武田 湖太郎

This review tackles the unresolved issue of the existence of oxygen sensor in the body. The sensor that would respond to changes in tissue oxygen content, possibly along the hypoxia-normoxia-hyperoxia spectrum, rather than to a given level of oxygen, and would translate the response into lung ventilation changes, the major adaptive process. Studies on oxygen sensing, for decades, concentrated around the hypoxic ventilatory response generated mostly by carotid body chemoreceptor cells. Despite gaining a substantial insight into the cellular transduction pathways in carotid chemoreceptors, the exact molecular mechanisms of the chemoreflex have never been conclusively verified. The article briefly sums up the older studies and presents novel theories on oxygen, notably, hypoxia sensing. These theories have to do with the role of transient receptor potential cation TRPA1 channels and brain astrocytes in hypoxia sensing. Although both play a substantial role in shaping the ventilatory response to hypoxia, neither can yet be considered the ultimate sensor of hypoxia. The enigma of oxygen sensing in tissue still remains to be resolved.

Mild hypoxia increases ventilation, but severe hypoxia depresses it. The mechanism of hypoxic ventilatory depression, in particular, the functional role of the cerebrum, is not fully understood. Recent progress in glial physiology has provided evidence that astrocytes play active roles in information processing in various brain functions. We investigated the hypothesis that astrocytic activation is necessary to maintain the cerebral function and ventilation in hypoxia, by examining the responses of EEG and ventilation to severe hypoxia before and after administration of a modulator of astrocytic function, arundic acid, in unanesthetized mice. Ventilatory parameters were measured by whole body plethysmography. When hypoxic ventilatory depression occurred, gamma frequency band of EEG was suppressed. Arundic acid further suppressed ventilation, and the EEG power was suppressed in a dose-dependent manner. Arundic acid also suppressed hypoxia-induced c-Fos expression in the hypothalamus. We conclude that severe hypoxia suppresses the cerebral function which could reduce the stimulus to the brainstem resulting in ventilatory depression. Astrocytic activation in hypoxia may counteract both cerebral and ventilatory suppression.

Dimethyl sulfoxide (DMSO) is commonly used as a solvent for hydrophobic substances, but the compound's innate bioactivity is an area of limited understanding. In this investigation we seek to determine the analgesic potential of DMSO. We addressed the issue by assessing the perception of thermal pain stimulus, using a 55 °C hotplate design, in conscious mice. The latency of withdrawal behaviors over a range of incremental accumulative intraperitoneal DMSO doses (0.5-15.5 g/kg) in the same mouse was taken as a measure of thermal endurance. The findings were that the latency, on average, amounted to 15-30 s and it differed inappreciably between the sequential DMSO conditions. Nor was it different from the pre-DMSO control conditions. Thus, DMSO did not influence the cutaneous thermal pain perception. The findings do not lend support to those literature reports that point to the plausible antinociceptive potential of DMSO as one of a plethora of its innate bioactivities. However, the findings concern the mouse's footpad nociceptors which have specific morphology and stimulus transduction pathways, which cannot exclude DMSO's antinociceptive influence on other types of pain or in other types of skin. Complex and as yet unresolved neural mechanisms of perception of cutaneous noxious heat stimulus should be further explored with alternative experimental designs.

BACKGROUND: Quantification of increased muscle tone for patients with spasticity has been performed to date using various devices to replace the manual scales, such as the modified Ashworth scale or the Tardieu scale. We developed a device that could measure resistive plantar flexion (PF) torque of the ankle during passive dorsiflexion (DF) as an indicator of muscle tone of ankle plantar flexors. METHODS: The primary objective was to explore the test-retest intrarater reliability of a custom-built device. Participants were 11 healthy subjects (7 men, 4 women; mean age 47.0 years) and 22 patients with poststroke hemiplegia (11 hemorrhagic, 11 ischemic; 14 men, 8 women; mean age 57.2 years). The device was affixed to the ankle. Subjects were seated with knees either flexed or extended. The ankle was passively dorsiflexed from 20° of PF to more than 10° of DF at 5°/second (slow stretch) or 90°/second (fast stretch). Angle and torque were measured twice during the stretches. The intraclass correlation coefficients (ICCs) of torque at 10° of DF (T10) in the 4 conditions-slow and fast stretches with knee flexed or extended-were calculated. RESULTS: The T10 ICCs of the 4 conditions were .95-.99 in both groups. The healthy subjects showed significantly higher T10 of knee extension than of knee flexion during slow and fast stretches. The patients showed increased velocity-dependent torque during fast stretches. CONCLUSIONS: Excellent reliability was observed. The device is suitable for measuring resistive PF torque during passive stretch in a flexed knee condition.

