Basic emotions induced by odorants: a new approach based on autonomic pattern results

Autonomic responses during inhalation of natural fragrance of “Cedrol” in humans

It is well known that odors affect behaviors and autonomic functions. Previous studies reported that some compounds in cedar wood essence induced behavioral changes including sedative effects. In the present study, we analyzed cardiovascular and respiratory functions while subjects were inhaling fumes of pure compound (Cedrol) which was extracted from cedar wood oil. Vaporized Cedrol (14.2+/-1.7 microg/l, 5 l/min) and blank air (5 l/min) were presented to healthy human subjects (n=26) via a face mask, while ECGs, heart rate (HR), systolic blood pressure (SBP), diastolic BP (DBP), and respiratory rates (RR) were monitored. Statistical analyses indicated that exposure to Cedrol significantly decreased HR, SBP, and DBP compared to blank air while it increased baroreceptor sensitivity. Furthermore, respiratory rate was reduced during exposure to Cedrol. These results, along with the previous studies reporting close relationship between respiratory and cardiovascular functions, suggest that these changes in respiratory functions were consistent with above cardiovascular alterations. Spectral analysis of HR variability indicated an increase in high frequency (HF) component (index of parasympathetic activity), and a decrease in ratio of low frequency to high frequency components (LF/HF) (index of sympathovagal balance) during Cedrol inhalation. Furthermore, Cedrol inhalation significantly decreased LF components of both SBP and DBP variability, which reflected vasomotor sympathetic activity. Taken together, these patterns of changes in the autonomic parameters indicated that Cedrol inhalation induced an increase in parasympathetic activity and a reduction in sympathetic activity, consistent with the idea of a relaxant effect of Cedrol.

Somatovisceral response following osteopathic HVLAT: a pilot study on the effect of unilateral lumbosacral high-velocity low-amplitude thrust technique on the cutaneous blood flow in the lower limb

INTRODUCTION

Spinal manipulative treatment is widely used among manual therapists, although knowledge regarding the absolute physiological effects has not been clearly established. In this study, 20 healthy male subjects underwent a unilateral high-velocity low-amplitude thrust (HVLAT) to the lumbosacral junction, while the cutaneous blood flow in the corresponding dermatome of the lower limb was monitored.

METHODS

Subjects underwent a sham manipulation before the actual manipulation and acted as their own control. Laser Doppler flowmetry was used to measure relative changes in the cutaneous blood flow over the L5 dermatome for 5 minutes before the sham manipulation, for 5 minutes between the sham and the actual manipulation, and for 5 minutes after the spinal adjustment. Analysis of variance (ANOVA) and Tukey post hoc analysis was used in the interpretation of the data.

RESULTS

Twelve nonsmoking subjects, who received a successful HVLAT manipulation, showed a significant increase (P <.001) in blood perfusion, both ipsilaterally and contralaterally. Six smokers responded with a significant decrease in blood flow ipsilaterally (P <.01) and contralaterally (P <.001) after HVLAT manipulation.

CONCLUSION

The results from this study support previous published hypotheses that spinal adjustments outside the region of the sympathetic outflow result in an increase in cutaneous blood flow. Further studies will be needed to confirm the outcome of this study, and more knowledge is needed regarding the specific neurophysiological effects of spinal manipulation.

Gender influence on emotional responses to primary tastes

Several studies have examined the gender differences in the area of emotion, but few data are available in the field of gustation. Yet, such differences are observed in clinical manifestations of nutritional disorders, such as a greater incidence of carbohydrate cravings in women. The aim of this study was consequently to examine the influence of gender on emotional responses to taste, by comparing autonomic responses and basic emotions associated with primary tastes between men and women. Thirty-four subjects (17 males, 17 females, mean age=28) participated in the experiment. Taste stimuli were solutions of 0.3 M sucrose (sweet), 0.15 M NaCl (salty), 0.02 M citric acid (sour) and 0.00015 M quinine sulfate (bitter). Evian mineral water served as the diluent and control (neutral taste). Five autonomic parameters [skin potential (SP) and resistance (SR), skin blood flow (SBF) and temperature (ST), instantaneous heart rate (IHR)] were simultaneously and continuously recorded when subjects tasted the five solutions. The patterns of autonomic responses, obtained for each primary taste and each subject, were transcribed into one of the six basic emotions defined by Ekman (happiness, surprise, sadness, fear, anger and disgust), according to a previously described method for odorants. Results evidenced that the mean variations of each autonomic parameter did not significantly differ between men and women, even if skin resistance and cardiac responses were stronger in men than in women. Concerning the basic emotions associated with each primary taste, a similar distribution for men and women was obtained for sweet, bitter and control solutions, whereas more differences were observed for salt (P=.02) and sour solutions.

