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Relationships Between Gum-Chewing and Stress
Abstract
Studies have shown that chewing is thought to affect stress modification in humans. Also, studies in animals have demonstrated that active chewing of a wooden stick during immobilization stress ameliorates the stress-impaired synaptic plasticity and prevents stress-induced noradrenaline release in the amygdala. On the other hand, studies have suggested that the right prefrontal cortex (PFC) dominates the regulation of the stress response system, including the hypothalamic-pituitary-adrenal (HPA) axis. The International Affective Digitized Sounds-2 (IADS) is widely used in the study of emotions and neuropsychological research. Therefore, in this study, the effects of gum-chewing on physiological and psychological (including PFC activity measured by NIRS) responses to a negative stimulus selected from the IADS were measured and analyzed. The study design was approved by the Ethics Committee of Tokyo Dental College (No. 436).
We studied 11 normal adults using: cerebral blood oxygenation in the right medial PFC by multi-channel NIRS; alpha wave intensity by EEG; autonomic nervous function by heart rate; and emotional conditions by the State-Trait Anxiety Inventory (STAI) test and the 100-mm visual analogue scale (VAS). Auditory stimuli selected were fewer than 3.00 in Pleasure value. Sounds were recorded in 3 s and reproduced at random using software. Every task session was designed in a block manner; seven rests: Brown Noise (30 s) and six task blocks: auditory stimuli or auditory stimuli with gum-chewing (30 s). During the test, the participants’ eyes were closed. Paired Student’s t-test was used for the comparison (P < 0.05). Gum-chewing showed a significantly greater activation in the PFC, alpha wave appearance rate and HR. Gum-chewing also showed a significantly higher VAS score and a smaller STAI level indicating ‘pleasant’. Gum-chewing affected physiological and psychological responses including PFC activity. This PFC activation change might influence the HPA axis and ANS activities. In summary, within the limitations of this study, the findings suggest that gum-chewing reduced stress-related responses. Gum-chewing might have a possible effect on stress coping.
... In contrast, there was no correlation between anxiety levels and pain scores in participants using chewing gum (Ireland et al., 2017). These results are similar to other research findings, which demonstrates that chewing gum reduces stress-related responses and, therefore, may indirectly affect pain perception and the need for analgesia (Konno et al., 2016). ...
... Many studies have shown that chewing gum can help reduce perceived daily stress levels associated with specific emotions and potentially lead to increased feelings of calmness and relaxation (Ono et al., 2008;Zibell & Madansky, 2009;Smith & Woods, 2012;Weijenberg & Lobbezoo, 2015;Konno et al., 2016). In another study, adults were made to chew chewing gum for at least 5 minutes twice a day for 14 days, and measurements were made after two weeks. ...
Amaç: Nedeni açıklanamayan infertil kadınlarda sakız çiğnemenin stres düzeyi üzerine etkisinin incelenmesidir. Yöntem: Üçüncü basamak bir merkezde In-vitro Fertilizasyon tedavisi alan 61 kadın çalışmaya dahil edildi. Araştırmada randomize kontrollü deneysel bir tasarım oluşturuldu. Günde en az 2 kez 5 dakika sakız çiğneyen grup “Deney Grubu-1”, en az 2 kez 20 dakika sakız çiğneyen grup “Deney Grubu-2”, sakız çiğnemeyen grup ise “Kontrol Grubu” olarak adlandırıldı. İnfertil kadınların üreme bilgileri ve stres düzeyleri verileri Tanıtıcı Bilgi Formu ve Fertilite Sorun Envanteri ile toplanmıştır. Bulgular: Gruplara göre sosyodemografik ve infertiliteye özgü özellikler arasında istatistiksel olarak anlamlı bir fark bulunmamıştır. Gruplar arası Fertilite Sorunu Envanteri ölçek puanlarının karşılaştırılmasında istatistiksel olarak anlamlı bir fark bulunamamıştır. Ancak Vaka 2 grubu zamanlara göre Fertilite Sorunu Envanteri alt ölçeklerinden çocuksuz yaşamın reddi ölçek puanı ortalama değerleri arasında istatistiksel olarak anlamlı bir fark bulunmuştur (p
... Therefore, methods for attenuating stress in daily life should be established to maintain health. Chewing is considered an effective stress coping behavior [2,[6][7][8][9]. Mastication affects the activity of the HPA system and autonomic nervous system [2]. ...
