36 research outputs found
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Όλ¬Έ (λ°μ¬) -- μμΈλνκ΅ λνμ : μ¬λ²λν 체μ‘κ΅μ‘κ³Ό, 2021. 2. λ°μ¬λ².The continuously varied states of human body and surrounding environment require instantaneous motor adaptations and the understanding of motor goal to achieve desired actions. These sensory and cognitive processes have been investigated as elements in motor control during last five decades. Specially, the task dependency on sensory and cognitive processes suggest the effects of movement properties in terms of environment situation and motor goal. However, these effects were mostly empirically summarized with the measurements of either neural activity or simple motor accomplishment unilaterally. The current thesis addresses the quantification of sensory and cognitive processes based on simultaneous measurements of brain activity and synergic motor performance during multi-digit actions with different movement properties. Multi-digit action as a representation of synergic movements has developed into a widespread agency to quantify the efficacy of motor control, as the reason applied in this thesis.
In this thesis, multi-digit rotation and pressing tasks were performed with different movement directions, frequencies, feedback modalities, or task complexities. (Chapter 3) The changes of movement direction induced a decrease in motor synergy but regardless of which direction. (Chapter 4 and 5) Increased frequency of rhythmic movement reduced synergic motor performance associate with decreased sensory process and less efficient cognitive process. (Chapter 6) More comprehensive feedback modality improved synergic performance with increased sensory process. (Chapter 7) Increased movement complexity had a consistent but stronger effect as increased frequency on synergic performance and efficiency of cognitive process. These observations suggest that several movement properties affect the contributions of sensory and cognitive processes to motor control which can be quantified through either neural activity or synergic motor performance. Accordingly, those movement properties may be applied in the rehabilitation of motor dysfunction by developing new training programs or assistant devices. Additionally, it may be possible to develop a simplified while efficient method to estimate the contribution of sensory or cognitive process to motor control.μμκ°κ°μΌλ‘ λ³ννλ μ 체 μνμ μ£Όλ³ νκ²½μ μνΈμμ© μμμ μλ§μ μμ§μμ μννκΈ° μν΄μλ κ·Έμ λ°λ₯Έ μ¦κ°μ μΈ μ΄λ μ μ(motor adaptation) κ³Όμ μ κ³Όμ λͺ©νμ λν μ΄ν΄κ° νμνλ€. μ΄λ₯Ό μν΄ μΈκ°μ κ°κ° λ° μΈμ§ μ²λ¦¬κ³Όμ μ μ΄λ μ μ΄ λΆμΌμ μ€μν μμλ‘ μ¬κ²¨μ‘λ€. μ νμ°κ΅¬μ λ°λ₯΄λ©΄, μ΄λ κ³Όμ μ λ°λΌ λ³ννλ κ°κ° λ° μΈμ§ μ²λ¦¬κ³Όμ μ μ£Όλ³ νκ²½κ³Ό κ³Όμ μ λͺ©νμ λ°λΌ μμ§μμ νΉμ±μ μν₯μ λ―ΈμΉλ€κ³ λ³΄κ³ λμ΄μλ€. κ·Έλ¬λ μ΄λ¬ν μν₯μ λλΆλΆ λ¨μν μ΄λκ³Όμ μν κ²°κ³Ό λλ μΈ‘μ λ μ κ²½ νλμ μν΄ κ²½νμ μΌλ‘ μμ½λ κ²°κ³Όμ κ΅νλμ΄ μλ€. λ°λΌμ λ³Έ λ
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ν©μ μΈ κ°κ° νΌλλ°±μ μ¦κ°λ κ°κ° μ²λ¦¬κ³Όμ κ³Ό ν¨κ» νμμ μΈ μμ§μμ ν₯μμμΌ°λ€. (λ¬Έλ¨ 7) κ³Όμ μ λμ΄λκ° μ¦κ°ν μλ‘ νμμ μΈ μμ§μκ³Ό μΈμ§ μ²λ¦¬κ³Όμ μ ν¨μ¨μ±μ κ°μλμμΌλ©°, μμ§μμ μ£ΌκΈ°λΉλ 쑰건μ λΉν΄ κ³Όμ μ λμ΄λμ λ°λΌ νμμ μΈ μμ§μκ³Ό μΈμ§ μ²λ¦¬κ³Όμ μ λ―ΈμΉλ μν₯μ μλμ μΌλ‘ λ ν¬κ² λνλ¬λ€. μ΄λ¬ν κ²°κ³Όλ μμ§μ νΉμ±μ λ°λ₯Έ λ νλκ³Ό νμμ μΈ κ³Όμ μν΄ κ²°κ³Όλ₯Ό ν΅ν΄ μ΄λ μ μ΄ κ³Όμ μμ κ°κ° λ° μΈμ§ μ²λ¦¬κ³Όμ μ κΈ°μ¬μ λλ₯Ό μ λνν μ μλ€λ μ μ μμ¬νλ€. λ°λΌμ μμ§μ νΉμ±μ λ°λ₯Έ κ°κ° λ° μΈμ§ μ²λ¦¬ κ³Όμ μ κΈ°μ¬μ λμ λ³νλ μ΄λ κΈ°λ₯ μ₯μ λ₯Ό κ°μ§ μ¬λλ€μ μλ‘μ΄ μ¬ν νλ ¨ νλ‘κ·Έλ¨ λ° μμ§μ 보쑰 μ₯μΉλ₯Ό κ°λ°νκΈ° μν μ€νμ μΈ κ·Όκ±°λ‘ μ μ©λ μ μλ€. λν κ°κ° λλ μΈμ§ κ³Όμ μ΄ μ΄λ μ μ΄μ λ―ΈμΉλ μν₯μ μΆμ νκΈ° μν ν¨μ¨μ μΈ λ°©λ²μ κ°λ°νλλ° λμμ΄ λ κ²μ΄λ€.Chapter 1. Introduction 1