Dimethyl sulfoxide (DMSO) is one of the most commonly used solvents for hydrophobic substances in biological experiments. In addition, the compound exhibits a plethora of bioactivities, which makes it of potential pharmacological use of its own. The influence on respiration, and thus on arterial blood oxygenation, of DMSO is unclear, contentious, and an area of limited study. Thus, in the present investigation we set out to determine the influence on lung ventilation of cumulated doses of DMSO in the amount of 0.5, 1.5, 3.5, 7.5, and 15.5 g/kg; each dose given intraperitoneally at 1 h interval in conscious mice. Ventilation and its responses to 7 % hypoxia (N(2) balanced) were recorded in a whole body plethsymograph. We demonstrate a dose-dependent inhibitory effect of DMSO on lung ventilation and its hypoxic responsiveness, driven mostly by changes in the tidal component. The maximum safe dose of DMSO devoid of meaningful consequences for respiratory function was 3.5 g/kg. The dose of 7.5 g/kg of DMSO significantly dampened respiration, with yet well preserved hyperventilatory response to hypoxia. The highest dose of 15.5 g/kg severely impaired ventilation and its responses. The study delineates the safety profile of DMSO regarding the respiratory function which is essential for maintaining proper tissue oxygenation. Caution should be exercised concerning dose concentration of DMSO.

In humans, body sway is observed in ataxic gait disorder. As gait ataxia develops due to degeneration and loss of cerebellar Purkinje cells in B6-wob/t mice (Wob/t), we measured body sway in these mice. The trajectory length (TL) per unit time in the horizontal direction and the weight variance (WV) in the vertical direction were compared with wild-type C57BL/6J (B6) mice as evaluation parameters. First, a rotarod test was performed to observe the coordinated movement of the four limbs with gait ataxia. The duration of walking on the rotating rod was significantly shorter in Wob/t than in B6 (p<0.001), demonstrating ataxia. In addition, TL and WV in the resting state were measured in an open field. The amplitudes of both body sway parameters were significantly greater in Wob/t than in B6 (p<0.001). Wob/t mice were divided into two groups consisting of training (Ex) and no training (NEx). The Wob/t (Ex) group was subjected to forced gait training to investigate the effect on trunk tremors compared to the Wob/t (NEx) group. The amplitudes of TL and WV were significantly reduced in the Ex compared to the NEx (p<0.05). TL remained significantly different between the Ex and B6 groups (p<0.05), but the difference in WV became insignificant. In contrast, in the standstill state, no difference was noted in either TL or WV among the three groups. Based on these findings, the amplitudes of TL and WV of body sway were greater in Wob/t than in B6. However, the body sway tremors were reduced in Ex after forced gait training compared with NEx. These findings clarified that the cause of gait ataxia in Wob/t was the impact of trunk tremors induced by cerebellar Purkinje cell loss, and that forced gait training reduced the tremors. Regarding the reason for the absence of a significant difference in the TL and WV of body sway in the resting state among the B6, Wob/t (NEx), and Wob/t (Ex) groups, the mice may have been somnolent in the resting state and the cerebellar tremors of Wob/t may have been postural tremors that appear during exercise, similarly to those in humans.

Objective: The therapeutic effectiveness of phenol motor point block in patients with spasticity of the lower extremity was assessed by measuring ankle plantar flexion torque. Patient factors influencing therapeutic effectiveness were evaluated. Methods: Twelve patients with spasticity of the lower extremity after cerebrovascular disorders were enrolled in this study. Plantar flexion torques at 5°/s or 90°/s under passive ankle dorsiflexion were measured before and after treatment with phenol motor block in flexor muscles of the lower leg. Patient factors influencing therapeutic effectiveness were evaluated before and after treatment using torque changes as an indicator of therapeutic effectiveness. Results: Therapeutic effectiveness showed a significantly negative correlation with plantar flexion torques at 5°/s before treatment (ρ= -0.741, p = 0.006) and with the time from onset (ρ= -0.680, p = 0.015). A significantly positive correlation between therapeutic effectiveness and presence of self-exercise (ρ= 0.661, p = 0.019) was observed. Conclusion: Patients who were less affected by immobilization including those with small plantar flexion torque at 5°/s or those who engaged in self-exercise are expected to achieve large therapeutic effects with regard to phenol motor point block against spasticity of the lower extremity.