Mastication interventions have previously been shown to alleviate acute stress. However, the relationship between masticatory performance and stress response among individuals remains unclear. This study aimed to examine the relationship between masticatory ability and stress response in young women by measuring the autonomic nerve function and salivary α-amylase activity during psychosocial stress. Eighty women (aged 20.0 ± 1.9 years) were divided into either a low or high masticatory performance group, and the Trier Social Stress Test was conducted. Moreover, the autonomic function was measured at rest, immediately before stress, immediately after stress, and 10 min after stress. The salivary α-amylase activity was also measured at rest, 5 min after stress, and 15 min after stress. The visual analog scale (VAS) was used for subjective stress evaluation. There was a significant increase in the autonomic balance of both groups immediately before stress loading, but whilst the high masticatory ability group showed a return to resting-state levels after stress loading, the low masticatory ability group showed elevated levels after stress loading. Salivary α-amylase activity significantly increased 5 min after stress loading in the low, but not high, masticatory ability group. Furthermore, the VAS scores for tension and confusion after stress were significantly higher in the low masticatory ability group than in the high masticatory ability group. Our findings suggest that high masticatory performance may contribute to alleviating psychosocial stress. This is the first study to clarify the relationship between habitual masticatory performance and psychosocial stress suppression in young women.
... The PFC has been shown to be involved in the neural mechanism underlying stress reduction by chewing. 26 In rodents, chewing on wooden sticks during stress exposure attenuates anxiety-like behavior. 27 In humans, studies have shown that chewing gum during stress lowers salivary cortisol level and mental stress. ...
Prenatal stress (PS) causes anxiety in mothers and their offspring and chewing is a commonly observed behavior during maternal stress. Prolactin (PRL) is an anti‐anxiety factor that suppresses the hypothalamic–pituitary–adrenal axis. Here, we studied the roles of PRL, corticosterone (CORT), and their receptors in PS‐induced anxiety‐like behavior in dams and their offspring. We further investigated whether chewing during maternal stress could prevent PS‐induced harmful consequences. Pregnant rats were randomly divided into PS, PS + chewing, and control groups. Anxiety‐like behaviors of dams and their adolescent offspring were assessed using the open field test and elevated plus maze. Serum levels of PRL and CORT were measured by ELISA. Expression of mRNA and protein of PRLR and glucocorticoid receptor (GR) in the prefrontal cortex (PFC) were evaluated by qRT‐PCR and western blotting, respectively. Compared to the control rats, dams and their female offspring, but not male offspring, in the PS group showed increased anxiety‐like behaviors. The PS‐affected rats had a lower serum PRL level and increased PRLR expression in the PFC. In contrast, these rats had a higher serum CORT level and decreased GR expression in the PFC. Chewing ameliorated anxiety‐like behaviors and counteracted stress‐induced changes in serum PRL and CORT, as well as the expression of their receptors in the PFC. Conclusion: PS‐induced anxiety‐like behavior is associated with changes in the serum levels of PRL and CORT and expression of their receptors in the PFC. Moreover, chewing blunts the hormonal and receptor changes and may serve as an effective stress‐coping method for preventing PS‐induced anxiety‐like behavior.
... Recent gum chewing studies have reported the effects on cognitive performance [6][7][8], stress control [9][10][11][12] and others, together with brain activity in PFC. However, these relationships are still controversial. ...
