Figure 1.

Patterns of motoneuron activity and spike timing. A, Chemically immobilized zebrafish larvae are pinned down to a Sylgard platform and recordings from a spinal motoneuron (Mn) and peripheral motor nerve (MN) are performed following dissection (see Materials and Methods for details). B, Image of a fluorescently filled Mn and its projection into the segmented axial musculature. Note the suction electrode for the MN recording placed in close proximity to the Mn recording site. C, Distribution of input resistance (Rin) values for low-, middle- (mid), and high-Rin pools of motoneurons. D–F, Cell-attached recordings from Mns with progressively greater Rin and simultaneous MN recordings. Expanded traces on the right are taken from regions boxed in gray. Gray lines and arrowheads mark the start of the motor burst cycle, used to quantify spike timing. G–I, Cumulative distributions of the absolute values of spike timing relative to the onset of the MN bursts (at time 0) at slower speeds (gray) and faster speeds (black) for low-Rin (G), middle-Rin (H), and high-Rin Mns (I). Double asterisks indicate a significant difference. See Results for statistical data.