When looking around without fixating the eyes on any particular objects, the image changes at a high frequency without any noticeable intervals between the images. This requires a high speed generation of retina signals and high speed transmission of the signals to the vision center. As an example of high speed neural interaction, each light stimulus generates two different bipolar cells response, transmitting different pieces of information to the vision center. This doubles the speed of information transmission to the vision center. The functional significance of Kuffler's "inhibitory surround" was revealed to maintain the brightness of the perceived images within a limited range. (C) 2010 Elsevier Inc. All rights reserved.