assessment of breathing. The multi-afferent system provides a spectrum of input that result in the ability to interpret the different types of respiratory interceptive sensations. This can result in a response, commonly reported as breathlessness or dyspnea. Dyspnea can be differentiated into specific modalities. These respiratory sensory modalities lead to a general sensation of an Urge-to-Breathe, driven by a need to compensate for the modulation of ventilation that has occurred due to factors that have affected breathing. The multiafferent system for respiratory interoception can also lead to interpretation of the sensory signals resulting in respiratory related sensory experiences, including the Urge-to-Cough and Urge-to-Swallow. These behaviors are modalities that can be driven through the differentiation and integration of multiple afferent input into the respiratory neural comparator. Respiratory sensations require neural somatic and visceral interoceptive elements that include gated attention and detection leading to respiratory modality discrimination with subsequent cognitive decision and behavioral compensation. Studies of brain areas mediating cortical and subcortical respiratory sensory pathways are summarized and used to develop a model of an integrated respiratory neural network mediating respiratory interoception.

Neural oscillations underlying the neural gating of respiratory sensations in generalized anxiety disorder

Individuals with generalized anxiety disorder (GAD) have been shown to have altered neural gating of respiratory sensations (NGRS) using respiratory-related evoked potentials (RREP); however, corresponding neural oscillatory activities remain unexplored. The present study aimed to investigate altered NGRS in individuals with GAD using both time and time-frequency analysis. Nineteen individuals with GAD and 28 healthy controls were recruited. Paired inspiratory occlusions were delivered to elicit cortical neural activations measured from electroencephalography. The GAD group showed smaller N1 amplitudes to the first stimulus (S1), lower evoked gamma and larger evoked beta oscillations compared to controls. Both groups showed larger N1, P3, beta power and theta power in response to S1 compared to S2, suggesting a neural gating phenomenon. These findings suggest that N1, gamma and beta frequency oscillations may be indicators for altered respiratory sensation in GAD populations and that the N1, P3, beta and theta oscillations can reflect the neural gating of respiratory sensations.

Age-related changes in the neural gating of respiratory sensations in humans

Background

Neural gating of respiratory sensations (NGRS) characterises the brain's ability to filter out repetitive respiratory sensory stimuli. This mechanism plays a crucial role in the neural processing of respiratory stimuli. However, whether ageing affects NGRS in healthy adults is still unclear. Therefore, we aimed to measure the effect of age on NGRS as well as the corresponding S1 and S2 components of the respiratory-related evoked potentials (RREPs).

Methods

Three age groups of healthy adults participated in this study: a young group (YG; age 20-39 years), a middle-aged group (MG; age 40-59 years) and an old group (OG; age ≥60 years). NGRS was measured by the RREPs in the electroencephalogram in response to short-paired respiratory occlusion stimuli (S1 and S2). The S2/S1 ratio of the RREP N1 amplitude (the negative deflection of the RREP at ∼85-135 ms) was used to characterise NGRS.

Results

The results showed a significantly smaller N1 S2/S1 ratio in the YG than in the MG (p=0.01) and OG (p=0.03). Further analysis showed that the S1 N1 amplitude was larger for the YG compared with the MG (p=0.03) and OG (p=0.007). Moreover, age was significantly correlated with the N1 S2/S1 ratio (r=0.43), with higher age relating to higher N1 S2/S1 ratios.

Conclusions

The greater N1 S2/S1 ratios observed in older adults suggest that ageing has a negative impact on the NGRS. This might contribute to increased experiences of respiratory sensations such as dyspnoea in ageing adults.

Severity and phenotypes of dyspnea in asthma: Impact of comorbidities

BACKGROUND

Dyspnea is a common but non-specific symptom of asthma, which in particular may be related to anxiety and hyperventilation syndrome, two frequent comorbidities of asthma.

METHODS

We conducted a prospective multicentric cohort study in dyspneic asthmatic adults. Dyspnea was assessed using the Multidimensional Dyspnea Profile questionnaire. We described the sensory (QS) and affective (A2) domains of dyspnea and investigated the effect of poor asthma control, hyperventilation and anxiety on each dimension at baseline and after 6 months.

