Fig. 9

Targeted photo-stimulation of tegmentum activates brain-wide functional connections. Representative images (a) and traces (b) showing activation of brain-wide downstream neurons evoked by targeted photo-stimulation. The left dorsal tegmentum (Teg-l, green area) in a 6-dpf Tg(elavl3:H2B-GCaMP6f;elavl3:ChrimsonR-tdTomato) larva was targeted for photo-stimulation, which activated widely distributed neurons in brain regions including Teg-l, Pa-l, Pa-r, Hb-l, Hb-r, Th-l, Th-r, OT-l, OT-r, Cb-l, and Hind-l (Pa: bilateral pallium; Th: thalmus; CB: cerebellum; Hind: hindbrain). The stimulation pattern designed based on the anatomical position of Teg-l on each depth. (b, right) Average responses expanded in time. The yellow arrows (b, left) and shaded area (b, right) indicate the targeted photo-stimulation events. The activities of the representative Th-l, Th-r, and Cb-l neurons were not recorded during the stimulation with the current experiment paradigm. (c) Activated neuron distribution (left) and differences in optogenetic response amplitude (middle) and latency (right) among regions across the whole brain. Neurons showing significant responses to three or four of four photo-stimulation repetitions were considered reliably responsive and included in the distribution. Box-and-whisker plots of the amplitude and latency represent the 25th, 50th, and 75th quartiles (box lines) and the extreme values (by whiskers). (d) Schematic showing brain-wide functional neural networks downstream of Teg-l. The red arrows represent the functional connections between Teg-l and the indicated brain areas.