Neurons in V1 and MT cortex play a determinant role in the analysis of the shape of objects, their spatial texture, and the estimation of retinal motion. In this course, we describe the basic psychophysical and physiological phenomena related to low-level spatio-temporal vision: the contrast sensitivity functions, masking, adaptation, and aftereffects. These facts are mediated by the context-dependent nonlinearities of the response of neurons with specific receptive fields. We analyze the geometric properties of the standard model of V1 and their consequences in image discrimination. We introduce the concept of optical flow, its properties, and how this description of motion can be estimated from the 3D wavelet sensors in V1 and the aggregated sensors in MT.