平野 好幸

Monte Carlo simulation is widely applied to evaluate the performance of three-dimensional positron emission tomography (3D-PET). For accurate scatter simulations, all components that generate scatter need to be taken into account. The aim of this work was to identify the components that influence scatter. The simulated geometries of a PET scanner were: a precisely reproduced configuration including all of the components; a configuration with the bed, the tunnel and shields; a configuration with the bed and shields; and the simplest geometry with only the bed. We measured and simulated the scatter fraction using two different set-ups: (1) as prescribed by NEMA-NU 2007 and (2) a similar set-up but with a shorter line source, so that all activity was contained only inside the field-of-view (FOV), in order to reduce influences of components outside the FOV. The scatter fractions for the two experimental set-ups were, respectively, 45% and 38%. Regarding the geometrical configurations, the former two configurations gave simulation results in good agreement with the experimental results, but simulation results of the simplest geometry were significantly different at the edge of the FOV. From the simulation of the precise configuration, the object (scatter phantom) was the source of more than 90% of the scatter. This was also confirmed by visualization of photon trajectories. Then, the bed and the tunnel were mainly the sources of the rest of the scatter. From the simulation results, we concluded that the precise construction was not needed; the shields, the tunnel, the bed and the object were sufficient for accurate scatter simulations.

Aim: The aims of this study were to determine whether the serum levels of precursor brain-derived neurotrophic factor (proBDNF), mature BDNF (mBDNF), and matrix metalloproteinase-9 (MMP-9) are altered in patients with eating disorders (ED), including anorexia nervosa (AN) and bulimia nervosa (BN), and to explore whether those levels are associated with decision-making abilities. Methods: Nineteen women with AN, 28 women with BN, and 22 age-matched healthy control women (HC) were enrolled in the current study. All participants had their decision-making abilities assessed using the Iowa Gambling Task (IGT). Their eating-related pathophysiology and depressive/anxiety symptoms were also evaluated. Results: The MMP-9 level in AN was significantly lower than that in either BN or HC, but the serum levels of proBDNF and mBDNF did not differ among the three groups. Investigation of the serum levels of proBDNF and MMP-9 in patients with ED and controls revealed a significant correlation between them. In the BN, there were positive correlations between mBDNF level and IGT performance and also between MMP-9 level and IGT performance, but these correlations did not occur in AN. The MMP-9 level was positively associated with the Symptom Scale, one of the subscales of the Bulimic Investigatory Test, Edinburgh, only in AN. Conclusion: These results suggest that the serum level of MMP-9 plays a role in the pathophysiology of AN, and both the serum levels of mBDNF and MMP-9 may be associated with decision-making abilities in patients with BN.

Background: Set-shifting (SS) difficulties and weak central coherence (CC) are commonly associated with autism spectrum disorders (ASD). Cognitive remediation therapy (CRT) aims to improve such cognitive processing; however, there are no reports on CRT for patients with ASD. This pilot study aimed to provide preliminary evidence to support the use of CRT for individuals with ASD and provide data to inform future studies. Participants and methods: Nineteen individuals with ASD were recruited and administered a series of neuropsychological and questionnaire measures to examine cognitive function and clinical outcomes such as anxiety and depression. Participants received CRT, and cognitive function and clinical variables were re-evaluated at postintervention and after 3 months. Results: The participants demonstrated significant improvement in CC and anxiety at postintervention, which was maintained at 3-month follow-up. Although SS scores had improved with a large effect size, this was not statistically significant. Conclusion: CRT improved CC and anxiety scores for individuals with ASD, suggesting that CRT is an effective treatment for individuals with ASD.

Obsessive-compulsive disorder (OCD) is known as a clinically heterogeneous disorder characterized by symptom dimensions. Although substantial numbers of neuroimaging studies have demonstrated the presence of brain abnormalities in OCD, their results are controversial. The clinical heterogeneity of OCD could be one of the reasons for this. It has been hypothesized that certain brain regions contributed to the respective obsessive-compulsive dimensions. In this study, we investigated the relationship between symptom dimensions of OCD and brain morphology using voxel-based morphometry to discover the specific regions showing alterations in the respective dimensions of obsessive-compulsive symptoms. The severities of symptom dimensions in thirty-three patients with OCD were assessed using Obsessive-Compulsive Inventory-Revised (OCI-R). Along with numerous MRI studies pointing out brain abnormalities in autistic spectrum disorder (ASD) patients, a previous study reported a positive correlation between ASD traits and regional gray matter volume in the left dorsolateral prefrontal cortex and amygdala in OCD patients. We investigated the correlation between gray and white matter volumes at

