Respiratory-related Evoked Potentials Research Articles

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

BackgroundNeural 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).MethodsThree 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.ResultsThe 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.ConclusionsThe 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.

Respiratory-related evoked potentials in chronic obstructive pulmonary disease and healthy aging.

Altered neural processing and increased respiratory sensations have been reported in chronic obstructive pulmonary disease (COPD) as larger respiratory-related evoked potentials (RREPs), but the effect of healthy-aging has not been considered adequately. We tested RREPs evoked by brief airway occlusions in 10 participants with moderate-to-severe COPD, 11 age-matched controls (AMC) and 14 young controls (YC), with similar airway occlusion pressure stimuli across groups. Mean age was 76 years for COPD and AMC groups, and 30 years for the YC group. Occlusion intensity and unpleasantness was rated using the modified Borg scale, and anxiety rated using the Hospital Anxiety and Depression Scale. There was no difference in RREP peak amplitudes across groups, except for the N1 peak, which was significantly greater in the YC group than the COPD and AMC groups (p= 0.011). The latencies of P1, P2 and P3 occurred later in COPD versus YC (p< 0.05). P3 latency occurred later in AMC than YC (p= 0.024). COPD and AMC groups had similar Borg ratings for occlusion intensity (3.0 (0.5, 3.5) [Median (IQR)] and 3.0 (3.0, 3.0), respectively; p= 0.476) and occlusion unpleasantness (1.3 (0.1, 3.4) and 1.0 (0.75, 2.0), respectively; p= 0.702). The COPD group had a higher anxiety score than AMC group (p= 0.013). A higher N1 amplitude suggests the YC group had higher cognitive processing of respiratory inputs than the COPD and AMC groups. Both COPD and AMC groups showed delayed neural responses to the airway occlusion, which may indicate impaired processing of respiratory sensory inputs in COPD and healthy aging.

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.

Error-related negativity relates to the neural processing of brief aversive bodily sensations

The error-related negativity (ERN) is an event-related potential occurring in the electroencephalogram (EEG) within 100 ms after the commission of an error. The ERN is thought to partially reflect emotionally aversive aspects of error commission, however, it has thus far not been related to the neural processing of other aversive events, such as brief aversive bodily sensations. Therefore, the present study investigated the links between the ERN and the N1 amplitudes of respiratory-related evoked potentials (RREP) and somatosensory evoked potentials (SEP). During the acquisition of high-density EEG, 41 healthy participants performed a Flanker task to evoke the ERN, while RREP and SEP were separately elicited, using inspiratory occlusions and electrocutaneous stimulation of the wrist. Significant positive correlations were observed between the amplitudes of the ERN and the N1 of RREP and SEP, suggesting relationships between the neural processing of different emotionally aversive events, namely errors and bodily sensations.

Brain Activations to Dyspnea in Patients With COPD.

We compared the perception and neural processing of respiratory sensations between 20 COPD patients and 20 healthy controls by means of respiratory-related evoked potentials (RREP) in the electroencephalogram (EEG). RREPs were induced by short inspiratory occlusions while 129-channel EEG was measured. COPD patients rated the occlusions as more intense and unpleasant (p’s < 0.001) and showed higher mean amplitudes for the RREP components P1 (p = 0.0004), N1 (p = 0.024), P2 (p = 0.019), and P3 (p = 0.018). Our results indicate that COPD patients demonstrate greater perception and neural processing of respiratory sensations, which presumably reflects the highly aversive and attention-demanding character of these sensations for COPD patients.

The presence of others reduces dyspnea and cortical neural processing of respiratory sensations

Dyspnea is a threatening symptom frequently experienced by patients within social contexts such as in the presence of family members, health professionals, or other patients. However, the effects of social presence on perceived dyspnea remain unknown. Therefore, this study examined the effects of social presence on dyspnea perception and cortical neural processing of respiratory sensations using respiratory-related evoked potentials (RREPs) in the electroencephalogram while additionally investigating the impact of dyspnea-specific fear. Thirty-one healthy females underwent four experimental conditions while RREPs were induced by inspiratory occlusions: (1)observer present/no dyspnea, (2)observer present/dyspnea, (3)alone/no dyspnea, (4)alone/dyspnea. The observer presence reduced ratings of perceived dyspnea during dyspnea conditions either significantly or at trend level. Additionally, reduced amplitudes at trend level of RREP component P2 in conditions with an observer present were found. No associations with dyspnea-specific fear were found. Findings suggest that social presence might have beneficial effects for individuals experiencing dyspnea.

