Multi-modal imaging of the auditory-larynx motor network for voicing perception.

Voicing is one of the most important characteristics of phonetic speech sounds. Despite its importance, voicing perception mechanisms remain largely unknown. To explore auditory-motor networks associated with voicing perception, we firstly examined the brain regions that showed common activities for voicing production and perception using functional magnetic resonance imaging. Results indicated that the auditory and speech motor areas were activated with the operculum parietale 4 (OP4) during both voicing production and perception. Secondly, we used a magnetoencephalography and examined the dynamical functional connectivity of the auditory-motor networks during a perceptual categorization task of /da/-/ta/ continuum stimuli varying in voice onset time (VOT) from 0 to 40 ms in 10 ms steps. Significant functional connectivities from the auditory cortical regions to the larynx motor area via OP4 were observed only when perceiving the stimulus with VOT 30 ms. In addition, regional activity analysis showed that the neural representation of VOT in the auditory cortical regions was mostly correlated with categorical perception of voicing but did not reflect the perception of stimulus with VOT 30 ms. We suggest that the larynx motor area, which is considered to play a crucial role in voicing production, contributes to categorical perception of voicing by complementing the temporal processing in the auditory cortical regions.

Bipolar temperaments and light.

BACKGROUND: Converging lines of evidence have established a relationship between exposure to ambient light and both mood state and mood disorders. In view of the association between mood disorder and affective disposition, in this study, the relationship between temperament (depressive, cyclothymic, hyperthymic, irritable and anxious) and daily light exposure was closely examined. METHODS: Fifty-six subjects completed the Japanese standardized version of the Temperament Evaluation of Memphis, Pisa, Paris and San Diego-auto questionnaire version (TEMPS-A) and illuminance of daytime using actigraphy. RESULTS: Cyclothymic temperament scores were significantly and negatively associated with illuminance of daytime whereas hyperthymic temperament scores were significantly and positively associated with illuminance of daytime. LIMITATIONS: Sample size was relatively small and they were only healthy subjects and no patients. CONCLUSIONS: The findings suggest that illuminance of daytime may be related to both cyclothymic and hyperthymic temperaments but that the associations lie in opposite directions. If this is the case, it seems important to consider individual patients' temperaments when light therapy is used to treat their depressive episode. Further studies are required to determine why and how these temperaments are associated with illuminance.

Infrared radiation has potential antidepressant and anxiolytic effects in animal model of depression and anxiety.

BACKGROUND: Bright light therapy has been shown to have antidepressant and anxiolytic effects in humans. OBJECTIVE: The antidepressant and anxiolytic effects of infrared radiation were evaluated using an experimental animal model. METHODS: Rats were randomly assigned to either an acutely or chronically exposed infrared radiation group or to a nonexposed control group. Acutely exposed rats were treated with an infrared radiation machine for one session, whereas chronically exposed animals were treated with an infrared radiation for 10 sessions. Control group rats were exposed to the sound of the infrared radiation machine as a sham treatment. After infrared radiation or control exposure, rats underwent behavioral evaluation, including elevated plus maze test, light/dark box, and forced swim test. RESULTS: Chronic infrared radiation exposure decreased indicators of depression- and anxiety-like behavior. No significant effect on general locomotor activity was observed. The number of BrdU-positive cells in CA1 of the hippocampus was significantly increased in both acutely and chronically exposed infrared radiation groups compared with the control group. CONCLUSIONS: These results indicate that chronic infrared radiation might produce antidepressant- and anxiolytic-like effects.