We developed an affordable and portable tDCS device for clinical studies. The block diagram and minimum number of necessary components of the device, and code of the stimulation program were also presented. The low-cost instrument may improve the quality of rehabilitation at a hospital or home. In addition, the high portability of the device may be useful for gait rehabilitation.

[Purpose] To develop a device for measuring the torque of an ankle joint during walking in order to quantify the characteristics of spasticity of the ankle and to verify the functionality of the device by testing it on the gait of an able-bodied individual and an equinovarus patient. [Subjects and Methods] An adjustable posterior strut (APS) ankle-foot orthosis (AFO) was used in which two torque sensors were mounted on the aluminum strut for measuring the anterior-posterior (AP) and medial-lateral (ML) directions. Two switches were also mounted at the heel and toe in order to detect the gait phase. An able-bodied individual and a left hemiplegic patient with equinovarus participated. They wore the device and walked on a treadmill to investigate the device's functionality. [Results] Linear relationships between the torques and the corresponding output of the torque sensors were observed. Upon the analyses of gait of an able-body subject and a hemiplegic patient, we observed toque matrices in both AP and ML directions during the gait of the both subjects. [Conclusion] We developed a device capable of measuring the torque in the AP and ML directions of ankle joints during gait.

Purpose: To evaluate the effects of short-term robot-assisted training on upper extremity paralysis after a stroke. Methods: The subjects consisted of 21 patients 6-12 weeks after their first stroke. Two weeks of robot-assisted training and 2 weeks of conventional training were performed using a crossover method. During the robot-assisted training period, robot-assisted training (1 hour/day, 5 days/week) was added to conventional training. At the initiation of training and after 2 and 4 weeks, motor function was evaluated in terms of the upper extremity items of the Stroke Impairment Assessment Set and Fugl-Meyer Assessment (FMA), active angles of shoulder flexion and abduction, and items of the Motor Activity Log (MAL). Values before and after each type of training and gains were compared between robot-assisted and conventional training using the Wilcoxon signed-rank test. Results: Compared with the conventional training after 2 weeks, significant improvements could be seen for the scores of the FMA of shoulder and elbow, the Amount of Use of MAL, and Quality of Movement of MAL items of robot-assisted training. Conclusion: After intensive robot-assisted training of the paralyzed extremity even for a short period, improvement was observed in the proximal function and frequency of use of the affected extremity in daily life.

BACKGROUND CONTEXT: During quiet standing, the gravity line (GL) can be located according to the sum of the ground reaction forces (GRFs) measured with a force platform. C7 plumb line (C7PL) is an easy method to estimate sagittal trunk balance, but discordance between C7PL and the GL is widely recognized. However, the prevalence of occiput-trunk (O-T) discordance (GL-C7PL>3 cm) and the factors affecting this type of discordance have not yet been determined. PURPOSE: The purpose of this study was to report the prevalence of O-T discordance in adult spinal deformity (ASD) patients and identify the factors affecting this type of discordance. STUDY DESIGN: This was a retrospective consecutive case series of ASD. PATIENT SAMPLE: This retrospective case series included 300 consecutive ASD patients. The inclusion criteria were age more than 50 years, Cobb angle of the main curve more than 20°, and C7PL more than 5 cm. The exclusion criteria consisted of inappropriate radiography; syndromic, neuromuscular, or other pathologic conditions; and previous joint replacement. OUTCOME MEASURES: The outcome measures included self-reported (Scoliosis Research Society 22 and Oswestry disability index [ODI]) and radiographic measures. METHODS: In a retrospective consecutive case series, demographic and radiographic patient data were reviewed. Demographic data included age, gender, curve type, SRS22, and ODI. Radiographic data included GL, C7PL, C2-C7, T2-T5, T5-T12, T10-L2, T2 tilt, lumbar lordosis (LL), sacrum slope (SS), pelvic tilt (PT), and pelvic incidence (PI). Global sagittal and spinopelvic alignments were also reviewed. Patients were categorized in either a O-T concordance (C group, GL-C7PL<3 cm) or a O-T discordance (D group, GL-C7PL more than +3 cm) group, and the demographic, radiographic, and clinical outcome data were compared between these groups. One-way analysis of variance, correlation coefficient tests, and multiple regression and logistic regression analyses were performed for statistical analysis. p Value less than .01 was considered statistically significant. Force platform analysis was performed to assess the relationship among GRF, GL, and C7PL. RESULTS: Among 300 consecutive ASD patients, 72 (24%) were categorized in the D group. There was no significant difference in terms of demographic data between the C and D groups. The SRS and ODI of patients with GL more than 10 cm were significantly lower than those of patients with GL less than 10 cm. Comparisons of regional sagittal alignment showed significantly higher T5-T12 values in the D group, and multiple regression analysis revealed significant correlations among T2-T5, T5-T12, and GL-C7PL. In contrast, the analysis of global sagittal alignment revealed a significantly large T2 sagittal tilt in the D group compared with the C group. Force platform analysis showed concordance between GRF and GL, whereas discordance was observed between GRF and C7PL. The D group could be classified into 2 groups based on the global sagittal alignment: 10 patients were classified as the hypo-compensation type (small SVA, small CL, small TK, and normal-to-small LL), whereas 62 were classified as the forward-leaning type (large sagittal vertical axis, large cervical lordosis, large thoracic kyphosis, and small LL). CONCLUSIONS: The prevalence of discordance between GL and C7PL in ASD patients was 24%, and thoracic kyphosis and global sagittal alignment were significantly correlated with this discordance. The concordance of GRF and GL and the discordance of GRF and C7PL highlight the importance and necessity of accounting for GL when considering surgical treatment.