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.

Supra-threshold inspiratory loads elicit respiratory related evoked potentials in healthy subjects

Objectives Respiratory-related evoked potential (RREP) are well-established cerebral correlates of respiratory perceptions. The early components N1/P1 reflect first-order sensory processing of afferent respiratory signals in brain sensorimotor regions while the late ones P2/P3 involve higher-order cognitive processing [1] . The current stimuli used to elicited RREP are short occlusions at the onset of an inspiration or a transiant interruption of the inspiration [1] . Durations of the inspiratory occlusion do not affect RREP components [3] while there is a linear relationship between inspiratory loads and RREP components amplitudes. Moreover, an inspiration load needs to reach some threshold value to elicit RREP [1] , [2] . Here, we investigated whether supra-threshold load inspiration could induce RREP without occlusion. Methods EEG was synchronously recorded with the respiratory signals in 11 healthy volunteers breathing into a mouthpiece connected to a non-rebreathing valve. Four consecutives inspiration loads were produced by a pressure-threshold device connected to the non-rebreathing valve: no_Load, 10, 20 and 30 cmH2O/L/sec. Each load was presented during 5 minutes and there is a 3-min resting time between two consecutives loads presentations. Magnitude estimation (ME) for each load was scored with the A1 subscale of the Multi-dimensional profile of dyspnea. Inspiration onset time locked EEG epochs were averaged for each breathing conditions and examined for presence of RREP components. Results The no_load condition did not elicit any peak of RREP, but 10, 20 and 30 cmH2O/L/sec produced N1 and P3 RREP components with amplitudes correlating with the loads as well as the loads’ magnitude estimation. Mean amplitudes of the N1 and P3 RREP components for 10, 20 and 30 cmH2O/L/sec were respectively 3.6 ± 0.5, 5.6 ± 0.9, 3.8 ± 1.3 and −4.5 ± 1.3, −11.4 ± 2.4, −7.6 ± 2.2 μV. Conclusion Supra-threshold load inspiration could induce RREP without occlusion. This method should be compared with the standard inspiration occlusion method.

Sensory detection of threshold intensity resistive loads in severe obstructive sleep apnoea

Respiratory related evoked potentials (RREPs) were used to investigate whether sensory detection of small mid-inspiratory resistive loads (≈1.2–6.2 cmH2OL−1s), delivered during wakefulness, was impaired in obstructive sleep apnoea (OSA). It was reasoned that impaired detection of minor airway patency challenge may lead to difficult-to-remedy further collapse. There was a significant reduction in OSA (n=16) vs. control (n=17) participants in the slope of the relationship between the P1 RREP component amplitude, which reflects arrival of somatosensory information at the cortex, and stimulus intensity, expressed as change in epiglottic pressure (mean [95% confidence intervals]: −0.50 [−0.97, −0.03] vs. −1.78 [−2.54, −1.02]; P=0.004), suggesting a reduction in sensitivity to small respiratory loads. However there was no significant difference in sensitivity after background Pepi was taken into account (P=0.268). Additionally, there were no significant group differences in the threshold of the P1 amplitude/stimulus intensity relationship, or in the P1 latency. These results indicate a reduced sensitivity to detection of small upper airway negative pressure stimuli in OSA related to a reduction in mechanoreceptor activation (likely related to increased airway resistance in OSA vs. controls; P=0.002) rather than defective mechanosensory function.

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.

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.

Respiratory cortical processing to inspiratory resistances during wakefulness in children with the obstructive sleep apnea syndrome

