A neuromorphic aVLSI model of global motion processing in the fly

Flies orientate themselves quickly in an unstructured environment through motion information computed from their low-resolution compound eyes. The fly visual system is an example of a robust motion system that works in a natural environment. In this paper, the author describes a low-power analog very large scale integration (aVLSI) chip that models motion computation in the fly. The architecture of this motion chip closely follows the anatomical layout of of the fly visual layers. The output of the chip corresponds to the responses of the wide-field direction-selective cells in the final layer of the visual system. The silicon chip has a one-dimensional array of 37 elementary motion detectors (EMDs) each of which provides local motion information. The EMD outputs are aggregated in a nonlinear way to produce a motion output that is independent of the stimulus size and contrast. The author employed various circuit techniques to ensure robust motion computation in each processing stage. Results from the circuit fabricated in a 1.2 /spl mu/m CMOS technology are compared with the responses of the direction-selective cells.