大内田 裕

The sense of body ownership, the feeling that one's body belongs to oneself, is a crucial subjective conscious experience of one's body. Recent methodological advances regarding crossmodal illusions have provided novel insights into how multisensory interactions shape human perception and cognition, underpinning conscious experience, particularly alteration of body ownership. Moreover, in post-stroke rehabilitation, encouraging the use of the paretic limb in daily life is considered vital, as a settled sense of ownership and attentional engagement toward the paralyzed body part may promote increased frequency of its use and prevent learned nonuse. Therefore, in addition to traditional methods, novel interventions using neurorehabilitation techniques that induce self-body recognition are needed. This study investigated whether the illusory experience of a patient's ownership alterations of their paretic hand facilitates the enhancement in the range of motion of succeeding imitation movements. An experiment combining a modified version of the rubber hand illusion with imitation training was conducted with chronic hemiplegia. A larger imitation movement of the paretic hand was observed in the illusion-induced condition, indicating that the feeling of ownership toward the observed limb promotes the induction of intrinsic potential for motor performance. This training, using subjective experience, may help develop new post-stroke rehabilitation interventions.

Patients with lower limb amputation experience "embodiment" while using a prosthesis, perceiving it as part of their body. Humans control their biological body parts and receive appropriate information by directing attention toward them, which is called body-specific attention. This study investigated whether patients with lower limb amputation similarly direct attention to prosthetic limbs. The participants were 11 patients with lower limb amputation who started training to walk with a prosthesis. Attention to the prosthetic foot was measured longitudinally by a visual detection task. In the initial stage of walking rehabilitation, the index of attention to the prosthetic foot was lower than that to the healthy foot. In the final stage, however, there was no significant difference between the two indexes of attention. Correlation analysis revealed that the longer the duration of prosthetic foot use, the greater the attention directed toward it. These findings indicate that using a prosthesis focuses attention akin to that of an individual's biological limb. Moreover, they expressed that the prosthesis felt like a part of their body when they could walk independently. These findings suggest that the use of prostheses causes integration of visual information and movement about the prosthesis, resulting in its subjective embodiment.

Learned nonuse is a major problem in upper limb (UL) rehabilitation after stroke. Among the various factors that contribute to learned nonuse, recent studies have focused on body representation of the paretic limb in the brain. We previously developed a method to measure body-specific attention, as a marker of body representation of the paretic limb and revealed a decline in body-specific attention to the paretic limb in chronic stroke patients by a cross-sectional study. However, longitudinal changes in body-specific attention and paretic arm use in daily life (real-world arm use) from the onset to the chronic phase, and their relationship, remain unknown. Here, in a longitudinal, prospective, observational study, we sought to elucidate the longitudinal changes in body-specific attention to the paretic limb and real-world arm use, and their relationship, by using accelerometers and psychophysical methods, respectively, in 25 patients with subacute stroke. Measurements were taken at baseline (T_BL), 2 weeks (T_2w), 1 month (T_1M), 2 months (T_2M), and 6 months (T_6M) after enrollment. UL function was measured using the Fugl-Meyer Assessment (FMA) and Action Research Arm Test (ARAT). Real-world arm use was measured using accelerometers on both wrists. Body-specific attention was measured using a visual detection task. The UL function and real-world arm use improved up to T_6M. Longitudinal changes in body-specific attention were most remarkable at T_1M. Changes in body-specific attention up to T_1M correlated positively with changes in real-world arm use up to T_6M, and from T_1M to T_6M, and the latter more strongly correlated with changes in real-world arm use. Changes in real-world arm use up to T_2M correlated positively with changes in FMA up to T_2M and T_6M. No correlation was found between body-specific attention and FMA scores. Thus, these results suggest that improved body-specific attention to the paretic limb during the early phase contributes to increasing long-term real-world arm use and that increased real-world use is associated with the recovery of UL function. Our results may contribute to the development of rehabilitation strategies to enhance adaptive changes in body representation in the brain and increase real-world arm use after stroke.

