Spacing of ocular dominance columns is not changed by monocular deprivation or strabismus

Purpose. Many of the current models for ocular dominance column formation are based upon activity-dependent, self-organizing principles. In this class of models the degree of correlation between the two eyes' inputs drives the segregation of the inputs into ocular dominance columns. In this scheme, if the degree of correlation between the two eyes is reduced then the periodicity of the columns will increase. The degree to which these predictions match the anatomy is an indication of which aspects of column formation are explained by activity-dependent rules. We have examined this by analyzing the spacing of ocular dominance columns in cats reared with either normal binocular vision, monocular deprivation, or strabismus. Methods. The complete pattern of one eye's ocular dominance columns in area 17 of normal, MD, and strabismic cats was visualized in unfolded and flattened cortex following eye injection with WGA-HRP. The spacing of ocular dominance columns was determined using 2-dimensional spatial statistics (Delaunay triangles). Results. The average spacing of the ocular dominance columns for each of the 3 groups examined is approximately 1mm (range 927-1050μm). The spacings of ocular dominance columns for the MD and stabismic cats are not significantly different from normal. Conclusions. While activity and the degree of correlation between the two eyes' inputs do play an important role in the development of ocular dominance columns they are not key to setting their periodicity. Instead these results indicate that other cues organize the periodicity of ocular dominance columns in the visual cortex and that these cues are not modified by experience.