片側変形性股関節症(OA)に対して人工股関節全置換術(THA)を行った女性19名(年齢63.7±7.6歳:THA群)と健常高齢女性17名(年齢72.7±4.0歳:健常群)を対象に、歩行時の前額面における重心移動パターンを測定して歩行速度で補正し歩容を評価した。その結果、測定値では、重心の左右方向の変位幅は健常群よりTHA術前群が有意に大きく、垂直方向の変位幅は2群間に有意差を認めなかった。しかし、歩行速度で補正した値は左右方向の変位幅はTHA術前群の方が有意に小さくなり、垂直方向の変位幅はTHA術前群の方が有意に大きくなった。THA術後群の重心の左右方向・垂直方向の変位幅の補正値は徐々に健常群に近づく傾向であったが、術後1ヵ月時でも有意差を認めた。

AIM: Recently, TRPA1 channels, richly expressed in both peripheral and central neural systems, have been proposed as novel sensors of changes in oxygen concentration along the hypoxic-hyperoxic continuum. In this study, we investigated the hypothesis that TRPA1 channels blockade should profoundly affect the hypoxic ventilatory response (HVR). METHODS: We examined the chemosensory ventilatory responses in conscious mice before and after intraperitoneal administration of the specific TRPA1 antagonist HC-030031 in two doses of 50 and 200 (cumulative dose 250) mg kg(-1) . Ventilation and its responses to mild 13% and severe 7% hypoxia, pure O2 , and 5% CO2 in O2 were recorded in a whole-body plethysmograph. RESULTS: TRPA1 antagonism caused a dose-dependent attenuation of the HVR. Ventilatory stimulation was virtually abrogated in response to the mild, but it remained viable, albeit slashed, at severe hypoxia after the bigger dose of HC-030031. The TRPA1 function seemed specific for the hypoxic chemoreflex as neither the response to pure O2 nor hypercapnia was appreciably influenced by the TRPA1 antagonist. CONCLUSIONS: The study unravelled the role of TRPA1 in shaping the ventilatory response to low-intensity hypoxia, liable to be mediated by vagally innervated respiratory chemosensors of lower functional rank, but contradicted the TRPA1 being indispensable for the powerful carotid body chemoreflex in face of a severe hypoxic threat.