Previous studies showed that food craving in eating disorders can be weakened with high-frequency repetitive transcranial magnetic stimulation (rTMS) on the left dorsolateral prefrontal cortex (DLPFC). The aims of this study were to assess cerebral oxygenation change induced with rTMS and to assess the short-term impact of rTMS on food craving and other bulimic symptoms in patients with bulimia nervosa (BN). Eight women diagnosed with BN according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria participated in this study. We measured haemoglobin concentration changes in the DLPFC with near-infrared spectroscopy during cognitive tasks measuring self-regulatory control in response to food photo stimuli, both at baseline and after a single session of rTMS. Subjective ratings for food cravings demonstrated significant reduction. A significant decrease in cerebral oxygenation of the left DLPFC was also observed after a single session of rTMS. Measurement with NIRS after rTMS intervention may be applicable for discussing the mechanisms underlying rTMS modulation in patients with BN. Copyright (c) 2015 John Wiley & Sons, Ltd and Eating Disorders Association.

Background: Although antidepressants are still a commonly used treatment for social anxiety disorder (SAD), a significant proportion of patients fail to remit following antidepressants. However, no standard approach has been established for managing such patients. This study aimed to examine the effectiveness of cognitive behavioral therapy (CBT) as an adjunct to usual care (UC) compared with UC alone in SAD patients who remain symptomatic following antidepressant treatment. Methods: This was a prospective randomized open-blinded end-point study with two parallel groups (CBT + UC, and UC alone, both for 16 weeks) conducted from June 2012 to March 2014. SAD patients who remain symptomatic following antidepressant treatment were recruited, and a total sample size of 42 was set based on pilot results. Results: Patients were randomly allocated to CBT + UC (n = 21) or UC alone (n = 21). After 16 weeks, adjusted mean reduction in the Liebowitz Social Anxiety Scale from baseline for CBT + UC and UC alone was -40.87 and 0.68, respectively; the between-group difference was -41.55 (-53.68 to -29.42, p < 0.0001). Response rates were 85.7 and 10.0% for CBT + UC and UC alone, respectively (p < 0.0001). The corresponding remission rates were 47.6 and 0.0%, respectively (p = 0.0005). Significant differences were also found in favor of CBT + UC for social anxiety symptoms, depressive symptoms, and functional impairment. Conclusions: Our results suggest that in SAD patients who have been ineffectively treated with antidepressants, CBT is an effective treatment adjunct to UC over 16 weeks in reducing social anxiety and related symptoms. (C) 2016 The Author(s) Published by S. Karger AG, Basel

Cognitive restructuring is a fundamental method within cognitive behavioural therapy of changing dysfunctional beliefs into flexible beliefs and learning to react appropriately to the reality of an anxiety-causing situation. To clarify the neural mechanisms of cognitive restructuring, we designed a unique task that replicated psychotherapy during a brain scan. The brain activities of healthy male participants were analysed using functional magnetic resonance imaging. During the brain scan, participants underwent Socratic questioning aimed at cognitive restructuring regarding the necessity of handwashing after using the restroom. The behavioural result indicated that the Socratic questioning effectively decreased the participants' degree of belief (DOB) that they must wash their hands. Alterations in the DOB showed a positive correlation with activity in the left posterior parietal cortex (PPC) while the subject thought about and rated own belief. The involvement of the left PPC not only in planning and decision-making but also in conceptualization may play a pivotal role in cognitive restructuring.

Chewing is crushing food not only to aid swallowing and digestion, but also to help stress relief and regulate cognitive function, especially in attention. It is well known that chewing gum is used for sleepiness prevention during work, learning, and driving, suggesting a link between chewing and sustained attention. We hypothesized that chewing elevates attention and/or alertness, leading to improvements in cognitive performance. We carried out a systematic review of the PubMed database. We inspected the attributes of effects on attention in studies investigating the effects of chewing on attention or alertness conducted with pre-post design in healthy subjects, except elderly. We identified 151 references, 22 of which were included: 14 (64%) showed positive attributes of effects on attention, 1 (5%) showed negative attributes of effects on attention, 5 (23%) showed both positive and negative attributes of effects on attention, and 2 (9%) showed no significant attributes of effects on attention. Thus, positive attributes of effects of chewing on attention, especially on sustained attention, were shown in over half of the reports. These effects also appeared with improvement in mood and stress relief and were influenced by time-on-task effect. Further studies are needed, but chewing could be useful for modifying cognitive function.