BACKGROUND: Imitative learning is highly effective from infancy to old age; however, little is known about the effects of observing errors during imitative learning. This study aimed to examine how observing errors affected imitative learning performance to maximize its effect. METHODS: In the pre-training session, participants were instructed to pinch at a target force (8 N) with auditory feedback regarding generated force while they watched videos of someone pinching a sponge at the target force. In the pre-test, participants pinched at the target force and did not view a model or receive auditory feedback. In Experiment 1, in the main training session, participants imitated models while they watched videos of pinching at either the incorrect force (error-mixed condition) or target force (correct condition). Then, the exact force generated was measured without receiving auditory feedback or viewing a model. In Experiment 2, using the same procedures, newly recruited participants watched videos of pinching at incorrect forces (4 and 24 N) as the error condition and the correct force as the correct condition. RESULTS: In Experiment 1, the average force was closer to the target force in the error-mixed condition than in the correct condition. In Experiment 2, the average force in the correct condition was closer to the target force than in the error condition. CONCLUSION: Our findings indicated that observing error actions combined with correct actions affected imitation motor learning positively as error actions contained information on things to avoid in the target action. It provides further information to enhance imitative learning in mixed conditions compared to that with correct action alone.

<p>One of the factors declining the function of a paretic limb of stroke patients in chronic stage is a learned nonuse phenomenon, learning the disuse of the paretic limb due to clumsiness in daily-life usage of it.Learned non-use causes "negative" use-dependent plasticity in the brain, hence the brain area involved in motor control of the hemiplegic limb shrinks, leading to further functional decline of the hemiplegic limb, which in turn, makes recovery from paralysis more difficult. To resolve this issue, we designed a new rehabilitation system aiming to prevent the learned nonuse of the paretic limb in stroke patients by monitoring the usage of the paretic limb in daily life. As an initial step, the purpose of this study is to quantitatively evaluate the muscle activities of upper limbs in daily-life activities by using a wearable electromyograph (EMG) sensor system.</p>

The right inferior fronto-parietal network monitors the current status of the musculoskeletal system and builds-up and updates our postural model. The kinesthetic illusion induced by tendon vibration has been utilized in experiments on the modulation of body awareness. The right inferior fronto-parietal cortices activate during the kinesthetic illusion. We aimed to determine the relationship between the right inferior fronto-parietal cortices and body awareness by applying transcranial alternating current stimulation (tACS) to exogenously modulate oscillatory neural activity in the right fronto-parietal cortices during the kinesthetic illusion. Sixteen young adults participated in this study. We counterbalanced the order in which participants received the three types of tACS (55 Hz enveloped by 6 Hz; synchronous, desynchronous, and sham) across the subjects. The illusory movement perception induced by tendon vibration of the left extensor carpi ulnaris muscle was assessed before and during tACS. Application of synchronous tACS over the right inferior fronto-parietal cortices significantly increased kinesthetic illusion compared with sham tACS. The kinesthetic illusion during desynchronous tACS decreased from baseline. There was no change in vibration sensation during any tACS condition. The modulation of oscillatory brain activity between the right fronto-parietal cortices alters the illusory movement perception without altering actual vibration sensation. tACS over the right inferior fronto-parietal cortices is considered to modulate the neural processing involved in updating the postural model when the stimulated muscle spindle sends kinesthetic signals. This is the first study that reveals that rhythmic communication between the right inferior fronto-parietal cortices has a causal role in body awareness.

