Fig. 1. Features of the depressor trochanteris system. (A) Schematic view of the three main parts of the depressor trochanteris (M103a, M103d and M103b/c) in a cross-section of half of the locust mesothorax. Cx, coxa; Tr, trochanter; Fe, femur; Ti, tibia; Ta, tarsus. (B) Morphology of the fast and slow depressor motoneurons of M103d, viewed in mesothoracic hemiganglia. The nerves are numbered. (C) Simultaneous recordings from the three thoracic nerves that supply the M103 as a whole. Upon stimulation by touching the ventral coxa with a small brush, the motor patterns appear similar, with some tonically active units of small amplitude and bursts of larger amplitude spikes occurring upon stimulation. (D) Intracellular recording of summating excitatory junction potentials (EJPs) in a fibre of M103d resulting from efferent spikes (small amplitudes) recorded from nerve N3C₂. (E) Intracellular recordings of EJPs in a fibre of M103d evoked by efferent spikes (lower trace) of the fast-depressor motoneuron (upper trace; large amplitude potentials) recorded at nerve N3C₂.