歩行解析のための新しい足底接地センサ(STANS)を開発した。STANSの機構は、検出回路部は電源および抵抗器を有し、装着部は非伝導性の靴下と、その足底部に配された導電糸で形成される電極からなる。歩行面は平らな床面に導電性シートを配置したものである。健常成人7例を対象とした。導電性シートを帯状床面に貼付し、分速75mの速度に設定したトレッドミル上を歩行した。安定歩容時における20歩分の右踵接地タイミングを分析対象とした。閾値を25%とした場合、すべての被験者で、STANSよりも圧センサのタイミングが遅く、また、踵後部、踵前部の順に応答が遅かった。各センサの閾値25%時と閾値75%時の時間差では、STANSは踵後部や踵前部圧センサに対し、有意に小さく変化が急峻であった。

Objective: This research aimed to develop a system to measure the stiffness of the ankle joint for evaluating spasticity or contracture, and for quantifying the characteristics of spasticity. Functionality of the system was verified by testing it on an able-bodied individual and a hemiplegic patient. Additionally, a biomechanical model was developed to estimate the plantar flexion torque caused by viscoelasticity and muscle contraction. Methods: An electromotor, rack and pinion, potentiometer, and torque sensor were installed on a double Klenzak ankle-foot orthosis (AFO). By rotating the electromotor, the ankle joint of the AFO moves dorsally at a fixed speed. The angle and torque of dorsiflexion were measured simultaneously. The subjects sat either in a chair or a wheelchair and wore the abovementioned AFO in the knee-extension and knee-flexion positions, while the AFO moved dorsally. Electromyograms of the tibialis anterior and gastrocnemius muscles were recorded concurrently. The contributions of elastic, viscous, and muscle-contraction components to the plantar flexion torque were calculated using the system identification approach. Results: The system’s ability to measure dynamic characteristics, and also its accuracy, were confirmed. The plantar flexion torque was found to be larger in the knee-extension position than in the knee-flexion position in both the able-bodied person and the patient. Moreover, the patient showed larger plantar flexion torque than the able-bodied subject. Conclusions: A system that measures ankle-joint stiffness for evaluating spasticity was developed, and sufficient functionality was verified by applying it to both an able-bodied individual and a hemiplegic patient. In addition, plantar flexion torque caused by viscoelasticity and muscle contraction was estimated.

Objectives: EMG-BF therapy in rehabilitation clinics requires the installation of an expensive electromyographic biofeedback (EMG-BF) device. However, many medical institutions find it difficult to purchase the device because of the high cost, and so the availability of EMG-BF therapy is limited. This study aimed to develop a low-cost and simply designed EMG-BF device using a stereo microphone port. The device can be easily fabricated even by people without knowledge and skills related to electronics. Methods: The proposed device comprises an EMG amplifier, personal computer (PC) with a microphone port, electrodes, and their cables. The device is designed to be as simple as possible and with minimum components so that medical staff can obtain the required components and easily fabricate the device themselves. Results: The amplifier consists of approximately 20 easily obtained components, and costs approximately 1,600 yen in total. This device can display the voluntary EMG of the extensor carpi radialis and flexor carpi ulnaris muscles in normal adults on a PC screen, enabling the amount of muscle contraction to be identified. Conclusion: This device may help increase the use of EMG-BF therapy, and thus improve the quality of rehabilitation in clinics and homes.

Near-infrared spectroscopy (NIRS) enables non-invasive measurement of hemoglobin concentration changes in the cerebral cortex. Creation of a topography map is an important evaluation method used in clinical NIRS studies. In this study, we used Laplace's equation method to create topography maps of NIRS. The method was tested and found to converge very precisely. The method was applied to NIRS signals, and it gave a smooth picture, which did not contradict our physiological knowledge. Finally, a noisy signal was omitted and a topography map was constructed without the information of the corresponding channel, with accurate results.

片側変形性股関節症に対して初回人工股関節全置換術を施行した後に外転枕を使用した外転枕群21例(平均年齢65.9歳)と不使用群7例(平均年齢62.0歳)を対象として、ハンドヘルドダイナモメーターを固定した徒手筋力測定器にて術前後の術側および健側の股関節外転筋力・内転筋力を経時的に計測した。外転筋力においては、不使用群の術前は外転枕群の術前より有意に高く、両群とも2週目から4週目にかけて有意な筋力の回復を認めたが、外転枕群では術前に対して4週目に有意な差がみられたのに対し不使用群では有意差を認めなかった。内転筋力においては、外転枕群では術前に対し2週目が低く4週目には術前と同等レベルまでしか改善しなかった一方、不使用群では経時的に改善を認めたため外転枕群よりも早期に改善したと考えられた。術後外転枕を使用しないことが早期筋力回復の一助になる可能性があると思われた。