OBJECTIVE: To examine whether reduced body-specific attention to a paretic limb is found in chronic stroke patients in a time-dependent manner. METHODS: Twenty-one patients with chronic hemiparesis (10 left and 11 right hemiparesis) after subcortical stroke and 18 age-matched healthy controls were recruited in this study. Standard neuropsychological examinations showed no clear evidence of spatial neglect in any patient. In order to quantitatively measure spatial attention to the paretic hand, a visual detection task for detecting a target appearing on the surface of either a paretic or dummy hand was used. This task can measure the body facilitation effect, which makes faster detection of a target on the body compared with one far from the body. RESULTS: In stroke patients, there was no difference in the reaction time for a visual target between the paretic and the dummy hands, while the healthy participants showed faster detection for the visual target on the real hand than on the dummy one. The index of the body facilitation effect, subtracting the reaction time for the target-on-paretic hand from that for the target-on-dummy one, was correlated with the duration since onset and with finger function test on the Stroke Impairment Assessment Set. CONCLUSIONS: The reduction of the body facilitation effect in the paretic limb suggests the decline of body-specific attention to the paretic one in patients with chronic hemiparesis. This decline of body-specific attention, leading to neglect for the paretic limb, will be one of the most serious problems for rehabilitation based on use-dependent plasticity.

The aim of the study was to investigate the effect of cathodal transcranial direct current stimulation to the supplementary motor area to inhibit involuntary movements of a child. An 8-year-old boy who developed hypoxic encephalopathy after asphyxia at the age of 2 had difficulty in remaining standing without support because of involuntary movements. He was instructed to remain standing with his plastic ankle-foot orthosis for 10 s at three time points by leaning forward with his forearms on a desk. He received cathodal or sham transcranial direct current stimulation to the supplementary motor area at 1 mA for 10 min. Involuntary movements during standing were measured using an accelerometer attached to his forehead. The low-frequency power of involuntary movements during cathodal transcranial direct current stimulation significantly decreased compared with that during sham stimulation. No adverse effects were observed. Involuntary movement reduction by cathodal stimulation to supplementary motor areas suggests that stimulations modulated the corticobasal ganglia motor circuit. Cathodal stimulation to supplementary motor areas may be effective for reducing involuntary movements and may be safely applied to children with movement disorders.

<p>Almost all the amputees feel the existence of the amputated limb after limb amputation, which is known to be phantom limb. Many amputees can move and control their phantom limb at their will and they report that they receive sensory feedback of the phantom limb while phantom limb moving. Further, approximately 50–80% of them have pain on the amputated limb, phantom limb pain. A possible mechanism for phantom limb is that the information of the body in the amputee's brain is not updated after amputation for some reason, causing this illusory feeling of the amputated limb. This phenomenon suggests that our body perception depends largely on the body information in the brain formed from sensory information of multimodal sensors in the body. For understanding the mechanism of our perceptual system, to examine the mismatch between actual sensory information in the environment and our perception is very useful. Thus, to elucidate the phantom limb will provide us with rich information to help understand the mechanism of our body perception.</p>

Recently, neurorehabilitation that uses virtual reality systems is being applied in clinical settings to deal with issues such as phantom limb pain (PLP) as an alternative to mirror box therapy. One of the weak points of mirror box therapy is that the desired analgesia effect might not be confirmed in some patients. One hypothesis to explain this phenomenon is that the subjective sense of the length of a phantom limb is different from that of an intact limb. Since the gap between body representation in the brain and actual sensory feedback is considered one of the causes of PLP, different lengths of a subjective phantom limb are a serious problem for mirror box therapy and similar VR-based rehabilitation methods. We are thus developing a VR system that displays an avatar that has the same length as the subjective phantom limb. The purpose of the current study is to determine the feasibility of the VR system - specifically, whether it has enough effect on sense of agency (SoA) and sense of ownership (SoO) for healthy subjects - before conducting experiments for actual phantom limb patients. To this end, we developed a VR system in which a virtual avatar performs a motion identical to that of the subject by means of a motion capturing device (Kinect V2). The subject wears a 3D head mounted display (Oculus Rift DK2) to experience seeing through the eyes of the avatar. Six conditions of avatar representation were used: two appearances of a normal human arm and a robot arm and three lengths of the arm (short, medium, and long). The subject executes elbow flexion-extension movement of the right arm, which causes the same movement in the VR avatar's arm. After the induction movement, the subjective sense of the length of the right arm is measured by a pointing gesture of the left hand. Twelve subjects participated in this experiment. Results showed that the subjective length of the arm was changed according to the length of the displayed arm in the VR environment. From the results of a questionnaire, we found that there is no negative effect on SoA. SoO when the subjects watch the natural human avatar is stronger than when the robot arm is shown. These results are positive, thus confirming the basic potential of the proposed VR system. In conclusion, the change of self-body appearance of a VR avatar has enough effect on subjective sense of arm length. Since the subjective sense of arm length is strongly related to body representation in the brain, we believe that the system can be a platform for research on embodied-brain science systems.

