A Non-Parametric Mixture Model for the fMRI Visual Field Map
نویسندگان
چکیده
The fMRI visual field map (VFM) is obtained by using a rotating-expanding visual target to identify the area of the retina that corresponds to activated visual cortex. Since fMRI data is (1) relative rather than absolute and (2) has a degree of noise that may mask the activation, identifying differences in VFMs requires a model that will differentiate changes in the underlying structure from differences due to imaging variability. The VFM produces a nonhomogenous, non-isotropic set of points on a disk that includes irregular features like the blind spot. A non-parametric mixture model, using a Dirichlet prior on a space of 2D density functions, will be used to model the VFM under experimental conditions where part of the visual field is masked by a circular wedge. The posterior probability of the difference in the models, will be used to quantify the probable location of the wedge..
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