Figure 7.
MooSEZs drive MDN-independent rotational backward locomotion
(A) Example trajectories of flies in which MooSEZs were optogenetically activated unilaterally (right, purple; left, orange) or bilaterally (black) for 2 s in the open arena. CsChrimson was expressed in left, right or both MooSEZs.
(B, D, and F) Single fly traces (light) of translational velocity (B), angular velocity (D), cumulative angular change (F), and their respective means (dark), for flies in which MooSEZs were optogenetically activated unilaterally (right, purple; left, orange) or bilaterally (black) for 2 s in the open arena. Angular velocity is defined as a change in the fly’s orientation angle in relation to a global orientation coordinate system. Left rotations are defined as positive values and right rotations as negative values. Cumulative angular change is defined as the cumulative integrated area under the angular velocity versus time curve. Total angular change is defined as the integrated area under the angular velocity versus time curve during the light pulse. The light pulse is labeled in light red. CsChrimson was expressed in left, right or both MooSEZs.
(C, E, and G) Mean translational velocity (C), mean angular velocity (E), and total angular change (G), during the 2-s light pulse for flies presented in (B, D, and F, respectively). Whereas translational velocity is similar across conditions, angular movement is tightly correlated with MooSEZ side of activation (8 ≤ n ≤ 11, ∗p < 0.05, ∗∗∗∗p < 0.0001, Kruskal-Wallis tests followed by Dunn’s post-hoc tests; see Table S1).
(H) Angular speed (left) ± SEM (shading) and single fly traces (light) of absolute cumulative angular change (right) and their respective means (dark) following 30 s long bilateral optogenetic stimulation of MDNs (green) and of GH146II-GAL4 neurons in the presence (black) or absence (blue) of TNT in MDNs in the open arena. Angular speed is defined as the absolute value of angular velocity. Absolute cumulative angular change is defined as the cumulative integrated area under the angular speed versus time curve. VT50660-GAL4 (MDNs) or GH146II-GAL4 were used to drive UAS-CsChrimson and MDN-LexA (VT44845-LexA) was used to drive LexAop-TNT (when required). The light pulse is labeled in light red. Continuous bilateral activation of MooSEZs generates MDN-independent sustained backward rotation.
(I and J) Mean angular speed (I) and absolute total angular change (J) during the 30-s light pulse for flies presented in (H). Absolute total angular change is defined as the integrated area under the angular speed versus time curve during the light pulse. Significantly higher angular speed and absolute total angular change are observed following MooSEZ long bilateral activation in the presence or absence of TNT in MDNs relative to MDN long bilateral activation (9 ≤ n ≤ 20, ∗∗ p < 0.01, Kruskal-Wallis test followed by Dunn’s post-hoc test; see Table S1).
(K) Connectivity diagram between MooSEZ and DNa01 (fragment #1170939344, top) or DNa02 (fragment #1140245595, bottom) in the FlyEM hemibrain. MooSEZ is strongly connected to DNa01 and DNa02 via various neurons. Each circle represents a cell type, and each arrow represents a directional synaptic connection. Arrow width represents synaptic connection strength derived from number of synapses forming the connection (indicated by the number above the arrow). Cell types connecting MooSEZ to both DNa01 and DNa02 are labeled in orange. For simplification purposes, connection with fewer than 15 synapses were omitted.
(L) Schematic of proposed MDN and MooSEZ pathways. Odors activate MDNs that are required for odor-induced backward locomotion. Odors also activate MooSEZs that activate MDNs and can also add a significant rotational component to the motor response presumably via DNa01 and DNa02.