Errors in force estimation can be explained by tendon organ desensitization
- 69 Downloads
Here we report observations on the sense of muscle tension in human subjects and compare them with responses of tendon organs in cat hindlimb muscles. Human subjects learned under visual guidance to estimate a 4% maximum voluntary contraction (m.v.c.) of elbow flexors of one arm. When they were able to reproduce this force reliably without visual feedback, they repeated the estimation immediately after a 5 second m.v.c or a 5 second period of relaxation. In a second experiment the 4% m.v.c was generated under visual control with one arm, and matched with the other, test arm, without visual feedback. The matching task was then repeated after test arm conditioning. In both experiments subjects reported an accurate match using significantly more than the reference force (“overmatched”) after an m.v.c. The overmatching was greatest during the first 5 second period following the conditioning contraction, and during the subsequent 20 seconds it gradually declined to near reference levels. The size of the matching error was directly proportional to the duration of the conditioning contraction. In the first experiment extension of the arm immediately following conditioning increased the error, in the second it slightly decreased it, although tension continued to be overmatched. In a series of experiments on the soleus muscle of anaesthetised cats responses of tendon organs to 10% of maximum contraction were seen to drop sharply when preceded by a conditioning maximum contraction. The time course of recovery was comparable to the decline in matching error in the human experiments. In conclusion, one explanation for the error in force matching seen in human subjects after an m.v.c is that sensitivity of tendon organs has been lowered as a result of the activity generated during the conditioning contraction.
Key wordsTendon organ Tension Proprioception Contraction Afferent Human
Unable to display preview. Download preview PDF.
- Gregory JE, Morgan DL, Proske U (1986) After-effects in the responses of cat muscle spindles. J Neurophysiol 56: 451–461Google Scholar
- Gregory JE, Morgan DL, Proske U (1987) Changes in size of the stretch reflex of cat and man attributed to after-effects in muscle spindles. J Neurophysiol 58: 628–640Google Scholar
- Gregory JE, Morgan DL, Proske U (1988) After-effects in the responses of cat muscle spindles and errors of limb position sense in man. J Neurophysiol 59: 1220–1230Google Scholar
- Mutton RS, Kaiya K, Suzuki S, Watanabe S (1987) Post contraction errors in human force production are reduced by muscle stretch. J Physiol (Lond) 393: 247–259Google Scholar
- Mark RF, Gregory JE, Morgan DL, Proske U (1988) Changes in amplitude of the H-reflex in human subjects after conditioning contractions of the triceps surae muscle at long and short lengths. Proc Aust Physiol Pharmacol Soc 19: 101PGoogle Scholar
- McCloskey DI (1978) Kinaesthetic sensibility. Physiol Rev 58: 763–820Google Scholar
- McCloskey DI, Ebeling P, Goodwin GM (1974) Estimation of weights and tensions and apparent involvement of a “sense of effort”. Exp Neurol 42: 220–232Google Scholar
- McIntyre AK, Proske U, Rawson JA (1984) Cortical projection of afferent information from tendon organs in the cat. J Physiol (Lond) 354: 395–406Google Scholar
- Rack PMH, Westbury DR (1969) The effects of length and stimulus rate on tension in the isometric cat soleus muscle. J Physiol (Lond) 204: 443–460Google Scholar
- Roland PE, Ladegaard-Pedersen H (1977) A quantitative analysis of sensations of tension and of kinaesthesia in man. Brain 100: 671–692Google Scholar
- Smith JL, Hutton RS, Eldred E (1974) Post-contraction changes in sensitivity of muscle afferents to static and dynamic stretch. Brain Res 78: 193–202Google Scholar