A Psychophysiological Study of Lavender Odorant

Transcription

1 Memoirs of Osaka Kyoiku University, Ser. DI, Vol. 47, No. 2, pp (January, 1999) A Psychophysiological Study of Lavender Odorant Naoyasu MOTOMURA, Akihiro SAKURAI and Yukiko YOTSUYA Department of Health Science, Osaka Kyoiku University, Kashiwara, Osaka , Japan (Received June 30, 1998) In the present experiment the effect of the lavender odorant to human beings was investigated. Japanese version of Cox and Mackay's stress / arousal adjective checklist (J-SACL), blood pressure, heart rate, stroop test, non-spatial working memory task and the computed electroencephalography (ceeg) was performed before and after the lavender odorants stimulation. The results indicated that lavender odorants have an anti-stress effect and reduce the arousal state in J-SACL, although lavender odorants did not influence blood pressure, heart rate, stroop test and non-spatial working memory task. Furthermore, the power spectrum of theta 1 (F4) was increased and beta 1 waves in T3, 01, P4 and F4 were decreased in the lavender stimulated group. These results suggest that the lavender odorants reduce an electrophysiological arousal state. Key Words: EEG, Stress, Stroop test, Non-spatial working memory, Lavender I Introduction Aromatherapy has been very popular in recent years and the effect of the odorants to mental health has been known from the ancient era. However, we have not had enough objective informations about the influence of odorants stimulation to human beings. Therefore, we conducted detailed psychophysiological and neuropsychological studies of the lavender odorants for human beings. In the present study we adopted Japanese version of Cox and Mackay's stress/arousal adjective checklist (J-SACL) for checking stress, blood pressure, heart rate and electroencephalography for checking physiological parameter and stroop test and non-spatial working memory task for frontal lobe function before and after the lavendor stimulation. II Material and methods Forty-two healthy college students with informed consent were participated in this study. These subjects were divided into three groups to attend three conditions, that is, psychologically stressful condition, psychologically stressful condition with lavender odorants and non-stressful condition. The subjects of

2 282 Naoyasu MOTOMURA, Akihiro SAKURAI and Yukiko YOTSUYA three groups were matched age, sex and educational level (Table 1). Table 1 Subjects N Age Sex (male/female) 1) Psychologically stressful 2) Psychologically stressful with lavender odorants 3) Non-stressful condition condition condition (1.3) 20.7(1.2) 22.2(1.1) 7/7 7/8 6/7 Psychologically stressful condition was made by staying silently without doing nothing in a sound protect room (2 X 2 X 3 m) for 20 minutes. Three milliliter of the lavender essential oil was used for odorant stimulation and lavender was diffused by a special diffuser (Metron aromastream) for 20 minutes. In each condition, Japanese version of Cox and Mackay's stress / arousal adjective checklist (J-SACL), blood pressure and heart rate were performed before and after the conditions. Cox and Mackay's stress / arousal adjective checklist (SACL) was firstly developed by Cox and Mackay (1985) and translated in Japanese by Hatta et al. (1992). Cox and Mackay developed a convenient inventry to measure subjective degrees of mental stress,which was called the stress/arousal adjective checklist (SACL). The checklist contains two dimensions. One dimension relates to feelings of unpleasantness or hedonic tone(stress) and the other to wakefulness or vigour (arousal) tone. According to Mackay et al. (1978), the stress dimension reflects the perceived favourability of the external environment, while the arousal factor relates to ongoing autonomic and somatic activities. Japanese version of SACL(J-SACL) was standardized by Hatta et al. (1992) and reliability and validity was also examined by Hatta et al. (1992). Blood pressure and heart rate were measured using an automatic degital sphygmomanometer (Omron HEM-706). Stroop test, non-spatial working memory task, the computed electroencephalography (ceeg) was performed only before and after the psychologically stressful conditions with odorants stimulation. Stroop test is a special cognitive task which is thought to be a frontal lobe task. We developed this test according to Bench et al. (1991). Non-spatial working memory task was developed according to Cohen et al. (1992). Subjects observed random sequences of letters appearing one at a time in the center of a visual display and were instructed to respond by pressing a button on a response box. Stimuli were presented for 500 ms, with an interstimulus interval of 1000 msec. Stimulus presentation was controlled by Machintosh Color Classics computer, using superlab software. In the control task, a target was any occurrence of the letter " X " (0 back test). In the memory task, targets were any letter that repeated with exactly one intervening nonidentical letter (2-back test). Target frequency and the frequency of repeated letters were matched in the two tasks. This, the only differences between the

