Scholl B, Burge J, Priebe NJ. Binocular integration and disparity selectivity in mouse primary visual cortex. J Neurophysiol 109: 3013-3024, 2013. First published March 20, 2013 doi:10.1152/jn.01021.2012.-Signals from the two eyes are first integrated in primary visual cortex (V1). In many mammals, this binocular integration is an important first step in the development of stereopsis, the perception of depth from disparity. Neurons in the binocular zone of mouse V1 receive inputs from both eyes, but it is unclear how that binocular information is integrated and whether this integration has a function similar to that found in other mammals. Using extracellular recordings, we demonstrate that mouse V1 neurons are tuned for binocular disparities, or spatial differences, between the inputs from each eye, thus extracting signals potentially useful for estimating depth. The disparities encoded by mouse V1 are significantly larger than those encoded by cat and primate. Interestingly, these larger disparities correspond to distances that are likely to be ecologically relevant in natural viewing, given the stereo-geometry of the mouse visual system. Across mammalian species, it appears that binocular integration is a common cortical computation used to extract information relevant for estimating depth. As such, it is a prime example of how the integration of multiple sensory signals is used to generate accurate estimates of properties in our environment. primary visual cortex; mouse binocularity; disparity tuning; ocular dominance TO ENABLE ACCURATE ESTIMATES of behaviorally relevant properties of the environment, sensory systems integrate information from multiple sources. For example, in the visual system, signals from the left and right eyes are integrated to provide information about depth. In mammals, left and right eye signals first converge in primary visual cortex (V1). The different vantage points of the eyes create local spatial offsets in the retinal images, offsets known as binocular disparities. Binocular disparity changes with the depths of objects in the environment. Neurons that encode retinal image information relevant for estimating binocular disparity therefore provide information relevant for binocular depth perception (Barlow et al. 1967;Blakemore 1969;Hubel and Wiesel 1973;Joshua 1970;Nikara et al. 1968;Pettigrew et al. 1968). Binocular disparity selectivity can be observed in individual neurons; some binocular stimuli elicit large increases in responses, while others reduce responses, relative to monocular stimulation alone (Hubel and Wiesel 1962;Ohzawa and Freeman 1986;Pettigrew et al. 1968).Disparity-selective binocular neurons have been reported in many animals, including carnivores and primates. Such neurons have not, however, been reported in rodents. In recent years, mice have become an increasingly important model for the study of visual processing and cortical plasticity. Genetic techniques are now available to dissect underlying circuitry and its emergence during development. Here, we rep...