Active flight increases the gain of visual motion processing in Drosophila

We developed a technique for performing whole-cell patch-clamp recordings from genetically identified neurons in behaving Drosophila. We focused on the properties of visual interneurons during tethered flight, but this technique generalizes to different cell types and behaviors. We found that the peak-to-peak responses of a class of visual motion–processing interneurons, the vertical-system visual neurons (VS cells), doubled when flies were flying compared with when they were at rest. Thus, the gain of the VS cells is not fixed, but is instead behaviorally flexible and changes with locomotor state. Using voltage clamp, we found that the passive membrane resistance of VS cells was reduced during flight, suggesting that the elevated gain was a result of increased synaptic drive from upstream motion-sensitive inputs. The ability to perform patch-clamp recordings in behaving Drosophila promises to help unify the understanding of behavior at the gene, cell and circuit levels

A Simple Vision-Based Algorithm for Decision Making in Flying Drosophila

Animals must quickly recognize objects in their environment and act accordingly. Previous studies indicate that looming visual objects trigger avoidance reflexes in many species 1, 2, 3, 4, 5; however, such reflexes operate over a close range and might not detect a threatening stimulus at a safe distance. We analyzed how fruit flies (Drosophila melanogaster) respond to simple visual stimuli both in free flight and in a tethered-flight simulator. Whereas Drosophila, like many other insects, are attracted toward long vertical objects 6, 7, 8, 9, 10, we found that smaller visual stimuli elicit not weak attraction but rather strong repulsion. Because aversion to small spots depends on the vertical size of a moving object, and not on looming, it can function at a much greater distance than expansion-dependent reflexes. The opposing responses to long stripes and small spots reflect a simple but effective object classification system. Attraction toward long stripes would lead flies toward vegetative perches or feeding sites, whereas repulsion from small spots would help them avoid aerial predators or collisions with other insects. The motion of flying Drosophila depends on a balance of these two systems, providing a foundation for studying the neural basis of behavioral choice in a genetic model organism

Beyond Poisson : increased spike-time regularity across primate parietal dortex

Cortical areas differ in their patterns of connectivity, cellular composition, and functional architecture. Spike trains, on the other hand, are commonly assumedto follow similarly irregulardynamics across neocortex. We examined spike-time statistics in four parietal areas using a method that accounts for nonstationarities in firing rate. We found that, whereas neurons in visual areas fire irregularly, many cells in association and motor-like parietal regions show increasingly regular spike trains by comparison. Regularity was evident both in the shape of interspike interval distributions and in spike-count variability across trials. Thus, Poisson-like randomness is not a universal feature of neocortex. Rather, many parietal cells have reduced trial-to-trial variability in spike counts that could provide for more reliable firing-rate signals. These results suggest that spiking dynamics may play different roles in different cortical areas and should not be assumed to arise from fundamentally irreducible noise sources

CAD files for high throughput egg-laying choice chambers

CAD files for high throughput egg-laying choice chambers.</p

CAD files for sloped ceiling egg-laying chamber

CAD files for sloped ceiling egg-laying chamber.</p

Plasmid Maps

Plasmid Maps for Kir2.1* and Kir2.1*Mut.</p

CAD files for egg-laying wheel

CAD files to create egg-laying wheel.</p

Source Data

Source Data.</p

Report A Simple Vision-Based Algorithm for Decision Making in Flying Drosophila

Summary Animals must quickly recognize objects in their environment and act accordingly. Previous studies indicate that looming visual objects trigger avoidance reflexes in many species Results Free Flight To test whether flies respond differently to large and small visual objects, we placed a long post (31 cm high; 1.27 cm diameter), a short post (1.27 cm high, 1.27 cm diameter, suspended centrally with thin nylon monofilament), or no post at the center of an enclosed tunnel and tracked the trajectories of Drosophila melanogaster with a multicamera system (Supplemental Experimental Procedures available online) ( Flies rarely landed on the long post and instead turned away just before contact to avoid collision. Preliminary evidence suggests that flies are more likely to land on long posts if these objects are associated with an attractive odor (data not shown). However, under the conditions used in these experiments (i.e., in the absence of odor) flies would often revisit the long object, turning away each time as they approached within 1-2 cm ( We calculated the minimum Euclidean distance between each trajectory and the central 3D coordinate of each post. As expected from inspection of individual trajectories, flies approached closer to the center of the long post than the short post ( What behavioral algorithms explain these free-flight results? One trivial possibility is that the flies took off closer to the long post than the short post but otherwise flew randomly within the arena. However, we found that the start locations of trajectories were consistent across the three experimental conditions ( We found that nondirectional mechanisms could not fully explain the observed differences in residence probability (see Supplemental Data an