Neural circuit to integrate opposing motions in the visual field.

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.
•Discovery of bi-stratified glutamatergic lobula plate-intrinsic (LPi) interneurons•LPi neurons provide visual null direction inhibition to wide-field tangential cells•Blocking LPi activity leads to target neurons responding to inadequate motion cues•Motion opponency thus increases flow-field selectivity
Newly identified inhibitory neurons are central to an integrative circuit that enables Drosophila to process visual cues with opposite motions generated during flight. The neurons are required to discriminate between distinct complex motion patterns, indicating that neural processing of opposing cues can yield outcomes beyond the simple sum of two inputs.

PMID: 26186189 [PubMed - indexed for MEDLINE]