RESULTS

We included 142 patients (65.5% women, age: 52 years). Dyspnea was severe and predominated on its sensory domain (median QS: 27/50; A2: 15/50). Uncontrolled asthma (ACQ≥1.5), hyperventilation symptoms (Nijmegen≥23) and anxiety (HAD-A≥10) were present in 75%, 45.7% and 39% of cases, respectively. Hyperventilation symptoms were associated with higher QS and A2 scores: QS at 28.4(10.7) vs. 21.7(12.8) (p = 0.001) and A2 at 24(14) vs. 11.3(11) (p < 0.001) in patients with vs. without hyperventilation symptoms. Anxiety was only associated with increased A2 (27(12.3) vs. 10.9(11), p < 0.001). At 6 months, QS and A2 decreased of 7 and 3 points, respectively, in relation with changes in ACQ-6 and Nijmegen scores as well as the HAD-A score for A2.

CONCLUSION

In breathless asthmatics, dyspnea is severe and worsened but differentially modulated by hyperventilation symptoms and anxiety. A multidimensional phenotyping of dyspnea in asthmatics could be useful to understand its origins and personalize treatment.

A Systematic Review of International Affective Picture System (IAPS) around the World

Standardized Emotion Elicitation Databases (SEEDs) allow studying emotions in laboratory settings by replicating real-life emotions in a controlled environment. The International Affective Pictures System (IAPS), containing 1182 coloured images as stimuli, is arguably the most popular SEED. Since its introduction, multiple countries and cultures have validated this SEED, making its adoption on the study of emotion a worldwide success. For this review, 69 studies were included. Results focus on the discussion of validation processes by combining self-report and physiological data (Skin Conductance Level, Heart Rate Variability and Electroencephalography) and self-report only. Cross-age, cross-cultural and sex differences are discussed. Overall, IAPS is a robust instrument for emotion elicitation around the world.

The impact of emotional context on neural substrates of respiratory sensory gating

Psychological challenges have been found to impact respiratory symptom perception in healthy individuals as well as in patients with various neurological disorders. Human respiratory sensory gating is an objective measure to examine respiratory sensory information processing of repetitive respiratory mechanical stimuli in the central nervous system. With this electrophysiological method, patients with higher anxiety levels showed reduced respiratory sensory gating function in the cortex, and increased symptom perception. In addition, positive emotional contexts were found to increase the respiratory sensory gating function using RREPs. However, neural substrates related to emotional impacts on respiratory sensory gating remain still unclear. In the present study, we examined the emotion processing of respiratory sensory gating using functional magnetic resonance imaging. We hypothesized that positive compared with neutral stimuli would result in reduced brain activations in cortical areas with the paired occlusion paradigm. Thirty-five healthy adults participated in this event-designed fMRI experiment. Paired inspiratory occlusions (two transient occlusions with a 500 ms inter-stimulus-interval are delivered during one inspiration) were provided using an external trigger outside of the scanner. At least 40 paired inspiratory occlusions were collected for each trial. The experiment contained three runs during which participants underwent 12 min for the paired inspiratory occlusion paradigm while watching a fixation cross (the control condition), neutral and positive emotional picture series. The order of emotional picture series was randomized across the participants. Our results revealed an overall trend of reduction of brain activity from the neutral (minus fixation) condition, to the pleasant (minus fixation) condition. For bilateral thalamus and primary visual cortices, there was no significant difference in neural activation between the two contrasts of pleasant (Contrast_P–F) and neutral condition (Contrast_N–F). The activation of the mid-cingulate and the orbitofrontal cortex was lower in Contrast_P–F compared to Contrast_N–F. In conclusion, our results suggest that emotional context, especially positive valence, modulates neural correlates in middle cingulate cortex and orbitofrontal cortex in terms of respiratory sensory gating. Future studies are recommended to test emotional impacts on respiratory sensations in patients with neurological disorders.