3 A Psychophysiological Study of Lavender Odorant283 tasks were the appearance of the letter "X" in the control but not the memory task, and the instructions given to subjects. Both the control and memory tasks required that subjects monitor sequences of letters presented visually one at a time, encode each letter, evaluate its identity, and respond to a target by pressing a button. However, the memory task had the additional requirement that the subject keep in mind both the identity and order of the two previous letters and continuously update this mental record as the sequence progressed. These operations are central to the concept of working memory, as it has been defined in cognitive psychology (Baddeley 1986). Each task was run in 60-s blocks, during which scans were aquired. Subjects were instructed not to vocalize or subvocalize stimuli in either of the tasks, but to do the task in the heads. In this non-spatial working memory task we adopted 0-back test, which is thought to be an attentional task and 2-back test, which is thought to be a working memory task. NEC Synafax 1000 EEG machine was used for EEG recordings and monopolar montage of scalp electrodes placed on eight areas (F3, F4, C3, C4, P3, P4, 01, 02) with reference on ear lobe of the same side according to the international 10/20 system. EEGs were recorded and performed FFT and power spectrum analyses with computer program. EEG was digitized and summarized in nine EEG frequency bands (delta up to 3.5 Hz; theta 1, Hz; theta 2, Hz; alpha 1, ; alpha 2, Hz; alpha 3, Hz; beta 1, Hz; beta 2, Hz; beta 3, 32.0 Hz up). ANOVA and post hoc analysis using Bonferroni method was adopted as a statistical analysis. III Results 1) J-SACL: The results of the SACL scores were shown in Table 2. The score of SACL was divided into two types, that is, stress points and arousal points. In nonstress condition both stress and arousal points were least. In psychologically stressful condition both scores were increased. However, both scores were reduced by lavender stimulation. There was a clear main effect among the factors and the conditions (p<0.01). The clear interactions were found(p<0.01). Subordinate analysis revealed that there was differences between the scores of stress conditions and other two conditions in both the scores of stress factor (p<0.01) and arousal factor (p<0.01). These results suggest that lavender odorants have an anti-stress effect and reduce an arousal state. 2) Blood pressure and heart rate: The results of the maximum blood pressure and minimum blood pressure were presented in Table 3, 4 and 5. Main effect or the interference was not found in blood pressure and heart rate among these conditions. 3) Stroop test: The results of the Stroop effects were shown in Table 6. There was not any main effects or interference effects in the data of Stroop effects.

4 Naoyasu MOTOMURA, Akihiro SAKURAI and Yukiko YOTSUYA Table 2 SACL of three conditions Table 3 Maximum blood pressure before and after the each conditions Table 4 Minimum blood pressure before and after the each conditions Table 5 Heart rate before and after the each conditions Table 6 Stroop effect before and after the each conditions These results indicated that Stroop effects did not change before and after the three conditions. 4) Non-spatial working memory task: The results of the nonspatial working memory task was showed in Table 7, 8, 9 and 10. Main effect or the interference was not found both in 0-back or 2-back task among these conditions. 5) ceeg: In the lavender stimulated group the power spectrum of theta 1 (F4) was increased and beta 1 waves in T3, 01, P4 and F4 were decreased. These results suggest that the lavender odorants reduce an electrophysiological arousal

