Perception of change in depth in the hummingbird hawkmoth Manduca sexta (Sphingidae, Lepidoptera)

Visual perception of depth change can be mediated monocularly by looming th e apparent size increase of an approaching object. In Manduca sexta we reco rded intracellularly from cells that detect both approach and retreat of an object. The cells compute looming in two fundamentally different ways: cla ss 1 neurons measure the change of perimeter/edge length of the object; cla ss 2 neurons respond to expansion/contraction flowfields. We created a netw ork model incorporating anatomical and physiological properties of class 1 neurons to understand the underlying computational principles for looming d etection. (C) 2001 Elsevier Science B.V. All rights reserved.