Characteristics of spatial summation in the magnocellular, parvocellular, and koniocellular pathways

In this study, we characterize the spatial summation properties of targeted magnocellular, parvocellular, and koniocellular pathways within the central 20{degrees} of visual field using chromatic transformations in DKL color space. For the magnocellular and koniocellular conditions, critical areas of complete spatial summation were found for all eccentricities. For the parvocellular conditions, complete spatial summation was absent within the stimulus size ranges tested. We also describe an anatomically and physiologically motivated model of receptive field pooling using probability summation. Model simulations suggest that the critical area of summation can be explained by the dendritic field size of underlying retinal ganglion cells, corroborating our psychophysical data.