Fig. 9. Two fast oblique (F/O) class depressor motor neurons. These neurons have large diameter main neurites that lie obliquely along the medial edge of the neuropil and a large extracellular spike. (Ai) Two neurons were recorded from and filled with different dyes in a single animal. While there are many similarities in the morphology of the two neurons, there are also some notable differences. For example, the rhodamine-filled neuron (red) has four branches in the lateral-most part of the lateral-posterior quadrant where CBCO sensory neurons may make monosynaptic contact with depressor motor neurons, whereas the Lucifer Yellow-filled neuron (green) has only one branch in this region. (Aii) The rhodamine-filled neuron shows a monosynaptic EPSP with a delay of 5.02 ms from the stimulus artifact and amplitude of 6.08 mV in response to CBCO stimulation (an average of 23 traces is shown). The dotted line indicates a resting membrane potential of –74 mV. (Aiii) The Lucifer Yellow filled neuron shows only an IPSP in response to CBCO stimulation. (Bi) The morphology of the rhodamine-filled neuron. (Ci) The morphology of the Lucifer Yellow-filled neuron. (Bii) The rhodamine-filled neuron showed a resistance response to movement of the CBCO strand. The resting potential was –74 mV. The data shown are averages of 10 cycles triggered off of the movement trace. (Cii) The Lucifer Yellow-filled neuron showed no response to movement of the CBCO strand. The resting potential was –72 mV. The data shown are averages of 11 cycles triggered from the movement trace.