Cognitive Science & Psychology Division, ULAB

fMRI imaging measures brain activity by detecting changes in the brain that are associated with blood flow and can be used in order to determine the size and location of visual field maps. This study measured BOLD responses in humans to understand spatial summation by showing them spatial contrast pattern images through vertical and horizontal apertures.Nonlinear responses can be computed from the visual field responses, from which the spatial summation ratio is calculated. A ratio of less than one indicates a smaller response to exposure to a full aperture or contrast image than predicted by the linear model. Datasets were analyzed using MATLAB, producing eccentricity maps of the visual cortices from stimuli. BOLD response curves identify the intensity of the maps within a particular voxel. The eccentricity maps can then be overlain on anatomical representations of the brain, characterizing the various visual field cortices. Methods of fMRI data analysis are confirmed with the results of this study.