Cortical Sources of Respiratory Mechanosensation, Laterality, and Emotion: An MEG Study

Airway obstruction activates mechanoreceptors that project to the cerebral cortices in humans, as evidenced by scalp encephalography recordings of cortical neuronal activation, i.e., respiratory-related evoked potential (RREP). However, neural evidence of both high spatial and temporal resolution of occlusion-elicited cortical activation in healthy individuals is lacking. In the present study, we tested our hypothesis that inspiratory mechanical stimuli elicit neural activation in cortical structures that can be recorded using magnetoencephalography (MEG). We further examined the relationship between depression and respiratory symptoms and hemispheric dominance in terms of emotional states. A total of 14 healthy nonsmoking participants completed a respiratory symptom questionnaire and a depression symptom questionnaire, followed by MEG and RREP recordings of inspiratory occlusion. Transient inspiratory occlusion of 300 ms was provided randomly every 2 to 4 breaths, and approximately 80 occlusions were collected in every study participant. Participants were required to press a button for detection when they sensed occlusion. Respiratory-related evoked fields (RREFs) and RREP peaks were identified in terms of latencies and amplitudes in the right and left hemispheres. The Wilcoxon signed-rank test was further used to examine differences in peak amplitudes between the right and left hemispheres. Our results showed that inspiratory occlusion elicited RREF M1 peaks between 80 and 100 ms after triggering. Corresponding neuromagnetic responses peaked in the sensorimotor cortex, insular cortex, lateral frontal cortex, and middle frontal cortex. Overall, the RREF M1 peak amplitude in the right insula was significantly higher than that in the left insula (p = 0.038). The RREP data also showed a trend of higher N1 peak amplitudes in the right hemisphere compared to the left (p = 0.064, one-tailed). Subgroup analysis revealed that the laterality index of sensorimotor cortex activation was significantly different between higher- and lower-depressed individuals (−0.33 vs. −0.02, respectively; p = 0.028). For subjective ratings, a significant relationship was found between an individual’s depression level and their respiratory symptoms (Spearman’s rho = 0.54, p = 0.028, one-tailed). In summary, our results demonstrated that the inspiratory occlusion paradigm is feasible to elicit an RREF M1 peak with MEG. Our imaging results showed that cortical neurons were activated in the sensorimotor, frontal, middle temporal, and insular cortices for the M1 peak. Respiratory occlusion elicited higher cortical neuronal activation in the right insula compared to the left, with a higher tendency for right laterality in the sensorimotor cortex for higher-depressed rather than lower-depressed individuals. Higher levels of depression were associated with higher levels of respiratory symptoms. Future research with a larger sample size is recommended to investigate the role of emotion and laterality in cerebral neural processing of respiratory sensation.

Critical roles for breathing in the genesis and modulation of emotional states

Breathing can be classified into metabolic and behavioral categories. Metabolic breathing and voluntary behavioral breathing are controlled in the brainstem and in the cerebral motor cortex, respectively. This chapter places special emphasis on the reciprocal influences between breathing and emotional processes. As is the case with neural control of breathing, emotions are generated by multiple control networks, located primarily in the forebrain. For several decades, a respiratory rhythm generator has been investigated in the limbic system. The amygdala receives respiratory-related input from the piriform cortex. Excitatory recurrent branches are located in the piriform cortex and have tight reciprocal synaptic connections, which produce periodic oscillations, similar to those recorded in the hippocampus during slow-wave sleep. The relationship between olfactory breathing rhythm and emotion is seen as the gateway to interpreting the relationship between breathing and emotion. In this chapter, we describe roles of breathing in the genesis of emotion, neural structures common to breathing and emotion, and mutual importance of breathing and emotion. We also describe the central roles of conscious awareness and voluntary control of breathing, as effective methods for stabilizing attention and the contents in the stream of consciousness. Voluntary control of breathing is seen as an essential practice for achieving emotional well-being.

Neck Pain and Disability: Are They Related to Dysfunctional Breathing and Stress?