話し言葉の理解では,音声だけでなく話者の顔の視覚情報も利用されており,視線計測はその実際に取得された情報を知るうえで有用である.本研究では音声言語知覚における視線の影響を検討するため,マガーク効果に着目し,2つの実験を行った.日本語を母語とする健常者を対象として,実験1ではマガーク効果における視線を計測した.その結果,マガーク効果が生起するときは様々な顔の部位を注視して視線の移動距離が長く,マガーク効果が生起しないときは口を限定的に注視して視線の移動距離が短かった.これを受けて,実験2では視線統制によるマガーク効果の変化を検討した.結果として,マガーク効果の生起率は注視部位や視線の移動距離の影響を受けた.以上のことから,マガーク効果と視線の関連性が示された.マガーク効果は視覚情報の利用度に応じて変化する.視線誘導による視覚情報を活用して音声言語知覚の向上が期待される.(著者抄録)

近年、脳神経科学の進歩により、主観的な意識的経験も科学的研究対象として扱われるようになってきた。リハビリテーションの臨床場面で、思い通りに麻痺肢を制御できないことが、麻痺肢における身体所有感の低下を導き、さらなる使用頻度の低下を招くと考えられているが、ここで得られる「思い通りに動かすことができない」という愁訴は極めて私的な感覚で、外部から観察することが困難であり、また「運動を引き起こす主体がまさに自分である」という運動主体感や「観測している身体が自分のものである」という身体所有感などの私的な意識的経験が運動制御にどのような影響を与えるのかについてもいまだ明らかにされていない。本稿では、使用頻度に応じて変化する脳の可塑性と、患側肢の使用頻度上昇を導くようなニューロリハビリテーション手法について概観し、自己身体認知に関わる知覚を変化させる新たなリハビリテーション戦略について検討する。(著者抄録)

Our brain has great flexibility to cope with various changes in the environment. Use-dependent plasticity, a kind of functional plasticity, plays the most important role in this ability to cope. For example, the functional recovery of paretic limb motor movement during post-stroke rehabilitation depends mainly on how much it is used. Patients with hemiparesis, however, tend to gradually disuse the paretic limb because of its motor impairment. Decreased use of the paretic hand then leads to further functional decline brought by use-dependent plasticity. To break this negative loop, body representation, which is the conscious and unconscious information regarding body state stored in the brain, is key for using the paretic limb because it plays an important role in selecting an effector while a motor program is generated. In an attempt to understand body representation in the brain, we reviewed animal and human literature mainly on the alterations of the sensory maps in the primary somatosensory cortex corresponding to the changes in limb usage caused by peripheral or central nervous system damage. (C) 2015 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

ミラーニューロンシステムは,主に視覚入力された他者の運動から運動情報を抽出し,それと同様の運動プログラムをつくりだす働きがある。この他者の運動からつくりだされた運動プログラムを実行することにより,観察している運動と同じ運動が出力することが可能となる。この模倣運動を利用し,中枢神経障害後の運動障害と四肢切断などの身体の変化により生じる幻肢痛という2つの病態に対する観察・模倣運動の臨床的応用を紹介する。(著者抄録)

