Fig. 1.

Fictive swimming activity in dorsal and ventral branches of the ventral root, and in motoneurons projecting out those branches. (A) Schematic showing the dorsal and ventral branches of the ventral roots (dorVR and venVR), the recordings of their spiking activity with suction electrodes, and recordings of intracellular membrane potential from motoneurons with sharp microelectrodes (dorMN and venMN). (B) Individual motoneurons can be identified according to their projection within the branches of the ventral root. (C) Intracellular recording of two motoneurons, both venMNs, in the same spinal segment during fictive swimming induced with d-glutamate. The two venMNs have similar oscillatory waveforms. (D) A pair of intracellular recordings of a dorMN and a venMN. These two motoneurons have somewhat different oscillatory waveforms.