Purpose: People with neck pain are likely to have negative respiratory findings. The purpose of this study was to investigate the relationship between neck pain and dysfunctional breathing and to examine their relationship to stress. Method: This cross-sectional study included 49 participants with neck pain and 49 age- and sex-matched controls. We measured neck pain using the numeric rating scale (NRS); neck disability using the Neck Disability Index (NDI); dysfunctional breathing using the Nijmegen Questionnaire (NQ), Self-Evaluation of Breathing Questionnaire (SEBQ), breath hold time, and respiratory rate (RR); and stress using the Perceived Stress Scale (PSS). Results:Participants with neck pain scored higher on the NQ ( p < 0.001) and the SEBQ ( p < 0.001) than controls. NQ and SEBQ scores correlated moderately with NDI scores ( r > 0.50; 95% CI: 0.25, 0.68 and 0.33, 0.73, respectively) and PSS scores ( r > 0.50; 95% CI: 0.29, 0.78 and 0.31, 0.73, respectively). SEBQ scores showed a fair correlation with NRS scores and RR a fair correlation with NDI scores. Conclusions: Participants with neck pain had more dysfunctional breathing symptoms than participants without neck pain, and dysfunctional breathing was correlated with increased neck disability and increased stress. The NQ and SEBQ can be useful in assessing dysfunctional breathing in patients with neck pain.

The test-retest reliability of the respiratory-related evoked potential

The respiratory-related evoked potential (RREP) is an established technique to study the neural processing of respiratory sensations. We examined the test-retest reliability of the RREP during an unloaded baseline condition (no dyspnea) and an inspiratory resistive loaded breathing condition (dyspnea) over a one-week period. RREPs were evoked by short inspiratory occlusions (150 ms) while EEG was continuously measured. The mean amplitudes of the RREP components Nf, P1, N1, P2, and P3 were studied. For the no dyspnea condition, moderate test-retest reliability for Nf (intraclass correlation coefficient ICC: 0.73) and P1 (ICC: 0.74), good test-retest reliability for N1 (ICC: 0.89) and P3 (ICC: 0.76), and excellent test-retest reliability for P2 (ICC: 0.92) was demonstrated. For the dyspnea condition, moderate test-retest reliability was found for Nf (ICC: 0.69) and P1 (ICC: 0.57) and good test-retest reliability for N1 (ICC: 0.77), P2 (ICC: 0.84), and P3 (ICC: 0.77). This indicates that the RREP components Nf, P1, N1, P2, and P3, elicited by inspiratory occlusions, show adequate reliability in a test-retest study design with or without parallel sustained resistive load-induced dyspnea.

The impact of unpredictability of dyspnea offset on dyspnea perception, fear, and respiratory neural gating

Dyspnea is a debilitating and threatening symptom in various diseases. Affected patients often report the unpredictability of dyspnea episodes being particularly anxiety-provoking and amplifying the perception of dyspnea. Experimental studies testing dyspnea unpredictability together with related neural processes, physiological fear responses, and dyspnea-related personality traits are sparse. Therefore, we investigated the impact of unpredictability of dyspnea offset on dyspnea perception and fear ratings, respiratory neural gating and physiological fear indices, as well as the influence of interindividual differences in fear of suffocation (FoS). Forty healthy participants underwent a task manipulating the offset predictability of resistive load-induced dyspnea including one unloaded safety condition. Respiratory variables, self-reports of dyspnea intensity, dyspnea unpleasantness, and fear were recorded. Moreover, respiratory neural gating was measured in a paired inspiratory occlusion paradigm using electroencephalography, while electrodermal activity, startle eyeblink, and startle probe N100 were assessed as physiological fear indices. Participants reported higher dyspnea unpleasantness and fear when dyspnea offset was unpredictable compared to being predictable. Individuals with high levels of FoS showed the greatest increase in fear and overall higher levels of fear and physiological arousal across all conditions. Respiratory neural gating, startle eyeblink, and startle probe N100 showed general reductions during dyspnea conditions but no difference between unpredictable and predictable dyspnea conditions. Together, the current results suggest that the unpredictable offset of dyspnea amplifies dyspnea perception and fear, especially in individuals with high levels of FoS. These effects were unrelated to respiratory neural gating or physiological fear responses, requiring future studies on underlying mechanisms.