BACKGROUND: Decision-making is reported to be impaired in anorexia nervosa (AN) and bulimia nervosa (BN), but the influence of mood status, pathophysiological eating, and weight concerns on the performance of decision-making ability between AN and BN is still unclear. The aims of this study were to investigate differential impairments in the decision-making process between AN, BN, and healthy controls (HC), and secondly, to explore the role of mood status, such as anxiety, depression, pathological eating, and weight concerns, in decision-making ability. METHODS: Patients suffering from AN (n = 22), BN (n = 36) and age-matched HC (n = 51) were assessed for their decision-making abilities using the Iowa Gambling Task (IGT). Self-reported questionnaires including the Eating Disorder Examination Questionnaire (EDE-Q), the Bulimia Investigatory Test, Edinburgh (BITE), the Eating Disorders Inventory, the Maudsley Obsessive-Compulsive Inventory measuring obsessive-compulsive traits, the Hospital Anxiety and Depression Scale, and the Toronto Alexithymia Scale were used to assess pathological eating concerns and attitude to feelings. RESULTS: Significant differences in IGT performance were observed between BN and HC. Significant negative correlation was found between IGT performance and the BITE symptom subscale in AN. In BN, there was a negative correlation between the EDE-Q weight concerns subscale and IGT performance. It was also found that increased anxiety, depression, and eating/weight concerns predicted poorer decision-making. CONCLUSION: Different patterns of association between pathological eating concerns/behaviors and performances in decision-making ability were found between AN, BN, and HC. Anxiety, depressive mood status, and eating/weight concerns were related to decision-making ability.

Objectives: Obsessive-compulsive disorder (OCD) is one of the most debilitating psychiatric disorders, with some speculating that a reason for difficulty in its treatment might be its coexistence with autism spectrum. We investigated the tendency for autistic spectrum disorders (ASD) in patients with OCD from a neuroimaging point of view using voxel-based morphometry. Methods: We acquired T-1-weighted images from 20 patients with OCD and 30 healthy controls and investigated the difference in regional volume between the groups as well as the correlation between Autism-Spectrum Quotient (AQ) scores and regional cerebral volumes of patients with OCD. Results: Volumes in the bilateral middle frontal gyri were significantly decreased in patients with OCD compared to controls. Correlational analysis showed significant positive correlations between AQ scores and regional gray matter (GM) volumes in the left dorsolateral prefrontal cortex (DLPFC) and left amygdala. Furthermore, GM volumes of these regions were positively correlated with each other. Conclusions: The positive correlation of ASD traits in patients with OCD with regional GM volumes in the left DLPFC and amygdala could reflect the heterogeneity of patient symptoms. Our results suggest that differences in GM volume might allow classification of patients with OCD for appropriate therapy based on their particular traits.

Chewing does not only crush food to aid swallowing and digestion it also helps to relieve stress and regulate cognitive functions, including alertness and executive function. It is well known that chewing gum is used for sleepiness prevention during work, learning, and driving. In addition, it has been shown in the elderly that a decrease in the number of residual teeth is related to dementia onset. These findings suggest a link between chewing and maintaining memory and attention. Recently, many studies regarding the effects of chewing on memory and attention were conducted using functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). When a working memory task was used, the middle frontal gyrus in the dorsolateral prefrontal cortex showed greater activation in addition to producing higher alertness after chewing. Furthermore, using an attentional network test, reaction time shortened, and the anterior cingulate cortex and left frontal gyrus were both activated for the executive network. From these results, it is suggested that chewing elevates alertness, consequently leading to improvements in cognitive performance. In this review, we introduce findings concerning the effects of chewing on cognitive performance, and discuss the neuronal mechanisms underlying these effects.

Chewing does not only crush food to aid swallowing and digestion it also helps to relieve stress and regulate cognitive functions, including alertness and executive function. It is well known that chewing gum is used for sleepiness prevention during work, learning, and driving. In addition, it has been shown in the elderly that a decrease in the number of residual teeth is related to dementia onset. These findings suggest a link between chewing and maintaining memory and attention. Recently, many studies regarding the effects of chewing on memory and attention were conducted using functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). When a working memory task was used, the middle frontal gyrus in the dorsolateral prefrontal cortex showed greater activation in addition to producing higher alertness after chewing. Furthermore, using an attentional network test, reaction time shortened, and the anterior cingulate cortex and left frontal gyrus were both activated for the executive network. From these results, it is suggested that chewing elevates alertness, consequently leading to improvements in cognitive performance. In this review, we introduce findings concerning the effects of chewing on cognitive performance, and discuss the neuronal mechanisms underlying these effects.