1.1 Problem statement 1
1.2 Study objective 2
1.3 Organization of dissertation 3
Chapter 2. Background 6
2.1 Motor system 6
2.1.1 Ascending pathway 6
2.1.2 Descending pathway 8
2.1.3 Brain networks 9
2.2 Motor synergy 11
2.2.1 Synergy in performance 12
2.2.2 Synergy in muscles 13
2.2.3 Synergy in neurons 14
2.3 Motor control 15
2.1.1 Sensory process 16
2.1.2 Cognitive process 19
Chapter 3. Effect of movement direction: Multi-Finger Interaction and Synergies in Finger Flexion and Extension Force Production 23
3.1 Abstract 23
3.2 Introduction 24
3.3 Method 28
3.4 Results 35
3.4.1 Maximal voluntary contraction (MVC) force and finger independency 36
3.4.2 Timing indices 37
3.4.3 Multi-finger synergy indices in mode space 39
3.4.4 Multi-finger synergy indices in force space 43
3.5 Discussion 44
3.5.1 Finger independency during finger flexion and extension 44
3.5.2 Multi-finger synergies in force and mode spaces 46
3.5.3 Anticipatory synergy adjustment 48
Chapter 4. Effect of Frequency: Brain Oxygenation Magnitude and Mechanical Outcomes during Multi-Digit Rhythmic Rotation Task 51
4.1 Abstract 51
4.2 Introduction 51
4.3 Methods 55
4.4 Results 61
4.4.1 PET imaging 61
4.4.2 Finger forces 62
4.4.3 UCM analysis 64
4.4.4 Correlation between neural activation and mechanics 65
4.5 Discussion 66
4.5.1 Regions involved in feedback 67
4.5.2 Regions involved in feedforward 69
4.5.3 Corporation of feedforward and feedback 71
4.6 Conclusions 72
Chapter 5. Effect of frequency: Prefrontal Cortex Oxygenation during Multi-Digit Rhythmic Pressing Actions using fNIRS 74
5.1 Abstract 74
5.2 Introduction 74
5.3 Method 77
5.4 Results 84
5.4.1 Performance 84
5.4.2 Multi-digit coordination indices 84
5.4.3 Functional connectivity (FC) 87
5.5 Discussion 88
5.6 Conclusion 91
Chapter 6. Effect of Sensory Modality: Multi-Sensory Integration during Multi-Digit Rotation Task with Different Frequency 92
6.1 Abstract 92
6.2 Introduction 92
6.3 Method 94
6.4 Results 100
6.4.1 Performance 100
6.4.2 Multi-digit coordination indices 101
6.5 Discussion 101
6.6 Conclusion 103
Chapter 7. Effect of Task Complexity: Prefrontal Cortex Oxygenation during Multi-Digit Pressing Actions with Different Frequency Components 104
7.1 Abstract 104
7.2 Introduction 104
7.3 Method 106
7.4 Results 112
7.4.1 Performance 112
7.4.2 Multi-finger coordination indices 113
7.4.3 Functional connectivity (FC) 114
7.5 Discussion 115
7.5.1 Relation between Frequency and task complexity 115
7.5.2 Cognitive process in motor control 116
7.5.3 Relation between motor coordination and cognitive process 118
7.6 Conclusion 119
Chapter 8. Conclusions and Future Work 120
8.1 Summary of conclusions 120
8.2 Future work 121
Bibliography 122
Abstract in Korean 160Docto
Glucuronidase beta is an early predictive marker for the use of antidepressant in the treatment of glioma patients
Purpose: To screen early targets and investigate the potential molecular mechanisms involved in the use of antidepressant in the treatment of glioma.