Children with the obstructive sleep apnea syndrome (OSAS) have impaired respiratory afferent cortical processing during sleep that persists after treatment of OSAS. However, it is unknown whether this impairment is present during wakefulness and, if so, whether it improves after OSAS treatment. We hypothesized that children with OSAS, during wakefulness, have abnormal cortical processing of respiratory stimuli manifested by blunted respiratory-related evoked potentials (RREP) and that this resolves after OSAS treatment. We measured RREP during wakefulness in 26 controls and 21 children with OSAS before and after treatment. Thirteen participants with OSAS repeated testing 3-6 mo after adenotonsillectomy. RREP were elicited by interruption of inspiration by total occlusion and 30 and 20 cmH2O/l per s resistances. Nf at Fz latency elicited by occlusion was longer in children with OSAS at baseline compared with controls (78.8 ± 24.8 vs. 63.9 ± 19.7 ms, P = 0.05). All other peak amplitudes and latencies were similar between the two groups. After OSAS treatment, Nf at Fz latency elicited by 30 cmH2O/l per s decreased significantly (before, 88 ± 26 vs. after, 71 ± 25 ms, P = 0.02), as did that elicited by 20 cmH2O/l per s (85 ± 27 vs. 72 ± 24 ms, P = 0.004). The amplitude of N1 at Cz elicited by occlusion increased from -3.4 ± 5.6 to -7.4 ± 3 μV (P = 0.049) after treatment. We concluded that children with OSAS have partial delay of respiratory afferent cortical processing during wakefulness that improves after treatment.

Respiratory perception measured by cortical neural activations in individuals with generalized anxiety disorder

There has been evidence for the effect of anxiety on the neural processing of respiratory sensation using the respiratory-related evoked potentials (RREP) elicited by inspiratory occlusions. This study tested the RREP elicited by inspiratory occlusions in a group of outpatients with generalized anxiety disorder (GAD) and a group of healthy controls. We hypothesized that the RREP P3 peak would be modulated in the GAD patients.A RREP oddball paradigm of 150-ms inspiratory occlusion protocol was used in 15 GAD patients and 11 healthy adults with normal lung functions. The RREP was recorded with a 40-channel electroencephalography (EEG) system. A minimum of 100 occlusions was collected for data analysis.We found that the averaged P3 latency of the GAD patients was significantly longer than the P3 latency of the healthy controls. In addition, the GAD group showed significantly reduced P3 amplitudes compared to the control group. No group differences in latency and amplitudes were found for earlier RREP components.These results demonstrated that a delayed and reduced attention peak (P3) is present in patients with GAD. This suggests that GAD as a disease state modulates the higher order processing of respiratory perception.

Negative emotional stimulation decreases respiratory sensory gating in healthy humans

We tested the hypothesis that negative emotions decrease the respiratory-related evoked potentials (RREP) sensory gating (RSG). RREP were elicited by paired inspiratory occlusions. RSG was calculated as the difference in the averaged RREP peak N1 amplitude between the second (S2) and the first occlusion (S1). RSG was compared between unpleasant and neutral emotional conditions elicited by viewing affective pictures from the IAPS system in thirteen healthy adults. Results are expressed as median [min; max]. Compared to neutral pictures, viewing unpleasant pictures decreased the RREP N1(S1) amplitude (−3.37μV [−4.62; −1.37] versus −4.59μV [−6.08; −1.36]; p=0.017) but not the RREP N1(S2) amplitude (−0.26 [−3.24; 2.36] versus −0.7 [−1.54; 3.6]; p=0.68), and reduced the difference score S2–S1 (3.73μV [0; 5.82] versus 4.79μV [3; 6.2]; p=0.038). We concluded that a negative emotional stimulation could attract subject's attention to the detriment of the respiratory sensory inputs and produced an overall decrease in the RSG. This latter finding might participate in an over-perception of repeatedly presented respiratory stimuli.

Respiratory and Auditory Cortical Processing in Children with Obstructive Sleep Apnea Syndrome

Children with obstructive sleep apnea syndrome (OSAS) have impaired cortical processing of respiratory afferent stimuli, manifested by blunted sleep respiratory-related evoked potentials (RREP). However, whether this impairment is limited to respiratory stimuli, or reversible after successful treatment, is unknown. We hypothesized that, during sleep, children with OSAS have (1) abnormal RREP, (2) normal cortical processing of nonrespiratory stimuli, and (3) persistence of abnormal RREP after treatment. To measure sleep RREP and auditory evoked potentials in normal control subjects and children with OSAS before and after treatment. Twenty-four children with OSAS and 24 control subjects were tested during N3 sleep. Thirteen children with OSAS repeated testing 4-6 months after adenotonsillectomy. RREP were blunted in OSAS compared with control subjects (N350 at Cz -27 ± 15.5 vs. -47.4 ± 28.5 μV; P = 0.019), and did not improve after OSAS treatment (N350 at Cz pretreatment -25.1 ± 7.4 vs. -29.8 ± 8.1 post-treatment). Auditory evoked potentials were similar in OSAS and control subjects at baseline (N350 at Cz -58 ± 33.1 vs. -66 ± 31.1 μV), and did not change after treatment (N350 at Cz -67.5 ± 36.8 vs. -65.5 ± 20.3). Children with OSAS have persistent primary or irreversible respiratory afferent cortical processing deficits during sleep that could put them at risk of OSAS recurrence. OSAS does not seem to affect the cortical processing of nonrespiratory (auditory) afferent stimuli during sleep.

