  This paper is an introduction to the membrane potential equation for neurons.
Its properties are described, as well as sample applications. Networks of these
equations can be used for modeling neuronal systems, which also process images
and video sequences, respectively. Specifically, (i) a dynamic retina is
proposed (based on a reaction-diffusion system), which predicts afterimages and
simple visual illusions, (ii) a system for texture segregation (texture
elements are understood as even-symmetric contrast features), and (iii) a
network for detecting object approaches (inspired by the locust visual system).