運動イメージは,脳卒中患者のリハビリテーションとして有効と考えられ,運動イメージを用いた具体的な訓練方法が求められている.本研究は手の心的回転課題が運動イメージ訓練に応用できるかを検証することを目的とした.対象は健常者12名と慢性期脳卒中患者11名とし,患者は麻痺手の肘屈筋腱振動刺激による運動錯覚あり群となし群の2群に分け解析を行った.被験者は,自己の手の位置を変化させ課題を行いその反応時間が計測された.その結果,健常群と錯覚あり群では手の位置変化により,最も遅くなる反応時間の回転角度(ピーク角度)が変化し,なし群は手の位置変化がピーク角度に影響しなかった.手の位置を変えて行う課題では,実際の身体の位置情報を参照し,自己の身体像の心的回転操作が行われていると考えられ,ピーク角度の変化は運動イメージを利用していることを反映している.この手の位置を変える課題は運動イメージ訓練への応用が期待できる.(著者抄録)

Although diffuse axonal injury (DAI) frequently manifests as cognitive and/or motor disorders, abnormal brain findings are generally undetected by conventional imaging techniques. Here we report the case of a patient with DAI and hemiparesis. Although conventional MRI revealed no abnormalities, diffusion tensor imaging (DTI) and fibre tractography (FT) revealed the lesion speculated to be responsible for hemiparesis. A 37-year-old woman fell down the stairs, sustaining a traumatic injury to the head. Subsequently, she presented with mild cognitive disorders and left hemiparesis. DTI fractional anisotropy revealed changes in the right cerebral peduncle, the right posterior limb of the internal capsule, and the right corona radiata when compared with the corresponding structures observed on the patient's left side and in healthy controls. On FT evaluation, the right corticospinal tract (CST) was poorly visualised as compared with the left CST as well as the CST in healthy controls. These findings were considered as evidence that the patient's left hemiparesis stemmed from DAI-induced axonal damage in the right CST. Thus, DTI and FT represent useful techniques for the evaluation of patients with DAI and motor disorders. © 2013 Ken Sugiyama et al.

Background and Purpose-The aim of this study was to determine if side of cerebral hemisphere lesion affects the prevalence and time course of pushing behavior (PB) after stroke. Methods-A total of 1660 patients with acute stroke were investigated. PB was assessed using the standardized Scale for Contraversive Pushing. Risk ratios were used to evaluate the differences in the prevalence of PB between right cerebral hemisphere-damaged (RCD) and left cerebral hemisphere-damaged (LCD) patients. The differences in the time course among 35 (27 RCD and 8 LCD) patients were evaluated by analyzing Scale for Contraversive Pushing scores with the Kaplan-Meier method using a log-rank test. Results-PB was observed in 156 (9.4%) patients. The prevalence of PB was significantly higher in RCD (97 of 556 [17.4%]) than in LCD (57 of 599 [9.5%]) patients; risk ratio was 1.83 (95% CI, 1.35-2.49). The log-rank test indicated that RCD patients exhibited a significantly slower recovery than LCD patients (P=0.027). Conclusions-The number of RCD patients who exhibited PB was higher than that of LCD patients. The duration of recovery from PB was longer in RCD patients than in LCD patients. (Stroke. 2012;43:1654-1656.)

This study aimed to investigate the manner in which healthy individuals execute robust whole body movements despite unstable body structure from the perspective of perception-action coupling. Twelve healthy adults performed sit-to-stand (STS) movements under conditions of constrained visual and somatic senses. During this movement, centre of mass (COM) of the body in the anterior-posterior, upward-downward and right-left directions was computed. The conditions of perceptual constraint were set as vision-restricted, somatosensory-restricted, vision- and somatosensory-restricted, and normal conditions. To evaluate COM control under these perceptual constraints, the variability in position and velocity of COM were assessed. The variabilities in COM velocity in the anterior-posterior and upward-downward directions decreased around the lift-off period only when both vision and somatic senses were constrained, whereas the variability of the COM position in the right-left direction increased under the somatosensory-restricted condition. Our findings suggested that control of COM velocity was enhanced in the major moving directions (anterior and upward directions) around the liftoff period during STS when both modalities of perception with regard to postural orientation were constrained. These motor regulations with perceptual constraints facilitate better adaptation to changes in body and environmental situations in daily life. (C) 2012 Elsevier B.V. All rights reserved.