Methods: The GSE89873 dataset, including expression levels of C6 cells under antidepressant treatment, non-antidepressant drug treatment, and untreated cells (control), was downloaded from database. Differentially expressed genes (DEGs) between antidepressant treatment and untreated cells, and between non-antidepressant drug treatment and untreated cells were identified and annotated. Genes that were significantly related to different drug treatment conditions were screened.
Results: In all, 416 differentially expressed genes (DEGs) were selected between cells of the antidepressant treatment and control groups, while 650 DEGs were selected between cells of the non-antidepressant treatment and control groups. The 402 overlapping DEGs were significantly associated with the apoptotic process, transforming growth factor beta receptor signaling pathway, and cell cycle arrest (p < 0.05). The DEGs ACOX1, ACSL1, GSTM3, and GSTP1 were significantly related to hormonal therapy (p < 0.05). Glucuronidase beta (GUSB) was significantly associated with age and targeted molecular therapy (p < 0.05). The GUSB was also significantly associated with overall survival time (p < 0.05). It is one of the unique DEGs in the antidepressant treatment group that participates in the drug metabolism-cytochrome P450 metabolic pathway.
Conclusion: Glucuronidase beta may be a specific biomarker for the early response of antidepressants to glioma treatment. This should, however, be further investigated to validate this finding
Multi-Finger Interaction and Synergies in Finger Flexion and Extension Force Production
The aim of this study was to discover finger interaction indices during single-finger ramp tasks and multi-finger coordination during a steady state force production in two directions, flexion, and extension. Furthermore, the indices of anticipatory adjustment of elemental variables (i.e., finger forces) prior to a quick pulse force production were quantified. It is currently unknown whether the organization and anticipatory modulation of stability properties are affected by force directions and strengths of in multi-finger actions. We expected to observe a smaller finger independency and larger indices of multi-finger coordination during extension than during flexion due to both neural and peripheral differences between the finger flexion and extension actions. We also examined the indices of the anticipatory adjustment between different force direction conditions. The anticipatory adjustment could be a neural process, which may be affected by the properties of the muscles and by the direction of the motions. The maximal voluntary contraction (MVC) force was larger for flexion than for extension, which confirmed the fact that the strength of finger flexor muscles (e.g., flexor digitorum profundus) was larger than that of finger extensor (e.g., extensor digitorum). The analysis within the uncontrolled manifold (UCM) hypothesis was used to quantify the motor synergy of elemental variables by decomposing two sources of variances across repetitive trials, which identifies the variances in the uncontrolled manifold (VUCM) and that are orthogonal to the UCM (VORT). The presence of motor synergy and its strength were quantified by the relative amount of VUCM and VORT. The strength of motor synergies at the steady state was larger in the extension condition, which suggests that the stability property (i.e., multi-finger synergies) may be a direction specific quantity. However, the results for the existence of anticipatory adjustment; however, no difference between the directional conditions suggests that feed-forward synergy adjustment (changes in the stability property) may be at least independent of the magnitude of the task-specific apparent performance variables and its direction (e.g., flexion and extension forces)
DIFFERENCES OF POSTURE ON PUSH-OFF PHASE BETWEEN ACTUAL SPEED SKATING AND SLIDE-BOARD TRAINING
The slide-board training is a feasible technology to exercise skating during the off-season. While slide-board is much different from ice surface of the actual skating situation, it may distort actual skating posture. The purpose of this study was to analyze the differences in posture during push-off phase between an actual speed skating condition and on slideboard. The result showed that on the slide-board distance between two feet were shorter, so were the rotation angles of both feet, the hip angle was lower during the whole phase, while knee and ankle angles were higher. In conclusion, the restriction of the space on slide-board affected the position and rotation of both stable and push-off feet as well as the joint extension of the stable leg. Hence, the structural design of slide-board needs to be improved to facilitate the extension of knee and ankle in the medial-lateral direction
Influence of moisture absorption on electrical properties and charge dynamics of polyethylene silica-based nanocomposites