Changes in NIRS signals are related to changes in local cerebral blood flow or oxy-Hb concentration. On the other hand, recent studies have revealed the effect of chewing gum on cognitive performance, stress control etc. which accompanied brain activity in the prefrontal cortex (PFC). However, these relationships are still controversial. To evaluate the chewing effect on PFC, NIRS seems to be a suitable method of imaging such results. When measuring NIRS on PFC, blood volume in superficial tissues (scalp, skin, muscle) might have some affect. The aim of the present study was to clarify the effect of the anterior temporal muscle on NIRS signals during gum chewing. Eight healthy volunteers participated. Two-channel NIRS (HOT-1000, NeU, Japan), which can distinguish total-Hb concentrations in deep tissue and superficial tissue layers, was used. In addition to a conventional optode separation distance of 3.0 cm, Hot 1000 has a short distance of 1.0 cm (NEAR channel) to measure NIRS signals that originate exclusively from surface tissues. NIRS probes were placed at Fp1 and Fp2 in the normal probe setting. The headset was displaced to the left in order to allow the left probe to be placed over the left anterior temporal muscle. In the normal setting, the superficial signal curve shows no notable change; however, the neural (calculated and defined in HOT-1000) and deep curves show an increase during the gum chewing task. At the deviated setting, all three signals show marked changes during the task. Total-Hb concentration in the deviated probe setting is significantly large (p < 0.05) than that of in the normal probe setting. When using gum chewing as a task, it would be better to consider a probe position carefully so that the influence of muscle activity on NIRS signal can be distinguished.
... One method that helps to reduce stress and anxiety and improve concentration and attention is chewing gum (Allen & Smith, 2012;Sasaki-Otomaru et al., 2011;Scholey, Robertson, Kennedy, Milne, & Wetherell, 2009;Smith & Woods, 2012). The neural mechanisms underlying the stress reducing effects of chewing gum involve the prefrontal cortex, which then affects the hypothalamic-pituitary-adrenal axis and autonomic nervous system activity (Konno et al., 2016;Kubo, Linuma, & Chen, 2015). Kamiya et al. (2010) showed that heightened activity in the ventral prefrontal cortex leads to increased activity of serotonergic neurons in the dorsal raphenucleus and a reduced nocioceptive flexion reflex. ...
Chewing gum is thought to increase focus via a reduction in stress and anxiety. Chewing gum contributes to success by improving short‐term memory. This study was conducted to determine the effect of chewing gum on stress, anxiety, depression, self‐focused attention, and exam success. A randomized controlled trial was conducted with a total of 100 students. In the long‐term (19 days) and short‐term (7 days) chewing gum groups, the pretest scores of depression, anxiety, and stress were significantly higher than the posttest scores. Although the posttest scores on the self‐focused attention subscale were higher than the pretest scores in long‐term chewing gum group, there was no significant difference between the pretest and posttest scores in this group. The academic success mean scores of the long‐term experimental group students were higher than those of the other groups. Students are recommended to chew gum before exams in order to overcome exam stress and to enhance exam success. However, chewing gum is not recommended in the long term for students who have difficulty focussing their attention.
... Gum-chewing influences the brain physiological and psychological responses, and evokes activation of the prefrontal cortex. Activation of the prefrontal cortex might also influence HPA axis activities[83]. Chewing increases cerebral blood flow and might thus decrease the risk of cognitive impairments[84]. Chewing itself may positively affect cerebral blood flow, alleviate stress, and therefore enhance cognitive function. ...
Mastication is mainly involved in food intake and nutrient digestion with the aid of teeth. Mastication is also important for preserving and promoting general health, including hippocampus-dependent cognition. Both animal and human studies indicate that mastication influences hippocampal functions through the end product of the hypothalamic-pituitary-adrenal (HPA) axis, glucocorticoid (GC). Epidemiologic studies suggest that masticatory dysfunction in aged individuals, such as that resulting from tooth loss and periodontitis, acting as a source of chronic stress, activates the HPA axis, leading to increases in circulating GCs and eventually inducing various physical and psychological diseases, such as cognitive impairment, cardiovascular disorders, and osteoporosis. Recent studies demonstrated that masticatory stimulation or chewing during stressful conditions suppresses the hyperactivity of the HPA axis via GCs and GC receptors within the hippocampus, and ameliorates chronic stress-induced hippocampus-dependent cognitive deficits. Here, we provide a comprehensive overview of current research regarding the association between mastication, the hippocampus, and HPA axis activity. We also discuss several potential molecular mechanisms involved in the interactions between mastication, hippocampal function, and HPA axis activity.
