大内田 裕

Prompted by our neuroimaging findings in 60 normal people, we examined whether focal damage to the hand section of precentral motor regions impairs hand kinesthesia in a patient, and investigated brain regions related to recovery of kinesthetic function. The damage impaired contralateral kinesthesia. The peri-lesional cerebral motor region, together with the ipsilateral intermediate cerebellum, participated in the recovered kinesthetic processing. The study confirmed the importance of precentral motor regions in human kinesthesia, and indicated a contribution of the peri-lesional cerebral region in recovered kinesthesia after precentral damage, which conceptually fits with cases of recovery of motor function.

It has been shown that mild to moderate exercise can accelerate gastric emptying in humans. However, understanding of the underlying mechanism is hampered by the lack of appropriate animal models. To investigate the effects of mild exercise on gastric motility, we developed an animal model, in which strain gauge transducers were surgically planted on the antral surfaces of female Sprague-Dawley rats. We continuously recorded the contractions of gastric circular muscle in unrestrained conscious rats, divided into four groups: sham-operated exercise, sham-operated sedentary, vagotomized exercise, and vagotomized sedentary. The rats were trained for 3 weeks, and gastric motility was monitored before and after exercise. Although exercise accelerates gastric antral contraction in sham-operated rats, this effect was absent in the vagotomized exercise group, indicating the involvement of the vagal nerve in the exercise-mediated increase in gastric motility. Among the four groups, daily food intake was highest in the sham-operated exercise group. In contrast, the vagotomized exercise group exhibited the smallest body weight gain. Severe gastric retention was observed in vagotomized rats, suggesting a role of the vagal nerve in facilitating food movement and digestion in the stomach. Moreover, at the end of the 3-week exercise, there were no differences in plasma levels of growth hormone, peptid YY, and ghrelin among the four groups. These results indicate that in response to a mild physical exercise challenge, the vagal nerve stimulates gastric motility and enhances the ability of the stomach to process food. Our findings highlight the significance of neuronal control of stomach function.

K. Sugiyama, T. Kondo, Y. Oouchida, Y. Suzukamo, S.-I. Izumi, 2010, 'P19-16 Clinical utility of diffusion tensor imaging for evaluating patients with diffuse axonal injury and cognitive disorders', <i>Clinical Neurophysiology</i>, vol. 121, p. S218

Y. Oouchida, T. Mori, E. Suzuki, S. Izumi, 2010, 'P11-1 Inhibitory 1Hz TMS to supplementary motor area reduced action tremor', <i>Clinical Neurophysiology</i>, vol. 121, p. S165

Although diffuse axonal injury (DAI) usually ellicits cognitive disorders, abnormal brain findings are generally undetected by conventional imaging techniques. The aim of this study was to evaluate the feasibility of using diffusion tensor imaging (DTI) to detect lesions in DAI patients and to investigate the correlation between DAI lesions and cognitive disorders. We examined 16 healthy controls and 11 patients with DAI. Using voxel-based analysis, we found that there were significantly more brain regions with decreased fractional anisotropy (FA) in the brain but DAI patients compared to healthy controls (p < 0.001), whereas few lesions were detected via conventional magnetic resonance imaging. There was a significant relationship between the results of the Wechsler Adult Intelligence Scale-Revised, Trail Making Test, and some indices of the Wechsler Memory Scale-Revised and the decreased FA observed in various areas of the brain (p < 0.001). The total cognitive scores on the functional independence and functional assessment measures, which represent behavioral problems, were correlated with the cluster (number of DAI lesions, p = 0.007) and voxel numbers (total size of all DAI lesions, p = 0.001). In the fiber tractography-based analysis, DAI patients with memory disorders showed an interruption of fibers within the fornix compared to healthy controls. These results indicate that DTI is a useful technique not only for detecting DAI lesions but also for examining cognitive disorders in DAI patients.

Satoshi Hirose, Yutaka Oouchida, Michikazu Matsumura, Eiichi Naito, 2009, 'Viewing hand grip enhances observerʼs grip force in a body-part-specific manner', <i>NeuroReport</i>, vol. 20, no. 16, pp. 1477-1480

Combination of visual and kinesthetic information is essential to perceive bodily movements. We conducted behavioral and functional magnetic resonance imaging experiments to investigate the neuronal correlates of visuokinesthetic combination in perception of hand movement. Participants experienced illusory flexion movement of their hand elicited by tendon vibration while they viewed video-recorded flexion (congruent: CONG) or extension (incongruent: INCONG) motions of their hand. The amount of illusory experience was graded by the visual velocities only when visual information regarding hand motion was concordant with kinesthetic information (CONG). The left posterolateral cerebellum was specifically recruited under the CONG, and this left cerebellar activation was consistent for both left and right hands. The left cerebellar activity reflected the participants' intensity of illusory hand movement under the CONG, and we further showed that coupling of activity between the left cerebellum and the "right" parietal cortex emerges during this visuokinesthetic combination/perception. The "left" cerebellum, working with the anatomically connected high-order bodily region of the "right" parietal cortex, participates in online combination of exteroceptive (vision) and interoceptive (kinesthesia) information to perceive hand movement. The cerebro-cerebellar interaction may underlie updating of one's "body image," when perceiving bodily movement from visual and kinesthetic information.

Does viewing someone's actions activate a viewer's somatosensory cortex? We tested if visual information of limb movements activated limb sections in somatosensory areas that are normally engaged in kinesthetic processing of the limb. We showed, with functional magnetic resonance imaging in 17 right-handed healthy subjects, that passive observation of flexion-extension movements of an experimenter's right hand activated the observer's contralateral hand section of area 2 which is involved in kinesthetic processing of right hand movements. This could be interpreted as a pragmatic function of the brain that permits visual information to reach the somatosersory area, and suggests human area 2 has an association function between kinesthesia and vision.