Feature-Detecting Neurons in Dragonflies

O'Carroll, D. Research School of Biological Sciences, Australian National University, Canberra, A.C.T. Nature, 1993, Vol.362, No.6420, pp.541-543

Since the earliest descriptions of the compound eye, the popular impression has prevailed that insects and mammals view the world differently. Recent work, however, underscores marked evolutionary convergence between the visual systems of vertebrates and insects at both optical and early processing levels. Here I describe several classes of cells from the third optic ganglion of dragonflies that respond selectively to different target classes. Several physiological properties of these cells are remarkably similar to those of cells from areas 17, 18 and 19 of the mammalian visual cortex. One class of bar-sensitive, orientation-biased cells could mediate discrimination of the orientation of low spatial frequency components of patterns. The existence of neurons functionally similar in many respects to those in the mammalian cortex suggests that evolutionary convergence in visual processing is not limited to early pathways. Insects, like mammals, seem to possess mechanisms for extracting spatial features from visual scenes.