In this locust, the probability of jumping was slightly lower for contralateral eye stimulation (njump-ipsi = 4, Probjump-ipsi = 33%, njump-contra = 2, Probjump-contra = 20%). The two jumps in response to contralateral eye stimulation occurred 60 and

140 ms after projected collision, considerably later than observed in intact animals for l/|v| = 80 ms (mean: 68 ms before collision; SD = 42 ms; nL = 7, nT = 89). Indeed, in intact animals, in only two trials for one animal—2.2% of all trials— did take-off occur after collision, with the latest take-off time being 35 ms after collision. In contrast, the two jumps elicited by ipsilateral stimulation at the same l/|v| value occurred 0 and 10 ms before collision, and were thus relatively close to the range observed in intact animals. Since one locust jumped in response to stimulation of the eye contralateral to the nerve cord where we had ablated the DCMD, this indicates that other contralateral descending www.selleckchem.com/products/dabrafenib-gsk2118436.html neurons respond to looming stimuli (as recently reported by Gray et al., 2010) and are able to activate the motor circuitry generating the jump. In fact, after all nine successful DCMD ablations, check details we could still record multiunit activity elicited by looming stimuli in the affected nerve cord (Figure S6B). The peak of the multiunit activity, however,

occurred significantly later than that of the DCMD (106 ms, difference of medians; pKWT < Tryptophan synthase 10−9). In three of the animals that jumped after DCMD laser ablation, including the one that jumped on both sides, we measured the activity of the nerve cord in response to looming stimuli presented to the eye ipsi and contralateral to the remaining nerve cord after the behavioral experiments (Figure S6C). The DIMD spikes were detectable as the largest in response to stimulation of the ipsilateral eye, while one or more unidentified units were activated in response to contralateral eye stimulation. We presented looming stimuli with nine different l/|v| values and compared the timing of the peak multiunit activity evoked in the contralateral nerve cord

to the stimulated eye with that of the DIMD. We found that the peak multiunit activity occurred later than that of the DIMD (Figure S6D). Because the DCMD peak firing rate occurs earlier or around the time of the DIMD peak (Figure S5B), we conclude that for all l/|v| values, the peak multiunit contralateral activity occurs later than the DCMD peak. These results indicate that, among contralateral descending neurons, the DCMD plays a critical role in the timely triggering of cocontraction and take-off but probably not in the generation of the initial hindleg flexion and joint movement. Furthermore, other descending contralateral units can trigger a jump, but given their delayed peak activity, these jumps occur close to, or even after expected collision. Such delayed jumps are rare in intact animals.