... This may be due to our patients not considering chewing gum to be an analgesic that would help alleviate their orthodontic pain. However, a recent experimental study has demonstrated that gum-chewing reduces stress-related responses and therefore may indirectly affect pain perception and the need for analgesia, by reducing the unwanted effects of anxiety (Konno et al. 2016). ...
Objectives: Pain is a common side effect of orthodontic treatment. An objective of this study, part of a large previously reported RCT on pain and analgesic use, was to determine the effect of anxiety on perceived pain and use of analgesia.
Methods: 1000 patients aged 11–17 years, undergoing upper and lower fixed appliance treatment in nine hospital departments were recruited into this two-arm parallel design randomised controlled trial. One arm was given sugar-free chewing gum and the other arm ibuprofen for pain relief. Neither the clinicians nor patients were blinded to assignment. In addition to recording pain experience and analgesic use for 3 days following appliance placement and first archwire change, each patient recorded their level of anxiety immediately following the fitting of the appliance and the first archwire change.
Results: 419 chewing gum group (84%) and 407 ibuprofen group (83%) questionnaires were returned following appliance placement, and 343 chewing gum group (70%) and 341 ibuprofen group (71%) questionnaires were returned following the first archwire change. The mean anxiety scores following fitting of the appliance and first archwire change were 2.7 (SD 2.1) and 1.6 (SD 1.8), respectively. There were weak but significant positive associations between anxiety scores and pain scores. Multi-level modelling produced a coefficient for anxiety of 0.23 (95% CI 0.17–0.28) for appliance placement, suggesting a small rise (0.23) on the 11-point pain scale for a one-point increase on the corresponding anxiety scale. Following archwire change, the corresponding coefficient was 0.32 (0.24–0.39). For ibuprofen use, again simple analyses suggested a relationship with anxiety. Multi-level logistic modelling produced an odds ratio for ibuprofen use of 1.11 (95% CI 1.07–1.15) at appliance placement and 1.21 (1.10–1.33) at the first archwire change. There was a 10–20% increase in the odds of using ibuprofen for each one-point increase on the anxiety scale. No such relationship was found between anxiety and chewing gum use. There were no adverse effects or harms reported during the trial. Approvals were granted by the Research Ethics Committee (08/H0106/139), R&D and MHRA (Eudract 2008-005522-36) and the trial was registered on the ISRCTN (79884739) and NIHR (6631) portfolios. Support was provided by the British Orthodontic Society Foundation.
Conclusions: There was a weak positive correlation between anxiety reported and pain experienced following both the initial fitting of the fixed appliances and at the subsequent archwire change. Patients that were more anxious tended to take more ibuprofen for their pain relief.
... Research has also shown that chewing gum positively affects postural stability (Kushiro and Goto, 2011). Finally, chewing gum reduces stress, fatigue, anxiety and depression and might have a possible effect on stress coping (Konno et al., 2016). Together, chewing gum has been known to benefit the bodily function of individuals. ...
... Overall, it would appear that chewing gum attenuates the sensory processing of external stressors and inhibits the propogation of stress-related information in the brain [24]. The neural mechanisms underlying the stress reducing effects of chewing gum involve the prefrontal cortex which then changes the HPA axis and ANS activity [25,26]. ...
The behavioral effects of chewing gum have been studied for over 80 years and much of the research has been concerned with increases in alertness and attention. Another line of research has addressed the issue of whether chewing gum reduces stress. This topic has been studied in the laboratory, in epidemiological studies and real-life interventions.
Relevance for patients:
The present article briefly reviews the area and makes the case for dissemination of the findings with the aim of reducing stress in the general population and patient groups.
... Then again, it is interesting that gum-chewing reduces stressrelated responses by the prefrontal cortex which in turn influences the hypothalamic-pituitary-adrenal axis, and thus exerts a beneficial effect on our cardiovascular system and emotional status [6]. ...
