Fig. 5.

Voltage-activated high-frequency fluctuations appear in some motoneurons before, during, and after MN discharge. The top of the figure shows the MN response to a current ramp; the panels below show truncated and expanded sections of this record at the start (A), peak (B), and end (C) of discharge. A: high-frequency fluctuations in membrane potential start shortly before discharge (open arrowhead) and similar transient potentials can be seen (arrows) in flattened regions between spikes (indicated by dots), which vanish after several interspike intervals (ISIs). B: oscillations and flattened trajectories are absent during most of the response. C: high-frequency fluctuations (open arrowheads) and flattened interspike trajectories (dots) reappear at the end of discharge.