Fig. 14. Intersegmental inhibitory effect of TSR-4 on TSR-3. The receptor muscle of TSR-3 was stretched manually (upward deflection below trace C), resulting in phasico-tonic (large spikes) and tonic (middle-sized spikes) impulse discharges (A). These responses are also shown in B and C through two sets of window discriminators. Since the stretch stimulus was delivered slowly, unevenness was seen in the rising phase of a stretch stimulus. After reaching a given stretch length, the receptor muscle of TSR-4 was stretched repeatedly (F). The stretch amplitudes were given in the order 0.7, 0.7, 1.0 and 1.0 mm. The impulse discharges of TSR-3 are suppressed at a stretch length of 1 mm in TSR-4 (B), but this inhibitory effect was weaker for tonic responses (C). Impulse discharges of the putative accessory neurone through a window discriminator (D) and its frequency histogram (E). (G) The region indicated by double-headed arrows in A shown on an expanded scale. Small spikes in nerve 3 (spike height indicated by facing double arrows to the right of the trace) coincide with the appearance of stretch-activated responses of TSR-4, whose small spikes are also presented as a frequency histogram (E).