Over the past years, numerous novel dosage forms, including gels, have been investigated for paediatric treatment due to the need to provide flexible dose adjustment possibilities, as well as a patient-friendly approach to drug delivery. Simultaneously, 3D printing technology is continuously advancing and gaining interest as a tool for personalised formulation development. Multiple additive manufacturing methods, including the semi-solid extrusion, especially used in gel printing, provide flexibility regarding the dose of active ingredients and the adjustment of the design of soft dosage forms. 3D printing techniques can be considered as a possible answer to the demand for medicines tailored to small patients’ needs. This review intends to present an overview of the current possibilities, comparing gel-like and non-gel-formulated dosage forms and crucial aspects of developing those cutting-edge dosage forms by 3D printing. This paper discusses soft formulations such as chewing gums, which still require extensive evaluation, and explores the question of the three-dimensional printing process. Furthermore, it highlights soft dosage forms, such as gel-based gummies and hydrogels, for which 3D fabrication has been intensively studied in previous years. However, the research still needs to advance.
Aging often results in a decline in cognitive function, related to alterations in the prefrontal cortex (PFC) activation. Maintenance of this function in an aging society is an important issue. Some practices/drills, moderate exercise, mastication, and a cognitive task itself could enhance cognitive function. In this validation study, before evaluating the effects of some drills on the elderly, we examined the neural substrate of blood oxygenation changes by the use of four cognitive tasks and fNIRS. Seven healthy volunteers (mean age 25.3 years) participated in this study. Each task session was designed in a block manner; 4 periods of rests (30 s) and 3 blocks of four tasks (30 s). The tasks used were: a computerized Stroop test, a Wisconsin Card Sorting Test, a Sternberg working memory paradigm, and a semantic verbal fluency task. The findings of the study are that all four tasks activated PFC to some extent, without laterality except for the verbal fluency task. The results confirm that NIRS is suitable for measurement of blood oxygenation changes in frontal brain areas that are associated with all four cognitive tasks.
The authors present an overview of the neural bases of emotion. They underscore the role of the prefrontal cortex (PFC) and amygdala in 2 broad approach- and withdrawal-related emotion systems. Components and measures of affective style are identified. Emphasis is given to affective chronometry and a role for the PFC in this process is proposed. Plasticity in the central circuitry of emotion is considered, and implications of data showing experience-induced changes in the hippocampus for understanding psychopathology and stress-related symptoms are discussed. Two key forms of affective plasticity are described—context and regulation. A role for the hippocampus in context-dependent normal and dysfunctional emotional responding is proposed. Finally, implications of these data for understanding the impact on neural circuitry of interventions to promote positive affect and on mechanisms that govern health and disease are considered.
Stress is prevalent in human life and threatens both physical and mental health; stress coping is thus of adaptive value for individual's survival and well-being. Although there has been extensive research on how the neural and physiological systems respond to stressful stimulation, relatively little is known about how the brain dynamically copes with stress evoked by this stimulation. Here we investigated how stress is relieved by a popular coping behavior, namely, gum chewing. In an fMRI study, we used loud noise as an acute stressor and asked participants to rate their feeling of stress in gum-chewing and no-chewing conditions. The participants generally felt more stressful when hearing noise, but less so when they were simultaneously chewing gum. The bilateral superior temporal sulcus (STS) and the left anterior insula (AI) were activated by noise, and their activations showed a positive correlation with the self-reported feeling of stress. Critically, gum chewing significantly reduced the noise-induced activation in these areas. Psychophysiological interaction (PPI) analysis showed that the functional connectivity between the left AI and the dorsal anterior cingulate cortex (dACC) was increased by noise to a lesser extent when the participants were chewing gum than when not chewing gum. Dynamic causality modeling (DCM) demonstrated that gum chewing inhibited the connectivity from the STS to the left AI. These findings demonstrate that gum chewing relieves stress by attenuating the sensory processing of external stressor and by inhibiting the propagation of stress-related information in the brain stress network.
In this study, we present the normative values of the adaptation of the International Affective Digitized Sounds (IADS-2; Bradley & Lang, 2007a) for European Portuguese (EP). The IADS-2 is a standardized database of 167 naturally occurring sounds that is widely used in the study of emotions. The sounds were rated by 300 college students who were native speakers of EP, in the three affective dimensions of valence, arousal, and dominance, by using the Self-Assessment Manikin (SAM). The aims of this adaptation were threefold: (1) to provide researchers with standardized and normatively rated affective sounds to be used with an EP population; (2) to investigate sex and cultural differences in the ratings of affective dimensions of auditory stimuli between EP and the American (Bradley & Lang, 2007a) and Spanish (Fernández-Abascal et al., Psicothema 20:104-113 2008; Redondo, Fraga, Padrón, & Piñeiro, Behavior Research Methods 40:784-790 2008) standardizations; and (3) to promote research on auditory affective processing in Portugal. Our results indicated that the IADS-2 is a valid and useful database of digitized sounds for the study of emotions in a Portuguese context, allowing for comparisons of its results with those of other international studies that have used the same database for stimulus selection. The normative values of the EP adaptation of the IADS-2 database can be downloaded along with the online version of this article.
