Fig. 7.

Instantaneous frequency and calcium response in model (left), and instantaneous frequency response in the LGMD in vivo (right) to translating squares having various velocity profiles (indicated at the bottom of each panel). All responses are Gaussian-convolved (σ = 20 ms) mean instantaneous frequency responses, with SEM shown in grey. Model data was obtained by simulating ten presentations; in vivo data was obtained by taking the mean of the averaged responses for each animal (n = 6 animals). All stimuli consisted of 10° by 10° squares moving across 60° of real or simulated visual space, at fixed azimuth (90°) starting and ending at elevations of 30° and −30°, respectively (0° azimuth corresponds to the animal's front, and 0° elevation is the equator of the eye; see Krapp and Gabbiani 2005 for detailed description of coordinate system). a Response to stimulus having fixed velocity of 40°/s. b Response to stimulus with starting velocity of 0°/s and ending with velocity of 80°/s. c Response to square with a loom-like velocity profile, with velocity governed by ψ(t) (Eq. 5) for a looming object's edge where l/|ν| = 50 ms