Exploring the blood volume amplitude and pulse transit time during anger recall in patients with coronary artery disease

The effect of background audio and audiovisual stimuli on students' autonomic responses during and after an experimental academic examination

BACKGROUND

Due to the Covid-19 pandemic lockdown during the online-distant education period, certain students tended to combine their courses and homework with TV or social media news or other media content, such as classical music, including a wealth of audio and audiovisual stimuli. As the audio and audiovisual stimuli existing in a learning environment may affect students' autonomic nervous system (ANS) responses negatively, the present study aimed to monitor the impact of background TV, classical music, and silence on students' ANS activity represented by heart rate (HR), heart rate variability (HRV), blood volume amplitude (BVA), and skin conductance level (SCL) during and after an experimental academic examination.

METHOD

Seventy-six students were randomly allocated to background TV, classical music, or silence groups. The experiment with repeated measures design consisted of four consecutive periods: baseline, anticipation, challenge, and recovery, lasting 4 min each.

RESULTS

Within-subject analyses indicated significant HRV decrement only in the background TV group. Regardless of the experimental groups, HR and SCL increased while BVA decreased during the task. In addition, the between-subject analysis showed that the background TV group experienced significantly larger changes in HR and HRV parameters compared to the other experimental groups relative to their respective baseline measurements.

CONCLUSIONS

Based on these results, we concluded that relative to classical music and silence, background TV, including audiovisual and verbal stimuli, extant in a learning environment might raise students' sympathetic activity. Further, classical music, without lyrics, may suppress the withdrawal of vagal activity and elevate the autonomic regulation capacity during the academic reading comprehension task. HRV is a more valid and reliable indicator of students' autonomic responses during a challenging academic task.

The Impact of Stretching Intensities on Neural and Autonomic Responses: Implications for Relaxation

Stretching is an effective exercise for increasing body flexibility and pain relief. This study investigates the relationship between stretching intensity and relaxation effects, focusing on brainwaves and autonomic nervous system (ANS) activity. We used a crossover design with low- and high-intensity conditions to elucidate the impact of varying stretching intensities on neural activity associated with relaxation in 19 healthy young adults. Participants completed mood questionnaires. Electroencephalography (EEG) and plethysmography measurements were also obtained before, during, and after stretching sessions. The hamstring muscle was targeted for stretching, with intensity conditions based on the Point of Discomfort. Data analysis included wavelet analysis for EEG, plethysmography data, and repeated-measures ANOVA to differentiate mood, ANS activity, and brain activity related to stretching intensity. Results demonstrated no significant differences between ANS and brain activity based on stretching intensity. However, sympathetic nervous activity showed higher activity during the rest phases than in the stretch phases. Regarding brain activity, alpha and beta waves showed higher activity during the rest phases than in the stretch phases. A negative correlation between alpha waves and sympathetic nervous activities was observed in high-intensity conditions. However, a positive correlation between beta waves and parasympathetic nervous activities was found in low-intensity conditions. Our findings suggest that stretching can induce interactions between the ANS and brain activity.

Affective Computing Based on Morphological Features of Photoplethysmography for Patients with Hypertension

Negative and positive emotions are the risk and protective factors for the cause and prognosis of hypertension. This study aimed to use five photoplethysmography (PPG) waveform indices and affective computing (AC) to discriminate the emotional states in patients with hypertension. Forty-three patients with essential hypertension were measured for blood pressure and PPG signals under baseline and four emotional conditions (neutral, anger, happiness, and sadness), and the PPG signals were transformed into the mean standard deviation of five PPG waveform indices. A support vector machine was used as a classifier. The performance of the classifier was verified by using resubstitution and six-fold cross-validation (CV) methods. Feature selectors, including full search and genetic algorithm (GA), were used to select effective feature combinations. Traditional statistical analyses only differentiated between the emotional states and baseline, whereas AC achieved 100% accuracy in distinguishing between the emotional states and baseline by using the resubstitution method. AC showed high accuracy rates when used with 10 waveform features in distinguishing the records into two, three, and four classes by applying a six-fold CV. The GA feature selector further boosted the accuracy to 78.97%, 74.22%, and 67.35% in two-, three-, and four-class differentiation, respectively. The proposed AC achieved high accuracy in categorizing PPG records into distinct emotional states with features extracted from only five waveform indices. The results demonstrated the effectiveness of the five indices and the proposed AC in patients with hypertension.

Differences in the Course of Physiological Functions and in Subjective Evaluations in Connection With Listening to the Sound of a Chainsaw and to the Sounds of a Forest

We explored differences in the course of physiological functions and in the subjective evaluations in response to listening to a 7-min recording of the sound of a chainsaw and to the sounds of a forest. A Biofeedback 2000x-pert apparatus was used for continual recording of the following physiological functions in 50 examined persons: abdominal and thoracic respiration and their amplitude and frequency, electrodermal activity (skin conductance level), finger skin temperature, heart rate (pulse, blood volume pulse and blood volume pulse amplitude) and heart rate variability (HRV). The group of 25 subjects listening to the sound of a chainsaw exhibited significantly lower values of blood volume pulse amplitude, lower values in peak alpha frequency HRV and higher values in peak high-frequency HRV. In the time interval from 80 s to 209 s, in which the two groups showed the greatest differences, lower values of blood volume pulse were also recorded while listening to the sound of a chainsaw. Listening to the sound of a chainsaw is associated with a greater feeling of fatigue and higher tension, while listening to the sounds of a forest is even considered to elicit feelings of improved learning abilities. The assumption that listening to the sound of a chainsaw results in higher defense arousal was confirmed. The greater variability which is exhibited by a majority of physiological functions while listening to the forest sounds may also be an innovative finding. It seems that there are two types of arousal (sympathetic and parasympathetic) following from correlations between physiological functions and subjective assessment. Low values of blood volume pulse amplitude are especially important from the health perspective. They correspond to the amount of vasoconstriction which occurs in the endothelial dysfunction related to increased mortality, incidence of myocardial infarction, leg atherosclerosis and topically to COVID-19.