Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- List of abbreviations
- 1 General methodology
- 2 Monosynaptic Ia excitation and post-activation depression
- 3 Muscle spindles and fusimotor drive: microneurography and other techniques
- 4 Recurrent inhibition
- 5 Reciprocal Ia inhibition
- 6 Ib pathways
- 7 Group II pathways
- 8 Presynaptic inhibition of Ia terminals
- 9 Cutaneomuscular, withdrawal and flexor reflex afferent responses
- 10 Propriospinal relay for descending motor commands
- 11 Involvement of spinal pathways in different motor tasks
- 12 The pathophysiology of spasticity and parkinsonian rigidity
- Index
- References
2 - Monosynaptic Ia excitation and post-activation depression
Published online by Cambridge University Press: 08 August 2009
- Frontmatter
- Contents
- Preface
- Acknowledgements
- List of abbreviations
- 1 General methodology
- 2 Monosynaptic Ia excitation and post-activation depression
- 3 Muscle spindles and fusimotor drive: microneurography and other techniques
- 4 Recurrent inhibition
- 5 Reciprocal Ia inhibition
- 6 Ib pathways
- 7 Group II pathways
- 8 Presynaptic inhibition of Ia terminals
- 9 Cutaneomuscular, withdrawal and flexor reflex afferent responses
- 10 Propriospinal relay for descending motor commands
- 11 Involvement of spinal pathways in different motor tasks
- 12 The pathophysiology of spasticity and parkinsonian rigidity
- Index
- References
Summary
The extent to which the spinal stretch reflex is involved in normal motor control and the contribution of monosynaptic Ia connections in its generation are not yet completely clarified. Regardless of these uncertainties, there is continuing interest in the reflex connections of the primary endings of muscle spindles, as detailed below.
Muscle synergies laid down in the spinal cord
The execution of even the simplest movement involves a large number of muscles, but the pattern of muscle activity is consistent for any given type of movement (see Illert, 1996). Beevor (1904, cited by Illert, 1996) claimed that the neuronal arrangements for stereotyped movements are laid down in the spinal cord. The various muscle synergies could thus be represented by different sets of spinal connections, which have been termed ‘spinal functional units’ (Baldissera, Hultborn & Illert, 1981), and are thought to be mobilised during voluntary movements, as was postulated long ago by Forster (1879, cited by Hultborn, 2001). One objective in the study of reflexes is to identify the pattern of connections underlying a particular form of behaviour. This entails tracing the effects of a given input to see how widely it is distributed to excite or inhibit different neurones. The classical example of such a study was provided by Sherrington (1910), who detailed the muscles that contract or relax in the flexor reflex (see Chapter 9).
- Type
- Chapter
- Information
- The Circuitry of the Human Spinal CordIts Role in Motor Control and Movement Disorders, pp. 63 - 112Publisher: Cambridge University PressPrint publication year: 2005
References
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