BACKGROUND: Sensory disturbance is common following stroke and can exacerbate functional deficits, even in patients with relatively good motor function. In particular, loss of appropriate sensory feedback in severe sensory loss impairs manipulation capability. We hypothesized that task-oriented training with sensory feedback assistance would improve manipulation capability even without sensory pathway recovery. METHODS: We developed a system that provides sensory feedback by transcutaneous electrical nerve stimulation (SENS) for patients with sensory loss, and investigated the feasibility of the system in a stroke patient with severe sensory impairment and mild motor deficit. The electrical current was modulated by the force exerted by the fingertips so as to allow the patient to identify the intensity. The patient had severe sensory loss due to a right thalamic hemorrhage suffered 27 months prior to participation in the study. The patient first practiced a cylindrical grasp task with SENS for 1 hour daily over 29 days. Pressure information from the affected thumb was fed back to the unaffected shoulder. The same patient practiced a tip pinch task with SENS for 1 hour daily over 4 days. Pressure information from the affected thumb and index finger was fed back to the unaffected and affected shoulders, respectively. We assessed the feasibility of SENS and examined the improvement of manipulation capability after training with SENS. RESULTS: The fluctuation in fingertip force during the cylindrical grasp task gradually decreased as the training progressed. The patient was able to maintain a stable grip force after training, even without SENS. Pressure exerted by the tip pinch of the affected hand was unstable before intervention with SENS compared with that of the unaffected hand. However, they were similar to each other immediately after SENS was initiated, suggesting that the somatosensory information improved tip pinch performance. The patient's manipulation capability assessed by the Box and Block Test score improved through SENS intervention and was partly maintained after SENS was removed, until at least 7 months after the intervention. The sensory test score, however, showed no recovery after intervention. CONCLUSIONS: We conclude that the proposed system would be useful in the rehabilitation of patients with sensory loss.

THA術前患者における患側立脚相の骨盤側方傾斜から逆トレンデレンブルク歩行が認められた群(TI群)と見られなかった群(NTI群)に分け、歩行時の前額面における姿勢や運動機能の特徴およびその回復過程における両群間の差を明らかにすることを目的とした。初回の片側THAを受ける女性患者18名(TI群10名、NTI群8名)を対象とし、術前・2週・4週・6ヵ月において、前額面における歩行時の骨盤側方傾斜や股関節可動域および筋力を比較した。術前の患側股関節内転可動域ではNTI群11.9度、TI群4.1度でありTI群が有意に低下していた。NTI群と比較してTI群では2週と4週で患側股関節外転筋力の低下、6ヵ月で患側股関節内転筋力低下を認めた。結果から、逆トレンデレンブルク歩行の原因は、股関節外転筋力の低下を伴った患側股関節内転可動域制限の可能性がある。また、TI群ではNTI群よりも歩行時の姿勢異常や運動機能の低下が顕著であった。(著者抄録)

経頭蓋直流電気刺激 (transcranial direct current stimulation: tDCS) は頭蓋上に配置した電極から微弱な電流を与える刺激法で, 脳機能を促進あるいは抑制すると言われている。本研究は15単語の記銘・再生を繰り返すRey's Auditory Verbal Learning Test (RAVLT) を用い, tDCSが聴覚言語性記憶に及ぼす影響について検証した。健常者12名 (21–32歳) を対象とし, RAVLTの記銘2回目からtDCSを用いて左頭頂葉下部, 後部側頭葉を刺激した (刺激強度: 2 mA) 。陽極刺激条件では10分間, 偽刺激条件では15秒間刺激を与えた。RAVLTの2回目再生数は, 陽極刺激条件が偽刺激条件より有意に多かった。健常者においてtDCS陽極刺激により聴覚言語性記憶の有意な増強が認められた。tDCSは記憶機能賦活に役立つ可能性がある。

