| Abstract: | Harmonic distortion (HD) from 1,055 responses of muscle spindles sensory endings to sinusoidal stretches (frequency range 0.0008 to 0.8333 Hz, amplitude range 0.019 to 3.09 mm) has been studied in the cat soleus muscle. Sixty-six per cent were primary afferents (Ia) and 34% secondary (II). HD mean value (0.28) did not show any significant differences between both types of endings. Analysis of variance for HD versus stimulation amplitude showed a greater HD when stretch amplitudes were beyond 1.599 mm or less than 0.031 mm on primary afferents (p less than 0.001) and less than 0.070 mm on secondary (p less than 0.001). The effect of stimulus frequency was also significant (p less than 0.01 Ia and p less than 0.001 II), however only at 0.8333 Hz and in secondary endings HD was significantly higher. The silent period in the response, at release of stretch, caused by half wave rectification could explain about 50% of measured HD. |