Effectiveness of Cognitive Behavioral Therapy on Health Outcomes in Patients with Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis

"The incidence of psychological distress (such as anxiety and depression) is high in COPD patients. CBT has been proved to reduce depression and anxiety and enhance quality of life. This meta-analysis evaluated the effectiveness of cognitive behavioral therapy(CBT) on patients with chronic obstructive pulmonary disease(COPD). The following electronic databases were searched from inception to March 2020: PubMed, EMBase, Cochrane Library, Web of Science, Medline, OVID, CINAHL, Chinese Biomedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI), Wangfang Database (WF), PsycARTICLES, VIP database. The Scopus and Google scholar database that we did not use. Randomized controlled trials (RCTs) that compared CBT with routine methods of care in COPD were retrieved in electronic databases. The Cochrane Risk of Bias Tool and Review Manager version 5.3 were used for risk of bias assessment and meta-analysis, respectively. Both data synthesis and descriptive analysis were used for outcome assessment. A total of 10 RCTs involving 1173 patients were included. Data synthesis showed that CBT was statistically significant in improving short- and medium-term depression and treatment compliance. Mediumterm anxiety and quality of life were improved among COPD patients receiving CBT, although no significant effect was found for short-term quality of life and anxiety. Descriptive analysis showed that CBT could reduce dyspnea. No clear evidence supports the effectiveness on improving self-efficacy in COPD patients with the use of CBT (P > 0.05). CBT can be a useful strategy to improve the symptoms of depression, dyspnea and treatment compliance in patients with COPD. It can also improve patients’ quality of life and anxiety to some extent, but there is still lack of strong evidence in improving patients’ self-efficacy."

Evidence against a subcortical gate preventing conscious detection of respiratory load stimuli

Respiratory related evoked potentials (RREP) were used to examine respiratory stimulus gating. RREPs produced by consciously detected vs. undetected loads, near the detection threshold, were compared. Participants (n = 17) were instrumented with EEG and a nasal mask connected to a loading manifold, which presented a range of mid-inspiratory resistive loads, plus a control, in a random block design. Participants were cued prior to the stimulus and signalled detection by a button press. There were statistically significant differences in peak-to-peak amplitude of the P1 RREP peak for detected (mean ± SD; 3.86 ± 1.45 μV; P =  0.020) and undetected loads (3.67 ± 1.27 μV; P =  0.002) vs. control (2.36 ± 0.81 μV), although baseline-to-peak differences were not significantly different. In contrast peak-to-peak P3 amplitude was significantly greater for detected (5.91 ± 1.54 μV; P <  0.001) but not undetected loads (3.33 ± 0.98 μV; P = 0.189) vs. control (3.69 ± 1.46 μV), with the same pattern observed for baseline-to-peak measurements. The P1 peak, thought to reflect arrival of somatosensory information, appeared to be present in response to both detected and undetected loads, but the later P3 peak, was present for detected loads only. This suggests that for sub-threshold loads sensory information may reach the cortex, arguing against a sub-cortical gating process.

Breathlessness amplifies amygdala responses during affective processing

Breathlessness is an aversive symptom in many prevalent somatic and psychiatric diseases and is usually experienced as highly threatening. It is strongly associated with negative affect, but the underlying neural processes remain poorly understood. Therefore, using fMRI, the present study examined the effects of breathlessness on the neural processing of affective visual stimuli within candidate brain areas including the amygdala, insula, and anterior cingulate cortex (ACC). During scanning, 42 healthy volunteers, mean (SD) age: 29.0 (6.0) years, 14 female, were presented with affective picture series of negative, neutral, and positive valence while experiencing either no breathlessness (baseline conditions) or resistive-load induced breathlessness (breathlessness conditions). Respiratory measures and self-reports suggested successful induction of breathlessness and affective experiences. Self-reports of breathlessness intensity and unpleasantness were significantly higher during breathlessness conditions, mean (SD): 45.0 (16.6) and 32.3 (19.8), as compared to baseline conditions, mean (SD): 1.9 (3.0) and 2.9 (5.5). Compared to baseline conditions, stronger amygdala activations were observed during breathlessness conditions for both negative and positive affective picture series relative to neutral picture series, while no such effects were observed in insula and ACC. The present findings demonstrate that breathlessness amplifies amygdala responses during affective processing, suggesting an important role of the amygdala for mediating the interactions between breathlessness and affective states.

