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. 2021 Sep 7;8(5):ENEURO.0537-20.2021. doi: 10.1523/ENEURO.0537-20.2021

Figure 1.

Figure 1.

The model and experiment of spatial orientation working memory for D. melanogaster (fruit fly). The performance of the wild-type flies indicated strong working memory of the landmark directions. A, The behavior arena featured a central platform surrounded by water and by a 360° LED screen that displayed two vertical black strips as the visual landmarks at 0° and 180°. B, The task, designed based on Buridan’s paradigm (Götz, 1980; Strauss and Pichler, 1998; Neuser et al., 2008), was divided into three stages: the prestimulus stage (90 s), stimulus stage (variable duration), and poststimulus stage (variable duration). In each trial, a single fruit fly was placed at the center of the platform and was allowed to freely move on the platform in the whole trial. C, Schematic diagram of the EB-PB neural network (Su et al., 2017). The EIP, PEI, and PEN neurons support the activity bump which encodes the head direction with respect to a cued location. The bump is modulated by three types of GABAergic ring neurons, EIP-ring, P-ring, and C-ring neurons, and each performs different functions. These ring neurons can be targeted by specific GAL4 drivers as shown in Extended Data Figure 1-1. D–F, The walking patterns as indicated by the red trajectories of the flies (n = 30) in the prestimulus, stimulus, and poststimulus stages. In the stimulus stage, there was a clear pattern of fixation toward the landmarks. The fixation behavior was reduced but still statistically significant in the poststimulus stage. The definition of the movement direction and the trajectory distribution are shown in Extended Data Figure 1-2. G, The fixation density (fixation duration/stage duration) of the poststimulus stage (black solid), the prestimulus stage (black dashed), and their differences, termed PI (red) as functions of the stimulus exposure duration. The strength of memory, which is indicated by PI, increases with the stimulus exposure duration. Schematics of neural mechanisms underlying spatial orientation memory and its circuit model are show in Extended Data Figure 1-3. Movement patterns of individual flies are displayed in Extended Data Figure 1-4.