A new method for estimating population receptive field topography in visual cortex

Image from Lee et al., NeuroImage, 2013

The visual cortex is retinotopically organized. That means that adjacent locations in the visual space map on to nearby locations in the visual cortex. Thanks to new analysis techniques we are able to estimate the population receptive fields (pRF) voxel by voxel in the visual cortex. Our team has developed a method to estimate a linear pRF topography model. The pRF structure is modeled as a set of weights that can be estimated by solving a linear model that predicts the Blood Oxygen Level-Dependent (BOLD) signal using the stimulus protocol and the canonical hemodynamic response function. The resulting linear equations can be solved for the pRF weight vector using the ridge regression, giving us the pRF topography. This method does not make a priori assumptions about the specific pRF shape and is therefore a useful tool for uncovering the underlying pRF structure at different spatial locations in an unbiased way. In addition, it is particularly attractive for monitoring pRF properties in the visual areas of subjects with lesions of the visual pathways, where it is difficult to anticipate what shape the reorganized pRF might take.

(Lee, Papanikolaou, et al., NeuroImage 2013)