Ventilatory Dysfunction in Parkinson's Disease

In contrast to some other neurodegenerative diseases, little is known about ventilatory dysfunction in Parkinson’s disease (PD). To assess the spectrum of ventilation disorders in PD, we searched for and reviewed studies of dyspnea, lung volumes, respiratory muscle function, sleep breathing disorders and the response to hypoxemia in PD. Among the studies, we identified some limitations: (i) small study populations (mainly composed of patients with advanced PD), (ii) the absence of long-term follow-up and (iii) the absence of functional evaluations under “off-drug” conditions. Although there are many reports of abnormal spirometry data in PD (mainly related to impairment of the inspiratory muscles), little is known about hypoventilation in PD. We conclude that ventilatory dysfunction in PD has been poorly studied and little is known about its frequency and clinical relevance. Hence, there is a need to characterize the different phenotypes of ventilation disorders in PD, study their relationships with disease progression and assess their prognostic value.

Exertional dyspnoea in obesity

The purpose of cardiopulmonary exercise testing (CPET) in the obese person, as in any cardiopulmonary exercise test, is to determine the patient's exercise tolerance, and to help identify and/or distinguish between the various physiological factors that could contribute to exercise intolerance. Unexplained dyspnoea on exertion is a common reason for CPET, but it is an extremely complex symptom to explain. Sometimes obesity is the simple answer by elimination of other possibilities. Thus, distinguishing among multiple clinical causes for exertional dyspnoea depends on the ability to eliminate possibilities while recognising response patterns that are unique to the obese patient. This includes the otherwise healthy obese patient, as well as the obese patient with potentially multiple cardiopulmonary limitations. Despite obvious limitations in lung function, metabolic disease and/or cardiovascular dysfunction, obesity may be the most likely reason for exertional dyspnoea. In this article, we will review the more common cardiopulmonary responses to exercise in the otherwise healthy obese adult with special emphasis on dyspnoea on exertion.

Increased ventilatory variability and complexity in patients with hyperventilation disorder

It has been hypothesized that hyperventilation disorders could be characterized by an abnormal ventilatory control leading to enhanced variability of resting ventilation. The variability of tidal volume (VT) often depicts a nonnormal distribution that can be described by the negative slope characterizing augmented breaths formed by the relationship between the probability density distribution of VT and VT on a log-log scale. The objectives of this study were to describe the variability of resting ventilation [coefficient of variation (CV) of VT and slope], the stability in respiratory control (loop, controller and plant gains characterizing ventilatory-chemoresponsiveness interactions) and the chaotic-like dynamics (embedding dimension, Kappa values characterizing complexity) of resting ventilation in patients with a well-defined dysfunctional breathing pattern characterized by air hunger and constantly decreased PaCO2 during a cardiopulmonary exercise test. Compared with 14 healthy subjects with similar anthropometrics, 23 patients with hyperventilation were characterized by increased variability of resting tidal ventilation (CV of VT median [interquartile]: 26% [19-35] vs. 36% [28–48], P = 0.020; slope: −6.63 [−7.65; −5.36] vs. −3.88 [−5.91; −2.66], P = 0.004) that was not related to increased chemical drive (loop gain: 0.051 [0.039–0.221] vs. 0.044 [0.012–0.087], P = 0.149) but that was related to an increased ventilatory complexity (Kappa values, P < 0.05). Plant gain was decreased in patients and correlated with complexity (with Kappa 5 − degree 5: Rho = −0.48, P = 0.006). In conclusion, well-defined patients suffering from hyperventilation disorder are characterized by increased variability of their resting ventilation due to increased ventilatory complexity with stable ventilatory-chemoresponsiveness interactions.

