Figure 5.

Interneurons considered to be part of the locomotor CPG express I_NaP-dependent bursting properties. A1, A2, Confocal projection images in the ventral part of upper lumbar segments showing the organization of dextran-labeled commissural interneurons (A1) and GFP⁺ neurones (A2) from the neonatal rat and the Hb9:eGFP transgenic mice, respectively. The dashed circles highlight the limits of both the central canal (CC) and the motoneuronal pool (MN). The arrows in A2 show bilaterally located GFP⁺ neurones targeted as putative Hb9 cells. Scale bars, 50 μm. The insets in A2 illustrate a GFP⁺ interneuron patch clamped under infrared-differential interference contrast. The GFP diffusion into the patch-clamp pipette confirmed that recordings were performed from GFP⁺ interneurons. B1, B2, Recurrent bursts induced by incrementing depolarizing currents in a descending commissural interneuron (B1) and in a Hb9 interneuron (B2) both recorded in [Ca²⁺]_o-free ACSF. C1, C2, Same cells as in B 15 min after the application of riluzole (10 μm). Membrane potentials are mentioned on the left of each trace.