An electromyogram (EMG)-driven neuromuscular stimulator for upper limb functional recovery (Muraoka et al., 1998) can stimulate target muscles in proportion to the amount of voluntary EMG of the identical target muscles. Furthermore, it can facilitate the contraction of paralyzed muscles by electrical stimulation at subthreshold intensity level. Although it has been suggested that to use the stimulator for as long a time as possible might be needed for more effective treatment, the utilization time was limited by the size of the stimulator, which involved a laptop personal computer. To use in daily life, the device was improved to be a smaller size of 95x65x40 mm (including batteries) which was equivalent to a mobile phone (in 2002). The stimulator was called the Integrated Volitional-control Electrical Stimulator (IVES). IVES has already been manufactured and its use has spread in Japan since 2008. Nowadays, therapy using IVES is an effective therapy to improve the motor function of the upper limb in post-stroke patients with hemiparesis. However, the signal processing and internal structure of IVES has not yet been reported. In this study the device specification of IVES is described, especially its electrical circuits and signal processing that detect voluntary EMG and stimulate from the same electrodes. IVES uses two DIACs for detecting voluntary EMG from stimulating electrodes. The DIACs switch passively between the stimulation circuit and the EMG amplifier circuit. Furthermore, the signal processing of the time-shifted difference of the 2-cycle EMG signal following identical stimulation pulses eliminates stimulation artifacts and evoked potentials, and extracts voluntary EMG.

BACKGROUND: We developed an electroencephalogram-based brain computer interface system to modulate functional electrical stimulation (FES) to the affected tibialis anterior muscle in a stroke patient. The intensity of FES current increased in a stepwise manner when the event-related desynchronization (ERD) reflecting motor intent was continuously detected from the primary cortical motor area. METHODS: We tested the feasibility of the ERD-modulated FES system in comparison with FES without ERD modulation. The stroke patient who presented with severe hemiparesis attempted to perform dorsiflexion of the paralyzed ankle during which FES was applied either with or without ERD modulation. RESULTS: After 20 minutes of training, the range of movement at the ankle joint and the electromyography amplitude of the affected tibialis anterior muscle were significantly increased following the ERD-modulated FES compared with the FES alone. CONCLUSIONS: The proposed rehabilitation technique using ERD-modulated FES for stroke patients was feasible. The system holds potentials to improve the limb function and to benefit stroke patients.

Recently there has been an increase in the number of stroke patients with motor paralysis. Appropriate re-afferent sensory feedback synchronized with a voluntary motor intention would be effective for promoting neural plasticity in the stroke rehabilitation. Therefore, BCI technology is considered to be a promising approach in the neuro-rehabilitation. To estimate human motor intention, an event-related desynchronization (ERD), a feature of electroencephalogram (EEG) evoked by motor execution or motor imagery is usually used. However, there exists various factors that affect ERD production, and its neural mechanism is still an open question. As a preliminary stage, we evaluate mutual effects of intrinsic (voluntary motor imagery) and extrinsic (visual and somatosensory stimuli) factors on the ERD production. Experimental results indicate that these three factors are not always additively interacting with each other and affecting the ERD production.

Depression has been known to reduce the prefrontal activity associated with the execution of certain cognitive tasks, although whether a temporarily depressed or anxious mood in healthy individuals affects the prefrontal blood oxygen level during cognitive tasks is unknown. Combining the measurement of prefrontal activity with near-infrared spectroscopy (NIRS) and the two cognitive tasks, namely the letter version of the verbal fluency test (VFT-l) and the Stroop test, we measured the effect of a depressed or anxious mood and gender on the changes in the prefrontal oxygenated hemoglobin (Oxy-Hb) levels during those cognitive tests in healthy individuals. Depressed mood or anxious mood was assessed by the Hospital Anxiety and Depression Scale (HADS). Thereby we aimed to explore the possibility of NIRS measurement for detecting the early subclinical manifestation of major depression. Moreover, we examined the possible relationships between prefrontal activation and the functional Val66Met polymorphisms of the brain derived neurotropic factor (BDNF) gene and serum BDNF level. As a result, the increased prefrontal Oxy-Hb levels during cognitive tasks were significantly correlated with the severity of depressed mood in males. The course of the prefrontal Oxy-Hb increase was different depending on the cognitive tasks, i.e., the VFT-l or the Stroop test, in both genders. Correlations of BDNF genotype and serum BDNF level with the prefrontal Oxy-Hb levels during those cognitive tasks were negative. Our results suggest that the early subclinical manifestation of depressed mood in males might be detected by the NIRS measurement, which is not correlated with the individual properties of BDNF.

