Fig. 8. Inhibition of stretch-activated responses of the thoracic stretch receptor by a putative accessory neuron. (A) In accordance with the injection of depolarizing currents into the putative accessory neuron (asterisks in B), the stretch-activated response was suppressed (asterisks in A). Each arrow in trace A shows rapidly adapting impulses caused by a jerky stretch stimulus delivered manually, which appears as inflection points on the monitor trace below trace A. Paired arrows on the right hand side of the trace A indicate the impulse size of slowly adapting stretch receptor. (B) Electrical activities from the putative accessory neuron. Depolarizing current was injected into the putative accessory neuron, resulting in regenerative action potentials (asterisks). (C) Enlargement of the parts enclosed by rectangles (i) and (ii) in A. Stretch-activated EPSPs occur while the stretch stimulus is applied (i and ii) and disappear upon termination of the stretch stimulus. Summation of EPSPs (Ci) produces an action potential, which is shown in smaller amplitude than it really is (Bi). Upward deflections in monitor traces below traces A, B and C show stretch stimuli (amplitude 0.5 mm).