Functional neuroimaging in animal models is essential for understanding the principles of neurovascular coupling and the physiological basis of fMRI signals that are widely used to study sensory and cognitive processing in the human brain. While hemodynamic responses to sensory stimuli have been characterized in humans, animal studies are able to combine very high resolution imaging with invasive measurements and pharmacological manipulation. To date, most high-resolution studies of neurovascular coupling in small animals have been carried out in anesthetized rodents. Here we report fMRI experiments in conscious, awake common marmosets (Callithrix jacchus), and compare responses to animals anesthetized with propofol. In conscious marmosets, robust BOLD fMRI responses to somatosensory stimulation of the forearm were found in contralateral and ipsilateral regions of the thalamus, primary (SI) and secondary (SII) somatosensory cortex, and the caudate nucleus. These responses were markedly stronger than those in anesthetized marmosets and showed a monotonic increase in the amplitude of the BOLD response with stimulus frequency. On the other hand, anesthesia significantly attenuated responses in thalamus, SI and SII, and abolished responses in caudate and ipsilateral SI. Moreover, anesthesia influenced several other aspects of the fMRI responses, including the shape of the hemodynamic response function and the interareal (SI-SII) spontaneous functional connectivity. Together, these findings demonstrate the value of the conscious, awake marmoset model for studying physiological responses in the somatosensory pathway, in the absence of anesthesia, so that the data can be compared most directly to fMRI in conscious humans. Published by Elsevier Inc.

In recent years, chewing has been discussed as producing effects of maintaining and sustaining cognitive performance. We have reported that chewing may improve or recover the process of working memory; however, the mechanisms underlying these phenomena are still to be elucidated. We investigated the effect of chewing on aspects of attention and cognitive processing speed, testing the hypothesis that this effect induces higher cognitive performance. Seventeen healthy adults (20-34. years old) were studied during attention task with blood oxygenation level-dependent functional (fMRI) at 3.0 T MRI. The attentional network test (ANT) within a single task fMRI containing two cue conditions (no cue and center cue) and two target conditions (congruent and incongruent) was conducted to examine the efficiency of alerting and executive control. Participants were instructed to press a button with the right or left thumb according to the direction of a centrally presented arrow. Each participant underwent two back-to-back ANT sessions with or without chewing gum, odorless and tasteless to remove any effect other than chewing. Behavioral results showed that mean reaction time was significantly decreased during chewing condition, regardless of speed-accuracy trade-off, although there were no significant changes in behavioral effects (both alerting and conflict effects). On the other hand, fMRI analysis revealed higher activations in the anterior cingulate cortex and left frontal gyrus for the executive network and motor-related regions for both attentional networks during chewing condition. These results suggested that chewing induced an increase in the arousal level and alertness in addition to an effect on motor control and, as a consequence, these effects could lead to improvements in cognitive performance. © 2012.

Background: The Kana Pick-out Test (KPT), which uses Kana or Japanese symbols that represent syllables, requires parallel processing of discrete (pick-out) and continuous (reading) dual tasks. As a dual task, the KPT is thought to test working memory and executive function, particularly in the prefrontal cortex (PFC), and is widely used in Japan as a clinical screen for dementia. Nevertheless, there has been little neurological investigation into PFC activity during this test. Methods: We used functional magnetic resonance imaging (fMRI) to evaluate changes in the blood oxygenation level-dependent (BOLD) signal in young healthy adults during performance of a computerized KPT dual task (comprised of reading comprehension and picking out vowels) and compared it to its single task components (reading or vowel pick-out alone). Results: Behavioral performance of the KPT degraded compared to its single task components. Performance of the KPT markedly increased BOLD signal intensity in the PFC, and also activated sensorimotor, parietal association, and visual cortex areas. In conjunction analyses, bilateral BOLD signal in the dorsolateral PFC (Brodmann's areas 45, 46) was present only in the KPT. Conclusions: Our results support the central bottleneck theory and suggest that the dorsolateral PFC is an important mediator of neural activity for both short-term storage and executive processes. Quantitative evaluation of the KPT with fMRI in healthy adults is the first step towards understanding the effects of aging or cognitive impairment on KPT performance.

The spatiotemporal characteristics of the hemodynamic response to increased neural activity were investigated at the level of individual intracortical vessels using BOLD-fMRI in a well-established rodent model of somatosensory stimulation at 11.7 T. Functional maps of the rat barrel cortex were obtained at 150 x 150 x 500 mu m spatial resolution every 200 ms. The high spatial resolution allowed separation of active voxels into those containing intracortical macro vessels, mainly vein/venules (referred to as macrovasculature), and those enriched with arteries/capillaries and small venules (referred to as microvasculature) since the macro vessel can be readily mapped due to the fast T2* decay of blood at 11.7 T. The earliest BOLD response was observed within layers IV-V by 0.8s following stimulation and encompassed mainly the voxels containing the microvasculature and some confined macrovasculature voxels. By 1.2 s, the BOLD signal propagated to the macrovasculature voxels where the peak BOLD signal was 2-3 times higher than that of the microvasculature voxels. The BOLD response propagated in individual venules/veins far from neuronal sources at later times. This was also observed in layers IV-V of the barrel cortex after specific stimulation of separated whisker rows. These results directly visualized that the earliest hemodynamic changes to increased neural activity occur mainly in the microvasculature and spread toward the macrovasculature. However, at peak response, the BOLD signal is dominated by penetrating venules even at layers IV-V of the cortex. (C) 2011 Elsevier Inc. All rights reserved.

Purpose: We used functional magnetic resonance imaging (fMRI) to investigate the change in brain regional activity during gum chewing when edentulous subjects switched from mandibular complete dentures to implant-supported removable overdentures. Methods: Four edentulous patients (3 males and 1 female, aged 64 to 79 years) participated in the study. All subjects received a set of new maxillary and mandibular complete dentures (CD), followed by a maxillary complete denture and a new mandibular implant-supported removable overdentures (IOD). A 3-T fMRI scanner produced images of the regional brain activity for each subject that showed changes in the blood-oxygenation- level-dependent (BOLD) contrast in the axial orientation during gum-chewing with CD and IOD. Results: Region-of-interest analysis showed that IOD treatment significantly suppressed chewing-induced brain activity in the prefrontal cortex. The chewing-induced brain activities in the primary sensorimotor cortex and cerebellum tended to decrease with IOD treatment, however they did not reach to significance level. There was no change in brain activity in the supplementary motor area, thalamus and insula between gum chewing with CD and IOD. Group comparison using statistical parametrical mapping further showed that, within the prefrontal cortex, the neural activity of the frontal pole significantly decreased during gum-chewing with IOD when compared to that with CD (P < 0.05). Conclusion: Despite the limitation of a small sample size, these results suggest that the gum-chewing task in elderly edentulous patients resulted in differential neural activity in the frontal pole within the prefrontal cortex between the 2 prosthodontic therapies-mandibular CD and IOD. (C) 2010 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved.

The specificity of the hemodynamic response function (HRF) is determined spatially by the vascular architecture and temporally by the evolution of hemodynamic changes. The stimulus duration has additional influence on the spatiotemporal evolution of the HRF, as brief stimuli elicit responses that engage only the local vasculature, whereas long stimuli lead to the involvement of remote vascular supply and drainage. Here, we used functional magnetic resonance imaging to investigate the spatiotemporal evolution of the blood oxygenation level-dependent (BOLD), cerebral blood flow (CBF), and cerebral blood volume (CBV) HRF to ultrashort forelimb stimulation in an anesthetized rodent model. The HRFs to a single 333-mu s-long stimulus were robustly detected and consisted of a rapid response in both CBF and CBV, with an onset time (OT) of 350 ms and a full width at half-maximum of 1 s. In contrast, longer stimuli elicited a dispersive transit of oxygenated blood across the cortical microvasculature that significantly prolonged the evolution of the CBV HRF, but not the CBF. The CBF and CBV OTs suggest that vasoactive messengers are synthesized, released, and effective within 350 ms. However, the difference between the BOLD and CBV OT (similar to 100 ms) was significantly smaller than the arteriolar-venular transit time (similar to 500 ms), indicating an arterial contribution to the BOLD HRF. Finally, the rapid rate of growth of the active region with stimulus elongation suggests that functional hyperemia is an integrative process that involves the entire functional cortical depth. These findings offer a new view into the spatiotemporal dynamics of functional hemodynamic regulation in the brain.

Several animal studies have demonstrated functional roles of dopamine (DA) D1 and D2 receptors in amygdala activity. However, the contribution of DA D1 and D2 receptors to amygdala response induced by affective stimuli in human is unknown. To investigate the contribution of DA receptor subtypes to amygdala reactivity in human, we conducted a multimodal in vivo neuroimaging study in which DA D1 and D2 receptor bindings in the amygdala were measured with positron emission tomography (PET), and amygdala response induced by fearful faces was assessed by functional magnetic resonance imaging (fMRI) in healthy volunteers. We used multimodality voxelwise correlation analysis between fMRI signal and DA receptor binding measured by PET. DA D1 binding in the amygdala was positively correlated with amygdala signal change in response to fearful faces, but DA D2 binding in the amygdala was not related to amygdala signal change. DA D1 receptors might play a major role in enhancing amygdala response when sensory inputs are affective.

High field (>= 7 T) MRI Studies based on signal phase have been used to improve visualization of the fine structure of the brain, most notably the major white matter fiber bundles, the gray-white matter Subdivision, and the laminar cortical architecture. The observed contrast has been attributed in part to local variations in magnetic susceptibility arising from iron in storage proteins and tissue lipid. Another contribution could come from the paramagnetic blood constituent deoxy-hemoglobin, the tissue concentration of which may vary through local variations in vascular density. To investigate this possibility, we examined phase contrast between gray and white matter in rats after intravenous administration Of a superparamagnetic contrast agent at various dosages. At the maximum dosage (3 mg Fe/kg), which resulted in all estimated paramagnetic susceptibility shift 4-8 times larger than deoxy-hemoglobin, we observed a negligible increase in phase contrast between gray and white matter. This result suggests that endogenous deoxy-hemoglobin has no significant contribution to phase contrast between gray and white matter. Published by Elsevier Inc.

A new interpretation is proposed for stimulus-induced signal changes in diffusion-weighted functional MRI. T(2)-weighted spin-echo echo-planar images were acquired at different diffusion-weightings while visual stimulation was presented to human volunteers. The amplitudes of the positive stimulus-correlated response and post-stimulus undershoot (PSU) in the functional time-courses were found to follow different trends as a function of b-value. Data were analysed using a three-compartment signal model, with one compartment being purely vascular and the other two dominated by fast- and slow-diffusing molecules in the brain tissue. The diffusion coefficients of the tissue were assumed to be constant throughout the experiments. It is shown that the stimulus-induced signal changes can be decomposed into independent contributions originating from each of the three compartments. After decomposition, the fast-diffusion phase displays a substantial PSU, while the slow-diffusion phase demonstrates a highly reproducible and stimulus-correlated time-course with minimal undershoot. The decomposed responses are interpreted in terms of the spin-echo blood oxygenation level dependent (SE-BOLD) effect, and it is proposed that the signal produced by fast- and slow-diffusing molecules reflect a sensitivity to susceptibility changes in arteriole/venule- and capillary-sized vessels, respectively. This interpretation suggests that diffusion-weighted SE-BOLD imaging may provide subtle information about the haemodynamic and neuronal responses. Copyright (C) 2009 John Wiley & Sons, Ltd.

Using functional magnetic resonance imaging (fMRI) in eight healthy human subjects, the present study measured blood oxygenation level-dependent (BOLD) signals during clenching in a malocclusion model, using a custom-made splint that forced the mandible to a retrusive position and a splint of no modification for control, and compared the results to the BOLD signals during the corresponding resting conditions. An individual visual analog scale (VAS) score was also examined during clenching to evaluate the interactions between fMRI data and psychiatric changes. During both clenchings, activations in four brain regions (premotor cortex, prefrontal cortex, sensorimotor cortex, and insula) were seen. However, clenching in the malocclusion model, with psychological discomfort, increased additionally BOLD signals in the anterior cingulate cortex and the amygdala. Furthermore, there was a parallel relationship between BOLD signal intensities and VAS scores in these two regions. The findings may suggest the involvement of clenching with malocclusal conditions in the emotion and/or pain-related neural processing in the brain.

Using functional magnetic resonance imaging (fMRI) in eight healthy human subjects, the present study measured blood oxygenation level-dependent (BOLD) signals during clenching in a malocclusion model, using a custom-made splint that forced the mandible to a retrusive position and a splint of no modification for control, and compared the results to the BOLD signals during the corresponding resting conditions. An individual visual analog scale (VAS) score was also examined during clenching to evaluate the interactions between fMRI data and psychiatric changes. During both clenchings, activations in four brain regions (premotor cortex, prefrontal cortex, sensorimotor cortex, and insula) were seen. However, clenching in the malocclusion model, with psychological discomfort, increased additionally BOLD signals in the anterior cingulate cortex and the amygdala. Furthermore, there was a parallel relationship between BOLD signal intensities and VAS scores in these two regions. The findings may suggest the involvement of clenching with malocclusal conditions in the emotion and/or pain-related neural processing in the brain.

BACKGROUND: The relationships between possible physiological properties of insoluble fibre and the viscosity of digesta are poorly understood. The aim of this study was to investigate the effect of insoluble fibres with different water-holding capacity, swelling, oil-holding capacity and cation exchange capacity on gastric, small intestinal and caecal contents in rats fed a semi-purified diet containing either no fibre (control), 50 g kg(-1) tossa jute fibre or 50 g kg(-1) shiitake fibre. RESULTS: The water-holding capacity, swelling, oil-holding capacity and cation exchange capacity of insoluble fibres of tossa jute were higher than those of shiitake (P < 0.001). The order of the viscosities of cligesta was control group < shiitake fibre group < tossa jute fibre group in gastric, small intestinal and caecal contents (P < 0.05). The cligesta viscosity at a shear rate of 40 s(-1) was strongly correlated with the free water content of cligesta (r = -0.89; P < 0.01). The free water content of digesta depended on the water-holding capacity of insoluble fibres represented as a linear function with negative slope (P < 0.0011). CONCLUSION: The viscosity of digesta depends on the free water content, and this is reduced by fibre that holds water and can swell. (C) 2008 Society of Chemical Industry

It has been generally suggested that chewing produces an enhancing effect on cognitive performance-related aspects of memory by the test battery. Furthermore, recent studies have shown that chewing is associated with activation of various brain regions, including the prefrontal cortex. However, little is known about the relation between cognitive performances affected by chewing and the neuronal activity in specified regions in the brain. We therefore examined the effects of chewing on neuronal activities in the brain during a working memory task using fMRI. The subjects chewed gum, without odor and taste components, between continuously performed two- or three-back (n-back) working memory tasks. Chewing increased the BOLD signals in the middle frontal gyrus (Brodmann's areas 9 and 46) in the dorsolateral prefrontal cortex during the n-back tasks. Furthermore, there were more prominent activations in the right premotor cortex, precuneus, thalamus, hippocampus and inferior parietal lobe during the n-back tasks after the chewing trial. These results suggest that chewing may accelerate or recover the process of working memory besides inducing improvement in the arousal level by the chewing motion. (C) 2008 Elsevier Ireland Ltd. All rights reserved.

The involvement of chewing in brain activity in humans has been studied. In our studies using functional magnetic resonance imaging (fMRI) and behavioral techniques, chewing resulted in a bilateral increase in blood oxygenation leveldependent (BOLD) signals in the sensorimotor cortex, supplementary motor area, insula, thalamus, and cerebellum. In addition, in the first three regions, chewing moderately hard gum produced stronger signals than chewing hard gum. However, in the aged group, the BOLD signal increases were smaller in the first three regions and higher in the cerebellum. Only the aged subjects showed significant increases in various association areas to which input activities in the primary sensorimotor cortex, supplementary area, or insula had positive path coefficients. Furthermore, chewing ameliorates the age-related decrease in hippocampal activities during encoding and that in retrieval memory. The findings suggest the involvement of chewing in memory processes.

In radiofrequency (RF) coil design for ultra-high-field magnetic resonance (MR) imaging, short RF wavelengths present various challenges to creating a big volume coil. When imaging a human body using an ultra-high magnetic field MR imaging system (magnetic flux density of 7 Tesla or more), short wavelength may induce artifacts from dielectric effect and other factors. To overcome these problems, we developed a patch antenna array coil (PAAC), which is a coil configured as a combination of patch antennas. We prototyped this type of coil for 7T proton MR imaging, imaged a monkey brain, and confirmed the coil's utility as an RF coil for ultra-high-field MR imaging.

The functional link between the amygdala and hippocampus in humans has not been well documented. We examined the effect of unpleasant loud noise on hippocampal and amygdaloid activities during picture encoding by means of fMRI, and on the correct response in humans. The noise reduced activity in the hippocampus during picture encoding, decreased the correct response and increased the activity of the amygdala. A path diagram using structural equation modeling suggested that hippocampus activity might be depressed by high amygdala activity. Therefore, noise should diminish memory by reducing hippocampal activity, which might be depressed by high amygdala activity. (c) 2006 Elsevier Inc. All rights reserved.

Using fMRI in young and aged human brains, we evaluated the link between masticatory function and senile processes. Chewing resulted in a bilateral increase in blood oxygenation level-dependent (BOLD) signals in the sensorimotor cortex, supplementary motor area, insula, thalamus, amygdala, and cerebellum in both age groups, but the increase was smaller in the first three regions and higher in the cerebellum in the aged subjects. Interestingly, only the aged subjects showed significant signal increases in the association areas, which received information from the primary sensorimotor cortex, supplementary area, or insula, and an increase in the hippocampal BOLD signal and memory acquisition. Similar effects in elderly subjects were seen as a result of more leisurely eating with increased chewing due to the wearing of dentures. The results indicate the involvement of chewing in the neuronal circuit to the hippocampus in the elderly, which plays an important role in preventing aged-related deterioration in the hippocampus. © 2004, Elsevier B.V.

近年高齢社会への一途を辿る日本において痴呆高齢者の増加が社会的な問題となっており,痴呆患者の早期発見・治療が求められている.そこで痴呆の早期発見のため,眼球運動計測による視線軌跡検出を組み込んだ短期記憶テストシステムを構築した.健常高齢者を対象とした実験によりヒューマン・インタフェイスの検討も行い,また本システムによる早期痴呆スクリーニング機能の有効性をfMRI画像診断結果と共に示した.

Age-related changes in mastication-induced brain neuronal activity have been suggested. However, in humans, little is known about the anatomical regions involved. Using fMRI during cycles of rhythmic gum-chewing and no chewing, we have examined the effect of aging on brain regional activity during chewing in young adult (19-26 yrs), middle-aged (42-55 yrs), and aged (65-73 yrs) healthy humans. In all subjects chewing resulted in a bilateral increase in the BOLD signals in the sensorimotor cortex, cerebellum, thalamus, supplementary motor area and insula, and a unilateral increase in the right prefrontal area. In the first three regions, the signal increases were attenuated in an age-dependent manner, whereas, in the right prefrontal area, the converse was seen. The remaining two regions showed no significant differences with ages. These results indicate that chewing causes regional increases in neuronal activity in the brain, some of which are age-dependent.

Mastication has been suggested to increase neuronal activities in various regions of the human brain. However, because of technical difficulties, the fine anatomical and physiological regions linked to mastication have not been fully elucidated. Using functional magnetic resonance imaging during cycles of rhythmic gum-chewing and no chewing, we therefore examined the interaction between chewing and brain regional activity in 17 subjects (aged 20-31 years). In all subjects, chewing resulted in a bilateral increase in blood oxygenation level-dependent (BOLD) signals in the sensorimotor cortex, supplementary motor area, insula, thalamus, and cerebellum. In addition, in the first three regions, chewing of moderately hard gum produced stronger BOLD signals than the chewing of hard gum. However, the signal was higher in the cerebellum and not significant in the thalamus, respectively. These results suggest that chewing causes regional increases in brain neuronal activities which are related to biting force.

Scientists in many fields have studied olfaction in dogs, but no simple method exists to study this function. The olfactory ability of dogs is used in many fields. However, the owners of the dogs have a frustrating experience because there is not an easy method to measure olfactory function. The purpose of this study was to examine the characteristics of olfactory function of the dog with electroencephalographic olfactometry (EEGO) recording. It was found that slow waves decreased and rapid waves increased in response to odours. From these results, it is suggested that the rapid waves of EEGO activity are important in determining a dop's olfactory ability. The EEGO recording is effective in diagnosing anosmia in the dog and is easier than a behavioural experiment. Additionally, this method may not cause distress to an animal. (C) 2000 Harcourt Publishers Ltd.

Although avian olfaction has been studied behaviorally and anatomically, few electrophysiological (EEG) studies exist. The purpose of this study is to examine the characteristics of the olfactory function of the fowl with EEG recording. We found that slow waves decreased and the rapid waves increased in response to a variety of odors. (C) 2000 Elsevier Science Inc. All rights reserved.

The decline in olfaction with age is well documented in histological, psychological, and electroencephalographical studies. However, there are few electrophysiological studies on changes in the sensitivity of the peripheral olfactory cells with age. We evaluated the behavior. the amplitude of electro-olfactogram (EOG), and the thickness of the olfactory epithelium in the Senescence-Accelerated Mouse (SAM-P1). This strain of mouse exhibits accelerated senescence and age-related pathologies, and it is commonly used as a model for research on aging. Its median survival time is 55 weeks. To ensure our results would be restricted to the olfactory system, we chose vanillin as a stimulus, because this stimulus has no definitive chorda tympani (VII) response, and we verified that it is tasteless. The data demonstrate that olfactory sensitivity to vanillin decreases dramatically with age in these mice, and that this is due to loss in the number of olfactory receptor cells. (C) 2000 Elsevier Science Inc. All rights reserved.