(A and B) Examples of recordings from a pair of bidirectionally connected Shox2 INs. In (A), responses of Shox2 IN 1 (gray) and Shox2 IN 2 (blue) to 1 s long hyperpolarizing and depolarizing current steps injected into Shox2 IN one are shown. In (B), the protocol was reversed and responses to current steps in Shox2 IN2 are shown. As typical in bidirectionally connected Shox2 INs, both hyperpolarizing and depolarizing responses were evident in the non-injected cell. Additionally, spikelets in the non-injected neuron corresponded to action potentials generated in the neuron receiving the current steps. Darker shading corresponds to increasing current steps. (C) Coupling coefficients were highly variable with a mean of 13%, indicated by the green line. (D and E) Examples of recordings from a pair of unidirectionally connected Shox2 INs. In (D), 1 s long current steps were injected into Shox2 IN one while responses of Shox2 IN 1 (black) and Shox2 IN 2 (red) were recorded in current clamp mode. In (E), the same protocol was performed but current was injected into Shox2 IN 2. Darker shading corresponds to increasing current steps. (F) Distance between recorded neurons was not significantly different by connection type but connected cells were significantly closer together in slices than in dorsal horn-removed preparations. Empty bars for dorsal horn-removed preparations (dhr), filled bars for slices (s), unidirectional (red), bidirectional (blue), or not connected (gray) pairs, mean ±SD.