Figure 3.

V3 neurons are essential for a large fraction of the PAD evoked by proprioceptive stimulation (drPAD). A and B: typical PAD evoked by proprioceptive sensory stimulation of a DR (S4 DR, 0.1 ms, 1.1xT, T sensory threshold) in adjacent DR (DRP measured in S3 DR) in Sim1//ArchT⁺ mice, before and after silencing V3 neurons with light (532 nm, 5 mW/mm²). Averages of 9 trials at 0.1 Hz. Light had no effect on drPAD in mice without ArchT (ArchT⁻). Lower trace: V3-dependent portion of drPAD including dorsal root reflexes (DRRs), estimated from the change with light. C: group averages of drPAD evoked by selective proprioceptive DR stimulation (1.1–1.3xT), with and without ArchT expression; *Significant reduction with light, P < 0.05, n = 8 roots from 3 mice. D: typical drPAD evoked by proprioceptive stimulation (DR 2xT) as in A, but in mice without and with V3 neurons silenced by VGLUT2 KO; top: control mouse (Sim1-Cre lacking flx-VGLUT1); bottom: Sim1-Cre//flx-VGLUT2 mouse. E: group averages of drPAD, *Significantly smaller with KO, P < 0.05, n = 15 and 36 roots tested for 6 control and 7 KO mice, respectively. DR, dorsal root; PAD, primary afferent depolarization.