Figure 1.

Increase in the locomotor burst frequency by 2-AG. A, Locomotor rhythm was induced by NMDA and recorded in opposing ventral roots. Intracellular recording from a MN that received on-cycle excitation in phase with the ipsilateral ventral root (vr-i) activity that alternated with midcycle inhibition occurring in phase with the contralateral ventral root (vr-c) burst. B, Application of the endocannabinoid 2-AG (2 μm) increased the burst frequency, decreased the oscillation amplitude, and increased spiking activity. C, Averaged synaptic inputs received by the motoneuron showing a decrease in the amplitude of the oscillation by 2-AG. In these recordings, the action potentials were filtered out using a low-pass filter and normalized. D, Averaged data from all the experiments showing the time course of decrease of the oscillation amplitude (red), which is paralleled with an increase in the locomotor burst frequency (blue) induced by 2-AG.