Considering results of recent neurophysiological experiments (Deangelis, G.C., Freeman, R.D., & Olzawa, I. (1994), Length and width timing of neurons in the cat's primary visual cortex, Journal of Neurophysiology, 71, 347-374) a model and a function of neural networks generating end- and side-inhibition in the primary visual cortex are proposed. The proposed neural network model consists of intracortical connections, and is the extension of a model proposed by Bolt et al. (Bolt, J., Gilbert, C.D., & Wiesel, T.N. (1989), Pharmacological analysis of cortical circuitry, Trends in Neuroscience, 12, 292-296). The proposed function is to extract important neuronal responses which represent main visual informations, for example, lines and edges which construct visual objects, removing excess neuronal responses before they are transmitted to higher visual areas in the cortex. (C) 1997 Elsevier Science Ltd.