Restricted sensory experience in early life often leads to a remarkable adaptation so that animals can make maximal use of information available in a particular environment.Such restriction inevitably leaves some neurons in the brain unused or underused for an original purpose.How do cortical neurons adapt to the statistical structure of restricted environment to represent sensory signals efficiently? We addressed the question by measuring receptive field of neurons in cats reared with vertical-pass cylindrical lenses.Such lenses severely limit the range of orientation experienced by the animals essentially to vertical only, filtering out horizontal and oblique orientations.Aspect ratios of receptive fields of neurons in these animals show a marked elongation in the length dimension compared with those from normal cats.The responses of individual neurons were also examined by presenting gratings of various combinations of orientation and spatial frequency.Orientation tuning of neurons in these animals was significantly sharpened for neurons tuned to vertical and broadened for those tuned to other orientations, compared with those in normal animals.Our results indicate that limited visual experience early in life not only increases the proportion of cells tuned to the experienced parameter, but also causes changes in the shape and tuning properties of receptive fields of individual neurons.