Fig. 2. Recruitment of three motor neurons in response to sensory input. Sinusoidal movements (mvt) were imposed on the CBCO strand while a depressor neuron (Dep MN) was recorded intracellularly from a neuritic branch in the posterior-lateral quadrant of the neuropil (see Fig. 5A for an explanation of quadrants) and extracellular spikes in the depressor nerve were monitored. In the uppermost trace the CBCO strand was stretched (S) and released (R). In this figure and in all subsequent figures an upward deflection of the movement trace corresponds to the release of tension on the CBCO strand, while a downward deflection corresponds to a stretch. The dotted line in the 2nd trace from the top indicates a membrane potential of –65 mV. It was possible to identify three distinct spike shapes in the extracellular record, using a method based on template matching. These spike shapes are shown at the bottom of the figure. A raster plot of the occurrence of these three spike shapes is shown below the raw extracellular record. A short vertical line represents a single spike. Note that the largest extracellular spike (L) corresponds one-for-one with the intracellular spikes.