We investigated cortical responses to electrical stimulation of the retina using epi- and sub-retinal electrodes of 20-100 mu m diameter. Temporal and spatial resolutions were assessed by recordings from the visual cortex with arrays of microelectrodes and optical imaging. The estimated resolutions were similar to 40 ms and similar to 1 degrees of visual angle. This temporal resolution of 25 frames per second and spatial resolution of about 0.8 cm at about I m and correspondingly 8 cm at 10 m distance seems sufficient for useful object recognition and visuo-motor behavior in many in- and out-door situations of daily life. (c) 2006 Elsevier Ltd. All rights reserved.