The Circuitry of the Human Spinal Cord: Its Role in Motor Control and Movement Disorders
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Studies of human movement have proliferated in recent years, and there have been many studies of spinal pathways in humans, their role in movement, and their dysfunction in neurological disorders. This comprehensive reference surveys the literature related to the control of spinal cord circuits in human subjects, showing how they can be studied, their role in normal movement, and how they malfunction in disease states. Chapters are highly illustrated and consistently organised, reviewing, for each pathway, the experimental background, methodology, organisation and control, role during motor tasks, and changes in patients with CNS lesions. Each chapter concludes with a helpful resume that can be used independently of the main text to provide practical guidance for clinical studies. This will be essential reading for research workers and clinicians involved in the study, treatment and rehabilitation of movement disorders.
Movement Phasic Contractions With brisk phasic contractions, the increase in spindle discharge follows the appearance of EMG in the contracting muscle by 10–50 ms (Vallbo et al. 1979). The degree of spindle activation increases with the degree of effort, and occurs only or predominantly for spindles in the contracting muscle. Spindles in nearby inactive synergists may be unloaded (Fig. 3.10(e)). Unloading would not be expected if reinforcement manoeuvres produced widespread activation of γ
Paraparesis Spasticity: Changes in Recurrent Inhibition during Motor Tasks Patients with Other Movement Disorders Résumé References 5 Reciprocal Ia Inhibition Background from Animal Experiments Methodology 146 147 147 148 148 148 152 152 152 153 154 155 157 157 158 158 158 158 160 161 162 163 163 165 165 165 167 169 169 169 169 170 170 170 174 178 178 180 vii viii Contents Methods to Investigate Reciprocal Ia Inhibition at Hinge Joints Inhibition of the Monosynaptic Reflex Modulation of the
facilitation produces a decrease in the current required to produce a test reflex of predetermined size. There are advantages of threshold tracking over the conventional technique of amplitude tracking: less variability, constant population of motoneurones contributing to the test response, avoiding the problem of size-related changes in test reflex sensitivity, and wider dynamic range. There are also disadvantages: when excitability changes, there is a delay before a new threshold can be
artificial inputs. However, these techniques demonstrate only the linear components of any correlated activity, and do not clarify the direction of the connection. Journal of Physiology 471, 445–464. Boroojerdi, B., Kopylev, L., Battaglia, F., Facchini, S., Ziemann, U., Muellbacher, W. & Cohen, L. G. (2000). Reproducibility of intracortical inhibition and facilitation using the paired-pulse paradigm. Muscle & Nerve 23, 1594–1597. Bostock, H., Cikurel, K. & Burke, D. (1998). Threshold tracking
Research 42, 337–350. Poliakov, A. V. & Miles, T. S. (1992). Quantitative analysis of reflex Mezzarane, R. A. & Kohn, A. F. (2002). Bilateral soleus H reflexes in humans elicited by simultaneous trains of stimuli: symmetry, variability, and covariance. Journal of Neurophysiology 87, 2074–2083. responses in the averaged surface electromyogram. Journal of Neuroscience Methods 43, 195–200. Powers, R. K. & Türker, K. S. (2010). Deciphering the contribution of intrinsic and synaptic currents to the