Fig. 11. Responsiveness of TSR-3 and TSR-4 to the same amplitude of stretching. (A) The inset shows stretch-activated responses of TSR-3, which consist of a phasico-tonic response (i) and a tonic response (ii). Scale bar, 10 s. The impulse frequency/stretch relationships for the phasico-tonic and tonic responses are shown separately in A and B. Both the phasico-tonic and tonic stretch receptors respond to a stretch of up to 3.8 mm without saturation. (C,D) The inset shows stretch-activated responses of TSR-4. Scale bar, 10 s. The impulse frequency/stretch relationship is presented in the same manner as for TSR-3. Both phasico-tonic (ii) and tonic (iv) responses at a stretch of 3.8 mm appear to reach a plateau impulse frequency or show a decrease in impulse frequency. The same signals indicate a pair of phasico-tonic and tonic responses from one animal.