Wide-field orientation sensitive neurons and perception of iso-dipole textures by bees

Purpose We have shown that bees have a set of visual neurons which pool rectified output from many small orientation sensitive neurons. Such neurons are a minimal model for a system to discriminate iso-dipole textures (IDTs) which differ only in their fourth and higher order statistics [Victor I.D. and Conte M.M. Vision Res. 31, 1457-1488]. Of particular interest are so-called Odd and Even IDTs. Methods Bees were trained in a Y-maze on a training set of 6 Odd and 6 Even IDTs, presented at 4 randomised orientations and were then tested with 6 different pairs. Bees were also trained with Odd patterns against random noise textures. Results Bees learned to distinguish Odd from Even IDTs (67.0%, p<1e^-6, N-200) and Odd IDTs from noise patterns with the same number and size of pixels (56.5%, P=0.038, N=200). Conclusions The orientation specific neurons would provide bees with the necessary neural machinery to discriminate IDT patterns. Like humans, bees can learn to discriminate IDTs even though different IDTs have power spectra and third order statistics which are identical to noise. This may indicate that the wide field orientation neurons are part of a general texture discrimination and learning system.