In the visual cortex, orientation domains are arranged in complex patterns. Although several experimental results are consistent with the hypothesis that during development the patterns emerge spontaneously by activity-dependent self-organisation, an innate predetermination of the patterns cannot be ruled out at present. If the pattern-layout is controlled by genetic factors, the patterns observed in pairs of genetically related individuals are expected to be more similar than in geneticallyunrelated individuals. A necessary prerequisite for evaluating the degree of similarity or dissimilarity between patterns is the quantitative characterisation of their overall interindividual variability. In the present study, we quantitatively analysedthe variability of 2deoxyglucose (2-DG) labeled patterns of orientation domains in area 17 of cat visual cortex. We calculated wavelengths, correlation-lengths, anisotropy parameters and band-parallelism parameters of patterns within the entire area 17and analysed their statistical relationships. Our results indicate that these parameters are statistically independent. They describe independent aspects of the layout of orientation domains. Furthermore a wavelet analysis showed that local wavelengthswere rather constant, whereas the local orientation of band-like 2-DG domains varied across area 17. Taken together, these analyses identify sensitive quantitative indicators for the overall similarity of cortical orientation maps.
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