Synergy

Contents......Page 12
1.1 Synergies and Non-Synergies: A Few Examples......Page 18
1.2 Palama’s Concept of Synergy......Page 22
1.3 Inanimate “Synergies”: The Table and the Rusty Bucket......Page 24
1.4 Examples of Biological Synergies......Page 29
1.5 The Definition: Three Components of a Synergy......Page 30
Part 2: A Brief History of Movement Studies......Page 34
2.1 Ancient Greece and Rome......Page 36
2.2 Renaissance......Page 37
2.3 The Century of Frogs, Photography, and Amazing Guesses......Page 40
2.4 The Twentieth Century: Wars of Ideas......Page 42
2.5 Nikolai Alexandrovich Bernstein and Movement Science in the Soviet Union......Page 47
2.6 History of Synergies and the Problem of Motor Redundancy......Page 52
2.7 Problems with Studying Biological Movement......Page 62
3.1 Israel Gelfand and Michael Tsetlin......Page 68
3.2 Structural Units and the Principle of Minimal Interaction......Page 73
3.3 Motor Control: Programs and Internal Models......Page 80
Digression #1. The Muscle: Slow and Visco-Elastic......Page 82
Digression #2. Neural Pathways: Long and Slow......Page 87
Digression #3. Sensors: Confusing and Unreliable......Page 89
Digression #4. Adaptation to Force Fields and After-Effects......Page 96
Digression #5. Brain Imaging Techniques: What Do They Image?......Page 98
3.4 The Equilibrium-Point Hypothesis......Page 105
3.4.1 Experimental Foundations of the Equilibrium-Point Hypothesis......Page 106
Digression #6. Reflexes and Nonreflexes......Page 108
3.4.2 Equilibrium-Point Control of Simple Systems......Page 117
3.4.3 Three Basic Trajectories within the Equilibrium-Point Hypothesis......Page 121
3.4.4 Equilibrium-Point Control of Multi-Muscle Systems......Page 122
3.4.5 The Mass–Spring Analogy and Other Misconceptions......Page 126
Part 4: Motor Variability: A Window into Synergies......Page 136
4.1 The Uncontrolled Manifold Hypothesis......Page 137
4.2 Modes as Elemental Variables......Page 148
4.2.1 Force Modes......Page 149
Digression #7: Digit Interaction and Its Indices......Page 151
4.2.2 Muscle Modes......Page 156
Digression #8: Electromyography......Page 157
4.2.3 Experimental Identification of the Jacobian......Page 164
4.3 Stability, Variability, and Within-a-Trial Analysis of Synergies......Page 165
4.4.1 Principal Component Analysis and Uncontrolled Manifold......Page 172
4.4.2 Analysis of Surrogate Data Sets......Page 176
4.5 Timing Synergies: Do They Exist?......Page 179
5.1 Kinematic Synergies......Page 184
5.1.1 Postural Synergies in Standing......Page 187
5.1.2 Sit-to-Stand Task......Page 191
Digression # 9: Optimization......Page 193
5.1.4 Reaching in a Changing Force Field......Page 197
5.1.5 Multi-Joint Pointing......Page 199
5.1.6 Quick-Draw Pistol Shooting......Page 201
5.2 Kinetic Synergies......Page 205
5.3.1 Force and Moment Stabilization during Multi-Finger Pressing......Page 209
5.3.2 The Role of Timing Errors......Page 212
5.3.3 Emergence and Disappearance of Synergies......Page 214
5.3.4 Anticipatory Synergy Adjustments and Purposeful Destabilization of Performance......Page 216
5.4 Prehensile Synergies......Page 221
5.4.1 Hierarchical Control of Prehension......Page 224
5.4.2 Principle of Superposition......Page 226
5.4.3 Adjustments of Synergies: Chain Effects......Page 229
5.4.4 Hierarchies of Synergies......Page 230
5.5 Multi-Muscle Synergies......Page 234
5.5.1 Anticipatory Postural Adjustments......Page 237
5.5.2 Making a Step......Page 239
5.5.3 Multi-Muscle Synergies in Hand Force Production......Page 241
6.1 Is There a “Normal Synergy”?......Page 244
6.2 Principle of Indeterminicity in Movement Studies......Page 249
6.3 Plasticity in the Central Nervous System......Page 250
Digression #10: Transcranial Magnetic Stimulation......Page 252
6.4.1 Effects of Age on Muscles and Neurons......Page 255
6.4.2 Effects of Age on Motor Coordination......Page 259
6.5 Synergies in Persons with Down Syndrome......Page 265
6.5.1 Movements in Persons with Down Syndrome......Page 266
6.5.2 Multi-Finger Coordination in Down Syndrome......Page 271
6.5.3 Effects of Practice on Movements in Down Syndrome......Page 274
6.5.4 Relation of Atypical Synergies to Changes in the Cerebellum......Page 278
6.6 Synergies After Stroke......Page 280
6.7.1 Traditional Views on Motor Learning......Page 283
6.7.2 What Can Happen with a Synergy with Practice?......Page 285
6.7.3 Practicing Kinematic Tasks......Page 286
6.7.4 Practicing Kinetic Tasks......Page 290
6.7.5 Plastic Neural Changes with Learning a Synergy......Page 297
Digression #11: What Is Localized in Neural Structures?......Page 302
7.2 Synergies in the Spinal Cord......Page 307
7.3 Synergies and the Cerebellum......Page 319
7.4 Synergies and the Basal Ganglia......Page 324
7.5 Synergies and the Cortex of the Large Hemispheres......Page 326
7.5.1 TMS and the Equilibrium-Point Hypothesis......Page 327
7.5.2 Studies of Neuronal Populations......Page 331
Part 8: Models and Beyond Motor Synergies......Page 338
8.1.1 Control: Basic Notions......Page 340
8.1.2 Open-Loop and Closed-Loop (Feed-Forward and Feedback) Control......Page 342
8.1.3 A Simple Feedback Scheme of Synergic Control of a Multi-Joint Movement......Page 345
8.1.4 Optimal Control and Synergies......Page 346
8.2 Synergies and Neural Networks......Page 348
8.3.1 Do Synergies Improve Accuracy?......Page 351
8.3.2 A Feed-Forward Model with Separate Specification of Good and Bad Variability......Page 354
8.4 Synergies and the Equilibrium-Point Hypothesis......Page 356
8.5 Sensory Synergies......Page 361
8.5.1 Sensory Synergies in Neurological Disorders......Page 362
Digression #12: Sensory and Motor Effects of Muscle Vibration......Page 363
8.5.2 Sensory–Motor Interactions......Page 366
8.5.3 Sensory Synergies in Vertical Posture......Page 369
8.5.4 Multi-Sensory Mechanisms......Page 371
8.6 Language as a Synergy......Page 374
8.7 Concluding Comments: What Next?......Page 377
References......Page 380
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