This study focuses on understanding how representations of moving visual patterns are elaborated within visual cortical areas V1, MT, and ST, combining the techniques of computational neuroscience with single-cell neuroanatomy and combination tracer/mapping studies. We construct models for how global pattern motion is extracted from local motion cues using anatomical and neurophysiological data from the magnocellular pathway to constrain our choice of parameters. Biologically plausible unsupervised learning models of V1 -> MT -> ST connections will be trained using various Hebb rules with stimulus sets consisting of flow fields and simple objects against moving textured backgrounds. Input patterns are filtered through an input layer with the properties of V1, layer 4B. Our primary goals are to determine: 1) how local estimates of pattern motion are combined to produce larger scale estimates of pattern translation, rotation, dilation and shear, and 2) to determine how motion discontinuities are represented given the substantial spatial convergence required to obtain those global estimates. The outputs of the higher layers can be compared directly with neurophysiological data on how MT and ST neurons respond to flow fields and simple objects. The concurrent set of neuroanatomical experiments are designed to provide explicit data on numbers of connections and degree of divergence in both between- and within-area connections. these results will be used in two ways. First, we want to find out if the connection patterns predicted by our models are consistent with real neurons. Second, these results can constrain our models to biologically realistic configurations so that we can make predictions about subsequent areas in the magnocellular processing stream. Finally, we propose to more directly test predictions about interareal connectivity patterns derived from the models by combining direction-selectivity mapping in MT with discrete tracer injections in ST. The results of this study will be important for improving the performance of visual prostheses designed to stimulate visual cortical areas directly.
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