Respiratory Sensory Gating in Children Measured by the Respiratory‐Related Evoked Potentials

Respiratory neural gating function in the cortices was measured in healthy children using the paired respiratory‐related evoked potential (RREP) measured elicited by inspiratory occlusions. We hypothesized that respiratory sensory gating of healthy children would be normal as represented by a reduced amplitude of the second stimulus (S2) compared by the first stimulus (S1) for the short latency Nf, P1, and N1 peaks. We further hypothesized that the gating peak would be normal as represented by a N1 peak S2/S1 ratio of less than 0.5.Paired 150‐msec inspiratory occlusions with an inter‐stimulus‐interval of 500 milliseconds were given to the subjects. The RREP was recorded with a 40‐channel electroencephalography system. A minimum of 100 paired occlusions were collected for data analysis. The RREP Nf, P1, and N1 peaks were identified in latencies and amplitudes. The S2/S1 ratio was calculated for the amplitudes for each peak.Our preliminary data showed that the averaged latencies for the Nf, P1, and N1 peaks were 40 and 42, 55 and 48, 94 and 81 msec, respectively. The averaged S2/S1 ratio for the RREP Nf, P1, and N1 peak amplitudes were 0.97, 1.13, and 0.64, respectively.The result suggested that young children may have a decreased respiratory gating function represented by increased P1 and N1 peak S2/S1 ratios for the first order neural information processing.Supported by: NSC100–2320‐B‐182–018, CMRPD1A0021, CMRPD1A0022

Emotions and Neural Processing of Respiratory Sensations Investigated With Respiratory-Related Evoked Potentials

Patients with respiratory diseases such as asthma and chronic obstructive pulmonary disease frequently experience respiratory sensations, which are often perceived as unpleasant or threatening. However, the accurate perception of respiratory sensations is important for the management and treatment of these diseases. Emotions can substantially influence the perception of respiratory sensations and might affect the course of respiratory diseases, but the underlying neural mechanisms are poorly understood. The respiratory-related evoked potential (RREP) recorded from the electroencephalogram is a noninvasive technique that allowed first studies to examine the impact of emotions on the neural processing of respiratory sensations. In this review, we will briefly introduce the importance of the perception of respiratory sensations and the influence of emotions on respiratory perception. We then provide an overview on the technique of RREP and present a systematic review on recent findings using this technique in the context of emotions. The evidence currently available from studies in healthy individuals suggests that short-lasting emotional states and anxiety affect the later RREP components (N1, P2, P3) related to higher-order neural processing of respiratory sensations, but not the earlier RREP components (Nf, P1) related to first-order sensory processing. We conclude with a discussion of the implications of this work for future research that needs to focus on respiratory patient groups and the associated clinical outcomes.

The effect of anxiety on respiratory sensory gating measured by respiratory-related evoked potentials

Respiratory sensory gating is evidenced by decreased amplitudes of the respiratory-related evoked potentials (RREP) N1 peak for the second (S2) compared to the first occlusion (S1) when two paired occlusions are presented with a 500-millisecond (ms) inter-stimulus-interval during one inspiration. Because anxiety is prevalent in respiratory diseases and associated with altered respiratory perception, we tested whether anxiety can modulate individuals’ respiratory neural gating mechanism.By using high-density EEG, RREPs were measured in a paired inspiratory occlusion paradigm in 11 low and 10 higher anxious individuals with normal lung function.The N1 peak gating S2/S1 ratio and the N1 S2 amplitudes were greater in higher compared to low anxious individuals (p's<0.05). In addition, higher anxiety levels were correlated with greater S2/S1 ratios (r=0.54, p<0.05) and S2 amplitudes (r=−0.49, p<0.05).The results demonstrate that anxiety is associated with reduced respiratory sensory gating which might underlie altered respiratory symptom perception in anxious individuals.