Being Anxious, Thinking Positively: The Effect of Emotional Context on Respiratory Sensory Gating

Respiratory sensory gating function has been found decreased by induced negative emotion in healthy adults. The increased ratio of the respiratory-related evoked potential (RREP) N1 peak amplitude for the second occlusion (S2) vs. the first occlusion (S1), S2/S1, is indicative of such decreased respiratory sensory gating. In this study, we tested the hypothesis that a positive emotional context would enhance respiratory sensory gating function in healthy individuals. In addition, we tested the modulating role of individual anxiety levels. We compared respiratory sensory gating in 40 healthy individuals by the paired inspiratory occlusion paradigm in a positive and neutral emotional context induced by emotional picture viewing. The results showed that the group averaged RREP N1 peak amplitudes S2/S1 ratios were significantly smaller in the positive compared to neutral context (0.49 vs. 0.64; p < 0.01). Further, analysis showed that the ratio decrease was due to a reduced response to the S2 and an enhanced response to S1 in the positive emotional context (p < 0.05). The subgroup analyses showed that in the positive emotional context, both individuals with low-moderate anxiety levels and those with no anxiety demonstrated a significant decrease of their S2/S1 ratio, but only those with low-moderate anxiety levels showed reduced S2 amplitudes compared to the neutral context (p < 0.01). In conclusion, our results suggest that a positive emotional context is related to better brain inhibitory mechanisms by filtering out repetitive respiratory stimuli in healthy individuals, especially in the presence of low-moderate anxiety levels. Further, investigation on how positive emotional contexts might contribute to improved respiratory sensory gating ability in clinical populations is necessary.

Respiratory sensory gating measured by respiratory-related evoked potentials in generalized anxiety disorder

The perception of respiratory sensations plays an important role both in respiratory diseases and in anxiety disorders. However, little is known about the neural processes underlying respiratory sensory perception, especially in patient groups. Therefore, the present study examined whether patients with generalized anxiety disorder (GAD) would demonstrate altered respiratory sensory gating compared to a healthy control group. Respiratory-related evoked potentials (RREP) were measured in a paired inspiratory occlusion paradigm presenting two brief occlusion stimuli (S1 and S2) within one inspiration. The results showed a significantly greater S2/S1 ratio for the N1 component of the RREP in the GAD group compared to the control group. Our findings suggest altered respiratory sensory processing in patients with GAD, which might contribute to altered perception of respiratory sensations in these patients.

Cognitive behaviour therapy reduces dyspnoea ratings in patients with chronic obstructive pulmonary disease (COPD)

There is evidence that psychological factors contribute to the perception of increased difficulty of breathing in patients with chronic obstructive pulmonary disease (COPD), and increase morbidity. We tested the hypothesis that cognitive behaviour therapy (CBT) decreases ratings of perceived dyspnoea in response to resistive loading in patients with COPD. From 31 patients with COPD, 18 were randomised to four sessions of specifically targeted CBT and 13 to routine care. Prior to randomisation, participants were tested with an inspiratory external resistive load protocol (loads between 5 and 45cmH2O/L/s). Six months later, we re-measured perceived dyspnoea in response to the same inspiratory resistive loads and compared results to measurements prior to randomisation. There was a significant 17% reduction in dyspnoea ratings across the loads for the CBT group, and no reduction for the routine care group. The decrease in ratings of dyspnoea suggests that CBT to alleviate breathing discomfort may have a role in the routine treatment of people with COPD.

The Effect of Development in Respiratory Sensory Gating Measured by Electrocortical Activations

The perception of respiratory sensations can be of significant importance to individuals for survival and greatly impact quality of life. Respiratory sensory gating, similar to somatosensory gating with exteroceptive stimuli, is indicative of brain cortices filtering out repetitive respiratory stimuli and has been investigated in adults with and without diseases. Respiratory gating can be tested with the respiratory-related evoked potential (RREP) method in the electroencephalogram with a paired inspiratory occlusion paradigm. Here, the RREP N1 component elicited by the second stimulus (S2) shows reduced amplitudes compared to the RREP N1 component elicited by the first stimulus (S1). However, little is known regarding the effect of development on respiratory sensory gating. The present study examined respiratory sensory gating in 22 typically developed school-aged children and 22 healthy adults. Paired inspiratory occlusions of 150-ms each with an inter-stimulus-interval of 500-ms were delivered randomly every 2–4 breaths during recording. The main results showed a significantly larger RREP N1 S2/S1 ratio in the children group than in the adult group. In addition, children compared to adults demonstrated significantly smaller N1 peak amplitudes in response to S1. Our results suggest that school-aged children, compared to adults, display reduced respiratory sensory gating.