Previous simulation and experimental studies have demonstrated that the application of Variational Bayesian Multimodal EncephaloGraphy (VBMEG) to magnetoencephalography (MEG) data can be used to estimate cortical currents with high spatio-temporal resolution, by incorporating functional magnetic resonance imaging (fMRI) activity as a hierarchical prior. However, the use of combined MEG and fMRI is restricted by the high costs involved, a lack of portability and high sensitivity to body-motion artifacts. One possible solution for overcoming these limitations is to use a combination of electroencephalography (EEG) and near-infrared spectroscopy (NIRS). This study therefore aimed to extend the possible applications of VBMEG to include EEG data with NIRS activity as a hierarchical prior. Using computer simulations and real experimental data, we evaluated the performance of VBMEG applied to EEG data under different conditions, including different numbers of EEG sensors and different prior information. The results suggest that VBMEG with NIRS prior performs well, even with as few as 19 EEG sensors. These findings indicate the potential value of clinically applying VBMEG using a combination of EEG and NIRS.

According to recent neuro-rehabilitation research, an appropriate reafferent sensory feedback synchronized with a voluntary motor intention would be effective for promoting neural plasticity during stroke rehabilitation. Therefore, a BCI-based neuro-rehabilitation is considered to be a promising approach. To detect the motor intention, an event-related desynchronization (ERD), which can be evoked by intrinsic motor imagery, is usually used. However there exists various factors that affect ERD production, and its neural mechanism is still an open question. As a preliminary stage for developing an effective neuro-rehabilitation system, in this study, we evaluate the mutual effects of extrinsic (visual and somatosensory stimuli) and intrinsic (spontaneous motor imagery) factors on ERD production. Experimental results indicate that these three factors interact with each other in a complex relationship and probably affect a person's sense of agency. © 2012 IEEE.

Background. Transcranial direct current stimulation (tDCS) of the motor cortex can enhance the performance of a paretic upper extremity after stroke. Reported effects on lower limb (LL) function are sparse. Objective. The authors examined whether tDCS can increase the force production of the paretic quadriceps. Methods. In this double-blind, crossover, sham-controlled experimental design, 8 participants with chronic subcortical stroke performed knee extension using their hemiparetic leg before, during, and after anodal or sham tDCS of the LL motor cortex representation in the affected hemisphere. Affected hand-grip force was also recorded. Results. The maximal knee-extension force increased by 21 N (13.2%, P < .01) during anodal tDCS compared with baseline and sham stimulation. The increase persisted less than 30 minutes. Maximal hand-grip force did not change. Conclusions. Anodal tDCS transiently enhanced knee extensor strength. The modest increase was specific to the LL. Thus, tDCS might augment the rehabilitation of stroke patients when combined with lower extremity strengthening or functional training.

Sensory disturbance is very common following stroke and may exacerbate a patient's functional impairment, even if the patient has good motor function. For instance, patients with sensory disturbances will often grip an object with excessive or underestimated pinch pressure, because they do not receive the appropriate sensory feedback and must rely only on visual feedback. In this study, we developed a sensory feedback system that used cutaneous electrical stimulation for patients with sensory loss. In the system, electrical stimulation is modulated by the strength of pinch pressure and the patients are able to identify their fingertip pinch pressure. To evaluate the efficacy of the system, a clinical case study was conducted in a stroke patient with severe sensory loss. The fluctuation in force control during grasping was gradually decreased as the training progressed and the patient was able to maintain a stable pinch pressure during grasping even without the system following 2 months of intervention. We conclude that the system described in this study may be a useful contribution towards the rehabilitation of patients with sensory loss.

目的:ヒトの脳活動を非侵襲的に計測できる近赤外分光法near-infrared spectroscopy(NIRS)を用いて健常成人の両眼融像刺激と両眼視野闘争刺激(以下;闘争刺激)に対する後頭葉視覚野の活動を比較した。対象および方法:21〜22歳の視覚健常者10名を対象とした。後頭葉Oz近傍を関心領域として酸素化ヘモグロビン・脱酸素化ヘモグロビン濃度長変化を計測した。視覚刺激は視角2°、空間周波数4cpdの矩形波刺激を使用し、融像刺激および縞を直交させた闘争刺激を25秒のレストを挟んで各20秒提示した。刺激前5秒間の各ヘモグロビン濃度長変化を0としてそれぞれの刺激提示による賦活量の最大値を比較した。結果と考按:後頭葉視覚野の酸素化ヘモグロビンと脱酸素化ヘモグロビン濃度長変化に明らかな賦活を認めたものは10名中3例であった。Ozの外側下方領域を中心として賦活が認められた。融像刺激と闘争刺激の反応には個人差がみられた。今後、大脳皮質における両眼視機能の解析手段として有用であることが示唆された。(著者抄録)