Fig. 9

Drosophila optogenetics experiment. a. Schematic of a fruit fly first instar larval head expressing the red-shifted channel rhodopsin CsChrimson in olfactory sensory neurons and GCaMP6s in pan-neuronally. b. Rendering of the experimental setup: The mounting chamber (Fig. 6d) is placed in a 3D-printed holder (c.f. 3), screwed onto a rigid stand (ThorLabs). c-d. Standard deviation projections of 2 photon scan fields of the larval brain with antennal lobes marked by red circles (left) and Ca²⁺ traces in response to red flashes (right). c. Stimulation duration = 0.5 s, inter-stimulus interval = 3 s, image dimensions = 256 × 230, scan rate (lines) = 1,081 Hz, frame rate = 4.7 Hz. d. Stimulation duration = 0.5 s, inter-stimulus interval = 10 s, image dimensions = 256 × 170, scan rate (lines) = 1,077 Hz, frame rate = 6.34 Hz. Middle panel is a heatmap of pixel intensities showing high GCaMP6 fluorescence in the antennal lobe following optogenetic stimulation; obtained by subtracting a pre-stimulus from a during-stimulus image (median filter, kernel size = 2).