Neural Circuit to Integrate Opposing Motions in the Visual Field

Abstract

When navigating in their environment, animals use visual motion cues as feedback signals that are elicited by their own motion. Such signals are provided by wide-field neurons sampling motion directions at multiple image points as the animal maneuvers. Each one of these neurons responds selectively to a specific optic flow-field representing the spatial distribution of motion vectors on the retina. Here, we describe the discovery of a group of local, inhibitory interneurons in the fruit fly Drosophila key for filtering these cues. Using anatomy, molecular characterization, activity manipulation, and physiological recordings, we demonstrate that these interneurons convey direction-selective inhibition to wide-field neurons with opposite preferred direction and provide evidence for how their connectivity enables the computation required for integrating opposing motions. Our results indicate that, rather than sharpening directional selectivity per se, these circuit elements reduce noise by eliminating non-specific responses to complex visual information.

Generation and Evolution of Neural Cell Types and Circuits: Insights from the Drosophila Visual System

“…The lobula plate is mostly innervated by neurons that are part of the motion circuit: T4/T5 neurons, lobula plate tangential cells (LPTCs), and, as discovered more recently, the lobula plate-intrinsic (LPi) interneurons (87). The lobula plate is thus rightfully known as the cockpit of the fly (14).…”

“…Finally, two new types of lobula plate-intrinsic interneurons were discovered recently, LPi3-4 and LPi4-3 (87). Although LPi3-4 arborize only in the lobula plate, they are generated by the OPC and their cell bodies lie in the cortex of the medulla.…”

“…This suggests that medulla and lobula plate once had a common ancestor, which was generated in part by the OPC. Given that both LPi neurons participate in the motion detection circuit and connect to the LPTCs of lobula plate layers three and four (87), this ancestral neuropil must have possessed features from both medulla (development from the OPC) and lobula plate (motion detection).…”

Konnektomik mit zellulärer Präzision

“…Interessanterweise ergeben Analysen des visuellen Systems der Fruchtfliege, dass hier wohl ähnliche Verrechnungsprinzipien in den Schaltkreisen umgesetzt sind [22], auch wenn die genaue Identität der beteiligten Zellen noch kontrovers bleibt [19,22], siehe [5] für eine ausführliche Diskussion.…”

Connectomics at cellular precision

“…Most interestingly, analyses in the visual system of the fruit fly have provided evidence that comparable connectomic principles are being used in the circuits of this rather evolutionarily distant animal [22]. However, the precise identity of the neurons involved is still controversial ( [19,22]; see also [5] for an extended discussion).…”