Force-feedback during human walking

Abstract

To continue to the correspondence of Duysens 1xReply. Duysens, J. Trends Neurosci. 2000; 23: 529–530Abstract | Full Text | Full Text PDFSee all References1 to my recent letter to the editor 2xControl of a ‘simple’ stretch reflex in humans. Capaday, C. Trends Neurosci. 2000; 23: 528–529Abstract | Full Text | Full Text PDF | PubMed | Scopus (5)See all References2, I should like to reply further. Duysens 1xReply. Duysens, J. Trends Neurosci. 2000; 23: 529–530Abstract | Full Text | Full Text PDFSee all References1 ended his letter by stating ‘…other human studies are controversial’, by which he means work other than that on force-feedback. This is true and good for the progress of science. However, the situation with force-feedback during human walking is different. In this case there are no controversies, all the studies that have tested the hypothesis find the same thing: little, if anything. This work, carried out by several capable physiologists using a variety of approaches, is summarized in my letter 2xControl of a ‘simple’ stretch reflex in humans. Capaday, C. Trends Neurosci. 2000; 23: 528–529Abstract | Full Text | Full Text PDF | PubMed | Scopus (5)See all References2. In addition, my original letter stated that even in the intact cat the effect (i.e. Ib-afferent input becoming excitatory during the stance phase of walking) is much weaker and often absent. Duysens retrenches by stating that it is not that the phenomenon does not exist, but instead that it is difficult to demonstrate, a position similar to that of supporters of cold-fusion.The argument based on physiology made by Duysens 1xReply. Duysens, J. Trends Neurosci. 2000; 23: 529–530Abstract | Full Text | Full Text PDFSee all References1 in his reply is that supramaximal stimulation of a mixed nerve (i.e. the tibial nerve) would be ‘…much more than selective activation of Ib afferents’ 1xReply. Duysens, J. Trends Neurosci. 2000; 23: 529–530Abstract | Full Text | Full Text PDFSee all