Fly motion vision: from optic flow to visual course control

Abstract

Abstract Optic flow-based navigation has been stud­ied extensively in flies, both in tethered as well as in freely flying animals. As neural con­trol elements, the tangential cells of the lobu­la plate seem to play a key role: they are sen­sitive to visual motion, have large receptive fields, and, with their spatial distribution of preferred directions, match the optic flow as elicited during certain types of flight maneu­vers. However, the neural circuit presynaptic to the tangential cells responsible for extract­ing the direction of motion locally has long escaped investigation, due to the small size of the participating neurons. Recent prog­ress was made here by combining genetic si­lencing of candidate neurons with whole-cell patch recording from tangential cells in Dro­sophila. This approach led to the identifica­tion of lamina neurons L1 and L2 providing the input signals to two parallel motion de­tection circuits, specialized for brightness in­crements (L1, ON-pathway) and decrements (L2, OFF-pathway), respectively.