A quadratic nonlinearity underlies direction selectivity in the nucleus of the optic tract

Abstract

A nonlinear interaction between signals from at least two spatially displaced receptors is a fundamental requirement for a direction-selective motion detector. This paper characterizes the nonlinear mechanism present in the motion detector pathway that provides the input to wide-field directional neurons in the nucleus of the optic tract of the wallaby, Macropus eugenii. An apparent motion stimulus is used to reveal the interactions that occur between adjacent regions of the receptive fields of the neurons. The interaction between neighboring areas of the field is a nonlinear facilitation that is accurately predicted by the outputs of an array of correlation-based motion detectors (Reichardt..