Fumiko Anzaki, Yoshimi Suzukamo, Yutaka Oouchida, Takeo Kondo, Shin-Ichi Izumi, 2012, &#039;Lesions responsible for phonological paraphasia and auditory–verbal short-term memory disturbances in aphasia&#039;, &lt;i&gt;The Official Journal of the Polish Neuropsychological Society&lt;/i&gt;, vol. 10, no. 1

The corpus callosum, which is the largest white matter structure in the human brain, connects the 2 cerebral hemispheres. It plays a crucial role in maintaining the independent processing of the hemispheres and in integrating information between both hemispheres. The functional integrity of interhemispheric interactions can be tested electrophysiologically in humans by using transcranial magnetic stimulation, electroencephalography, and functional magnetic resonance imaging. As a brain structural imaging, diffusion tensor imaging has revealed the microstructural connectivity underlying interhemispheric interactions. Sex, age, and motor training in addition to the size of the corpus callosum influence interhemispheric interactions. Several neurological disorders change hemispheric asymmetry directly by impairing the corpus callosum. Moreover, stroke lesions and unilateral peripheral impairments such as amputation alter interhemispheric interactions indirectly. Noninvasive brain stimulation changes the interhemispheric interactions between both motor cortices. Recently, these brain stimulation techniques were applied in the clinical rehabilitation of patients with stroke by ameliorating the deteriorated modulation of interhemispheric interactions. Here, we review the interhemispheric interactions and mechanisms underlying the pathogenesis of these interactions and propose rehabilitative approaches for appropriate cortical reorganization.

We assessed whether subitem scores on the Mini-Mental State Examination (MMSE) associated independently with cerebral white matter hyperintensity (WMH) and lacunar infarction (LI). Magnetic resonance imaging (MRI) and neuropsychological evaluation (MMSE) were performed in 1008 elderly individuals from the Ohasama Study (348 men, 660 women [65.5%]; age 68.0 +/- 6.0 [mean +/- SD] years; MMSE score, 26.5 +/- 2.9). The relationships between MRI findings and MMSE subitem scores were analyzed by logistic regression. Significant associations were observed between the MMSE subitems "Orientation to place" and WMH, and "Copy a figure" and LI. Pathological changes were detected by brain MRI associated with a decrease in cognitive function in healthy elderly individuals.

可聴範囲の高周波帯域(20kHz以下)を増幅加工した音楽の聴取が自律神経系活動および心理状態に影響を与えるか、健常被験者11名を対象に実験を行い検討した。ストレス課題を5分間行った後に、実験課題として原曲(OG)または高周波帯域増幅曲(HF)を5分間聴取させた。実験課題前後の唾液アミラーゼ活性(sAMY)、POMS(Profile of Mode States)短縮版の得点を比較し分析した。被験者は2群に無作為に割り付け、Group A(GA)およびGroup B(GB)には異なる実験課題曲を聴取させた。結果は、GA、GBのOG課題およびHF課題前後においてsAMYは有意な変化がなかったが、GAのHF課題前後でsAMYが有意に減少した。POMS短縮版の得点は7項目に関して評価を行い、GAのHF課題前後において疲労(F)項目の得点のみが有意に低下した。高周波帯域を増幅した音楽を聴取することにより、交感神経活動が抑制され、疲労感が軽減される場合があると示唆された。(著者抄録)

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.