Fig. 7

Activating iTB-L Projection Neurons Is Sufficient to Evoke Directed Approach Behavior (A) 2P optogenetic stimulation of the iTB-L. ChR2-expressing fish in the tectum were mounted under a 2P microscope to stimulate regions of the iTB-L. (B) Example of stimulated zones in a Gal4:s1013t;UAS:ChR2-mcherry fish. The cyan outline represents the targeted area (10.5 × 16.7 μm2) to induce swims, whereas the gray box indicates the control stimulation where no ChR2 is expressed. (C) Stimulation protocol and behavioral outcome. The laser was repeatedly scanned (32.7 Hz) for 3 s with 920 nm over the target area. The target stimulation (cyan boxes) consistently induced ipsilateral turns, whereas behavior only rarely coincides with stimulation of the control region (gray box). (D) Quantification of average stimulation efficiency for target (cyan) and control (gray) stimulations in three fish (∗p = 3.8 × 10−2). (E) Mean bout angle distributions for the most common bout types (kernel density estimation > 95%) for five fish. (F) Correlation between stimulation site and tail directionality (∗∗p = 1.3 × 10−3). Comparing the registered stimulation areas for five fish indicates a bias in bout directionality that increases with medial to lateral position in the iTB-L. The scale bar represents 50 μm. Data are presented as mean ± SEM.