5 A Psychophysiological Study of Lavender Odorant Table 7 Reaction times of 0-back test before and after the each conditions Table 8 Number of errors of 0-back test before and after the each conditions Table 9 Reaction times of 2-back test before and after the each conditions Table 10 Number of errors of 2-back test before and after the each conditions state in electrophysiologically. IV Discussion In the present experiments the lavender odorants showed the clear anti-stress effect and reduced the arousal state in J-SACL test. Hatta et al.(1992) reported that music tapes reduce mental stress by using J-SACL test and we could find the similar effect in the lavender odorants. However, we could not find any influences of Lavendor odorants in the blood pressure, heart rate, Stroop test and non-spatial working memory task. Further studies must be done using other odorants or other physiological and psychological parameter. In ceeg study we found the clear evidences that the lavender odorants reduce an electrophysiological arousal state in electrophysiologically. EEG studies have been used to evaluate odor response in humans (Monchieff 1962). Harada et al. (1996) reported that the alpha 2 wave was activated over the fronto-temporal area, whereas the delta wave and the theta wave were suppressed using

6 286Naoyasu MOTOMURA, Akihiro SAKURAI and Yukiko YOTSUYA topographic spectral mapping during odorant stimulation with methylcyclopentenonolone. Koga et al. (1989) investigated the effect of the Jasmine flower note, Woody herb note and Citrus floral note to EEG. They concluded that all three odorants increased the alpha power spectrums and suggested that the favorite of the odorants may be related to the power spectrum of the alpha waves. Motomura et al. (1995) investigated the comparative studies of the effect of the lavender odorants and the cedar odorants. We concluded that the cedar odorants have more arousal effect than that of the lavender odorants. These results are consistent with the data of Yagyu et al. (1992). They demonstrated that the lemon odorants have more arousal effect than that of the lavender odorants. Recently, Harada et al. (1990) also reported that the coherence in the delta band decreased in the frontal region, while that in the alpha 1 and alpha 2 bands increased in the temporal region during odorant stimulation with methylcyclopentenolone. During odorant stimulation with scatol, the coherence in the delta band decreased in the frontal region, while that in the alpha 2 bands increased. These results indicate that EEG changes are influenced by the kinds or the features of the odorants. Lorig et al. (1989) examined EEG activity in response to food imagery in the absence of odors. During imagery of food, the changes in EEG activity were indicated. These findings were interpreted as suggesting that direct qualities of odors and their indirect cognitive attributes may affect EEG recordings. Odorant stimulations have been thought to be related with arousal state. Motokizawa et al. (1973) reported that the olfactory arousal response is produced by the projection of olfactory impulses to the mesencephalic reticular formation. These evidences suggest that the lavender odorant might effect the reticular formations. References 1) 2) 3) 4) 5) 6) 7) 8) 9) Baddeley AD. Working memory. New York: Oxford University Press 1986 Bench CJ et al. Investigation of the functional anatomy of attention using the stroop test. Neuropsychologia 1991; 31: Cohen JD et al. Activation of the prefrontal cortex in a nonspatial working memory task with functional MRI. Human Brain Mapping 1994; 1: Cox T et al. The measurement of self-reported stress and arousal. Br J Psychol 1985;76: Harada H et al. Topographic EEG changes during odorant stimulation. Brain topography 1990; 3: Harada H et al. Coherence analysis of EEG changes during odor stimulation in humans. J Laryngol and Otol 1996; 110: Hatta T et al. Can antistress music tapes reduce mental stress? Stress medicine 1991; 7: Koga Yet al. The influence of odors to the brain function-a psychophysiological studies. Flegrance Journal 1989; 17: Lorig TS. Human EEG and odor response. Progress in Neurobiology 1989; 33:

7 A Psychophysiological Study of Lavender Odorant 10) 11) 12) 13) 14) Mackay CJ et al. An inventry for the measurement of selfreported stress and arousal. Br J Clin Psychol 1978;17: Moncrieff RW. Effect of odors on EEG records. Progress in Neurobiol 1962; 33: Motokizawa F et al. Neural pathway associated with the EEG arousal response by olfactory stimulation. Electroencephal and Clin Neurophysiol 1973; 35: Motomura N et al. Electroencephalographic changes due to the stimulation of the cedar odorants. Memoire of Osaka Kyoiku University 1995; 43: Yagyu T et al.the changes of the background EEG activities and P300 after the stimulation of the odorants. Clin Encephal 1992; 34: