Cerebral activation caused by dental sounds: a functional magnetic resonance imaging study.

Dental drilling sounds can induce anxiety in some patients. This study aimed to use functional magnetic resonance imaging (fMRI) to assess the relationship between dental fear and auditory stimuli. Thirty-four right-handed individuals (21 women and 13 men; average age, 31.2 years) were selected. The level of dental fear was assessed using the dental fear survey (DFS). Based on a threshold DFS score > 52, participants were categorized into two groups: dental fear (DF) group (n = 12) and control group (n = 22). Two types of stimuli were presented in a single session: dental and neutral sounds. Cerebral activation during the presentation of these sounds was evaluated using contrast-enhanced blood oxygenation level-dependent fMRI. In the DF group, dental sounds induced significantly stronger activation in the left inferior frontal gyrus and left caudate nucleus (one-sample t test, P < 0.001). In contrast, in the control group, significantly stronger activation was observed in the bilateral Heschl's gyri and left middle frontal gyrus (one-sample t test, P < 0.001). Additionally, a two-sample t test revealed that dental sounds induced a significantly stronger activation in the left caudate nucleus in the DF group than in the control group (P < 0.005). These findings suggest that the cerebral activation pattern in individuals with DF differs from that in controls. Increased activation of subcortical regions may be associated with sound memory during dental treatment.

Effects of anodal transcranial direct current stimulation on implicit motor learning and language-related brain function: An fMRI study.

AIM: Anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) is known as a useful application for improving depressive symptoms or cognitive performance. Antidepressive effects by anodal tDCS over the left DLPFC are expected, but the neural mechanisms of these effects are still unclear. Further, in depression, reduced performance and left prefrontal hypofunction during the verbal fluency task (VFT) are generally known. However, few studies have examined the effect of tDCS on the language-related cerebral network. We aimed to investigate whether anodal tDCS at the left DLPFC affects cognitive performance and the neural basis of verbal fluency. METHODS: Nineteen healthy volunteers participated in this study. The effects of tDCS on cognitive behavior and cerebral function were evaluated by (i) performance and accuracy of implicit/explicit motor learning task (serial reaction time task/sequential finger-tapping task), and (ii) cerebral activation while the subjects were performing the VFT by using a functional MRI protocol of a randomized sham-controlled, within-subjects crossover design. RESULTS: Reaction times of the implicit motor learning task were significantly faster with tDCS in comparison with the sham. Further, language-related left prefrontal-parahippocampal-parietal activation was significantly less with tDCS compared with the sham. Significant correlation was observed between shortened response time in serial reaction time task and decreased cerebral activation during VFT with tDCS. CONCLUSION: Anodal tDCS over the left DLPFC could improve cognitive behavior of implicit motor learning by improving brain function of the frontoparietal-parahippocampal region related to motor learning, as well as language-related regions.

Comparison of Aversion to Visual Dental Stimuli Between Patients and Dentists: A Preliminary Study.

Purpose: Fearful dental patients often cite various dental instruments or procedures as triggers for their dental fear. Thus, visual dental stimuli provoke anxiety. This preliminary study aimed to assess the level of aversion to visual stimuli in dental patients and compare it with that in dentists. Patients and Methods: A total of 43 dental patients (25 women, 18 men; average age, 29.9 ± 13.3 years; patient group) and 13 dentists (4 women, 9 men; average age, 28.2 ± 2.0 years; dentist group) were included. All participants had previously undergone dental treatment. The dental fear level was assessed using the self-reported Dental Fear Survey (DFS). Thirty-two images associated with dental treatment were prepared and classified into three categories: dental instruments, dental procedures, and the dental environment. All participants rated their level of disgust toward each image on a visual analog scale with scores ranging from 0 to 100. Results: In the patient group, the disgust ratings for tooth extraction, dental drilling, and local anesthesia were >60, which were significantly different from those in the dentist group (Mann-Whitney U-test, p<0.001, p=0.001, and p=0.001, respectively). The ranking order of the disgust ratings for the 32 images showed significant correlation between the patient and dentist groups (Spearman correlation coefficient, r=0.80, p<0.001). In the patient group, the disgust ratings for dental impressions and the interdental brush, dental light, and dental chair were significantly correlated with DFS scores (r=0.61, p<0.001; r=0.47, p=0.001; r=0.41, p=0.006; and r=0.40, p=0.008, respectively). Conclusion: This study revealed that patients have more negative feelings toward invasive procedures than dentists. However, a significant correlation was identified between the ranking of aversion-provoking dental stimuli by patients and dentists. Furthermore, the level of aversion to several dental-related items that do not cause pain was correlated with the dental fear level.

Characteristics of healthy Japanese young adults with respect to recognition of facial expressions: a preliminary study.

BACKGROUND: Emotional cognitive impairment is a core phenotype of the clinical symptoms of psychiatric disorders. The ability to measure emotional cognition is useful for assessing neurodegenerative conditions and treatment responses. However, certain factors such as culture, gender, and generation influence emotional recognition, and these differences require examination. We investigated the characteristics of healthy young Japanese adults with respect to facial expression recognition. METHODS: We generated 17 models of facial expressions for each of the six basic emotions (happiness, sadness, anger, fear, disgust, and surprise) at three levels of emotional intensity using the Facial Acting Coding System (FACS). Thirty healthy Japanese young adults evaluated the type of emotion and emotional intensity the models represented to them. RESULTS: Assessment accuracy for all emotions, except fear, exceeded 60% in approximately half of the videos. Most facial expressions of fear were rarely accurately recognized. Gender differences were observed with respect to both faces and participants, indicating that expressions on female faces were more recognizable than those on male faces, and female participants had more accurate perceptions of facial emotions than males. CONCLUSION: The videos used may constitute a dataset, with the possible exception of those that represent fear. The subject's ability to recognize the type and intensity of emotions was affected by the gender of the portrayed face and the evaluator's gender. These gender differences must be considered when developing a scale of facial expression recognition.

Cerebral response to emotional working memory based on vocal cues: an fNIRS study.

Introduction: Humans mainly utilize visual and auditory information as a cue to infer others' emotions. Previous neuroimaging studies have shown the neural basis of memory processing based on facial expression, but few studies have examined it based on vocal cues. Thus, we aimed to investigate brain regions associated with emotional judgment based on vocal cues using an N-back task paradigm. Methods: Thirty participants performed N-back tasks requiring them to judge emotion or gender from voices that contained both emotion and gender information. During these tasks, cerebral hemodynamic response was measured using functional near-infrared spectroscopy (fNIRS). Results: The results revealed that during the Emotion 2-back task there was significant activation in the frontal area, including the right precentral and inferior frontal gyri, possibly reflecting the function of an attentional network with auditory top-down processing. In addition, there was significant activation in the ventrolateral prefrontal cortex, which is known to be a major part of the working memory center. Discussion: These results suggest that, compared to judging the gender of voice stimuli, when judging emotional information, attention is directed more deeply and demands for higher-order cognition, including working memory, are greater. We have revealed for the first time the specific neural basis for emotional judgments based on vocal cues compared to that for gender judgments based on vocal cues.

Bupropion increases cerebral activation in auditory affective processing: A randomized controlled fMRI study.

INTRODUCTION: Bupropion is an antidepressant with less possibility to give rise to emotional blunting as side effect, and it also acts on improving negative self-recognition in a depressive state. Previous neuroimaging studies indicated a change in brain function by facial expression as an effect of antidepressants. As well as facial expression, vocal affective processing is essential for accurately recognizing another's feelings, but to our knowledge, no study has investigated whether bupropion affects the cerebral function of recognition of auditory affective processing. In this study, we aimed to investigate the acute effect of bupropion on cerebral response to vocal affective processing. METHODS: Sixteen healthy volunteers (male = 8) participated in this study. With a randomized placebo-controlled within-subject trial, two series of fMRI scans, using either placebo or bupropion (150 mg), were examined. An auditory emotional valence judgement task was performed during fMRI scanning. The acute effects of bupropion on cerebral activation in the emotional circuit and behavioral performance during emotional processing were analyzed. RESULTS: Compared with placebo, bupropion caused a significantly greater activation of emotional voices in the left insula and right superior temporal gyrus, whereas the amygdala was not activated. By bupropion, a significantly greater activation of the positive emotional circuit was observed at the superior temporal gyrus and middle frontal gyrus. As for behavioral performance, no significant difference was observed between placebo and bupropion. CONCLUSIONS: Our findings suggest that bupropion enhances the cerebral response to affective processing, especially positive emotional vocalizations, indicating a possible mechanism underlying the therapeutic effects for patients with depression.

Modafinil Decreased Thalamic Activation in Auditory Emotional Processing: A Randomized Controlled Functional Magnetic Resonance Imaging Study.

BACKGROUND: Modafinil improves wakefulness and attention, is approved in Japan for treatment of narcolepsy, and was reported to be effective for attention-deficit/hyperactivity disorder. However, it was reported to induce emotional instability, including mania, depression, and suicidal ideation. Such side effects may be related to changes in cognitive behavior caused by the effects of modafinil on emotional recognition. However, the effects of modafinil on the neural basis of emotional processing have not been fully verified. We used functional magnetic resonance imaging to investigate the effects of modafinil on the neural basis of auditory emotional processing. METHODS: This study adopted a placebo-controlled within-subject crossover design. Data from 14 participants were analyzed. The effects of modafinil on cerebral activation and task performance during an emotional judgement task were analyzed. RESULTS: Task accuracy decreased significantly and response time of emotional judgement was significantly delayed by modafinil, as compared with placebo. Right thalamic activation in auditory emotional processing was significantly less in the modafinil condition than in the placebo condition. In addition, reduction of right thalamic activation by modafinil was positively correlated with accuracy of emotional judgement. CONCLUSIONS: Our findings suggest that modafinil acts on the right thalamus and changes behavior and brain function associated with auditory emotional processing. These results indicate that modafinil might change emotional recognition by reducing emotional activation related to social communication.

Cross-cultural differences in the processing of non-verbal affective vocalizations by Japanese and canadian listeners.

The Montreal Affective Voices (MAVs) consist of a database of non-verbal affect bursts portrayed by Canadian actors, and high recognitions accuracies were observed in Canadian listeners. Whether listeners from other cultures would be as accurate is unclear. We tested for cross-cultural differences in perception of the MAVs: Japanese listeners were asked to rate the MAVs on several affective dimensions and ratings were compared to those obtained by Canadian listeners. Significant Group × Emotion interactions were observed for ratings of Intensity, Valence, and Arousal. Whereas Intensity and Valence ratings did not differ across cultural groups for sad and happy vocalizations, they were significantly less intense and less negative in Japanese listeners for angry, disgusted, and fearful vocalizations. Similarly, pleased vocalizations were rated as less intense and less positive by Japanese listeners. These results demonstrate important cross-cultural differences in affective perception not just of non-verbal vocalizations expressing positive affect (Sauter et al., 2010), but also of vocalizations expressing basic negative emotions.