Control of a ‘simple’ stretch reflex in humans

Abstract

In their recent review article on control of the crayfish ‘stretch reflex’ during ‘walking’ Clarac et al.1. Clarac, F. et al. (2000) Central control components of a ‘simple’ stretch reflex. Google Scholar concluded that it would be important to understand ‘…how sensory–motor pathways operate in a real behavioral context’. Indeed this has been done during human standing, walking and running 2. Capaday C. Stein R.B. Amplitude modulation of the soleus H-reflex in the human during walking and standing. J. Neurosci. 1986; 6: 1308-1313 PubMed Google Scholar , 3. Fitzpatrick R.C. et al. Postural proprioceptive reflexes in standing human subjects: bandwidth of response and transmission characteristics. J. Physiol. 1992; 458: 69-83 PubMed Google Scholar , 4. Crenna P. Frigo C. Excitability of the soleus H-reflex arc during walking and stepping in man. Exp. Brain Res. 1987; 66: 49-60 Crossref PubMed Scopus (200) Google Scholar , 5. Yang, et al. (1991) Contribution of peripheral afferents to the activation of the soleus muscle during walking in humans. Exp. Brain Res. 87, 679–687 Google Scholar , 6. Andersen J.B. Sinkjaer T. The stretch reflex and H-reflex of the human soleus muscle during walking. Motor Control. 1999; 3: 151-157 PubMed Google Scholar , 7. Dietz V. et al. Neuronal mechanisms of human locomotion. J. Neurophysiol. 1979; 42: 1212-1222 PubMed Google Scholar , 8. Capaday C. Stein R.B. Difference in the amplitude of the human soleus H reflex during walking and running. J. Physiol. 1987; 392: 513-522 PubMed Google Scholar , 9. Ferris D.P. et al. Soleus H–reflex gain during walking and running under simulated reduced gravity. Soc. Neurosci. Abstr. 1999; 25: 121 Google Scholar and some of this work was reviewed in this journal more than a decade ago 10. Stein R.B. Capaday C. The modulation of human reflexes during functional motor tasks. Trends Neurosci. 1988; 11: 328-332 Abstract Full Text PDF PubMed Scopus (218) Google Scholar . Clarac et al.1. Clarac, F. et al. (2000) Central control components of a ‘simple’ stretch reflex. Google Scholar did not mention this body of work in their article. In fact, the authors have done a nice job comparing control of the ‘stretch reflex’ in several walking invertebrates, as well as a com-parison with results in decerebrate cats. A brief comparison with results in human subjects would have provided a nicely integrated view of the subject. My purpose, therefore, is to complete the picture by succinctly summarizing some of the rel-evant work on modulation of the ‘stretch reflex’ in human subjects and point to some differences with the crayfish and decerebrate cat.