Figure 1.

Activation of Just the Fast Extensor Tibiae Motor Neuron Generates Natural Extension and Subsequent Passive Flexion Movements in the Locust

(A) Single fast extensor tibiae (FETi) motor neuron spikes elicited fast tibial extensions that did not carry the tibia to its fully extended angle of 19°. Each extension was followed by a passive flexion of the tibia toward the starting angle. The inset indicates the femorotibial joint angle notation (femur represented by gray bar, tibia represented by red bar [start position] and black bar [maximally extended position]) and directions of joint movement (arrows).

(B) Five FETi spikes at 7.5 Hz elicited a series of extensions separated by smaller passive flexions. The inset shows at an expanded timescale the video sampling frequency in one example trial; each frame is represented by one dot, and the timing of the stimulus (to the nearest frame) is shown in red.

(C) Five FETi spikes at 20 Hz elicited a full extension. The tibia remained fully extended for approximately 250 ms and then returned passively toward the starting angle. Each line represents a single trial of the same animal within each panel; each panel shows data from a different animal. Inset is as in (A).

The black vertical tick marks in the lower left corner of each panel indicate the timing of stimulus pulses. Note that movement could begin between frames. All trials were aligned to stimulus onset. All movements started from the current resting state, i.e., the start angle was not imposed. FT, femur tibia. See also Table S1.