EEG signatures change during unilateral Yogi nasal breathing.

Airflow through the left-and-right nostrils is said to be entrained by an endogenous nasal cycle paced by both poles of the hypothalamus. Yogic practices suggest, and scientific evidence demonstrates, that right-nostril breathing is involved with relatively higher sympathetic activity (arousal states), while left-nostril breathing is associated with a relatively more parasympathetic activity (stress alleviating state). The objective of this study was to further explore this laterality by controlling nasal airflow and observing patterns of cortical activity through encephalographic (EEG) recordings. Thirty subjects participated in this crossover study. The experimental session consisted of a resting phase (baseline), then a period of unilateral nostril breathing (UNB) using the dominant nasal airway, followed by UNB using the non-dominant nasal airway. A 64-channel EEG was recorded throughout the whole session. The effects of nostril-dominance, and nostril-lateralization were assessed using the power spectral density of the neural activity. The differences in power-spectra and source localization were calculated between EEG recorded during UNB and baseline for delta, theta, alpha, beta and gamma bands. Cluster-based permutation tests showed that compared to baseline, EEG spectral power was significantly (1) decreased in all frequency bands for non-dominant nostril UNB, (2) decreased in alpha, beta and gamma bands for dominant nostril UNB, (3) decreased in all bands for left nostril UNB, and (4) decreased in all bands except delta for right nostril UNB. The beta band showed the most widely distributed changes across the scalp. our source localisation results show that breathing with the dominant nostril breathing increases EEG power in the left inferior frontal (alpha band) and left parietal lobule (beta band), whereas non-dominant nostril breathing is related to more diffuse and bilateral effects in posterior areas of the brain.These preliminary findings may stimulate further research in the area, with potential applications to tailored treatment of brain disorders associated with disruption of sympathetic and parasympathetic activity.

Can binaural beats facilitate autonomic recovery following exposure to an acute stressor?

BACKGROUND AND PURPOSE: Binaural beats are seen as a new type of 'digital-drug'. The aim of this study was to determine if binaural beats could facilitate physiological recovery from a mental stressor. MATERIALS AND METHODS: 92 adults were exposed five times each to a 2-min mental stressor and a subsequent 4-min rest period containing silence or 1-of-4 examples of binaural beats (2, 5, 10, and 24 Hz). Physiological recovery across the five rest periods, as measured using skin conductance, heart rate, and breathing, were compared using one-way analysis of variance. RESULTS: Binaural beats were linked to enhanced physiological recovery relative to silence. However, the expected pattern of results whereby lower frequency binaural beats would be associated with greater physiological recovery, was not observed. CONCLUSION: Our findings do not support a relationship between binaural beats and systematic changes in emotional states as measured physiologically. On the basis of our results the acute administration of binaural beats in primary care to lower sympathetic arousal cannot yet be considered an evidence-based practice.

Electrophysiological indices of amplitude modulated sounds and sensitivity to noise.

Annoyance to unwanted sound differs across individuals, though why noise sensitive individuals are more reactive to noise while others are more resilient remains unanswered. The Information Processing Hypothesis posits that noise sensitive individuals are vulnerable to higher-order auditory processing deficits. The aim of this study was to test the veracity of this hypothesis by documenting differences in pre-attentive auditory evoked potentials (ERP) between high noise sensitive and low noise sensitive individuals. Participants provided annoyance measures for three amplitude-modulated sounds, and were exposed to the sounds while undergoing electroencephalogram recording. Results indicated that annoyance increased with modulation, and that modulation affected both N1 and P2 components. At the group level, highly noise sensitive individuals exhibited significantly greater annoyance to a low-frequency tone, alongside significantly higher P2 amplitude, than individuals reporting low levels of noise sensitivity. Overall, the results partially supported the Information Processing Hypothesis of noise sensitivity, but also suggest that acoustic features may be more important than hitherto argued.

