Concerns regarding the ecological validity of movement-related cortical potential (MRCP) experimental tasks that are related to motor learning have recently been growing. Therefore, we compared MRCP ...during real movement task (RMT) and simulated movement task (SMT) from an ecological validity perspective.
The participants performed both RMT and SMT, and MRCP were measured using electroencephalogram (EEG). EEG was based on the 10-20 method, with electrodes placed in the motor cortex (C3 and C4) and supplementary motor cortex (FCz between Fz and Cz and Cz) areas. This experiment examined the MRCP using Bereitschaftspotential (BP) and negative slope (NS') onset times, and BP, NS', and motor potential (MP) amplitudes during the task.
The results revealed that the SMT exhibited later BP and NS' onset times and smaller BP, NS', and MP amplitudes than the RMT. Furthermore, in RMT, the onset time of MRCP was delayed, and the amplitude of MRCP was smaller in the second half of the 200 times task than in the first half, whereas in SMT, there was no change in onset time and amplitude. The SMT showed a different MRCP than the RMT, suggesting that the ecological validity of the task should be fully considered when investigating the cortical activity associated with motor skill learning using MRCP.
Ecological validity of the study should be fully considered when investigating the cortical activity associated with motor skill learning using MRCP. Moreover, it is important to understand the differences between the two methods when applied clinically.
Although motor imagery enhances the excitability of the corticospinal tract, there are no peripheral afferent inputs during motor imagery. In contrast, peripheral nerve electrical stimulation (ES) ...can induce peripheral afferent inputs; thus, a combination of motor imagery and ES may enhance the excitability of the corticospinal tract compared with motor imagery alone. Moreover, the level of stimulation intensity may also be related to the modulation of the excitability of the corticospinal tract during motor imagery. Here, we evaluated whether a combination of motor imagery and peripheral nerve ES influences the excitability of the corticospinal tract and measured the effect of ES intensity on the excitability induced during motor imagery. The imagined task was a movement that involved touching the thumb to the little finger, whereas ES involved simultaneous stimulation of the ulnar and median nerves at the wrist. Two different ES intensities were used, one above the motor threshold and another above the sensory threshold. Further, we evaluated whether actual movement with afferent input induced by ES modulates the excitability of the corticospinal tract as well as motor imagery. We found that a combination of motor imagery and ES enhanced the excitability of the motor cortex in the thenar muscle compared with the other condition. Furthermore, we established that the modulation of the corticospinal tract was related to ES intensity. However, we found that the excitability of the corticospinal tract induced by actual movement was enhanced by peripheral nerve ES above the sensory threshold.
While previous studies have assessed changes in corticospinal excitability following voluntary contraction coupled with electrical stimulation (ES), we sought to examine, for the first time in the ...field, real-time changes in corticospinal excitability. We monitored motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation and recorded the MEPs using a mechanomyogram, which is less susceptible to electrical artifacts. We assessed the MEPs at each level of muscle contraction of wrist flexion (0%, 5%, or 20% of maximum voluntary contraction) during voluntary wrist flexion (flexor carpi radialis (FCR) voluntary contraction), either with or without simultaneous low-frequency (10 Hz) ES of the median nerve that innervates the FCR. The stimulus intensity corresponded to 1.2 × perception threshold. In the FCR, voluntary contraction with median nerve stimulation significantly increased corticospinal excitability compared with FCR voluntary contraction without median nerve stimulation (p<0.01). In addition, corticospinal excitability was significantly modulated by the level of FCR voluntary contraction. In contrast, in the extensor carpi radialis (ECR), FCR voluntary contraction with median nerve stimulation significantly decreased corticospinal excitability compared with FCR voluntary contraction without median nerve stimulation (p<0.05). Thus, median nerve stimulation during FCR voluntary contraction induces reciprocal changes in cortical excitability in agonist and antagonist muscles. Finally we also showed that even mental imagery of FCR voluntary contraction with median nerve stimulation induced the same reciprocal changes in cortical excitability in agonist and antagonist muscles. Our results support the use of voluntary contraction coupled with ES in neurorehabilitation therapy for patients.