The use of nanocomposites as dielectric materials is expected to lead to improved electrical performance. However, recent research has shown that moisture absorption can cause a deterioration in the electrical performance of nanocomposites. Although it is generally accepted that hydroxyl groups attached to nanoparticle surfaces are the main cause of moisture absorption, the impact of this absorption on the electrical properties of nanocomposites is still not fully understood. In this paper, a series of measurements, including thermogravimetric analysis, DC breakdown, surface potential decay and space charge, are conducted with the aim of determining the impact of moisture absorption on the electrical properties of polyethylene/silica nanocomposites. The results show that the loading ratio of nanosilica and the humidity of the conditioning environment determine the amount of absorbed moisture. According to the Zhuravlev model, the main contribution to the deterioration in electrical properties of nanocomposites comes from the large amount of moisture absorbed in multilayer form. It is found that the loading ratio of nanosilica is the most significant factor in reducing DC breakdown strength
Effect of Kinetic Degrees of Freedom on Multi-Finger Synergies and Task Performance during Force Production and Release Tasks
Abstract Complex structures present in a human body has relatively large degrees-of-freedom (DOFs) as compared to the requirement of a particular task. This phenomenon called motor redundancy initially deemed as a computational problem rather can be understood as having the flexibility to perform the certain task successfully. Hence, the purpose of our study was to examine the positive impact of extra DOFs (redundant DOFs) during force production tasks. For this purpose, an experimental setup was designed to simulate archery-like shooting, and purposeful organization of a redundant set of finger forces determined the stability of important performance variables as well as accurate and precise performance. DOFs were adjusted by changing the number of fingers explicitly involved in the task. The concept of motor synergy and computational framework of uncontrolled manifold (UCM) approach was used to quantify stability indices during finger force production. As a result, accuracy and precision of the task improved with an increase in DOFs. Also, the stability indices of net finger forces and moment increased with active DOFs of fingers. We concluded that the controller actively utilizes extra DOFs to increase the stability of the performance, which is associated with the improved accuracy and precision of the task
EFFECTS OF GRAVITY ON MULTI-DIGIT TORQUE PRODUCTION TASK IN HUMANS
In this study we investigated the effect of gravity on multi-digit prehension to know how the digits' force and moment are organized in the imposed static constraints according to the gravity. Specfically, we tested if decoupling of grasping and rotational equilibrium control is even valid during grasping in the microgravity condition. There were two experimental conditions: gravity-induced (GI), and microgravity conditions (MG). For the MG condition, the handle was attached to the end of the robot-arm, which produced a count-balanced force for the weight of the handle and hand. The results showed that the selected experimental variables were separated into two sub-sets in both GI and MG conditions. Thus, we can conclude that the grasping stability is independent from the rotational equilibrium control regardless of the gravity acting on the hand-held object
Negotiation progress of the Nagoya Protocol on the access of genetic re-sources and benefit-sharing and countermeasures
Experimental demonstration of deep traps in silica-based polyethylene nanocomposites by combined isothermal surface potential decay and pulsed electro-acoustic measurements
The ability to suppress space charge accumulation at high electric fields makes nanocomposites attract significant research interest as potential insulation materials in high-voltage direct current cable development. At present, the deep trap introduced by nanoparticles is frequently applied to be responsible for the observed space charge suppression in nanocomposites. However, the experimental results that support deep-trap formation have not been rigorously examined. We therefore propose herein a simple and more direct approach based on isothermal surface potential decay combined with pulsed electro-acoustic measurements to verify the presence of deep traps in silica-based blend polyethylene nanocomposites. The results indicate that the deep traps are indeed introduced by filling nanosilica and the space charge suppression observed in the nanocomposite with a low loading ratio is caused by deeply trapped charges in the sub-surface region of specimens