EEG Revealed That Fragrances Positively Affect Menopausal Symptoms in Mid-life Women

Time-Dependent Analysis of Human Neurophysiological Activities during an Ecological Olfactory Experience

It has been demonstrated that odors could affect humans at the psychophysiological level. Significant research has been done on odor perception and physiological mechanisms; however, this research was mainly performed in highly controlled conditions in order to highlight the perceptive phenomena and the correlated physiological responses in the time frame of milliseconds. The present study explored how human physiological activity evolves in response to different odor conditions during an ecological olfactory experience on a broader time scale (from 1 to 90 s). Two odors, vanilla and menthol, together with a control condition (blank) were employed as stimuli. Electroencephalographic (EEG) activity in four frequency bands of interest, theta, alpha, low beta, and high beta, and the electrodermal activity (EDA) of the skin conductance level and response (SCL and SCR) were investigated at five time points taken during: (i) the first ten seconds of exposure (short-term analysis) and (ii) throughout the entire exposure to each odor (90 s, long-term analysis). The results revealed significant interactions between the odor conditions and the time periods in the short-term analysis for the overall frontal activity in the theta (p = 0.03), alpha (p = 0.005), and low beta (p = 0.0067) bands, the frontal midline activity in the alpha (p = 0.015) and low beta (p = 0.02) bands, and the SCR component (p = 0.024). For the long-term effects, instead, only one EEG parameter, frontal alpha asymmetry, was significantly sensitive to the considered dimensions (p = 0.037). In conclusion, the present research determined the physiological response to different odor conditions, also demonstrating the sensitivity of the employed parameters in characterizing the dynamic of such response during the time. As an exploratory study, this work points out the relevance of considering the effects of continuous exposure instead of short stimulation when evaluating the human olfactory experience, providing insights for future studies in the field.

Regulation of brain cognitive states through auditory, gustatory, and olfactory stimulation with wearable monitoring

Inspired by advances in wearable technologies, we design and perform human-subject experiments. We aim to investigate the effects of applying safe actuation (i.e., auditory, gustatory, and olfactory) for the purpose of regulating cognitive arousal and enhancing the performance states. In two proposed experiments, subjects are asked to perform a working memory experiment called n-back tasks. Next, we incorporate listening to different types of music, drinking coffee, and smelling perfume as safe actuators. We employ signal processing methods to seamlessly infer participants' brain cognitive states. The results demonstrate the effectiveness of the proposed safe actuation in regulating the arousal state and enhancing performance levels. Employing only wearable devices for human monitoring and using safe actuation intervention are the key components of the proposed experiments. Our dataset fills the existing gap of the lack of publicly available datasets for the self-management of internal brain states using wearable devices and safe everyday actuators. This dataset enables further machine learning and system identification investigations to facilitate future smart work environments. This would lead us to the ultimate idea of developing practical automated personalized closed-loop architectures for managing internal brain states and enhancing the quality of life.

Psychophysiological Responses of College Students to Audio-Visual Forest Trail Landscapes

Forest trails provide urban residents with contact with nature that improves health and well-being. Vision and hearing are important forms of environmental perception, and visual and auditory stimuli should not be overlooked in forest trail landscapes. This study focused on the health benefits of the audio-visual perception of forest trail landscapes. Forest density (FD) and forest sounds (FS) in forest trail landscapes were examined as visual and auditory variables, respectively. FD was divided into three levels: high (Hd), medium (Md), and low density (Ld). FS were divided into four levels: quiet natural and anthropogenic sounds (QnQa), quiet natural and loud anthropogenic sounds (QnLa), loud natural and quiet anthropogenic sounds (LnQa), and loud natural and loud anthropogenic sounds (LnLa). The levels of these two variables were combined to create 12 conditions. A total of 360 college students were randomly assigned to 12 groups (mapping onto the 12 conditions; N=30 per group). All subjects performed the same 5-min high-pressure task indoors, followed by a 5-min recovery period of experiencing a simulated forest trail landscape (viewing pictures and listening to sounds). Brain waves, blood pressure, blood oxygen saturation (SpO2, measured with a finger monitor), the pulse rate, and mood indicators were collected to analyse the physiological and psychological responses to the audio-visual forest trail landscapes. The results indicated that higher FD and lower FS improved health benefits. The interaction between FD and FS revealed a pattern of combinations that facilitated stress reduction and positive mood recovery. These results are of theoretical value in that they indicate important audio-visual characteristics of forest trail landscapes. In terms of practical applications, these findings support the construction of urban forest trails to provide health benefits.

Study on the Effect of Mentha × piperita L. Essential Oil on Electroencephalography upon Stimulation with Different Visual Effects

Essential oils have long been used to fight infections and treat various diseases. Peppermint (Mentha × piperita L.) is an herbal medicine that has been widely used in daily life since ancient times, and it has a wide range of applications in food, cosmetics, and medicine. Mint oil is refreshing because of its cool and comfortable smell; therefore, it is often used in ethnopharmacological studies. The present study investigated the effects of peppermint essential oil in electroencephalographic activity response to various visual stimuli. The electroencephalographic changes of participants during peppermint essential oil inhalation under white, red, and blue colour stimulations were recorded. A rapid Fourier transform analysis was used to examine the electroencephalograph power spectra of the various microstates induced by inhaling the oils. Peppermint essential oil had various effects on the brain when subjected to different visual stimuli. Alpha waves increased in the prefrontal area in the white-sniffing group, which facilitated learning and thinking. In the blue-sniffing group, the changes were less pronounced than those in the red group, and the increased alpha wave activity in the occipital area was more controlled, indicating that the participants’ visual function increased in this state. Based on EEG investigations, this is the first study to indicate that vision influences the effects of peppermint essential oils. Hence, the results of this study support the use of essential oils in a broader context to serve as a resource for future studies on the effects of different types of essential oils.