To assess the relationships between trait anger (T-Anger) and anger expression styles and emotional states-suicide probability, depression, state and trait anxiety and self-esteem--in alcohol-dependent inpatients.
The patients included in this study were 142 male inpatients with alcohol dependence according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria. The Suicide Probability Scale, the Coopersmith Self-Esteem Inventory, the Beck Depression Inventory, the Beck Hopelessness Scale, the Spielberger State-Trait Anxiety Scales, and the T-Anger and Anger Expressions Scales were used for the assessment of the emotional states of the patients. Pearson correlation, analysis of variance and linear regression were used in the statistical analysis.
There were significant correlations between suicide probability, depression, state and the trait anxiety, and the T-Anger and all of the anger expression subscales. The presence of high probability for suicide was related to a high level of T-Anger, Anger-out and Anger-in. Finally, a low level of hopelessness was associated with a high level of T-Anger, and a high level of the trait anxiety was associated with a low level of the Anger Control (AEX-Con).
The findings indicated that suicide probability, hopelessness and trait anxiety predict T-Anger levels and anger expression styles. Therefore, anxiety, hopelessness and suicide probability must be considered as risk for anger and anger expressions in alcohol-dependent patients. Furthermore, alcohol treatment programmes should attach importance to anger management and AEX-Con training.
This chapter discusses the major brain regions implicated in homeostatic stress and emotional stress systems, but attention is paid to the role of the hypothalamus in integrating emotional stress information from higher brain structures, such as the amygdala, hippocampus, septum, and prefrontal cortex. Because the stress response can be measured for a large part as a hormonal response orchestrated by the hypothalamus, recent experimental data are discussed that shed new light on how hypothalamic nuclei play an essential role in sensitizing organs of the body to the hormones of the pituitary as well. In results, the forebrain control of the neuroendocrine and autonomic paraventricular nucleus of the hypothalamus (PVN ) shows many similarities between the participating structures. The suprachiasmatic nucleus, ventral hippocampus, amygdala, septum, and prefrontal cortex all have access to the neuroendocrine PVN via, mainly, indirect pathways. The amygdala and PFC will set the endocrine/ autonomic balance, depending on the emotional status. It is propose that this interaction forms part of the explanation why emotional disturbances have such profound effects on the homeostatic balance of the individual and vice versa.
Examination was made of the effects of gum hardness on cerebral blood flow (CBF), oxygen uptake (VO2), heart rate (HR) and blood pressure during gum-chewing. Ten healthy male and female volunteers chewed 6 g of each of five gums differing in hardness (I, soft gum 6.4×10³ poise ; II, regular gum 2.0×10⁴ poise ; III, semi-hard gum 5.7×10⁴ poise ; N, hard gum 7.7×10⁴ poise ; V, super hard gum 1.4×10⁵ poise) for ten minutes chewing 60 times per minute. Right common carotid blood flow volume (rCCBFV) for 30 to 60 second interval, blood pressure for 2 min interval and continuous measurements of right tympanic membrane temperature (rTty), right skin temperature on muscle of mastication (rTskin), VO2 and HR were measured during rest for 10 min, chewing and recovery.
The following results were obtained:
1) rCCBFV increased significantly from 6 to 15% the resting level onset of chewing and continued during gum-chewing. Increased rCCBFV returned quickly to resting level on cessation of mastication. rCCBFV increased most during the mastication of semi-(III) and hard gum (IV), and was least when chewing soft (I), regular (II) and super-hard gum (V). The response of rCCBFV to gum-chewing depended on change of common carotid blood velocity (r=0.629, p<0.001).
