Journal: bioRxiv

Article Title: On the adaptive behavior of head-fixed flies navigating in two-dimensional, visual virtual reality

doi: 10.1101/462028

Figure Lengend Snippet: ( A ) Schematic of the projector-based visual display and its position relative to the tethered walking fly. The inset shows an image taken from behind the fly with an IR camera used for calibration and fly positioning. ( B, C ) Photographs of a fly in VR viewed from the side. The IR LEDs used for illuminating the ball are visible in the lower right corner. In (C), the fly receives optogenetic stimulation (red light). ( D ) Example trace of a fly exploring a cone (black circle) in a virtual 2D plane. The position fly (center of mass) is indicated with a dot and a short line marks the fly’s viewing direction. The progression of time is color-coded. ( E ) Illustration of absolute and relative heading angles. ( F ) Rendered images of the scene from the point of view of the fly at the four time points marked by black circles in the trace fragment in (D). Note that these rendered images are for illustration and do not contain the perspective corrections applied to images that were projected onto the screen during the experiment. See for screenshots of projected images. ( G ) Relative heading angle of the fly with respect to the landmark in the trace fragment shown in (D). A relative heading angle of 0 corresponds to facing the landmark. Note that the gap in the panoramic screen behind the fly means that the landmark is only visible for relative heading angles smaller than ⅔ π or larger than -⅔ π. Color-code as in (D). ( H ) Trajectory of a fly exploring a periodic world with cone-shaped landmarks ( single landmark forest ) over the course of a 10 min trial. Shaded box: section of the trajectory shown in (D). Grey dashed circles: circular area around each landmark that was included in the analysis. ( I ) Trajectory from (H) after “collapsing” the trajectory fragments within a 60 mm radius circle around each landmark to one circular reference “arena” (60 mm radius) with a centrally placed landmark. ( J ) Schematic illustrating how a landmark’s (10 mm wide, 40 mm high cone) angular dimensions change as a function of distance, as seen from the fly’s point of view. The blue line indicates visibility of the landmark through the virtual fog (100%: full visibility, 0%: zero visibility). The distance at which the cone has an angular width of 20 is highlighted. DLP, digital light processing; LM, landmark.

Article Snippet: The visual display consisted of a triangular screen onto which a panoramic image was back-projected by two DLP (Digital Light Processing, also referred to as digital mirror device or DMD) projectors (DepthQ WXGA 360 HD 3D Projector, developed by Anthony Leonardo, Janelia, and Lightspeed Design, Bellevue, WA, USA).

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