Figure 4.
Physiology and anatomy of Vi. (a) Double intracellular recording of Vi and VS9. Shown is a stretch of the membrane potential of Vi (black line) and VS9 (red line). Whenever a spike is elicited in Vi, an EPSP can be measured in VS9. (b) Spike-triggered average of the VS9 membrane potential. The black line shows the average spike in Vi, which served as a trigger to average the membrane potential of VS9 (red line). (c) Two-photon imaging of Vi. The cell was filled with the green fluorescent dye Alexa488 and imaged with a two-photon microscope at a resolution of 0.4 × 0.4 × 2 μm3. This resulted in a total of 19 XYZ stacks that were merged and further processed with Amira software. Vi connects the lobula plates from the left and right brain hemisphere and has arborizations in both lobula plates. The cell was penetrated and dye injected in the arborization in the right lobula plate. The arborizations in the left lobula plate are likely not completely filled. Overall, Vi was recorded in five experiments, three of which are double recordings with proximal VS cells. Vi was stained in three experiments.