2) Changes in rTty and rTskin depended on gum hardness. Significant temporary decrease in rTty onset of chewing was observed for soft (I), regular (II) and semihard gum (III), but not for hard (N) and super-hard gum (V). Gradual increase in rTty was noted starting at 5 min after the onset of mastication for all gums examined. Peak levels of rTty could be seen at about 5 min after cessations of mastication. Magnitude of increase in rTty after gum-chewing depended on gum hardness. The hardest gum (V) coused the greatest increase in rTty. rTskin increased significantly at the onset of mastication, and peaked immediately following cessation of gum-chewing.
3) The response of VO2, HR and systolic and diastolic blood pressure during gumchewing depended on gum hardness. VO2 quickly decreased to less than the resting level immediately after cessation of gum-chewing. Slight increase in HR and blood pressure persisted throughout the recovery period.
The present results suggest that gum-chewing increases cerebral blood flow due to change in rCCBFV and rTty, which is indication of change in internal carotid arterial blood flow. Moderate hardness of food may possibly lead to greater increase in CBF during mastication than soft and/or very hard food.
Synopsis
The reliability and validity of the Visual Analogue Mood Scale (VAMS) has been demonstrated in both a military and a private psychiatric hospital, inpatient population. The repeated and concurrent administration of the VAMS and the Digit-Symbol test identifies a mood-performance correlation which distinguishes patients with affective disorders, of manic or depressed type, from other psychiatric patients.
The present paper investigated response of electroencephalogram (EEG) to aerobic exercise with low intensity after performing mental task with listening to acoustic stimuli in order to measure a recovery effect of the acute exercise on the EEG. The mean amplitude of the alpha wave (8-13 Hz) was significantly reduced during performing mental arithmetic and/or listening to 5 KHz unpleasant tone. In particular, the mean reduction rate of the amplitude was more than 20 % in the low-frequency range of the alpha wave (8-10 Hz) under both stressors. On the other hand, the alpha wave was fixed after an acute exercise of 20 min; the mean amplitude of the alpha wave exceeded 30 % of spontaneous level prior to stressed conditions in the low-frequency range but unchanged in the high-frequency range. Response of the theta wave was similar to the low-alpha wave, while beta and gamma waves showed no significant change in response to the stressors and exercise. The observation indicates that the acute exercise with low intensity may be responsible for the rapid recovery and enhancement of the alpha wave in the low-frequency range and theta wave.
We have proposed a concept that prolonged rhythmic gum chewing causes a suppressed nociceptive flexion reflex via the serotonergic (5-HT) descending inhibitory pathway. However, the mechanism of activation of the 5-HT system by gum chewing remains undetermined. Several human and animal studies have reported that a direct connection exists between the prefrontal cortex (PFC) and 5-HT neurons in the dorsal raphe nucleus; therefore, we hypothesized that activation of the PFC region might be responsible for augmented 5-HT activity. To evaluate this hypothesis, oxygenated hemoglobin (oxyHb) and deoxygenated hemoglobin concentrations in the PFC were measured in the PFC during a 20-min time period of gum chewing using 24-channel near-infrared spectroscopy. A significant increase in oxyHb level was observed in the ventral part of PFC compared with the dorsal part of PFC. We confirmed the previous results in that the nociceptive flexion reflex was significantly suppressed and the 5-HT level in blood was significantly increased following prolonged gum chewing. These results support the hypothesis that activation of the ventral part of PFC during gum chewing evokes augmented activity of 5-HT neurons in the dorsal raphe nucleus, which in turn suppress nociceptive responses.
Research in animals and humans has shown that mastication maintains cognitive function in the hippocampus, a brain area important for learning and memory. Reduced mastication, an epidemiological risk factor for the development of dementia in humans, attenuates spatial memory and causes hippocampal neurons to deteriorate morphologically and functionally, especially in aged animals. Active mastication rescues the stress-attenuated hippocampal memory process in animals and attenuates the perception of stress in humans by suppressing endocrinological and autonomic stress responses. Active mastication further improves the performance of sustained cognitive tasks by increasing the activation of the hippocampus and the prefrontal cortex, the brain regions that are essential for cognitive processing. Abnormal mastication caused by experimental occlusal disharmony in animals produces chronic stress, which in turn suppresses spatial learning ability. The negative correlation between mastication and corticosteroids has raised the hypothesis that the suppression of the hypothalamic-pituitary-adrenal (HPA) axis by masticatory stimulation contributes, in part, to preserving cognitive functions associated with mastication. In the present review, we examine research pertaining to the mastication-induced amelioration of deficits in cognitive function, its possible relationship with the HPA axis, and the neuronal mechanisms that may be involved in this process in the hippocampus.