Electrophysiological approaches to noise sensitivity.

BACKGROUND: Noise sensitivity describes an individual's general reactivity to sound. It is a common trait found in many clinical populations and describes approximately 20% of the general population. Little is known about its underlying mechanisms, however. OBJECTIVES: Here we present findings from three studies designed to expose differences in electrophysiological measures between noise-sensitive and noise-resistant individuals. METHOD: Noise sensitivity was estimated using self-report measures, while electrophysiological indices included both cardiac (heart rate, heart rate variability) and electroencephalographic (event-related potential) measures. All three studies were designed with reference to preexisting theoretical frameworks. RESULTS: Significant differences in heart rate change and heart rate variability indices between noise-sensitive and noise-resistant groups were found. Further, the noise-sensitive group exhibited less sensory gating than the noise-resistant group. CONCLUSIONS: While the findings from all three studies were not definitive in indicating a likely biological mechanism underlying noise sensitivity, they do suggest that electrophysiological investigation of noise sensitivity is viable and has potential to inform clinical research into a relatively understudied symptom.

Masking functions and fixed-signal functions for low-level 1000-Hz tones.

Masking functions and fixed-signal functions were constructed using a narrow range of pedestal intensities for 10-ms, 1000-Hz gated tones. Data from three experiments agreed with previously reported data, clearly demonstrating negative masking and the pedestal effect. The data extend earlier findings by showing (1) the resilience of the pedestal effect when a background noise masker is introduced; (2) a possible indifference of the fixed-signal function to stimulus duration; (3) the ability of a set of psychometric functions to produce both masking and fixed-signal functions; (4) depending on method, the impact of unit choice on the interpretation of both the pedestal effect and negative masking data. Results are discussed in relation to current psychophysical models, and suggest that accounting for the auditory system's sensitivity to differences in low-level sounds remains a challenge.

How religious coping is used relative to other coping strategies depends on the individual's level of religiosity and spirituality.

Results from empirical studies on the role of religiosity and spirituality in dealing with stress are frequently at odds, and the present study investigated whether level of religiosity and spirituality is related to the way in which religious coping is used relative to other coping strategies. A sample of 616 university undergraduate students completed the Brief COPE (Carver in Int J Behav Med 4:92-100, 1997) questionnaire and was classified into groups of participants with lower and higher levels of religiosity and spirituality, as measured by the WHOQOL-SRPB (WHOQOL-SRPB Group in Soc Sci Med 62:1486-1497, 2006) instrument. For participants with lower levels, religious coping tended to be associated with maladaptive or avoidant coping strategies, compared to participants with higher levels, where religious coping was more closely related to problem-focused coping, which was also supported by multigroup confirmatory factor analysis. The results of the present study thus illustrate that investigating the role of religious coping requires more complex approaches than attempting to assign it to one higher order factor, such as problem- or emotion-focused coping, and that the variability of findings reported by previous studies on the function of religious coping may partly be due to variability in religiosity and spirituality across samples.

Evidence of stochastic resonance in an auditory discrimination task may reflect response bias.

Stochastic resonance is a mechanism that improves the detection of weak periodic signals when an optimal level of background noise is present. This counterintuitive concept is thought to involve a cooperative effect that arises out of a physical coupling between deterministic and random dynamics in nonlinear systems. We report the results of three psychophysical experiments designed to probe the auditory system for evidence of stochastic resonance. In all three experiments, participants judged which of two 1000-Hz tones was greater in intensity, with one of the tones embedded in a background of Gaussian noise. Experiment 1 used a two-alternative forced choice task and provided evidence of enhanced discriminability at an optimal level of noise. The aim of Experiment 2 was to determine whether the apparent enhancement observed in Experiment 1 was due to sensory processes or to a response bias. Receiver operating characteristic analysis supported an explanation based on decision processes, rather than a genuine sensory enhancement. An additional experiment (Experiment 3) was used to discount experimental artifacts.