Psychophysiological correlates of affects in human olfaction

Pleasantness and arousal have been identified as the main dimensions of affective responses to environment. Pleasantness is defined as the degree of favorable feelings a subject can experience under given circumstances. Arousal is defined as the degree of excitement (general activation) the subject feels under these circumstances. In visual and auditory modalities, many studies using measures such as facial electromyographic (EMG) activity and skin conductance (SC) have found those parameters to vary as a function of either pleasantness or arousal: for example, facial corrugator EMG activity covaries with the pleasantness dimension, while SC increases together with arousal. The first objective of this research is to study the possible covariation between peripheral measures and pleasantness/arousal in olfaction. We also examined the effect of odor intensity on facial and autonomic variations. The second objective was to investigate whether odors could evoke verbally specific emotions (e.g. joy, anger, fear, surprise, disgust or sadness) and also induce specific patterns of peripheral responses. Participants were exposed to 12 different odors while their facial and autonomic parameters were recorded, and estimated their intensity, pleasantness, and arousal capacity. Then, they chose between seven words for emotions (fear, anger, sadness, surprise, neutral, joy or disgust) to describe their reaction to the odor. As in vision, olfactory pleasantness covaries (negatively) with facial activity of the corrugator muscle, and arousal (positively) with skin conductance. No relationships were observed between physiological changes and variations in perceived intensity. Results also showed that emotions of "disgust" and "joy" were more frequently evoked verbally than any other emotions, and that only facial EMG activity distinguishes them (e.g. "disgust" vs. "joy" and "neutral state"). The results are discussed in terms of possible existence of two brain systems (defensive and appetitive), each of them being able to vary in metabolic arousal.

Alleviating effects of plant-derived fragrances on stress-induced hyperthermia in rats

In the present study, the effects of exposure to plant-derived odors on the autonomic and behavioral responses to novel environment were examined in rats. Male rats (n=42) carrying a telemetry transmitter were individually housed, and on the test day each rat was transferred to a new cage containing bedding that had been sprayed immediately before testing with 200 microl of 0.03% dilution of either lavender essential oil, green leaf odor (a mixture of hexenol and hexenal), alpha-pinene, or solvent (triethyl citrate) as a control. Following the transfer to this novel environment, the body temperature of the rats increased by nearly 1 degrees C, showing a stress-induced hyperthermia. Stress-induced hyperthermia was attenuated by the green odor and the alpha-pinene, but not by the lavender or solvent. There was no clear effect of fragrances on heart rate or behavioral responses. These results suggest that plant-derived fragrances, such as green odor and alpha-pinene, have calming effects on autonomic stress response to novel environments.

The color of odors

The interaction between the vision of colors and odor determination is investigated through lexical analysis of experts' wine tasting comments. The analysis shows that the odors of a wine are, for the most part, represented by objects that have the color of the wine. The assumption of the existence of a perceptual illusion between odor and color is confirmed by a psychophysical experiment. A white wine artificially colored red with an odorless dye was olfactory described as a red wine by a panel of 54 tasters. Hence, because of the visual information, the tasters discounted the olfactory information. Together with recent psychophysical and neuroimaging data, our results suggest that the above perceptual illusion occurs during the verbalization phase of odor determination.

The psychobiology of obsessive-compulsive disorder: how important is the role of disgust?

Psychobiologic models of obsessive-compulsive disorder (OCD) have focused on cortico-striatal-thalamic-cortical (CTSC) circuits, noting normal function in cognitive and motoric procedural strategies. Such models have relied on the classification of OCD as an anxiety disorder, seldom exploring other relevant emotions. Based on the hypothesis that a central emotion in OCD is disgust, the authors review the literature on its psychobiology and its relevance to current models of OCD. There are important parallels between the psychobiology of OCD and that of disgust. Obsessive- compulsive disorder may be conceptualized in terms of a false contamination alarm in which disgust plays a crucial organizing or embodying role, not only at a basic brain level, but also in terms of the psychosocial aspects of the disorder. Just as psychobiologic models of panic disorder and post- traumatic stress disorder have been strengthened by the inclusion of preclinical work on amygdala-mediated fear conditioning, so findings on disgust and its mediating CSTC circuits may generate useful hypotheses for OCD research.