The prefrontal cortex (PFC) - the most evolved brain region - subserves our highest-order cognitive abilities. However, it is also the brain region that is most sensitive to the detrimental effects of stress exposure. Even quite mild acute uncontrollable stress can cause a rapid and dramatic loss of prefrontal cognitive abilities, and more prolonged stress exposure causes architectural changes in prefrontal dendrites. Recent research has begun to reveal the intracellular signalling pathways that mediate the effects of stress on the PFC. This research has provided clues as to why genetic or environmental insults that disinhibit stress signalling pathways can lead to symptoms of profound prefrontal cortical dysfunction in mental illness.
The notion that chewing gum may relieve stress was investigated in a controlled setting. A multi-tasking framework which reliably evokes stress and also includes performance measures was used to induce acute stress in the laboratory. Using a randomised crossover design forty participants (mean age 21.98 years) performed on the multi-tasking framework at two intensities (on separate days) both while chewing and not chewing. Order of workload intensity and chewing conditions were counterbalanced. Before and after undergoing the platform participants completed the state portion of the State-Trait Anxiety Inventory, Bond-Lader visual analogue mood scales, a single Stress Visual Analogue Scale and provided saliva samples for cortisol measurement. Baseline measures showed that both levels of the multi-tasking framework were effective in significantly reducing self-rated alertness, calmness and contentment while increasing self-rated stress and state anxiety. Cortisol levels fell during both levels of the stressor during the morning, reflecting the predominance of a.m. diurnal changes, but this effect was reversed in the afternoon which may reflect a measurable stress response. Pre-post stressor changes (Delta) for each measure at baseline were subtracted from Delta scores under chewing and no chewing conditions. During both levels of stress the chewing gum condition was associated with significantly better alertness and reduced state anxiety, stress and salivary cortisol. Overall performance on the framework was also significantly better in the chewing condition. The mechanisms underlying these effects are unknown but may involve improved cerebral blood flow and/or effects secondary to performance improvement during gum chewing.
Frontal EEG asymmetry appears to serve as (1) an individual difference variable related to emotional responding and emotional disorders, and (2) a state-dependent concomitant of emotional responding. Such findings, highlighted in this review, suggest that frontal EEG asymmetry may serve as both a moderator and a mediator of emotion- and motivation-related constructs. Unequivocal evidence supporting frontal EEG asymmetry as a moderator and/or mediator of emotion is lacking, as insufficient attention has been given to analyzing the frontal EEG asymmetries in terms of moderators and mediators. The present report reviews the frontal EEG asymmetry literature from the framework of moderators and mediators, and overviews data analytic strategies that would support claims of moderation and mediation.
Although there are many well-characterized affective visual stimuli sets available to researchers, there are few auditory sets available. Those auditory sets that are available have been characterized primarily according to one of two major theories of affect: dimensional or categorical. Current trends have attempted to utilize both theories to more fully understand emotional processing. As such, stimuli that have been thoroughly characterized according to both of these approaches are exceptionally useful. In an effort to provide researchers with such a stimuli set, we collected descriptive data on the International Affective Digitized Sounds (IADS), identifying which discrete categorical emotions are elicited by each sound. The IADS is a database of 111 sounds characterized along the affective dimensions of valence, arousal, and dominance. Our data complement these characterizations of the IADS, allowing researchers to control for or manipulate stimulus properties in accordance with both theories of affect, providing an avenue for further integration of these perspectives. Related materials may be downloaded from the Psychonomic Society Web archive at www.psychonomic.org/archive.
Physiological response to unpleasant sounds
- A Horii
- C Yamamura
- T Katsumata