Mechanisms underlying the somatosensory temporal discrimination threshold and its relationship with motor control have been reported; however, little is known regarding the change in temporal ...processing of tactile information during motor learning. We investigated the somatosensory temporal discrimination threshold changes during motor learning in a feedback-control task.
We included 15 healthy individuals. The somatosensory temporal discrimination threshold was measured on the index finger. A 10-session coin rotation task was performed, with 2 min' training per session. The coin rotation scores were determined through tests (continuous coin rotation at 180° at maximum speed for 10 s). The coin rotation test score and the somatosensory temporal discrimination threshold were determined at baseline and after 5 and 10 sets of training, as follows: pre-test; training
5set
(1 set × 5); post-test
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; training
5set
(1 set × 5); and post-test
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. The coin rotation score and the somatosensory temporal discrimination threshold were compared between the tests. The latter was also compared between the right (the within-subject control) and left fingers.
The coin rotation score showed significant differences among all tests. In the somatosensory temporal discrimination threshold, there was a significant difference between the pre-test and post-test
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values, pre-test and post-test
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values of the left side and between the right and left sides in the post-test
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and the post-test
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values.
The somatosensory temporal discrimination threshold decreased along with task-performance progress following motor learning during a feedback-control task.
Abstract
The present study aimed to investigate corticospinal excitability changes during muscle relaxation with a tracking task. The motor-evoked potential, which was elicited from the flexor carpi ...radialis (agonist) and extensor carpi radialis (antagonist) muscles, was analyzed in terms of both the relaxation velocity and phase. Our results suggest that increasing corticospinal excitability in the antagonist muscle plays an important role in controlling the relaxation of the agonist muscle during gradual relaxation with a tracking task.
Purpose: The purpose of this study was to describe the features of gait and activities of daily living (ADL) progress of two patients with toxic paraplegia (L1 level) due to intrathecal chemotherapy. ...Methods: Based on clinical records for 1 year in term of Walking Index for Spinal Cord Injury (WISCI) and Functional Independence Measure (FIM), a retrospective study was executed. Results: WISCI for both cases improved from level 0 to 15 in 3 months. FIM at 2 months after onset of gait disorder improved from 48 to 97 for case 1, and from 77 to 114 for case 2. WISCI and FIM showed improvement 1 year later. Conclusion: The findings suggest that gait ability and ADL of two patients with toxic paraplegia (L1 level) due to intrathecal chemotherapy was greatly improved in a certain period, and improved for a long term afterwards.
Purpose: The purpose of this study was to describe the features of gait and activities of daily living (ADL) progress of two patients with toxic paraplegia (L1 level) due to intrathecal chemotherapy. ...Methods: Based on clinical records for 1 year in term of Walking Index for Spinal Cord Injury (WISCI) and Functional Independence Measure (FIM), a retrospective study was executed. Results: WISCI for both cases improved from level 0 to 15 in 3 months. FIM at 2 months after onset of gait disorder improved from 48 to 97 for case 1, and from 77 to 114 for case 2. WISCI and FIM showed improvement 1 year later. Conclusion: The findings suggest that gait ability and ADL of two patients with toxic paraplegia (L1 level) due to intrathecal chemotherapy was greatly improved in a certain period, and improved for a long term afterwards.
【目的】本実践報告の目的は，髄腔内化学療法後の神経毒性により不全対麻痺（L1レベル）を呈した二症例の歩行と日常生活活動（Activities of Daily Living：ADL）経過の特徴について考察を行うことである。【方法】対象症例の歩行障害発症から1年間の経過について，歩行能力はWalking Index for Spinal Cord ...Injury（WISCI），ADLはFunctional Independence Measure（FIM）を用い，カルテを基に後方視的に調査した。【結果】WISCIは，両症例とも，3ヵ月間をかけLevel 0から15まで改善された。FIMは発症から約2ヵ月後に症例1では48から97，症例2は77から114まで改善した。その後，WISCI・FIMともに1年後まで改善を示した。【結論】髄腔内化学療法後の神経毒性によるL1レベルの不全対麻痺患者は，歩行とADLはある一定期間に大幅に改善し，その後も長期間に渡り改善する可能性が示された。
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